@article{Pentek2008,
abstract = {Footwall-type Cu-Ni-PGE (Platinum-group element) deposits are a major focus of recent exploration in theSudbury mining camp, owing to their higher Cu and precious metal contents compared to orebodies situatedalong the lower contact of the Sudbury Igneous Complex. The most important footwall-type orebodies occurin the Onaping-Levack area of the North Range, but economic deposits are found along the East Range of thestructure as well. Recently, promising occurrences were also discovered in Wisner Township of the NorthRange.In this paper we report results from two main footwall-type Cu-Ni-PGE occurrences (the Broken Hammerzone and the South zone) of Wisner Township. Both discoveries are situated in intensely brecciated zones ofthe footwall (Sudbury Breccia), 1,300 and 500 m, respectively, north of the present Sudbury Igneous Complex-footwall contact. The mineralization consists of (1) massive sulfide veins, (2) disseminated/replacement sul-fides, and (3) silicate-quartz–dominated veins. Although massive sulfide veins account for the major part of theresource, sulfide-poor disseminations may have similarly high precious metal contents. Ore assemblages aredominated by chalcopyrite, millerite, magnetite, and/or pyrite, quartz, and hydrous silicates. These are accom-panied by platinum-group minerals (PGM) and other trace minerals, which commonly occur as compositegrains within sulfides and hydrous silicates. These include minerals typical of footwall-type deposits (e.g.,merenskyite, michenerite, hessite), but also minerals found only in a few Sudbury deposits (e.g., clausthalite,sopcheite, naumannite, bohdanowiczite). An unnamed CuPdBiS3mineral is one of the most abundant PGMat Broken Hammer and might be a Pd-equivalent of m\"{u}ckeite (CuNiBiS3).Statistical investigation of metal distribution patterns using grab sample and drilling data sets from both lo-calities indicate important differences between the two occurrences and the various mineralization styles (e.g.,increasing Cu/(Cu+Ni) and decreasing Pt/(Pt+Pd) ratio with increasing sulfide content; metal concentrationsrecalculated to 100\% sulfides decrease by up to two orders of magnitude for all metals from the disseminatedto the massive sulfides).Fluid inclusion studies revealed three fluid generations which are very similar to those described from wellknown footwall-type deposits of the Onaping-Levack area. Primary polyphase fluid inclusions in Cu-Ni-PGE–bearing assemblages represent a highly saline (30–40 wt \% NaCl equiv) magmatic-hydrothermal systemwith a high temperature (min 450°–500°C) and a lower temperature (min 300°–350°C) stage. A later low-tem-perature Ca-rich fluid (min 100°–200°C) is most probably part of a post-Sudbury Igneous Complex regionalfluid flow in which temperature was controlled by the geothermal gradient and not related to ore-formingprocesses.The fluid inclusion data indicate that mobilization of highly saline and relatively high temperature(400°–500°C) Sudbury Igneous Complex-related magmatic-hydrothermal fluids similar to those describedfrom the Onaping-Levack embayment also occurred in the Wisner footwall. Although our studies do not ruleout the possibility of an initial magmatic sulfide melt emplacement, they prove that magmatic-hydrothermalfluids played a significant role in the transport and deposition of metals.},
author = {P\'{e}ntek, Attila and Moln\'{a}r, Ferenc and Watkinson, David H. and Jones, Peter C.},
doi = {10.2113/gsecongeo.103.5.1005},
isbn = {0361-0128},
issn = {03610128},
journal = {Economic Geology},
pages = {1005--1028},
title = {{Footwall-type Cu-Ni-PGE mineralization in the Broken Hammer area, wisner township, north range, Sudbury structure}},
volume = {103},
year = {2008}
}
@article{Rondot2000,
abstract = {On the basis of detailed field investigations and the study of impact breccias at the Charlevoix impact structure (Quebec), a structural analysis is given. This analysis shows that the annular arrangement of both topography and lithology can be applied to subdivide the two craters discussed in this review. Successive rings characterize the central uplift and its collapsed ring graben in the Charlevoix structure. Fault breccias show an annular distribution and indicate diverse directions of movement suggesting progressive readjustment. They formed cohesionless products inside fault planes, named mylolisthenite, and are believed to have acted as lubricants during the modification stage of the formation of the structure: listric readjustment by gravity after the formation of the transient crater. The Sudbury Structure (Ontario) shows fault breccias in a concentric arrangement similar to that of Charlevoix. It may be compared with the Charlevoix structure by applying the same mechanical readjustment model with deep listric faults. The only difference is the amount of the rise structural uplift, that is, the height of central uplift, which is less important in the larger impact structure.},
author = {Rondot, J},
isbn = {0026-1114},
issn = {10869379},
journal = {Meteoritics and Planetary Science},
keywords = {16 Structural geology,Canada,Charlevoix,Eastern Canada,Ontario,Quebec,Sudbury District Ontario,breccia,clastic rocks,deformation,faults,impact craters,impact features,listric faults,mylolisthenite,ring structures,sedimentary rocks,tectonic breccia,tectonics},
pages = {707--712},
pmid = {562},
title = {{Charlevoix and Sudbury as gravity-readjusted impact structures}},
volume = {35},
year = {2000}
}
@article{Mukwakwami2012,
abstract = {The Garson deposit is one of several deformed magmatic Ni-Cu-platinum group element (PGE) deposits in the South Range of the 1.85Ga Sudbury structure. The deposits occur along the southeast limb of the folded Sudbury Igneous Complex (SIC), at the contact between the SIC basal norite and underlying Paleoproterozoic metabasalt and metasedimentary rocks of the Huronian Supergroup. At the Garson deposit inclusion-rich breccia and disseminated Ni-Cu-PGE sulfide ores are hosted by steeply south-dipping shear zones and splays that underwent two major ductile deformation events (D 1 and D 2). D 1 is characterized by a steeply, south-dipping, S 1 foliation and a down-dip L 1 mineral stretching lineation defined by ferrotschermakite in metabasalt and by magnesiohornblende in norite. Coexisting ferrotschermakite and oligoclase in metabasalt indicate amphibolite facies conditions during D 1. The shear zones formed along or near the SIC-Huronian contact during the 1.7-1.6Ga Mazatzal-Labradorian Orogeny. They formed as layer-parallel, north-dipping, north-over-south thrusts in response to flexural slip during buckling of the SIC. As the general transport direction was from south to north during the Mazatzal-Labradorian Orogeny, the D 1 shear zones are back-thrusts with opposite transport direction. The thrusts imbricated the SIC, underlying Huronian rocks, and ore zones, and emplaced slivers of Huronian rocks and metabreccia into the overlying norite. In contrast to the D 1 shear zones at Garson, the Thayer Lindsley and the regional South Range shear zones, which transgress the SIC-Huronian contact at a high angle, formed as moderately SE-dipping reverse shear zones as a result of localization of folding-induced strain near the hinge zone in order to accommodate further flattening and tightening of the SIC with progressive D 1 shortening. Together with the southeast limb of the SIC, the D 1 shear zones were overturned into their present steep southerly dips and were reactivated as south-over-north shear zones either later during the Mazatzal-Labradorian Orogeny or during the 1.5-1.45Ga Chieflakian event, which was coeval with accretion of juvenile Andean-style, calc-alkaline magmatic arcs along the entire southeastern margin of Laurentia. During this D 2 reactivation event, S 1 was transposed and locally preserved in crenulations bounded by a S 2 chloritic shear foliation, which has a strong down-dip L 2 mineral chlorite lineation and parallel L 2 ductile slickenlines. ?? 2011 Elsevier B.V..},
author = {Mukwakwami, Joshua and Lafrance, Bruno and Lesher, C. Michael},
doi = {10.1016/j.precamres.2011.10.020},
isbn = {0301-9268},
issn = {03019268},
journal = {Precambrian Research},
keywords = {Deformed magmatic nickel deposit,Garson mine,Layer-parallel shear zones,Sudbury Igneous Complex,Sudbury structure},
pages = {81--105},
title = {{Back-thrusting and overturning of the southern margin of the 1.85Ga Sudbury Igneous Complex at the Garson mine, Sudbury, Ontario}},
volume = {196-197},
year = {2012}
}
@article{Lightfoot1997,
abstract = {Petrologicmalo delrse latingth ed ifferenrto ckt ypesc onstitutinthge 1.85G a SudburIyg neouCs omplex arec onstrainewdit he xtensivnee wg eochemicdaal ta.W e showth att he mainm assfe lsien oritct, ransition zoneq uartzg abbroa,n dg ranophyhrea ves imilarra tioso f theh ighlyin compatibtrlea cee lement(se .g.,L aJ Sm= 4.5-7, LaJNb= 2.8-4.2,T t•Zr = 0.04-0.05)a ndt hatt hesev ariationasr ec onsistewntit ht hec rystallizationa ndd ifferentiationf m agmtay pesla rgely(> 80\%)d erivedfr omt heu pperc rustw, itha smallecro ntributionf roma mantles oumeA. lthougthh erei s presentlnyo c onclusivpero oft hatm agmwa asg enerateidn situ asa melts heept roducebdy m eteoritiem pacwt, ef indn op rinciparel asown hyt hism odesl houlbde r ejected. Howevewr, ep roposteh ata smalcl ontributioonf m antle-derivpeide riflem agmias requiredto explainth e abundanNti , Cu,a ndp latinum-groeulpe ment(sP GE)i n the Sudburdye positass, w ella st hec ompositions of the ultramarien clusion(Ms gO = 12-36 wt \%; Foes\_os7li vinews ith4 50-3,700p pmN i, anda bundant chrome-ricshp inel)a,n dt hem agnesicaonm positiofn t hem arien oritc( 8-14 wt \% MgO)a ndt hes ublayer (6-12 wt \% MgO).W e believeth att hem ainm asso f the SudburCy ompleaxc hieveidts p resencto mposition througihn corporatatoiofn u pt o 20 percenmt antle-derivpeidc riticm agmeam placeadlo ngc rustafrl actures producebdy thei mpacet ventT. hesep icriticm agmaesn teredth e melts heeat sa densep lumev, igorously mixingw ithi t, andd uet o them arkedco mpositionshali ftt,h em ixedm agmfao rmedm agmatsicu lfidewsh ich sankth roughth em agmcao lumnd,e pletintgh em elti n Ni, Cu,a ndP GE.S inceb otht hef elsicn oritca nd granophyhrea vein distinguisharbalteio so f thei ncompatibtlrea cee lementws,e s een or equiremetnot d erive theseu nitso f rockb yt hec rystallizatioofn m agmadse rivedfr omd ifferenst ourceRs.a thert,h ec ompositional differencbee tweetnh ef elsicn oritca ndg ranophyirse a ttributetdo thei n situd ifferentiatioonf t he magma. We showt hatt he mainm assh asm anyc ompositiontraal itss imilarto thoseo f mosto f the offsetd ike quartzd iorites(e .g.,t he Parkino ffsedt ike:L a/Sm= 6.3,L a/Nb= 4.5;T t•Zr = 0.05)a ndo f embaymentrelated leucocratic norires from the Whistle mine (La/Sm = 6.2, La/Nb = 5.0, Tt•Zr = 0.02). These rocks havec ompositiointse rmediabtee tweetnh ef elsicn oritca ndt heg ranophyraen, dt hereforcer ystallizefrdo m the samem agmtay pe;a rguabltyh, e unmineralizeqdu artzd ioriteps rovidteh eb estp ossiblees timatoef the originaml agmfar omw hichth eS udburCyo mplecxr ystallizeInd .d etailt,h erea res ubtlev ariationins c ompositionw ithina ndb etweeno ffsedt ikesw, itht hel argesdt ifferencbee ingb etweenth e Northa ndS outhR ange offsetsth; e NorthR angeo ffsedt ikesc utA rchcagnr anitoidasn dg neisseasn dh avee levatedS r,L a/Yb,L aJ Sm,a ndG d/Yba ndl owT iO2w hereatsh eS outhR anged ikesc utE arlyP roterozosice dimentms,a riev olcanics, andi ntrusionasn, dh avel owS r, La/Yb,G d/Yb,L a/Sm,a ndh ighT iO•. Thesed ifferencems ayb e causedb y thea ssimilatiofn d ifferencto untrryo cksd uringe mplacemeonft t hed ike.A stronglmy ineralizeodff sedt ike at the Creightomn ineh asg eochemicvaalr iationtsh ata red ifferenwt henc omparetdo the mainm assa, nd int hec aseo fC reightoanr, em ores imilatro t hel ocaml ineralizesdu blayeTrh. esed atas uggetshta tm ineralized andb arrenq uartzd ioritesh aved ifferengt eochemiccaol mpositionasn,d t hatt hesetr aitsm ayb e of valuein minerael xploratio},
author = {Lightfoot, Peter G. and Keays, Reid R. and Morrison, Gordon G. and Bite, Andy and Farrell, Keith P.},
doi = {10.2113/gsecongeo.92.3.289},
issn = {03610128},
journal = {Economic Geology},
pages = {289--307},
title = {{Geochemical relationships in the sudbury igneous complex: Origin of the main mass and offset dikes}},
volume = {92},
year = {1997}
}
@article{Lafrance2008,
abstract = {In the North Range of the ca. 1.85 Ga Sudbury impact structure, massive bodies of Sudbury breccia cut across the Archean Levack gneiss complex and Early Proterozoic Matachewan diabase dykes. The complex underlies the Sudbury Igneous Complex (SIC), which represents an impact melt sheet that lined the floor of the impact crater. The breccia occurs as 1-100 m wide irregular bodies that contain rounded clasts of diabase and tonalitic and dioritic Levack gneiss within a fine-grained to aphanitic, black to dark grey matrix. Mineral chemical analyses and Rietveld analyses based on X-ray diffraction patterns show that the breccia matrix contains microclasts of magnesiohornblende, oligoclase, and quartz, surrounded by metamorphic andesine laths, actinolite, Kfeldspar, albite, and chlorite, which crystallized during cooling of the SIC. On binary oxide-SiO2 diagrams, breccia values plot on a compositional mixing line between those of the more felsic tonalitic gneiss and the more mafic dioritic gneiss and diabase. The breccia has concentrations in rare earth elements (REEs) intermediate between those of the dioritic and tonalitic gneisses and a REE pattern with a negative slope that is less pronounced than those of the gneisses. This is due to the addition of a minor diabase component that has a slightly negative REE slope, suggesting that the breccia is a mix of comminuted tonalitic gneiss, dioritic gneiss, and minor diabase. Comminution and cataclasis of these source rocks occurred along pre-existing anisotropies and fractures that formed and were reactivated during the growth and collapse of the transient crater. The comminuted materials mixed together as large bodies of breccia that were injected in dilational sites that opened during the upward expansion and collapse of the crater. ?? 2008 Elsevier B.V. All rights reserved.},
author = {Lafrance, Bruno and Legault, David and Ames, Doreen E.},
doi = {10.1016/j.precamres.2008.06.004},
issn = {03019268},
journal = {Precambrian Research},
keywords = {Cataclasite,Rietveld modal mineralogy,Sudbury breccia,Sudbury impact structure,Trace element geochemistry},
pages = {107--119},
title = {{The formation of the Sudbury breccia in the North Range of the Sudbury impact structure}},
volume = {165},
year = {2008}
}
@article{Kuo1979,
abstract = {Abstract The rare earth element content of rocks from the Sudbury Nickel Irruptive has been determined by neutron activation analysis. The Irruptive rocks are characterized by high absolute rare earth element contents and chondrite-normalized rare earth element fractionation patterns },
author = {Kuo, H. Y. and Crocket, J. H.},
doi = {10.2113/gsecongeo.74.3.590},
issn = {03610128},
journal = {Economic Geology},
pages = {590--605},
title = {{Rare earth elements in the Sudbury Nickel irruptive: Comparison with layered gabbros and implications for nickel irruptive petrogenesis}},
volume = {74},
year = {1979}
}
@misc{Lugli2005,
abstract = {Several geological features, including sedimentary cone-in-cone structures$\backslash$nand percussion marks, may resemble impact-generated shatter cones.$\backslash$nEspecially inexperienced workers may mistake such features for impact$\backslash$ndeformation. In 1997, our group investigated an alleged occurrence$\backslash$nof shatter cones in the Hamada area of southeastern Morocco and found$\backslash$nthat these are actually cone-in-cone structures, probably from the$\backslash$nLower Visean Merdani Formation. Here, a detailed discussion of cone-in-cone$\backslash$nstructures, as well as a short review of shatter cone characteristics,$\backslash$nis presented in an effort to clarify some distinguishing criteria.$\backslash$nImportant differences include: (1) Shatter cone striations are of$\backslash$ndistinctly roundish shape, whereas cone-in-cone striae are step-like;$\backslash$n(2) shatter cones never show scaled surfaces; (3) broken cone-in-cone$\backslash$nstructures invariably produce one surface with striated cone features,$\backslash$nbut its opposite side would display scaled cone cups; (4) shatter$\backslash$ncones do not telescope out of the bedding-plane, as cone-in-cone$\backslash$nstructures may do; (5) at the thin section scale, the internal structure$\backslash$nof cone-in-cone features is well preserved, even after complete silicification$\backslash$nof the primary carbonate. Thus, careful observations should allow$\backslash$nunambiguous decision whether certain rocks contain shatter cones$\backslash$nor cone-in-cone structures.},
author = {Lugli, Stefano and Reimold, Wolf U and Koeberl, Christian},
booktitle = {Impact Tectonics},
pages = {81--110},
title = {{Silicified Cone-in-Cone Structures from Erfoud (Morocco): A Comparison with Impact-Generated Shatter Cones}},
url = {http://dx.doi.org/10.1007/3-540-27548-7\_3},
year = {2005}
}
@article{Fackelman2008,
abstract = {Field mapping, morphologic description, and petrographic analysis of recently discovered shatter cones within Paleoproterozoic crystalline rocks exposed over an area > 5??km2, located ??? 8??km northeast of Santa Fe, New Mexico, USA, give robust evidence of a previously unrecognized terrestrial impact structure. Herein, we provisionally name this the "Santa Fe impact structure". The shatter cones are composed of nested sub-conical, curviplanar, and flat joint surfaces bearing abundant curved and bifurcating striations that strongly resemble the multiply striated joint surfaces (MSJS) documented from shatter cones at Vredefort dome. The cones occur as a penetrative feature in intrusive igneous and supracrustal metamorphic rocks, are unusually large (up to 2??m long and 0.5??m wide at the base), display upward-pointing apices, and have subvertical, northeastward-plunging axes that crosscut regional host-rock fabrics. Key characteristics of superficially similar, but non-shock-generated conical and striated features are inconsistent with the properties of the Santa Fe cones. In thin section, sub-millimeter-scale, dark, semi-opaque to isotropic veneers on cone surfaces and veinlets within cone interiors closely resemble previously described shock-induced melt features. Microscopic grain alteration, restricted generally to within 1??mm of the cone surfaces, includes random fractures, fluid micro-inclusions, sericite replacement in feldspar, rare kink bands in mica, optical mosaicism, and decorated planar fractures (PFs) and planar deformation features (PDFs) in quartz. The PFs and PDFs are dominated by a basal (0001) crystallographic orientation, which indicate a peak shock pressure of ??? 5-10??GPa that is consistent with shatter cone formation. Regional structural and exhumation models, together with anomalous breccia units that overlie and crosscut the shatter cone-bearing rocks, may provide additional age constraints for the impact event. The observed shatter cone outcrop area suggests that the minimum final crater diameter of the Santa Fe impact structure was ??? 6-13??km. ?? 2008 Elsevier B.V. All rights reserved.},
author = {Fackelman, Siobhan P. and Morrow, Jared R. and Koeberl, Christian and McElvain, Thornton H.},
doi = {10.1016/j.epsl.2008.03.033},
issn = {0012821X},
journal = {Earth and Planetary Science Letters},
keywords = {New Mexico, USA,Santa Fe impact structure,shatter cones,shock metamorphism,terrestrial impact structure},
pages = {290--299},
title = {{Shatter cone and microscopic shock-alteration evidence for a post-Paleoproterozoic terrestrial impact structure near Santa Fe, New Mexico, USA}},
volume = {270},
year = {2008}
}
@phdthesis{Johnson1964,
abstract = {Shatter cones are striated, conical structures usually found in fine-grained, homogeneous rocks. The investigation resulted in the development of a theory which predicts that conical fracture surfaces will be produced as the result of the interaction of a shock wave with a small obstacle. The obstacle is a region of anomalous density and/or compressibility in the transmitting medium. The shock wave must have the property that the amplitude of the compressive stress at and behind the front must be equal to the yield strength of the transmitting medium. A theoretical derivation of the stress distribution which results from the interaction of the shock wave and the obstacle demonstrated that a conical fracture surface should be produced. This fracture surface is shown to be an almost perfect pair of cones whose axis of symmetry is parallel to the direction of propagation of the shock wave. At a distance of several obstacle radii, the flanks of the cones are inclined at an angle of 45 degrees to the axis of revolution. This result is independent of the composition of the transmitting medium or the obstacle. There is reason for believing that the cone whose apex points in the direction of shock propagation will be smaller that its companion which points toward the source and in some cases may not exist at all.},
author = {Johnson, George Peter and Talbot, Richard Joseph},
booktitle = {A theoretical study of the shock wave origin of shatter cones},
keywords = {16:Structural geology,30:Engineering geology,compression,conical fractures,cryptoexplosion features,deformation,fractures,genesis,rock mechanics,shatter cones,shock waves,stress,theoretical studies},
pages = {103},
title = {{A theoretical study of the shock wave origin of shatter cones}},
url = {https://www.lib.uwo.ca/cgi-bin/ezpauthn.cgi/docview/50206278?accountid=15115 LA  - English},
year = {1964}
}
@article{Baratoux2003,
abstract = {In this paper we present a new model for the formation of shatter cones. The model follows earlier suggestions that shatter cones are initiated by heterogeneities in the rock, but does not require the participation of an elastic precursor wave: the conical fractures are initiated after the passage of the main plastic compression pulse, not before. Numerical simulations using the hydrocode SALE 2D, enhanced by the Grady-Kipp-Melosh fragmentation model, support the model. The conditions required for the formation of shatter cones are explored numerically and are found to be consistent with the pressure range derived from both explosion experiments and the analysis of shock metamorphic features in impact structures. This model permits us to deduce quantitative information about the shape of the shock wave from the shape and size of the observed shatter cones. Indeed, the occurrence of shatter cones is correlated with the ratio between the width of the compressive pulse and the size of the heterogeneity that initiates the conical fracture. The apical angles of the shatter cones are controlled by the shape of the rarefaction wave. ?? 2003 Elsevier B.V. All rights reserved.},
author = {Baratoux, D. and Melosh, H. J.},
doi = {10.1016/S0012-821X(03)00474-6},
issn = {0012821X},
journal = {Earth and Planetary Science Letters},
keywords = {Impact craters,Shatter cones,Shock waves},
pages = {43--54},
pmid = {610},
title = {{The formation of shatter cones by shock wave interference during impacting}},
volume = {216},
year = {2003}
}
@misc{Reimold1995,
abstract = {Fault-related pseudotachylites are generated as the result of brittle or brittle-ductile deformation related to seismic faulting. It is generally accepted among tectonic workers that, while cataclasis plays a role in pseudotachylite formation, friction melting is involved. In addition, pseudotachylite and “pseudotachylite-like” breccias have been repeatedly described from the basement exposures of impact and cryptoexplosion structures, and as veinlets in shocked meteorites and lunar samples. The relevant literature is reviewed with regard to controversial usage of the term “pseudotachylite”, and attention is drawn to several problematic aspects: (1) The term “pseudotachylite” is currently used both as a purely descriptive term and with genetic implications. (2) No unambiguous criteria for comparison and distinction of tectonically and impact-generated pseudotachylites have been identified. (3) It needs to be considered that, in impact structures, pseudotachylite could be generated by two distinct processes — namely, by shock brecciation/melting and by friction melting. Pseudotachylite in impact structures could be the result of either of these two processes, or of both. (4) It is recommended to adhere more stringently, when describing breccias from impact or cryptoexplosion structures, to nomenclature accepted for the description of fault rocks in tectonic environments. This would help to avoid confusion when discriminating between melt rocks (pseudotachylite, impact melt rock), “fragmental” breccias (cataclasite, fragmental impact breccia) and mylonitic rocks. (5) No criteria for the distinction of melt-bearing impact breccias (impact melt rock) and pseudotachylite have been established either. In order to solve these problems, close interaction between structural geologists and impact workers is warranted. It is suggested that the understanding of breccias in impact structures would be improved by paying particular attention to the temporal relationships between different breccia types. This would facilitate recognition of possibly different formational processes for impact-produced melt and fragmental breccias, and their distinction from pre- and post-shock deformation products.},
author = {Reimold, W.U.},
booktitle = {Earth-Science Reviews},
doi = {10.1016/0012-8252(95)00033-X},
issn = {00128252},
pages = {247--265},
pmid = {870},
title = {{Pseudotachylite in impact structures — generation by friction melting and shock brecciation?: A review and discussion}},
volume = {39},
year = {1995}
}
@misc{Hearst2001,
abstract = {In the vicinity of Sudbury, Ontario, Canada, the boundary between the Southern and Superior tectonic provinces is overlain by the elliptical Sudbury Structure. On the basis of gravity modeling, genesis of the Sudbury Structure has been attributed to either amagmatic origin (having a dense hidden differentiate zone) or ameteorite impact origin (there being no dense hidden mass). The difference between the two gravity models centers on the problem of regional-residual separation. As shown by numerous previous studies, any such separation of components is nonunique.This becomes especially problematic when, as in Sudbury, a portion of the near-surface geology has a similar orientation and dimension to more deep-seated sources. In this paper, several numerical methods (upward continuation, downward continuation, wavelength filtering, trend-surface analysis) for determining the regional component of the gravity field associated with the Sudbury Structure have been applied and evaluated. Of the numerical methods used, the upward and downward continuation operators provided the most insight into the deep structural controls of the Sudbury Basin. Our preferred interpretation of the regional gravity field invokes a two-component structure. Underlying the southern half of the Sudbury Structure is a laterally continuous gravity anomaly that is probably associated with a zone of uplifted Huronian volcanics. The gravity anomaly under the northern portion of the Sudbury Structure has a more restricted spatial extent. The close association between the northern limit of the gravity anomaly and the surface outcrop of the Levack Gneiss suggests the source of this anomaly is probably a slab of dense Levack Gneiss. This interpretation favors a meteorite impact origin for the Sudbury Structure.},
author = {Hearst, R. B. and Morris, W. A.},
booktitle = {Geophysics},
doi = {10.1190/1.1487110},
issn = {00168033},
pages = {1680},
title = {{Regional gravity setting of the Sudbury Structure}},
volume = {66},
year = {2001}
}
@article{Zieg2005,
abstract = {The Sudbury Igneous Complex of Ontario, Canada, is the remnant of a voluminous melt sheet produced in a few minutes by impact of a massive meteorite into continental crust 1.85 Ga ago. The transient cavity and melting zone reached the Moho and instantly (∼2 min) relaxed to form a more familiar large, shallow crater holding a thick, superheated (∼1700 °C) melt sheet covered by ∼2 km of breccia. There is little about the resulting bimodal igneous complex that resembles crystallization of well-known sheet-like bodies of similar composition. Yet, the norite and granophyre exhibit a remarkable similarity in isotopic and trace element compositions, suggesting an intimate common parentage from the surrounding crust. This petrogenetic enigma is explained here as a natural, unavoidable consequence of the impact process in the rapid formation of a superheated magmatic emulsion, which we take as the high-temperature equivalent of breccia. A wide spectrum of viscously discrete, interdispersed parcels of mafic and felsic liquids, reflecting the compositional heterogeneity of the target crustal materials, formed the emulsion. Within days to months, the emulsion components separated according to their relative densities into a bimodal norite-granophyre assemblage that formed the basic structure of the present Sudbury Igneous Complex. There is clear evidence of this emulsion in the earliest dikes (i.e., offsets), which likely give the earliest state of the nascent melt sheet. Immediately following emulsion separation, the strongly superheated bimodal melt sheet underwent vigorous thermal convection in each layer. These convective motions homogenized and rapidly cooled the magma to the liquidus temperatures, whereupon convection ceased. The pattern of convection was pinned in place by the embayment topography of the crater floor, which in turn played a pivotal role in directing sulfide deposition into the embayments. All further cooling was by conduction of heat through the upper and lower boundaries during which time solidification fronts were established and propagated inward from the upper and lower margins. There is clear evidence of solidification from the floor upward and the roof downward. Minimal differentiation and compositional modification took place throughout cooling and solidification. Nevertheless, during the solidification stage, granitic rock fragments on the crater floor and rafts of fallback breccia from the thick overlying Onaping Formation became unstable and entered the melt sheet, and the partially melted remnants collected at the interface between the norite and granophyre. Some interstitial melt from the norite also percolated upward, and, altogether, the blocks and melt produced the distinctive chemical and physical characteristics of the unusual Transition Zone. The Sudbury melt sheet is, in essence, a full-scale magmatic experiment. The conditions of formation, relative to any other large terrestrial magma, are “precisely” known. Thus the clear lack of any significant modal layering, the overall homogeneous nature of each unit, and the lack of any significant chemical differentiation through crystal fractionation establish Sudbury as a valuable example of what does happen under the initial conditions long assumed to prevail at the formation of most large magma chambers.},
author = {Zieg, Michael J. and Marsh, Bruce D.},
doi = {10.1130/B25579.1},
issn = {00167606},
journal = {Bulletin of the Geological Society of America},
keywords = {Differentiation,Impact melt,Magma,Melt sheet,Sudbury,Viscous emulsion},
pages = {1427--1450},
title = {{The Sudbury Igneous Complex: Viscous emulsion differentiation of a superheated impact melt sheet}},
volume = {117},
year = {2005}
}
@misc{Joreau1996,
abstract = {The Sudbury basin in Canada is an elliptical feature (approx. 60X27 km in size) that is now widely believed to be part of a large (approx. 200 km diameter) meteorite impact structure which formed about 1.85 Ga ago and was subsequently deformed and metamorphosed. Despite prolonged debate over the origin and original size of the Sudbury structure, strong evidence for meteorite impact has been provided by the discovery in its rocks of a wide range of shock-metamorphic features, especially the optically observable traces (fluid inclusion arrays) of former Planar Deformation Features (PDFs) in quartz parallel to \{1013\} planes. In this new examination of Sudbury samples, no preserved original PDFs (glassy lamellae) were observed optically in quartz grains from basement rock fragments in the Onaping Formation, a unit interpreted as a "fallback breccia" deposited within the original crater. However, TEM revealed other thin lamellar features preserved in the quartz; these are identified as Brazil twin lamellae parallel to the basal plane (0001). These lamellae are 15-200 nm thick, show a typical spacing of 30 nm to several microns apart, and are occasionally decorated with fluid inclusions (< or =0.5 mu m in size), which probably formed during post-shock alteration and annealing. Numerous subgrain boundaries (SGBs) were also detected, many of them oriented roughly parallel to the basal plane (0001). The SGBs apparently formed during post-shock recrystallization, leading to the local disappearance of Brazil twin lamellae. Experimental evidence suggests that such basal Brazil twins are the unique product of high-pressure shock waves. The features in the Sudbury samples are identical to those observed in the Vredefort structure, South Africa, which is also widely accepted as an ancient impact structure about 2.0 Ga old. The recognition of basal Brazil twins in quartz at Sudbury provides additional evidence for meteorite impact origin and also emphasizes the high value of these durable shock features for identifying old and tectonically metamorphosed impact structures.},
author = {Joreau, Pascal and French, Bevan M. and Doukhan, Jean-Claude},
booktitle = {Earth and Planetary Science Letters},
doi = {10.1016/0012-821X(95)00236-6},
isbn = {0012-821X},
issn = {0012821X},
pages = {137--143},
title = {{A TEM investigation of shock metamorphism in quartz from the Sudbury impact structure (Canada)}},
volume = {138},
year = {1996}
}
@article{Grieve2008,
abstract = {The structural, topographic and other characteristics of the Vredefort, Sudbury, and Chicxulub impact structures are described. Assuming that the structures originally had the same morphology, the observations/interpretations for each structure are compared and extended to the other structures. This does not result in any major inconsistencies but requires that the observations be scaled spatially. In the case of Vredefort and Sudbury, this is accomplished by scaling the outer limit of particular shock metamorphic features. In the case of Chicxulub, scaling requires a reasoned assumption as to the formation mechanism of an interior peak ring. The observations/interpretations are then used to construct an integrated, empirical kinematic model for a terrestrial peak-ring basin. The major attributes of the model include: a set of outward-directed thrusts in the parautochthonous rocks of the outermost environs of the crater floor, some of which are pre-existing structures that have been reactivated during transient cavity formation; inward-directed motions along the same outermost structures and along a set of structures, at intermediate radial distances, during transient cavity collapse; structural uplift in the center followed by a final set of radially outward-directed thrusts at the outer edges of the structural uplift, during uplift collapse. The rock displacements on the intermediate, inward and innermost, outward sets of structures are consistent with the assumption that a peak ring will result from the convergence of the collapse of the transient cavity rim area and the collapse of the structural uplift.},
author = {Grieve, Richard A F and Reimold, W Uwe and Morgan, Joanna V and Riller, Ulrich and Pilkington, Mark},
isbn = {1086-9379},
issn = {1086-9379, 1086-9379},
journal = {Meteoritics \& Planetary Science},
keywords = {16:Structural geology,23:Geomorphology,Africa,Canada,Chicxulub Crater,Eastern Canada,Free State South Africa,Mexico,Ontario,South Africa,Southern Africa,Sudbury Structure,Vredefort Dome,basins,collapse structures,cryptoexplosion features,displacements,faults,geophysical methods,geophysical profiles,geophysical surveys,impact craters,impact features,kinematics,metamorphism,models,morphology,planar deformation features,ring structures,seismic methods,seismic profiles,shatter cones,shock metamorphism,surveys,topography,transient phenomena,uplifts},
pages = {855--882},
title = {{Observations and interpretations at Vredefort, Sudbury, and Chicxulub; towards an empirical model of terrestrial impact basin formation}},
url = {https://www.lib.uwo.ca/cgi-bin/ezpauthn.cgi?url=http://search.proquest.com/docview/50090207?accountid=15115$\backslash$nhttp://sfx.scholarsportal.info/western?url\_ver=Z39.88-2004\&rft\_val\_fmt=info:ofi/fmt:kev:mtx:journal\&genre=article\&sid=ProQ:ProQ:georefmodule\&atitle=Observations+and+interpretations+at+Vredefort,+Sudbury,+and+Chicxulub;+towards+an+empirical+model+of+terrestrial+impact+basin+formation\&title=Meteoritics+\&+Planetary+Science\&issn=10869379\&date=2008-05-01\&volume=43\&issue=5\&spage=855\&au},
volume = {43},
year = {2008}
}
@article{Becker1994,
abstract = {Fullerenes (C60 and C70) have been identified by laser desorption, laser desorption post-ionization, and high-resolution electron-impact mass spectrometry in shock-produced breccias (Onaping Formation) of the Sudbury impact structure in Ontario, Canada. The C60 isotope is present at a level of a few parts per million. The fullerenes were likely synthesized within the impact plume from the carbon contained in the bolide. The oxidation of the fullerenes during the 1.85 billion years of exposure was apparently prevented by the presence of sulfur in the form of sulfide-silicate complexes associated with the fullerenes.},
author = {Becker, L and Bada, J L and Winans, R E and Hunt, J E and Bunch, T E and French, B M},
doi = {10.1126/science.11536660},
isbn = {0036-8075 (Print)$\backslash$n0036-8075 (Linking)},
issn = {0036-8075},
journal = {Science (New York, N.Y.)},
keywords = {NASA Center ARC,NASA Discipline Exobiology,Non-NASA Center},
pages = {642--645},
pmid = {11536660},
title = {{Fullerenes in the 1.85-billion-year-old Sudbury impact structure.}},
volume = {265},
year = {1994}
}
@article{Ross2006,
abstract = {The arrival of the massive body that led to the Sudbury impact structure has been interpreted as a relatively gentle event, with temperatures not exceeding 1300 K on the basis of the presence of fullerene-caged helium. Such temperatures are well below the 10,000 K peaks suggested in large impact modeling, and in contrast to that higher temperature regime they can accommodate the survival of exogenous precursors to life. A reexamination of the kinetics of the thermolysis of C
                        60-helium shows that the impact was probably not extraordinary, and yielded temperatures in the extreme range. Thermodynamic and kinetics arguments suggest, moreover, that the fullerenes were not extraterrestrial in origin but produced during impact. ?? 2006 Elsevier Inc. All rights reserved.},
author = {Ross, David S.},
doi = {10.1016/j.icarus.2006.02.017},
issn = {00191035},
journal = {Icarus},
keywords = {Asteroids,Comets,Exobiology,Geochemistry,Prebiotic chemistry},
pages = {233--234},
title = {{A reexamination of the Sudbury landing}},
volume = {183},
year = {2006}
}
@article{Riller2005,
abstract = {Orogenic deformation, both preceding and following the impact event at Sudbury, strongly hinders a straightforward assessment of impact-induced geological processes that generated the Sudbury impact structure. Central to understanding these processes is the state of strain of the Sudbury Igneous Complex, the solidified impact melt sheet, its underlying target rocks, overlying impact breccias and post-impact sedimentary rocks. This review addresses (1) major structural, metamorphic and magmatic characteristics of the impact melt sheet and associated dikes, (2) attempts that have been made to constrain the primary geometry of the igneous complex, (3) modes of impact-induced deformation as well as (4) mechanisms of pre- and post-impact orogenic deformation. The latter have important consequences for estimating parameters such as magnitude of structural uplift, tilting of pre-impact (Huronian) strata and displacement on major discontinuities which, collectively, have not yet been considered in impact models. In this regard, a mechanism for the emplacement of Offset Dikes is suggested, that accounts for the geometry of the dikes and magmatic characteristics, as well as the occurrence of sulfides in the dikes. Moreover, re-interpretation of published paleomagnetic data suggests that orogenic folding of the solidified melt sheet commenced shortly after the impact. Uncertainties still exist as to whether the Sudbury impact structure was a peak-ring or a multi-ring basin and the deformation mechanisms of rock flow during transient cavity formation and crater modification.},
author = {Riller, Ulrich},
doi = {10.1111/j.1945-5100.2005.tb00140.x},
issn = {10869379},
journal = {Meteoritics \& Planetary Science},
keywords = {tectonics of crater formation},
pages = {1723--1740},
pmid = {6},
title = {{Structural characteristics of the Sudbury impact structure, Canada: Impact-induced versus orogenic deformation-A review}},
url = {http://www.ingentaconnect.com/content/arizona/maps/2005/00000040/00000011/art00010$\backslash$nhttp://onlinelibrary.wiley.com/doi/10.1111/j.1945-5100.2005.tb00140.x/abstract$\backslash$nhttp://doi.wiley.com/10.1111/j.1945-5100.2005.tb00140.x},
volume = {40},
year = {2005}
}
@article{Islands2005,
author = {Islands, Cayman and Republic, Dominican},
pages = {73--83},
title = {{7. The Effects oy coral bleaching in the northern Caribbean and Western Atlantic}},
year = {2005}
}
@incollection{Therriault1999,
abstract = {The SIC is a layered body within the Sudbury Structure, Canada. A detailed mineralogical and petrological study reveals that the original SIC melt crystallized in a water-rich environment. Its unusual petrology is evidence of its derivation from an impact melt.},
author = {Therriault, A M and Fowler, A D and Grieve, R A F},
booktitle = {Lunar and planetary science, XXX; Papers presented to the Thirtieth lunar and planetary science conference.},
keywords = {05A Igneous and metamorphic petrology,Canada,Eastern Canada,Ontario,Sudbury Structure,Sudbury igneous complex,cores,cumulates,differentiation,gabbros,geochemistry,granophyre,hydrothermal alteration,igneous rocks,impact features,impacts,intergrowths,layered materials,melts,metasomatism,mineral composition,norite,petrology,plutonic rocks,textures,volcanic rocks},
pages = {; abstr. no. 1801},
title = {{The Sudbury igneous complex; mineralogy and petrology of a differentiated impact melt sheet}},
volume = {30},
year = {1999}
}
@article{Scott2002,
abstract = {Quartz diorite dikes in the footwall of the 1.85 Ga Sudbury impact structure were emplaced within fractures formed during hypervelocity impact. The anisotropy of magnetic susceptibility of the radial Copper Cliff dike reveals a steeply dipping foliation that is counterclockwise oblique along both the eastern and western sides of the dike, and a steeply northwest plunging lineation. The data suggest that the Copper Cliff dike acted as a melt-filled dextral transfer fault during collapse of the inner rim of the central peak ring of the impact crater to accommodate ultrahigh-strain-rate displacements. Peak-ring rim collapse may have caused sulfide-rich melts to be injected into the Copper Cliff dike, leading to the formation of large Cu–Ni–platinum group element deposits.},
author = {Scott, R. G. and Benn, K.},
doi = {10.1130/0091-7613(2001)029<0747:PRRCAB>2.0.CO;2},
issn = {00917613},
journal = {Geology},
keywords = {Impact melt,Offset dike,Rim collapse,Sudbury impact crater},
pages = {747--750},
title = {{Peak-ring rim collapse accommodated by impact melt-filled transfer faults, Sudbury impact structure, Canada}},
volume = {29},
year = {2002}
}
@article{Ames1998,
abstract = {New U-Pb geochronologic data from the Sudbury structure directly link extensive hydrothermal activity in crater-fill breccias with the 1850 Ma impact event, and constrain complex impact-induced processes to <4 m.y. Semiconformable alteration of breccias in the Onaping Formation includes silicification, albitization, chloritization, calcitization, and complex feldspathization, which directly underlies Zn-Cu-Pb ore deposits. Geochronologic data demonstrate a middle to lower crustal source for the crater-fill deposit that was subsequently affected by the hydrothermal event at 1848.4 +3.8/-1.8 Ma. These and other data confirm that the crater-fill breccia, hydrothermal system, Sudbury igneous complex, and its sublayer Ni-ore-bearing units were emplaced as a result of impact. The ages of events associated with the Sudbury structure are now more closely constrained than in any other meteorite impact structure.},
author = {Ames, D. E. and Watkinson, D. H. and Parrish, R. R.},
doi = {10.1130/0091-7613(1998)026<0447:DOARHS>2.3.CO;2},
isbn = {0091-7613},
issn = {00917613},
journal = {Geology},
pages = {447--450},
pmid = {822},
title = {{Dating of a regional hydrothermal system induced by the 1850 Ma Sudbury impact event}},
volume = {26},
year = {1998}
}
@article{Powers1997,
abstract = {The purpose of this study was to document gait patterns in a group of individuals with transtibial amputations (TTA) during stair ambulation, and to identify the functional limitations associated with this task. Ten persons with TTA fitted with a Seattle LightFoot prosthetic component, and 14 nondisabled subjects participated in this study. Electromyographic activity (EMG) of the vastus lateralis (VL), rectus femoris (RF), gluteus maximus (GMAX), semimembranosus (SMEMB), biceps femoris long head (BFLH), and biceps femoris short head (BFSH) was assessed using indwelling wire electrodes during ascending and descending stairs. Lower limb kinematics (VICON) and stride characteristics (Footswitch Stride Analyzer System) also were collected. Stride characteristics revealed that those with TTA had a significantly slower rate of stair ambulation and demonstrated stance phase asymmetry between limbs compared to the nondisabled. Kinematic analysis determined significant limitations in prosthetic ankle motion, which necessitated compensatory functions at the hip and knee to accomplish stair ascent and descent and resulted in significantly greater muscular effort (increased EMG intensity and duration) compared to nondisabled.},
author = {Powers, C M and Boyd, L A and Torburn, L and Perry, J},
file = {:C$\backslash$:/fieldlog/Mendeley/1997/Powers et al. - 1997.pdf:pdf},
isbn = {0748-7711 (Print)},
issn = {0748-7711},
journal = {Journal of rehabilitation research and development},
pages = {9--18},
pmid = {9021622},
title = {{Stair ambulation in persons with transtibial amputation: an analysis of the Seattle LightFoot.}},
volume = {34},
year = {1997}
}
@misc{Nicolaysen1999,
abstract = {Shatter cones have been described from a number of circular and polygonal structures worldwide, the origin of which has been alternatively ascribed to the impacts of large extraterrestrial projectiles or to catastrophic endogenic processes. Despite their association with enigmatic, catastrophic processes, the nature of shatter cones and the physics involved in their formation have not been comprehensively researched. Results of detailed field and laboratory studies of shatter cones from three areas in the collar of the Vredefort Dome in South Africa are presented. Vredefort shatter cones are directly related to a widely displayed fracture phenomenon, termed ``multiply striated joint sets (MSJS)''. MSJs are planar to curviplanar fractures occuring at spacings of <1 to several millimeters. The joint sets have a fractal character. When a new measurement protocol is used in the field, involving study of all joint surfaces and all steps and striae exposed on these surfaces, new information is gained on the genesis and significance of the MSJS and on their relationship to striated conical fractures. The internal constitution of a rock specimen with MSJS was examined in detail, by documenting the precise geometry of many fractures in a suite of parallel thin sections transecting the specimen. The steps and striae on shatter cone surfaces have the characteristics of displacement fractures (microfaults), along which evidence of melting is observed. Shatter cone and MSJS surfaces are often covered with glassy films; we evaluate whether these fracture phenomena are linked to the formation of pseudotachylitic (friction) melt. Our field and petrographic observations can be interpreted as consistent with the generation of shatter cones/MSJS relatively late in the formation of the Vredefort structure. This scenario contrasts sharply with the widely held view that shatter cones are formed during the early ``compression'' phase of a shock event that affected horizontal strata.},
author = {Nicolaysen, L. O. and Reimold, W. U.},
booktitle = {Journal of Geophysical Research},
doi = {10.1029/1998JB900068},
issn = {0148-0227},
pages = {4911},
title = {{Vredefort shatter cones revisited}},
volume = {104},
year = {1999}
}
@article{Borsch-Supan2004,
author = {B\"{o}rsch-Supan, Axel},
issn = {00167460},
journal = {MEA (Mannheim Research Institute for the Economics of Aging) Discussion Papers},
keywords = {Capital Markets,Demographic Change,Labour Supply,Macroeconomics},
title = {{Gesamtwirtschaftliche Folgen des demografischen Wandels}},
url = {http://mea.uni-mannheim.de/publications/meadp\_051-04.pdf},
year = {2004}
}
@article{Gibson1998,
abstract = {Abstract— Analytical scanning electron microscopy has been used to investigate the surface textures and compositions of newly exposed shatter cones from the 1.85 Ga Sudbury impact structure, Canada. Unusual surface microstructures are observed at the micron scale, including silicate melt smears, melt fibres and melt splats. Silicate and Ni-rich spherules up to 5 $\mu$m in diameter adorn earlier-formed surface features, and we interpret these to be condensates formed due to shock-induced vaporization of the shatter cone surfaces. The development of striations on the shatter cones is attributed to shock-related fracture and slip. Formation of melts and spherules indicates that the highest ranks of shock metamorphism (Stages IV and V) were realized, but only on a very localized scale. Shatter cone surfaces are, therefore, likely sites for the development of high-pressure polymorphs and, if the chemistry is appropriate, fullerenes. As such, they may be equivalent to “Type A” pseudotachylytes and shock veins in meteorites.},
author = {Gibson, Heather M and Spray, John G},
doi = {10.1111/j.1945-5100.1998.tb01637.x},
issn = {1945-5100},
journal = {Meteoritics \& Planetary Science},
pages = {329--336},
pmid = {265},
title = {{Shock-induced melting and vaporization of shatter cone surfaces: Evidence from the Sudbury impact structure}},
url = {http://dx.doi.org/10.1111/j.1945-5100.1998.tb01637.x},
volume = {33},
year = {1998}
}
@article{Grieve2010,
abstract = {Abstract– The 1.4–1.6 km thick Onaping Formation consists of a complex series of breccias and “melt bodies” lying above the Sudbury Igneous Complex (SIC) at the Sudbury impact structure. Based on the presence of shocked lithic clasts and various “glassy” phases, the Onaping has been described as a “suevitic” breccia, with an origin, at least in part, as fallback material. Recent mapping and a redefined stratigraphy have emphasized similarities and differences in its various vitric phases, both as clast types and discrete intrusive bodies. The nature of the Onaping and that of other “suevitic” breccias overlying impact melt sheets is reviewed. The relative thickness, internal stratigraphic and lithological character, and the relative chronology of depositional units indicate multiple processes were involved over some time in the formation of the Onaping. The Sudbury structure formed in a foreland basin and water played an essential role in the evolution of the Onaping, as indicated by a major hydrothermal system generated during its formation. Taken together, observations and interpretations of the Onaping suggest a working hypothesis for the origin of the Onaping that includes not only impact but also the interaction of sea water with the impact melt, resulting in repeated explosive interactions involving proto-SIC materials and mixing with pre-existing lithologies. This is complicated by additional brecciation events due to the intrusion of proto-SIC materials into the evolving and thickening Onaping. Fragmentation mechanisms changed as the system evolved and involved vesiculation in the formation of the upper two-thirds of the Onaping.},
author = {Grieve, Richard A F and Ames, Doreen E. and Morgan, Joanna V. and Artemieva, Natalia},
doi = {10.1111/j.1945-5100.2010.01057.x},
isbn = {1945-5100},
issn = {10869379},
journal = {Meteoritics and Planetary Science},
pages = {759--782},
title = {{The evolution of the Onaping Formation at the Sudbury impact structure}},
volume = {45},
year = {2010}
}
@article{Tropea2010,
abstract = {Paleolimnological techniques were utilized to determine whether diatom and scaled chrysophyte assemblages in Daisy, Swan, and Tilton lakes (Sudbury, Ontario) have recovered toward their preimpact conditions as a result of reduced inputs of anthropogenic pollutants (SO (4) (2-) and metals) or whether other environmental stressors have affected recovery trajectories. In addition, geochemical analysis was used to track trends in sedimentary nickel and copper concentrations through time. Preindustrial algal assemblages were primarily dominated by circumneutral to alkaline and pH-indifferent taxa. However, with the onset of open-pit roasting and smelting operations, there was a stratigraphic shift toward acid-tolerant species. With wide-scale smelter emission reductions commencing in the 1970s, scaled chrysophyte assemblages in Swan and Daisy lakes have started to show signs of biological recovery in similar to 1984 and similar to 1991, respectively. Although the scaled chrysophyte assemblage in Tilton Lake has not recovered toward the predisturbance assemblage, the decline in acidophilic taxa and increase in circumneutral taxa in recently deposited lake sediments indicate that the community is responding to increased lake water pH. Conversely, diatom assemblages within each of the study lakes have not begun to recover, despite well-documented chemical recovery. It is suspected that biological recovery in Sudbury area lakes may be impeded by other environmental stressors such as climate warming. Copper and nickel concentrations in lake sediments increased with the onset of mining activities and subsequently declined with emission controls. However, metal concentrations in lake sediments remain elevated compared to preindustrial concentrations. Together, biological and geochemical evidence demonstrates the clear environmental benefits associated with smelter emission controls.},
author = {Tropea, Amy E. and Paterson, Andrew M. and Keller, Wendel and Smol, John P.},
doi = {10.1007/s11270-009-0255-x},
isbn = {0049-6979},
issn = {00496979},
journal = {Water, Air, and Soil Pollution},
keywords = {Acidification,Diatoms,Metals,Paleolimnology,Recovery,Scaled chrysophytes},
pages = {317--333},
title = {{Sudbury sediments revisited: Evaluating limnological recovery in a multiple-stressor environment}},
volume = {210},
year = {2010}
}
@article{Dietz1968,
abstract = {Fracture patterns, possible meteorite impact phenomena, list of known shatter-cone structures.},
author = {Dietz, Robert},
issn = {0028-6664, 0028-6664},
journal = {New Scientist (1956-1971)},
keywords = {05 Igneous and metamorphic petrology,cryptoexplosion features,explosion phenomena,meteorites,products,shatter cones},
pages = {501--503},
title = {{Shatter cones and star wounds}},
volume = {40},
year = {1968}
}
@misc{Keays2004,
abstract = {Summary The Ni–Cu–Platinum Group Element (PGE) sulfide deposits of the Sudbury Structure have provided a major portion of the world’s total nickel production and their host rocks have been the subject of numerous research studies, yet a number of perplexing problems remain to be solved. On the one hand, studies seeking to explain the formation of the Sudbury Structure have now converged on a genetic model which proposes that the Main Mass and Offset Dykes of the Sudbury Igneous Complex (SIC) were produced by crystallization of an impact-generated melt sheet. On the other hand, these models have yet to be fully reconciled with the production of the very large volume of magmatic Ni, Cu, Co, and PGE-rich sulfide mineralization and the associated mafic rock types. This paper explores this problem using new precious metal data from the Main Mass and Offset Dykes. These data are used to understand the relationships between these rocks, and to provide constraints on how the Ni–Cu–PGE sulfide ore deposits fit into the geological evolution of the Sudbury Structure. In the two drill cores selected for study in this project, the Mafic Norite has 1–5 modal percent pyrrhotite plus chalcopyrite, and elevated Ni (40–1000 ppm), Cu (40–1140 ppm), and PGE (1.9–7.8 ppb Pd, 1.8–7.3 ppb Pt); this is overlain by Felsic Norite that contains pyrrhotite, and has a wide range in concentration of Ni (13–257 ppm), Cu (7–328 ppm), and PGE (Marsh and Zieg, 1999), which may have formed discrete magma cells. As the temperature of the melt sheet decreased, some of these magma cells became S-saturated and the resultant Ni–Cu–PGE sulfides settled downwards and on reaching magma cells lower in the melt sheet were re-dissolved thereby raising the Ni, Cu and PGE contents of the lower magma cells. It was from these “enriched” magma cells that precipitation of the ore-forming Ni–Cu–PGE sulfide melts eventually took place. The mineral potential of Offset and embayment structures appears to be empirically linked to the thickness of the overlying noritic rocks; for example, the most heavily mineralized embayments and Offset Dykes are located in areas where the Felsic Norite is thickest. It appears unlikely that the entire 1–3 km-thick melt sheet was convectively mixing throughout its lateral extent, and so the heterogeneity in sulfide distribution was retained after crystallization and cooling.},
author = {Keays, R. R. and Lightfoot, P. C.},
booktitle = {Mineralogy and Petrology},
doi = {10.1007/s00710-004-0050-8},
issn = {09300708},
pages = {217--258},
title = {{Formation of Ni-Cu-Platinum Group Element sulfide mineralization in the Sudbury impact melt sheet}},
volume = {82},
year = {2004}
}
@article{Riller2010,
abstract = {The Sudbury Basin is a non-cylindrical fold basin occupying the central portion of the Sudbury Impact Structure. The impact structure lends itself excellently to explore the structural evolution of continental crust containing a circular region of long-term weakness. In a series of scaled analogue experiments various model crustal configurations were shortened horizontally at a constant rate. In mechanically weakened crust, model basins formed that mimic several first-order structural characteristics of the Sudbury Basin: (1) asymmetric, non-cylindrical folding of the Basin, (2) structures indicating concentric shortening around lateral basin termini and (3) the presence of a zone of strain concentration near the hinge zones of model basins. Geometrically and kinematically this zone corresponds to the South Range Shear Zone of the Sudbury Basin. According to our experiments, this shear zone is a direct mechanical consequence of basin formation, rather than the result of thrusting following folding. Overall, the models highlight the structurally anomalous character of the Sudbury Basin within the Paleoproterozoic Eastern Penokean Orogen. In particular, our models suggest that the Basin formed by pure shear thickening of crust, whereas transpressive deformation prevailed elsewhere in the orogen. The model basin is deformed by thickening and non-cylindrical synformal buckling, while conjugate transpressive shear zones propagated away from its lateral tips. This is consistent with pure shear deformation of a weak circular inclusion in a strong matrix. The models suggest that the Sudbury Basin formed as a consequence of long-term weakening of the upper crust by meteorite impact. © 2010 Elsevier B.V.},
author = {Riller, Ulrich and Boutelier, David and Schrank, Christoph and Cruden, Alexander R.},
doi = {10.1016/j.epsl.2010.07.009},
issn = {0012821X},
journal = {Earth and Planetary Science Letters},
keywords = {Analogue experiments,Deformation,Meteorite impact,Strain concentration,Sudbury Basin},
pages = {587--597},
title = {{Role of kilometer-scale weak circular heterogeneities on upper crustal deformation patterns: Evidence from scaled analogue modeling and the Sudbury Basin, Canada}},
volume = {297},
year = {2010}
}
@incollection{Avermann1999,
abstract = {The Green Member, the chlorite-shard horizon of the older literature of the impact breccias of the Onaping Formation of the Sudbury Structure, is characterized by a unique, cryptocrystalline matrix and small, strongly tempered, and shock metamorphosed mineral and rock fragments. It is distinctly different from the clastic matrix breccias of the Gray Member underlying it and from those of the Black Member overlying it. The member is continuous around the Sudbury Basin, is up to 70 m thick, and is believed to represent the collapsed fireball of the Sudbury impact structure. As such, it originated from condensation of a vapor phase collapsed from high atmospheric regimes onto earlier deposited suevitic breccias of the Gray Member before deposition and redeposition of the Black Member breccias. The mineral and rock fragments of the Green Member represent early excavated fall-back components.},
author = {Avermann, M E},
booktitle = {Large meteorite impacts and planetary evolution; II.},
doi = {10.1130/0-8137-2339-6.323},
issn = {00721077},
keywords = {Canada,Eastern Canada,Green Member,Huronian,Onaping Formation,Ontario,Precambrian,Proterozoic,SEM data,Sudbury Basin,Sudbury Structure,breccia,chlorite,chlorite group,clastic rocks,fireballs,impact craters,impact features,matrix,metamorphism,mineral composition,outcrops,petrography,sedimentary rocks,sheet silicates,shock metamorphism,silicates,upper Precambrian},
pages = {323--330},
title = {{The Green Member of the Onaping Formation, the collapsed fireball layer of the Sudbury impact structure, Ontario, Canada}},
volume = {339},
year = {1999}
}
@article{Wren1988,
abstract = {Determined whether negative relationships between lake pH and fish Hg content, which have been reported for several areas, are consistent over a wide range of lake conditions. Samples of crayfish Cambarus, fish, mink Mustela vison and otter Lutra canadensis from different sites in Ontario, were analyzed for total Hg and Se in some tissues. Concentrations of Hg were lowest in specimens from watersheds near the smelter at Sudbury. Crayfish Hg levels displayed a positive correlation with lake pH. Crayfish and perch Perca flavescens Hg levels increased linearly with distance from Sudbury. Selenium, and possibly other heavy metals emitted from the smelters, are probably inhibiting Hg methylation and uptake by aquatic biota in lakes near Sudbury.},
author = {Wren, C D and Stokes, P M},
issn = {00447447},
journal = {Ambio},
pages = {28--30},
title = {{Depressed mercury levels in biota from acid and metal stressed lakes near Sudbury, Ontario}},
volume = {17},
year = {1988}
}
@incollection{Dence1972,
abstract = {Shock metamorphism phenomena, brecciation, hypothetical model for impact, comparisons with other similar craters, Ontario.},
author = {Dence, M R},
booktitle = {New developments in Sudbury geology.},
keywords = {16 Structural geology,Canada,Eastern Canada,Ontario,Sudbury,breccia,clastic rocks,cryptoexplosion features,geomorphology,igneous rocks,impact features,metamorphism,models,sedimentary rocks,shock,structural geology,structure},
pages = {7--18},
title = {{Meteorite impact craters and the structure of the Sudbury Basin}},
volume = {10},
year = {1972}
}
@misc{Dietz1964,
abstract = {Formation of the Sudbury structure in northern Ontario is attributed to impact of a 1.7 billion-year-old asteroid, with a diameter of about four kilometers. The sequence of events following the impact to the present appearance of the area, as well as associated ore formation, is discussed.},
author = {Dietz, Robert S.},
booktitle = {The Journal of Geology},
doi = {10.1086/626999},
issn = {0022-1376},
pages = {412--434},
title = {{Sudbury Structure as an Astrobleme}},
volume = {72},
year = {1964}
}
@article{Ames2008,
abstract = {A NEW, 1:100,000 SCALE compilation bedrock geology map provided with this issue presents a geologic synthesis of Canada’s most prolific mining camp, the world-class Sudbury structure with total past production and current reserves of over 1.7 billion tonnes of Ni, Cu, Co, Pt, Pd, Au, Ag ore (Lydon, 2007). The polymetallic ore is hosted within one of Earth’s largest preserved impact craters. The new map of the Ni-Cu-PGE Sudbury district (after Ames et al., 2005) is included in a pocket at the back of this issue (Map 1) and is linked to mineral deposit-commodity and geochronology data in Tables 1 and 2 of this paper. Since 1891, six compilation maps of the geology of Sudbury have been published (Bell, 1891; Collins, 1937; Cooke, 1946; Card, 1969; Dressler, 1984; Ames et al., 2005) (Fig. 1). Some of the Ni-Cu-PGE mines have operated for over a century, whereas new ore deposits, discovered as recently as 2004, are already in production or are in the process of being developed (i.e., advanced prospects). In the last 15 years, Sudbury has been the training ground for \~{}60 postgraduate geoscience students in North America (Fig. 1). From 1903 to 1990, only 23 graduate theses were completed on Sudbury-related topics; eight of them in the 1970s, after the discovery of shatter cones (Dietz, 1964). Map 1 presents new information on (1) the impactites (St\"{o}ffler and Grieve, 2007) of the Sudbury impact crater (units 34–46), which include the Sudbury Igneous Complex and related radial and concentric offset dikes, the impact crater infill breccia dikes, the impact crater infill of the Onaping Formation, pseudotachylite and other impact features such as shatter cones, (2) the Neoarchean Levack gneiss complex in the northern footwall, and (3) the Grenville Front area. The explicit interpretation of the origin of the igneous complex as a differentiated melt sheet in the Sudbury impact structure, overlain by and assimilating its own fallback breccias (Grieve et al., 1991), is now widely accepted as a general framework. New data on these features, described in more detail below, are integrated with a compilation of U-Pb geochronology, mineral deposits, and occurrences (including surface projections of mineralization and recent discoveries), and previous bedrock mapping. This compilation map contributes to our understanding of one of the world’s geologic features of extraordinary economic and scientific importance},
author = {Ames, D. E. and Davidson, A. and Wodicka, N.},
doi = {10.2113/gsecongeo.103.5.1057},
isbn = {0361-0128},
issn = {03610128},
journal = {Economic Geology},
pages = {1057--1077},
title = {{Geology of the giant Sudbury polymetallic mining camp, Ontario, Canda}},
volume = {103},
year = {2008}
}
@article{Wichman1993,
abstract = {The Sudbury Structure is presently identified as a plausible terrestrial$\backslash$nexample of crater floor fracture. A comparison is conducted between the$\backslash$npattern of early crater-centered structures around Sudbury to the$\backslash$nfracture patterns in two alternative lunar analogs. The dimensions of$\backslash$nthe original Sudbury crater forms are modeled, and the implications of$\backslash$nthe deformation sequence at Sudbury are discussed with a view to the$\backslash$nmechanisms of crater-floor fracturing; attention is given to flexure of$\backslash$nthe basin floor in response to isostatic equilibration.},
author = {Wichman, R. W. and Schultz, P. H.},
doi = {10.1111/j.1945-5100.1993.tb00760.x},
issn = {00261114},
journal = {Meteoritics},
pages = {222--231},
pmid = {583},
title = {{Floor-fractured crater models of the Sudbury Structure, Canada - Implications for initial crater size and crater modification}},
url = {http://adsabs.harvard.edu.ezproxy1.lib.asu.edu/abs/1993Metic..28..222W},
volume = {28},
year = {1993}
}
@misc{Cannon2010,
abstract = {A layer of breccia that contains fragments of impact ejecta has been found at 10 sites in the Paleoproterozoic iron ranges of northern Michigan, in the Lake Superior region of the United States. Radiometric age constraints from events predating and postdating deposition of the breccia are ca. 1875 Ma and 1830 Ma. The major bolide impact that occurred at 1850 Ma at Sudbury, Ontario, 500-700 km east of these sites, is the likely causative event. The Michigan sites described here, along with previously described sites in Minnesota and Ontario, define an extensive ejecta-bearing deposit throughout the Paleoproterozoic iron ranges of the Lake Superior region that we refer to as the Sudbury impact layer. The layer at the sites in Michigan exhibits a range of thicknesses, lithologic characters, and sedimentary settings. The diversity of rock types and internal stratigraphic details of the layer imply that several different processes of transport and deposition are represented, but the detailed investigations needed to document them are incomplete. Many of the sites had been described and interpreted previously as products of common terrestrial processes, but the presence of relict shock-induced planar deformation features in quartz indicates that the breccia layer is in fact the product of an extraterrestrial impact. At most localities, this layer also contains relict fragments of altered devitrified glass and/or accretionary lapilli. One immediate use of the impact layer is as an ultraprecise time line that ties together the well-known stratigraphic sequences of the various geographically separated iron ranges, the correlation of which has remained controversial for many decades. The Sudbury impact layer most commonly lies at a horizon that records a significant change in the character of sediments across the region. The impact layer marks the end of a major period of banded iron formation deposition that was succeeded by deposition of fine clastic rocks, commonly black shales. The impact may have produced regional, if not global, changes in the environment that resulted in this widespread synchronous change in sedimentation style.},
author = {Cannon, W.F. and Schulz, K.J. and Horton, J. W. and Kring, D. A.},
booktitle = {Geological Society of America Bulletin},
doi = {10.1130/B26517.1},
isbn = {0016-7606$\backslash$n1943-2674},
issn = {0016-7606},
pages = {50--75},
title = {{The Sudbury impact layer in the Paleoproterozoic iron ranges of northern Michigan, USA}},
volume = {122},
year = {2010}
}
@misc{Parmenter2002,
abstract = {Fig. 3. Simplified  of  , highlighting the distribution of Sudbury breccia through the middle of the laminated argillite of the  Formation (modified from Young 1983). The box west of Highway 6 indicates the approximate area shown in Fig. 5. 4 },
author = {Parmenter, Andrew C and Lee, Christopher B and Coniglio, Mario},
booktitle = {Canadian Journal of Earth Sciences},
doi = {10.1139/e02-006},
issn = {0008-4077},
pages = {971--982},
title = {{"Sudbury Breccia" at Whitefish Falls, Ontario: evidence for an impact origin}},
volume = {39},
year = {2002}
}
@misc{Grieve1993,
abstract = {The origins of the Sudbury Structure and associated Igneous Complex have $\backslash$nbeen controversial. Most models call for a major impact event followed $\backslash$nby impact-induced igneous activity, although totally igneous models are $\backslash$nstill being proposed. Much of the controversy is due to a $\backslash$nmisunderstanding of the size of the original Sudbury Structure. By $\backslash$nanalogy with other terrestrial impact structures, the spatial $\backslash$ndistribution of shock features and Huronian cover rocks at the Sudbury $\backslash$nStructure suggest that the transient cavity was about 100 km in $\backslash$ndiameter, which places the original final structural rim diameter in the $\backslash$nrange of 150-200 km. Evidence is presented from least squares mixing $\backslash$nmodels that the average composition of the Igneous Complex corresponds $\backslash$nto a mix of Archean granite-greenstone terrain, with possibly a small $\backslash$ncomponent of Huronian cover rocks. The Igneous Complex is $\backslash$ndifferentiated, which is not a characteristic of previously studied $\backslash$nterrestrial impact melt sheets. This can be ascribed to its great $\backslash$nthickness and slower cooling. If this working hypothesis is accepted, $\backslash$nnamely, that both the Sudbury Structure and the Igneous Complex are $\backslash$nimpact in origin, then previous hybrid impact-igneous hypotheses can be $\backslash$ndiscarded and the Sudbury Structure can be studied specifically for the $\backslash$nconstraints it provides to large-scale cratering and the formation of $\backslash$nbasin-sized (multiring?) impact structures.},
author = {Grieve, R. A. F. and St\"{o}ffler, D. and Deutsch, A.},
booktitle = {Journal of Geophysical Research},
doi = {10.1029/93JE02139},
issn = {0148-0227},
pages = {20903},
title = {{Clarification to “The Sudbury structure: Controversial or misunderstood?”}},
volume = {98},
year = {1993}
}
@article{Therriault2002,
abstract = {THE SUDBURY STRUCTURE, Ontario, is the remnant of a 1.85 Ga old impact crater, which originally had a diameter of 200 to 250 km. The Sudbury Igneous Complex occurs within the Sudbury structure. The Sudbury Igneous Complex is a 2.5- to 3.0-km-thick, \~{}60- x 27-km elliptical igneous-rock body, which consists of four major lithologies (from top to bottom) traditionally termed "granophyre," "quartz gabbro," "norite," and "contact sublayer" (sulfide- and inclusion-bearing noritic rock). With the exception of the latter, all these lithologies are continuous across the structure. Modal analyses reveal that, following the IUGS system of nomenclature, quartz gabbro samples are in fact quartz monzogabbros, a few of the norite samples are quartz gabbros, and most norite samples are quartz monzogabbros. In view of these observations, and in order to clarify the nomenclature, an updated terminology is proposed (from top to bottom): upper unit, middle unit, lower unit, and contact sublayer. The bulk composition of the Sudbury Igneous Complex, from North Range data, is granodioritic. Continuous and gradational mineralogical and geochemical variations between the lithological units are evidence that the Complex behaved as a single melt system. All the Sudbury Igneous Complex lithologies have the same light to heavy rare earth element (REE) ratio and an overall pattern of increased light REE and depleted heavy REE. The occurrence of primary hydrous minerals (hornblende and biotite), deuteric alteration, and abundant micrographic and granophyric intergrowths demonstrate that the melt was rich in H2O. Moreover, the granophyric and other far-from-equilibrium textures are most likely due to rapid crystallization triggered by exsolution of a volatile phase. The Sudbury Igneous Complex differs from traditional layered mafic complexes in the following aspects. It has an overall intermediate composition, a hydrous nature, a crustal isotopic signature, normative corundum, and an unusually large volume of granophyre. The Sudbury Complex differs from known terrestrial impact melt sheets only by its great thickness and the presence of chemical, and therefore, mineralogical layering. Reported here for the first time, and similar to those found in impact melt rocks elsewhere, are the occurrences of plagioclase xenocrysts with complex twinning and zoning patterns and planar deformation features in quartz xenocrysts. The well-known ore deposits of the Sudbury region are directly related to the genesis of the Sudbury Igneous Complex. Some ores precipitated from the Sudbury melt, whereas others were concentrated by hydrothermal fluids that percolated through the crystallized complex. It is concluded that the Sudbury Igneous Complex is the best exposed and only well-documented, to date, terrestrial impact melt sheet to have differentiated.},
author = {Therriault, Ann M. and Fowler, Anthony D. and Grieve, Richard A F},
doi = {10.2113/gsecongeo.97.7.1521},
issn = {03610128},
journal = {Economic Geology},
pages = {1521--1540},
title = {{The Sudbury Igneous Complex: A differentiated impact melt sheet}},
volume = {97},
year = {2002}
}
@inproceedings{Long2004,
abstract = {Whereas both meteorite impact and volcanic mechanisms have been proposed to explain the rocks and associated ore deposits within the Sudbury structure (1.85Ga), few models take into consideration the paleogeographic constraints implied by the history of the region before, and following the "Sudbury event". Huronian depositional style south of the Sudbury structure appears to have been strongly influenced by the early development of transtensional extensional basins. These basins were initiated by sinistral strike-slip movement along part of a Paleoproterozoic continental margin, which later evolved into a passive margin. Transition from a rifted strike-slip margin to a passive margin was accompanied by major slope failure and soft sediment deformation south of the Murray Fault. Diabase dikes were intruded into unconsolidated sediments at considerable depth, producing round-stone breccias, which are texturally similar to Sudbury breccia. Minor compressional folding occurred prior to emplacement of the Nipissing Diabase Suite at around 2.2Ga. The abundance of diabase intrusions near the Sudbury structure suggests that the area may have been a focal point for magma emplacement. The post "event" fill of the Paleoproterozoic Sudbury Basin reflects initial deposition in a deep-water, anoxic setting. There is no evidence to suggest that sedimentation was influenced by the steep-walls of an impact crater. Carbonate in the basal, Vermilion Member is of sedimentary-exhalative origin and was not derived from a shallow marine shelf. Turbidites in the Chelmsford Formation show no evidence of centripetal fill as might be expected from a restricted, circular basin. They appear to have been emplaced along the depositional axis of an elongate foreland basin developed in front of the rising Penokean mountain chain. Penokean deformation continued after the "Sudbury event" and influenced strata well into the Archean Craton. Deformation of Huronian strata in paleovalleys north and west of the Sudbury structure does not appear to be genetically related to the "Sudbury event". If "superfaults" were generated around the Sudbury structure in response to compression and crustal rebound following a meteorite impact, these do not appear to have caused offset of pre-existing steeply dipping contacts between the Huronian and underlying Archean basement. A new model, consistent with these observations needs to be developed. ?? 2003 Elsevier B.V. All rights reserved.},
author = {Long, Darrel G F},
booktitle = {Precambrian Research},
doi = {10.1016/j.precamres.2003.10.003},
isbn = {0301-9268},
issn = {03019268},
keywords = {Meteorite impact,Palaeogeography,Proterozoic,Sedimentology,Seismites,Structure,Tectonics},
pages = {203--223},
title = {{The tectonostatigraphic evolution of the Huronian basement and the subsequent basin fill: Geological constraints on impact models of the Sudbury event}},
volume = {129},
year = {2004}
}
@incollection{Fedorowich1999,
abstract = {The distribution patterns and brecciation intensity of Sudbury Breccia are generally not well constrained within a 5-15-km-wide zone that surrounds the Sudbury Igneous Complex. This zone is punctuated by local areas of abundant Sudbury Breccia. The object of this chapter is to quantify the distribution and orientation within one such area, the Strathcona Embayment. Estimates of the percentage distribution of Sudbury Breccia are based on detailed field mapping. For example, in a 7-km (super 2) area, only 4.7\% of the total outcrop area (22.8\%) consists of Sudbury Breccia. The area was subdivided into subareas varying from 2 to 8\% Sudbury Breccia content, with the highest concentration in the immediate vicinity of the Strathcona Embayment. Embayments are interpreted as slump features in the footwall to the Sudbury Igneous Complex and reflect a reworking of ground that has been structurally weakened by meteorite impact brecciation. One of the conclusions from these measurements is that Sudbury Breccia distribution can be used to predict embayment structures, which host nickel-copper-platinum group element (Ni-Cu-PGE) deposits throughout the Sudbury Basin. A large network of Sudbury Breccia in the Strathcona mine consists of 46\% breccia in the center, and only 4-18\% in the adjoining hangingwall and footwall. Dike-like bodies and veins of Sudbury Breccia have widely variable orientations that cluster subparallel to the outer margin of the Sudbury Igneous Complex and, like the complex, decrease in dip with depth. Envelopes of Sudbury Breccia are controlled by reverse and normal shears that are interactive with tensional openings in an overall compressional regime with maximum compression approximately orthogonal to the outer contact of the Sudbury Igneous Complex.},
author = {Fedorowich, John S and Rousell, Don H and Peredery, Walter V},
booktitle = {Large meteorite impacts and planetary evolution; II.},
doi = {10.1130/0-8137-2339-6.305},
issn = {00721077},
keywords = {Canada,Eastern Canada,Ontario,Strathcona Embayment,Strathcona Mine,Sudbury Irruptive,Sudbury Structure,brecciation,cartography,compression tectonics,copper ores,dip,foot wall,hanging wall,metal ores,mines,nickel ores,orientation,outcrops,platinum ores,spatial distribution,tectonics,tension},
pages = {305--315},
title = {{Sudbury Breccia distribution and orientation in an embayment environment}},
volume = {339},
year = {1999}
}
@article{Lightfoot2005,
abstract = {The formation of the Sudbury igneous complex (SIC) is widely believed to be the result of brecciation and crustal melting due to a meteorite impact; the igneous rocks that comprise the complex are diorites,  norites, gabbros, and granophyres, and they have compositions that are consistent with a crustal source. However, the generation of the Ni–Cu–PGE sulfide ores which are located at or close to the lower contact of the SIC are generally considered to result from segregation of magmatic sulfide from mafic magmas, not crustal melts.  This dilemma can be resolved by understanding the distribution of the mineralization in relation to the thickness of the Main Massif of the SIC and the extent of depletion of the noritic rocks in Ni, Cu, and PGE. The enormous reserves and resources of Ni–Cu–PGE sulfide ores associated with the sublayer and offsets of the SIC are considered to be a consequence of saturation of the Sudbury melt in immiscible sulfide and protracted evolution of  the magma at temperatures well above the liquidus temperature of the magma. The noritic, gabbroic, and granophyric rocks of the Main Massif have similar, yet elevated ratios of incompatible trace elements, and they are silica-rich and have radiogenic Sr and unradiogenic Nd isotope ratios. This indicates that the magma was homogenized in terms of the incompatible trace element abundances and had a large chemical contribution from an upper crustal source. Variations in chemical composition of rocks across the Main Massif near Creighton Mine illustrate systematic changes in major and trace element abundance levels. There are no clear compositional breaks that can be attributed to displacement along major W–E faults. Some of the chemical variations may be due to differentiation, but much of the variation was produced by crystallization from the base-upwards, and the top-downwards of a magma type that had a narrow range in ratios of incompatible trace element abundance levels and comparable abundance levels to that found in the quartz diorite offset dykes of the SIC. The development of the noritic and granophyric layers appears to postdate the development of a homogeneous quartz diorite melt as recorded in the early-formed offset dykes, but it predates the development of variations due to crystallization away from the base and the top in melts with mafic and felsic compositions, respectively. Models that explain this include liquid immiscibility and efficient expulsion of trapped liquid. Noritic rocks from the base of the southern segment of the SIC near Creighton Mine have 1–5\% model sulfide (pyrrhotite, chalcopyrite, and pentlandite), a relatively wide range in MgO (4–8.5 wt \%), and elevated Ni (30–200 ppm) and Cu (20–200 ppm); these are overlain by norites which contain trace pyrite, but low Ni (20–50 ppm) and Cu (10–50 ppm). The amount of disseminated sulfide mineralization in the noritic rocks overlying the sublayer is  remarkably low, given the proximity to the deposits of the Creighton embayment, and so it appears that there  is no obvious geochemical halo of Ni + Cu enrichment in the Main Massif norites adjacent to the Creighton  embayment. The noritic rocks with low Ni and Cu are depleted by a factor of 5–10 relative to that expected for  rocks with similar MgO content, but they are not as heavily depleted as the uppermost noritic rocks of the North  Range. The depletion of the noritic rocks in Ni is likely to result from equilibration of the magma with mag- matic sulfide, and this is consistent with the formation of the Ni–Cu–PGE sulfide deposits from the overlying  Main Massif by accumulation of dense magmatic sulfide. The sulfides were localized in embayment structures  at the lower contact. Our data indicates that the detailed crystallization and sulfide saturation history of the SIC  was not uniform throughout the melt sheet. In the thicker South Range melt, saturation appears to have resulted  in less efficient removal of Ni and Cu from the melt sheet. However, the greater overall thickness of the melt  sheet in the southern sector likely explains the localization of the largest known deposits of Ni–Cu–PGE sulfide  in places like Creighton, Copper Cliff, and Frood–Stobie.},
author = {Lightfoot, P C and Zotov, I A},
issn = {10757015},
journal = {Geology of Ore Deposits (Geologiia Rudnykh Mestorozhdenii)},
pages = {349--381},
title = {{Geology and geochemistry of the Sudbury Igneous Complex, Ontario, Canada: Origin of nickel sulfide mineralization associated with an impact-generated melt sheet}},
url = {http://www.maik.rssi.ru/cgi-bin/search.pl?type=abstract\&name=geolore\&number=5\&year=5\&page=349},
volume = {47},
year = {2005}
}
@article{Wieland2006,
abstract = {Shatter cones have been described from many meteorite impact structures and are widely regarded as a diagnostic macroscopic recognition feature for impact. However, the origin of this meso- to macroscopic striated fracture phenomenon has not yet been satisfactorily resolved, and the timing of shatter cone formation in the cratering process still remains enigmatic. Here, previous results from studies of shatter cones from the Vredefort impact structure and other impact structures are discussed in the light of new field observations made in the Vredefort Dome. Contrary to earlier claims, Vredefort cone fractures do not show uniform apex orientations at any given outcrop, nor do small cones show a pattern consistent with the previously postulated "master cone" concept. Simple back-rotation of impact-rotated strata to a horizontal pre-impact position also does not lead to a uniform centripetal-upward orientation of the cone apices. Striation patterns on the cone surfaces are variable, ranging from the typically diverging pattern branching off the cone apex to subparallel-to-parallel patterns on almost flat surfaces. Striation angles on shatter cones do not increase with distance from the center of the dome, as alleged in the literature. Instead, a range of striation angles is measured on individual shatter cones from a specific outcrop. New observations on small-scale structures in the collar around the Vredefort Dome confirm the relationship of shatter cones with subparallel sets of curviplanar fractures (so-called multipli-striated joint sets, MSJS). Pervasive, meter-scale tensile fractures cross-cut shatter cones and appear to have formed after the closely spaced MSJ-type fractures. The results of this study indicate that none of the existing hypotheses for the formation of shatter cones are currently able to adequately explain all characteristics of this fracturing phenomenon. Therefore, we favor a combination of aspects of different hypotheses that includes the interaction of elastic waves, as supported by numerical modeling results and which reasonably explains the variety of shatter cone shapes, the range of striation geometries and angles, and the relationship of closely spaced fracture systems with the striated surfaces. In the light of the currently available theoretical basis for the formation of shatter cones, the results of this investigation lead to the conclusion that shatter cones are tensile fractures and might have formed during shock unloading, after the passage of the shock wave through the target rocks.},
author = {Wieland, F and Reimold, W Uwe and Gibson, R L},
doi = {10.1111/j.1945-5100.2006.tb00449.x},
issn = {1086-9379, 1086-9379},
journal = {Meteoritics \& Planetary Science},
keywords = {23:Geomorphology,Africa,Free State South Africa,South Africa,Southern Africa,Vredefort Dome,cratering,cryptoexplosion features,deformation,elastic waves,fractures,geometry,impact features,morphology,numerical models,orientation,shatter cones,shock waves,striations,tension},
pages = {1737--1759},
pmid = {13},
title = {{New observations on shatter cones in the Vredefort impact structure, South Africa, and evaluation of current hypotheses for shatter cone formation}},
url = {https://www.lib.uwo.ca/cgi-bin/ezpauthn.cgi/docview/51080414?accountid=15115$\backslash$nhttp://cavern.uark.edu/~meteor/ LA  - English},
volume = {41},
year = {2006}
}
@article{Dietz1966,
abstract = {Shatter cones have been discovered in two residual boulders in the central uplift eye of the Middlesboro structure, Kentucky. This finding gives additional support to the interpretation of Englund and Roen (1962) that this is probably an astrobleme, i. e., an ancient meteorite impact scar.},
author = {Dietz, Robert S},
journal = {Meteoritics},
keywords = {16 Structural geology,Kentucky,Middlesboro astrobleme,Middlesboro structure,United States,astrobleme,cryptoexplosion features,cryptoexplosion structure,explosion phenomena,impact craters,impact features,meteor craters,products,shatter cones,structural geology},
pages = {27--29},
title = {{Shatter cones at the Middlesboro structure, Kentucky}},
volume = {3},
year = {1966}
}
@misc{Hargraves1990,
abstract = {Shatter cones that point steeply upward are present in abundance over an area >100 km (super 2) in Belt Supergroup sandstone outcrops in Beaverhead County, southwestern Montana. Crushed sandstone with fragments dispersed in a fluidal textured, cryptocrystalline matrix of similar chemical composition has also been found. Absence of cones in adjacent units of Mississippian and younger age suggests a late Precambrian-early Paleozoic age for the formation of this newly discovered impact structure, only a small part of which is preserved in the complexly faulted terrain.},
author = {Hargraves, R. B. and Cullicott, C. E. and Deffeyes, K. S. and Hougen, S. and Christiansen, P. P. and Fiske, P. S.},
booktitle = {Geology},
doi = {10.1130/0091-7613(1990)018<0832:SCASRI>2.3.CO;2},
issn = {00917613},
pages = {832--834},
pmid = {566},
title = {{Shatter cones and shocked rocks in southwestern Montana: The Beaverhead impact structure}},
volume = {18},
year = {1990}
}
@article{Howard1968,
abstract = {Shatter cones abound in the central uplift of Sierra Madera and they occur as far as 6.5 kilometers from the center. Apical angles average near 90 degrees. Whole cones and full cones represented by diversely oriented cone segments in any structural block show relatively uniform orientations of axes and a dominant direction of point. The cones predate faulting and folding in the central uplift, and, when beds are restored to horizontal, most cones point inward and upward, a pattern that supports the hypothesis of an impact origin.},
author = {Howard, K A and Offield, T W},
doi = {10.1126/science.162.3850.261},
issn = {0036-8075},
journal = {Science (New York, N.Y.)},
pages = {261--265},
pmid = {17779378},
title = {{Shatter cones at sierra madera, Texas.}},
volume = {162},
year = {1968}
}
@article{Versh2005,
abstract = {The impact-induced hydrothermal system in the well-preserved, 4 km-diameter K\"{a}rdla impact crater on Hiiumaa Island, western Estonia, was investigated by means of mineralogical, chemical, and stable C and O isotope studies. The mineralization paragenetic sequence, with gradually decreasing temperature, reveals at least three evolutionary stages in the development of the post-impact hydrothermal system: 1) an early vapor-dominated stage (>300 °C) with precipitation of submicroscopic adularia type K-feldspar; 2) the main stage (300 to 150/100 °C) with the development of a two-phase (vapor to liquid) zone leading to precipitation of chlorite/corrensite, (idiomorphic) euhedral K-feldspar, and quartz; and 3) a late liquid-dominated stage (<100 °C) with calcite I, dolomite, quartz, calcite II, chalcopyrite/pyrite, Fe-oxyhydrate, and calcite III precipitation. },
author = {Versh, Evelin and Kirsim\"{a}e, Kalle and J\~{o}eleht, Argo and Plado, J\"{u}ri},
doi = {10.1111/j.1945-5100.2005.tb00361.x},
issn = {10869379},
journal = {Meteoritics \& Planetary Science},
pages = {3--19},
pmid = {2},
title = {{Cooling of the K\"{a}rdla impact crater: I. The mineral paragenetic sequence observation}},
url = {http://doi.wiley.com/10.1111/j.1945-5100.2005.tb00361.x},
volume = {40},
year = {2005}
}
@article{Addison2005,
abstract = {A 25-70-cm-thick, laterally correlative layer near the contact between the Paleoproterozoic sedimentary Gunflint Iron Formation and overlying Rove Formation and between the Biwabik Iron Formation and overlying Virginia Formation, western Lake Superior region, contains shocked quartz and feldspar grains found within accretionary lapilli, accreted grain clusters, and spherule masses, demonstrating that the layer contains hypervelocity impact ejecta. Zircon geochronologic data from tuffaceous horizons bracketing the layer reveal that it formed between ca. 1878 Ma and 1836 Ma. The Sudbury impact event, which occurred 650-875 km to the east at 1850 \{+/-\} 1 Ma, is therefore the likely ejecta source, making these the oldest ejecta linked to a specific impact. Shock features, particularly planar deformation features, are remarkably well preserved in localized zones within the ejecta, whereas in other zones, mineral replacement, primarily carbonate, has significantly altered or destroyed ejecta features.},
author = {Addison, William D. and Brumpton, Gregory R. and Vallini, Daniela A. and McNaughton, Neal J. and Davis, Don W. and Kissin, Stephen A. and Fralick, Philip W. and Hammond, Anne L.},
doi = {10.1130/G21048.1},
issn = {00917613},
journal = {Geology},
keywords = {Distal ejecta,Gunflint and Biwabik Formations,Minnesota,Ontario,Precise U-Pb dates,Sudbury impactite},
pages = {193--196},
title = {{Discovery of distal ejecta from the 1850 Ma Sudbury impact event}},
volume = {33},
year = {2005}
}
@article{Spray2004,
abstract = {Impact structures developed on active terrestrial planets (Earth and Venus) are susceptible to pre-impact tectonic influences on their formation. This means that we cannot expect them to conform to ideal cratering models, which are commonly based on the response of a homogeneous target devoid of pre-existing flaws. In the case of the 1.85 Ga Sudbury impact structure of Ontario, Canada, considerable influence has been exerted on modification stage processes by late Archean to early Proterozoic basement faults. Two trends are dominant: 1) the NNW-striking Onaping Fault System, which is parallel to the 2.47 Ga Matachewan dyke swarm, and 2) the ENE-striking Murray Fault System, which acted as a major Paleoproterozoic suture zone that contributed to the development of the Huronian sedimentary basin between 2.45-2.2 Ga. Sudbury has also been affected by syn- to post-impact regional deformation and metamorphism: the 1.9-1.8 Ga Penokean orogeny, which involved NNW-directed reverse faulting, uplift, and transpression at mainly greenschist facies grade, and the 1.16-0.99 Ga Grenville orogeny, which overprinted the SE sector of the impact structure to yield a polydeformed upper amphibolite facies terrain. The pre-, syn-, and post-impact tectonics of the region have rendered the Sudbury structure a complicated feature. Careful reconstruction is required before its original morphometry can be established. This is likely to be true for many impact structures developed on active terrestrial planets. Based on extensive field work, combined with remote sensing and geophysical data, four ring systems have been identified at Sudbury. The inner three rings broadly correlate with pseudotachylyte (friction melt)-rich fault systems. The first ring has a diameter of \~{}90 km and defines what is interpreted to be the remains of the central uplift. The second ring delimits the collapsed transient cavity diameter at \~{}130 km and broadly corresponds to the original melt sheet diameter. The third ring has a diameter of \~{}180 km. The fourth ring defines the suggested apparent crater diameter at \~{}260 km. This approximates the final rim diameter, given that erosion in the North Range is <6 km and the ring faults are steeply dipping. Impact damage beyond Ring 4 may occur, but has not yet been identified in the field. One or more rings within the central uplift (Ring 1) may also exist. This form and concentric structure indicates that Sudbury is a peak ring or, more probably, a multi-ring basin. These parameters provide the foundation for modeling the formation of this relatively large terrestrial impact structure.},
author = {Spray, John G. and Butler, Hadyn R. and Thompson, Lucy M.},
doi = {10.1111/j.1945-5100.2004.tb00341.x},
isbn = {1086-9379},
issn = {10869379},
journal = {Meteoritics \& Planetary Science},
pages = {287--301},
pmid = {668},
title = {{Tectonic influences on the morphometry of the Sudbury impact structure: Implications for terrestrial cratering and modeling}},
url = {http://doi.wiley.com/10.1111/j.1945-5100.2004.tb00341.x},
volume = {39},
year = {2004}
}
@article{Darling2010,
abstract = {A unique terrestrial large impact melt sheet is preserved in the 1850 Ma Sudbury Structure, Ontario. We have undertaken a Pb isotope investigation of the southern limb of the melt sheet, termed the South Range Main Mass. The model initial Pb isotope ratios (207Pb/204Pbm) vary stratigraphically through the predominantly quartz monzogabbroic Lower Unit, varying from 15.40 to 15.45 at the base to ca. 15.35 at the top of the sequence. Lateral variations of similar range occur in basal Lower Unit samples over scales of less than 5 km. The range of these variations is similar to those of locally exposed upper crustal target rocks, and it is evident that the melt sheet has efficiently preserved inherited variability. During the violent phases of crater formation superheated impact melts are expected to be well-mixed mechanically, therefore significant post-impact melting of target rocks, fallback material and entrained clasts is required to explain such heterogeneity. The Sudbury Structure hosts world class Ni-Cu-PGE sulphide ore deposits. Systematic variation in 207Pb/204Pbm occurs throughout sulphide ores within the Creighton Embayment, from massive (15.42-15.45) to interstitial (ca. 15.40-15.41) and disseminated (ca. 15.39) sulphide. Linking the Pb isotope composition of these ores to the immediately overlying Lower Unit stratigraphy, a protracted sulphide segregation history is apparent. Massive sulphides segregated early, prior to or during initial silicate crystallisation, although the total time involved in sulphide accumulation spanned much of the crystallisation of the Lower Unit. It is also shown that lateral variations in Ni depletion throughout the Main Mass correlate with Pb isotopes. Those segments with the strongest chalcophile element depletion signatures, reflecting the accumulation of significant basal sulphides, have high initial Pb isotope values, consistent with early sulphide segregation. The characterisation of Pb isotopic heterogeneity has therefore provided insights into the evolution and scales of mixing of the melt sheet, with the identified chemical variability between melt cells having a significant influence on ore forming processes. ?? 2009 Elsevier B.V. All rights reserved.},
author = {Darling, J. R. and Hawkesworth, C. J. and Lightfoot, P. C. and Storey, C. D. and Tremblay, E.},
doi = {10.1016/j.epsl.2009.11.023},
issn = {0012821X},
journal = {Earth and Planetary Science Letters},
keywords = {Sudbury,lead isotopes,melt sheet,meteorite impact,sulphide},
pages = {347--356},
title = {{Isotopic heterogeneity in the Sudbury impact melt sheet}},
volume = {289},
year = {2010}
}
@misc{Milkereit2000,
abstract = {Following extensive petrophysical studies and presite surveys, the Trill area of the Sudbury basin was selected for conducting the first 3-D seismic survey for mineral exploration in North America. The 3-D seismic experiment confirms that in a geological setting such as the Sudbury Igneous Complex, massive sulfide bodies cause a characteristic seismic scattering response. This provides an excellent basis for the direct detection of massive sulfides by seismic methods. The feasibility study suggests that high-resolution seismic methods offer a large detection radius in the order of hundreds to thousands of meters, together with accurate depth estimates.},
author = {Milkereit, Bernd and Berrer, E. K. and King, Alan R. and Watts, Anthony H. and Roberts, B. and Adam, Erick and Eaton, David W. and Wu, Jianjun and Salisbury, Matthew H.},
booktitle = {Geophysics},
doi = {10.1190/1.1444873},
isbn = {0016-8033},
issn = {00168033},
pages = {1890},
title = {{Development of 3-D seismic exploration technology for deep nickel-copper deposits—A case history from the Sudbury basin, Canada}},
volume = {65},
year = {2000}
}
@article{Darling2010a,
abstract = {The largest known terrestrial impact melt sheet occurs within the 1850Ma Sudbury Structure, Ontario. In order to evaluate the relative contributions of different target lithologies to the melt sheet, we have investigated the Pb isotope compositions of feldspar separates from early-formed quartz diorite magmas within Offset Dykes from around the impact structure. The samples define a linear array on plots of age-corrected 206Pb/204Pb versus 207Pb/204Pb. Samples from Offset Dykes hosted by the Huronian Supergroup (South Range) have a range of 206Pb/204Pb1850 from 15.424 to 17.255 and 207Pb/204Pb1850 from 15.390 to 15.801, whilst those hosted by Archean gneisses of the Superior Province (North Range) cluster around 206Pb/204Pb1850???14.8 and 206Pb/204Pb1850???15.1. These values can be approximated by binary mixing between the two major groups of target lithologies. A mix of 60-70\% of Superior Province gneisses with 30-40\% of Huronian metasedimentary material closely matches the Pb isotope compositions of North Range Offset Dyke samples, whereas in the South Range the required Huronian component is up to ca. 80\%. These mixing proportions are consistent with Sr, Nd and Os isotope and trace element constraints. A third minor component, either locally-exposed Paleoproterozoic mafic rocks or the lower crust is also required. However, the isotopic, trace element and Ni-Cu-platinum group element characteristics of the melt sheet can be accommodated without the involvement of an average lower crustal or meteoritic component. A major contribution of Huronian supracrustal material, which had a pre-impact thickness of up to 12. km, is required to explain the chemical characteristics of the impact melts, which also have a strong upper crustal affinity (e.g. Eu/Sm = 0.22, Rb/Sr = 0.2-0.35). As such, a shallower level of melting is apparent than that predicted by many previous impact models for the Sudbury event. This can be accommodated by considering approach trajectories for the impactor oblique to the Earth's surface. In addition, the isotopic and trace element variability identified indicates that the melt sheet was heterogeneous at an early stage, and may not have been completely homogenised during crater formation. Our findings have significant implications for the nature of the Sudbury impact event, the evolution of the melt sheet and the crustal sources of metals contained in Sudbury's world class Ni-Cu-PGE sulphide ores. ?? 2010 Elsevier Ltd.},
author = {Darling, J. R. and Hawkesworth, C. J. and Storey, C. D. and Lightfoot, P. C.},
doi = {10.1016/j.gca.2010.06.021},
isbn = {0016-7037},
issn = {00167037},
journal = {Geochimica et Cosmochimica Acta},
pages = {5680--5696},
title = {{Shallow impact: Isotopic insights into crustal contributions to the Sudbury impact melt sheet}},
volume = {74},
year = {2010}
}
@article{Marshall1999,
abstract = {The elliptically zoned Sudbury Structure in northern Ontario is host to world-class nickel-copper-PGE deposits, which are generally regarded as the products of a single magmatic event. However, there is increasing evidence of multi-episodic fluid rock (including Ni-Cu sulphide) interactions in the Sudbury Structure that range from early remobilization of the cooling ores (ca. 1850 Ma), through metamorphism and deformation related to the Penokean Orogeny to neotectonic fracturing (ca. 5-13 Ma). Previous fluid inclusion studies have identified an H2O-NaCl ± CO2 ± KCl fluid of highly variable phase ratios intimately associated with the ores, and a distinct population of primary two-phase fluid inclusions associated with post-intrusion metasomatic alteration. This study introduces two new distinct populations of fluid inclusions: (1) a population represented by two-phase CO2-bearing fluid inclusions hosted along healed-fracture planes in quartz that offset ore minerals, that was trapped between 280-340°C and 1750 to 3500 bars pressure. As the fluid inclusion trails offset and therefore post-date the ore, their genesis is consistent with a late Penokean (1.83-1.89 Ga) or later (ca. 1450) contractional event; (2) a two-phase highly-saline (> 16 wt.\% NaCl equivalent) fluid hosted within neotectonic (5-13 Ma Rb-Sr) galena-sphalerite-calcite-quartz-chlorite veins. Inclusions of this fluid were trapped at temperatures ranging from 60 to 135°C and maximum confining pressures of 950 bars. Stable isotope data ($\delta$O, $\delta$D) from biotite, amphibole and epidote from the alteration assemblages of remobilized veins within the Sudbury Structure show distinct evidence of a mixing trend of fluids originating within or near the 'magmatic water box' and trending towards a metamorphic fluid of isotopic composition similar to an evolved Sudbury Structure groundwater. Ar-Ar data from the amphiboles within Sudbury Intrusive Complex (SIC) footwall breccia from the Craig Mine are consistent with a mixed Ar-Ar spectrum. The step-heating Ar release spectrum yields ages ranging from ca. 1800 Ma at the low temperature end to approximately 2640 Ma for high temperature steps. These dates are in agreement with the ca. 1850 and 2647 Ma ages for the SIC and Levack gneisses, respectively, and are interpreted as the reinjection of country rocks partially melted by the SIC back into the Sudbury Structure. The isotopic evidence for mixed fluids derived from a combination of a magmatic fluid and a regional groundwater/metamorphic fluid suggests that the highly variable phase-ratio fluid inclusions associated with the ore may be divided into two end-member fluids represented by an exsolved SIC fluid and a regional groundwater/metamorphic fluid. This is consistent with at least five distinct fluids being present during the evolution of the Sudbury structure.},
author = {Marshall, Dan and Watkinson, David and Farrow, Catharine and Moln\'{a}r, Ferenc and Fouillac, Anne Marie},
doi = {10.1016/S0009-2541(98)00122-3},
isbn = {0009-2541},
issn = {00092541},
journal = {Chemical Geology},
keywords = {Fluids,Inclusions,Isotopes,Mixing,Sudbury},
pages = {1--19},
pmid = {807},
title = {{Multiple fluid generations in the Sudbury igneous complex: Fluid inclusion, Ar, O, H, Rb and Sr evidence}},
volume = {154},
year = {1999}
}
@article{Boger2000,
abstract = {The Sudbury Neutrino Observatory is a second-generation water Cherenkov detector designed to determine whether the currently observed solar neutrino deficit is a result of neutrino oscillations. The detector is unique in its use of D2O as a detection medium, permitting it to make a solar model-independent test of the neutrino oscillation hypothesis by comparison of the charged- and neutral-current interaction rates. In this paper the physical properties, construction, and preliminary operation of the Sudbury Neutrino Observatory are described. Data and predicted operating parameters are provided whenever possible.},
archivePrefix = {arXiv},
arxivId = {nucl-ex/9910016},
author = {Boger, J. and Hahn, R. L. and Rowley, J. K. and Carter, A. L. and Hollebone, B. and Kessler, D. and Blevis, I. and Dalnoki-Veress, F. and Dekok, A. and Farine, J. and Grant, D. R. and Hargrove, C. K. and Laberge, G. and Levine, I. and McFarlane, K. and Mes, H. and Noble, A. T. and Novikov, V. M. and O'Neill, M. and Shatkay, M. and Shewchuk, C. and Sinclair, D. and Clifford, E. T H and Deal, R. and Earle, E. D. and Gaudette, E. and Milton, G. and Sur, B. and Bigu, J. and Cowan, J. H M and Cluff, D. L. and Hallman, E. D. and Haq, R. U. and Hewett, J. and Hykawy, J. G. and Jonkmans, G. and Michaud, R. and Roberge, A. and Roberts, J. and Saettler, E. and Schwendener, M. H. and Seifert, H. and Sweezey, D. and Tafirout, R. and Virtue, C. J. and Beck, D. N. and Chan, Y. D. and Chen, X. and Dragowsky, M. R. and Dycus, F. W. and Gonzalez, J. and Isaac, M. C P and Kajiyama, Y. and Koehler, G. W. and Lesko, K. T. and Moebus, M. C. and Norman, E. B. and Okada, C. E. and Poon, A. W P and Purgalis, P. and Schuelke, A. and Smith, A. R. and Stokstad, R. G. and Turner, S. and Zlimen, I. and Anaya, J. M. and Bowles, T. J. and Brice, S. J. and Esch, Ernst Ingo and Fowler, M. M. and Goldschmidt, Azriel and Hime, A. and McGirt, A. F. and Miller, G. G. and Teasdale, W. A. and Wilhelmy, J. B. and Wouters, J. M. and Anglin, J. D. and Bercovitch, M. and Davidson, W. F. and Storey, R. S. and Biller, S. and Black, R. A. and Boardman, R. J. and Bowler, M. G. and Cameron, J. and Cleveland, B. and Ferraris, A. P. and Doucas, G. and Heron, H. and Howard, C. and Jelley, N. A. and Knox, A. B. and Lay, M. and Locke, W. and Lyon, J. and Majerus, S. and Moorhead, M. and Omori, M.},
doi = {10.1016/S0168-9002(99)01469-2},
eprint = {9910016},
isbn = {0168-9002},
issn = {01689002},
journal = {Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
pages = {172--207},
primaryClass = {nucl-ex},
title = {{Sudbury neutrino observatory}},
volume = {449},
year = {2000}
}
@article{Manton1965,
abstract = {The shatter cones, striated conical surfaces over which fracture has taken place, have been plotted on a stereographic net as segments of commonly oriented cones. Full shatter cones characteristically point in one direction only, the same as that plotted for cone segments. The history of the Vredefort ring structure (South Africa) is outlined. Shatter coning is thought to have occurred before completion of the doming process, and evidence for a tectonic origin is presented.},
author = {Manton, W I},
doi = {10.1111/j.1749-6632.1965.tb20415.x},
isbn = {1749-6632},
issn = {0077-8923, 0077-8923},
journal = {Annals of the New York Academy of Sciences},
keywords = {16:Structural geology,Africa,Dynamic geology,South Africa,Southern Africa,Vredefort ring structure,cryptoexplosion features,shatter cones,tectonics},
pages = {1017--1049},
title = {{The orientation and origin of shatter cones in the Vredefort ring}},
url = {https://www.lib.uwo.ca/cgi-bin/ezpauthn.cgi/docview/52934188?accountid=15115 LA  - English},
volume = {123},
year = {1965}
}
@article{Becker1996,
abstract = {Fullerenes (C60 and C70) in the Sudbury impact structure contain trapped helium with a 3He/4He ratio of 5.5 x 10(-4) to 5.9 x 10(-4). The 3He/4He ratio exceeds the accepted solar wind value by 20 to 30 percent and is higher by an order of magnitude than the maximum reported mantle value. Terrestrial nuclear reactions or cosmic-ray bombardment are not sufficient to generate such a high ratio. The 3He/4He ratios in the Sudbury fullerenes are similar to those found in meteorites and in some interplanetary dust particles. The implication is that the helium within the C60 molecules at Sudbury is of extraterrestrial origin.},
author = {Becker, L and Poreda, R J and Bada, J L},
doi = {10.1126/science.272.5259.249},
issn = {0036-8075},
journal = {Science (New York, N.Y.)},
keywords = {NASA Center ARC,NASA Discipline Exobiology,NASA Discipline Number 52-70,NASA Discipline Number 93-10,NASA Program Exobiology,NASA Program NSCORT,Non-NASA Center},
pages = {249--252},
pmid = {8602508},
title = {{Extraterrestrial helium trapped in fullerenes in the Sudbury impact structure.}},
volume = {272},
year = {1996}
}
@article{Lafrance2010,
abstract = {Pseudotachylitic breccias occur in the crater floor of large impact structures. Their origin is widely attributed either to shock melting and cataclasis during propagation of an impact shock wave, or to frictional melting and cataclasis during large slip displacements along crater collapse superfaults. By contrast, some models propose that the breccia matrices are allochthonous superheated melts from overlying impact melt sheets or from sites within the crater floor, which leaked into dilational fractures during collapse of the crater. In an effort to test these models, the compositions of pseudotachylite Sudbury breccias in the South Range of the Sudbury impact structure, Canada, were here compared to those of its associated impact melt sheet, the Sudbury Igneous Complex (SIC). The studied breccias occur along the contact between sandstone and a gabbro stock, and additional breccia bodies are located solely within these two lithologies. Major, trace element and lead isotope systematics suggest that the contact breccias are derived by mixing of comminuted gabbro and sandstone and that breccias hosted exclusively by sandstone or gabbro have compositions similar to their host rocks. The SIC has distinct chemical and isotopic compositions which argue strongly against the involvement of the impact melt sheet in the makeup of the breccias. Quartz and plagioclase in clasts and matrix of the breccias are transected by multiple microfractures and they have pervasive mosaic textures characterized by rolling and mottled undulatory extinction of micron-sized subgrain-like domains and new grains. These textures and strong local host control on chemical and clast composition of the breccias suggest that the breccias formed in situ by shock-induced compression and cataclasis of their host rocks during propagation of the shock wave. ?? 2010 Elsevier B.V. All rights reserved.},
author = {Lafrance, Bruno and Kamber, Balz S.},
doi = {10.1016/j.precamres.2010.04.006},
issn = {03019268},
journal = {Precambrian Research},
keywords = {Geochemistry,In situ comminution,Mosaic subgrain texture,Pseudotachylitic breccia,Shock cataclasis,Sudbury impact structure},
pages = {237--250},
title = {{Geochemical and microstructural evidence for in situ formation of pseudotachylitic Sudbury breccia by shock-induced compression and cataclasis}},
volume = {180},
year = {2010}
}
@article{Hanley2003,
abstract = {An assemblage of hydrous, Cl-bearing alteration-induced minerals is present within 150 m of footwall-style Cu–Ni–PGE sulfide mineralization hosted by the Sudbury Breccia at the Fraser Copper zone, Fraser mine, Onaping–Levack area, Ontario. The pyroxene hornfels to hornblende hornfels contact-metamorphic aureole of the Sudbury Igneous Complex (SIC) contains less than 15 modal \% hydroxysilicates. Near the mineralized areas, a diagnostic assemblage of secondary minerals of the albite–epidote hornfels facies is present in the matrix of the Sudbury Breccia; it contains 25 to 80\% actinolite + chamosite as well as epidote + sodic plagioclase (An ) + quartz ± titaniferous magnetite ± biotite ± K-feldspar ± titanite. The Cl content and Cl/(Cl + F) values of amphibole and biotite in this matrix are elevated within 150 m of mineralization, and increase toward known occurrences of sulfides. Parameters of K, Na, and A-site occupancy correlate with Cl content in actinolite in such matrix material. The value of Mg\# is lower in biotite in the matrix near mineralized areas and is inversely correlated with Cl/(Cl + F) in the biotite, reflecting Mg–Cl or Fe–F avoidance. Calculated temperatures of amphibole–plagioclase equilibration for the diagnostic hydrous assemblage are between 442 to 540 ± 75°C. The assemblage formed during a retrograde metamorphic event during or after footwall Cu–Ni–PGE mineralization, and after passage of peak conditions of contact metamorphism at the base of the SIC. The enrichment of Cl in this assemblage was the result of the increased amounts of free Cl relative to F in the equilibrating fluid, and favorable cation proportions for incorporation of Cl into the structure of hydroxysilicate minerals. The Cl-bearing assemblage accounts for a significant portion of the bulk halogen content of Sudbury Breccia matrix. It is unique to zones of Sudbury Breccia that host mineralization, and hence may be used to identify prospective areas. 2.8–42},
author = {Hanley, Jacob J. and Mungall, James E.},
doi = {10.2113/gscanmin.41.4.857},
issn = {00084476},
journal = {Canadian Mineralogist},
keywords = {Alteration,Amphibole,Biotite,Cu-Ni-PGE mineralization,Halogens,Metamorphism,Ontario,Pseudotachylite,Retrograde effects,Sudbury,Sudbury Breccia},
pages = {857--881},
title = {{Chlorine enrichment and hydrous alteration of the Sudbury Breccia hosting footwall Cu-Ni-PGE mineralization at the Fraser mine, Sudbury, Ontario, Canada}},
volume = {41},
year = {2003}
}
@article{McCauley2005,
abstract = {The Sudbury Neutrino Observatory (SNO) is a one kiloton heavy water Cherenkov detector sensitive to the flavor content of the 8B neutrinos from the sun. Results from the first two phases of SNO, the pure D2O phase and the salt phase, show evidence for neutrino flavor change as the solution to the solar neutrino problem. SNO is now entering its third phase of operation in which 3He proportional counters have been deployed inside the D2O. ?? 2005 Published by Elsevier B.V.},
archivePrefix = {arXiv},
arxivId = {nucl-ex/9910016},
author = {McCauley, N.},
doi = {10.1016/j.nuclphysbps.2005.05.024},
eprint = {9910016},
issn = {09205632},
journal = {Nuclear Physics B - Proceedings Supplements},
pages = {128--130},
primaryClass = {nucl-ex},
title = {{The Sudbury Neutrino Observatory}},
volume = {149},
year = {2005}
}
@article{Crosta2009,
abstract = {The Vista Alegre structure, centered at 25 degrees 57'S and 52 degrees 42'W, has been recently proposed as a meteorite impact structure due to findings of small clasts of shatter cones and possible microscopic evidence of shock metamorphism in breccias within the 9.5-km-diameter feature. The structure is located in the Parana State of southern Brazil, within the Parana Basin, which contains one of the largest and most extensive flood basalt provinces on Earth. The Parana flood basalts belong to the Serra Geral Formation and are temporally related to the opening of the Atlantic Ocean, having been dated at about 133-132 Ma. Tholeiitic basalts dominate, with some minor rhyodacites. The Vista Alegre structure has a circular outline (in the form of an incomplete ring of hills) and a central depression. The presence of a central uplift is not obvious, but is indicated by the limited occurrence of sandstones, possibly related to the Botucatu formation, that are normally at a stratigraphic depth of about 800 m. The structure must be deeply eroded, and is heavily vegetated and agriculturally used. There are limited outcrops of polymict breccias (some of them possibly melt-bearing). We report on the recent finding of extensive shatter cone occurrences in the form of large (and small) clasts of a fine-grained sedimentary rock within the polymict breccias. The shatter cone-bearing breccias are found at different locations within the structure, separated by several kilometers. The nested shatter cones range in size from about 0.5 to 20 cm for individual cones, and up to half a meter for complete assemblages. This finding clearly confirms the impact origin of Vista Alegre, which may thus be an important analog for impact craters in basalts on Mars and other planets.},
author = {Crosta, Alvaro P and Koeberl, Christian and Jalufka, Dona and Anonymous},
issn = {0016-7592, 0016-7592},
journal = {Abstracts with Programs - Geological Society of America},
keywords = {12:Stratigraphy,23:Geomorphology,Brazil,Cretaceous,Mesozoic,Parana Brazil,Parana Province,South America,Vista Alegre impact structure,basalts,breccia,clastic rocks,cryptoexplosion features,depth,flood basalts,geomorphology,igneous rocks,impact craters,impact features,metamorphism,meteorites,sandstone,sedimentary rocks,shatter cones,shock metamorphism,southern Brazil,volcanic rocks},
pages = {532},
title = {{Shatter cones confirm the Vista Alegre meteorite impact structure in the Parana flood basalt province, southern Brazil}},
url = {https://www.lib.uwo.ca/cgi-bin/ezpauthn.cgi?url=http://search.proquest.com/docview/864944534?accountid=15115$\backslash$nhttp://sfx.scholarsportal.info/western?url\_ver=Z39.88-2004\&rft\_val\_fmt=info:ofi/fmt:kev:mtx:journal\&genre=article\&sid=ProQ:ProQ\%3Ageorefmodule\&atitle=Shatter+cones+confirm+the+Vista+Alegre+meteorite+impact+structure+in+the+Parana+flood+basalt+province\%2C+southern+Brazil\&title=Abstracts+with+Programs+-+Geological+Society+of+America\&issn=00167592\&date=2009-10-01\&volume=41\&issue=7\&spage=532},
volume = {41},
year = {2009}
}
@article{Magyarosi2002,
author = {Magyarosi, Z. and Watkinson, D. H. and Jones, P. C.},
doi = {10.2113/gsecongeo.97.7.1471},
issn = {03610128},
journal = {Economic Geology},
pages = {1471--1486},
title = {{Mineralogy of Ni-Cu-platinum-group elements sulfide ore in the 800 and 810 orebodies, Copper Cliff South Mine, and P-T-X conditions during the formation of platinum-group minerals}},
volume = {97},
year = {2002}
}
@article{Pope2004,
abstract = {Chicxulub and Sudbury are 2 of the largest impact structures on Earth. Research at the buried but well-preserved Chicxulub crater in Mexico has identified 6 concentric structural rings. In an analysis of the preserved structural elements in the eroded and tectonically deformed Sudbury structure in Canada, we identified ring-like structures corresponding in both radius and nature to 5 out of the 6 rings at Chicxulub. At Sudbury, the inner topographic peak ring is missing, which if it existed, has been eroded. Reconstructions of the transient cavities for each crater produce the same range of possible diameters: 80-110 km. The close correspondence of structural elements between Chicxulub and Sudbury suggests that these 2 impact structures are approximately the same size, both having a main structural basin diameter of \~{}150 km and outer ring diameters of \~{}200 km and \~{}260 km. This similarity in size and structure allows us to combine information from the 2 structures to assess the production of shock melt (melt produced directly upon decompression from high pressure impact) and impact melt (shock melt and melt derived from the digestion of entrained clasts and erosion of the crater wall) in large impacts. Our empirical comparisons suggest that Sudbury has \~{}70\% more impact melt than does Chicxulub (\~{}31,000 versus \~{}18,000 km3) and 85\% more shock melt (27,000 km3 versus 14,500 km3). To examine possible causes for this difference, we develop an empirical method for estimating the amount of shock melt at each crater and then model the formation of shock melt in both comet and asteroid impacts. We use an analytical model that gives energy scaling of shock melt production in close agreement with more computationally intense numerical models. The results demonstrate that the differences in melt volumes can be readily explained if Chicxulub was an asteroid impact and Sudbury was a comet impact. The estimated 70\% difference in melt volumes can be explained by crater size differences only if the extremes in the possible range of melt volumes and crater sizes are invoked. Preheating of the target rocks at Sudbury by the Penokean Orogeny cannot explain the excess melt at Sudbury, the majority of which resides in the suevite. The greater amount of suevite at Sudbury compared to Chicxulub may be due to the dispersal of shock melt by cometary volatiles at Sudbury. },
author = {Pope, K O and Kieffer, S W and Ames, D E},
doi = {10.1111/j.1945-5100.2004.tb00052.x},
issn = {10869379},
journal = {Meteoritics \& Planetary Science},
keywords = {impact melting},
pages = {97--116},
title = {{Empirical and theoretical comparisons of the Chicxulub and Sudbury impact structures }},
volume = {39},
year = {2004}
}
@article{Faggart1985,
abstract = {Samarium-neodymium isotopic data on whole rocks and minerals of the Sudbury Complex in Canada gave an igneous crystallization age of 1840 +/- 21 x 10(6) years. The initial epsilon neodymium values for 15 whole rocks are similar to those for average upper continental crust, falling on the crustal trend of neodymium isotopic evolution as defined by shales. The rare earth element concentration patterns of Sudbury rocks are also similar to upper crustal averages. These data suggest that the Sudbury Complex formed from melts generated in the upper crust and are consistent with a meteoritic impact.},
author = {Faggart, B E and Basu, A R and Tatsumoto, M},
doi = {10.1126/science.230.4724.436},
issn = {0036-8075},
journal = {Science (New York, N.Y.)},
pages = {436--439},
pmid = {17816075},
title = {{Origin of the sudbury complex by meteoritic impact: neodymium isotopic evidence.}},
volume = {230},
year = {1985}
}
@article{Pufahl2007,
abstract = {An ejecta layer produced by the Sudbury impact event ca. 1850 Ma occurs within the Baraga Group of northern Michigan and provides an excellent record of impact-related depositional processes. This newly discovered, \~{}2–4-m-thick horizon accumulated in a peritidal environment during a minor sea-level lowstand that punctuated a period of marine transgression. Common ejecta clasts include shock-metamorphosed quartz grains, splash-form melt spherules and tektites, accretionary lapilli, and glassy shards, suggesting sedimentation near the terminus of the continuous ejecta blanket. Sedimentologic and geochemical data indicate that primary fallout from a turbulent ejecta cloud was reworked to varying degrees by an impact-generated tsunami wave train. Observed platinum group element anomalies (Ir, Rh, and Ru) within the Sudbury ejecta horizon are sufficient to suggest that the impactor was a meteorite. Documenting and interpreting the detailed characteristics of the Sudbury ejecta horizon in Michigan have yielded a fingerprint to identify this chronostratigraphic marker in other Paleoproterozoic basins. For the first time a foundation exists to assess the consequences of the Sudbury impact on Precambrian ocean chemistry and early life.},
author = {Pufahl, Peir K. and Hiatt, Eric E. and Stanley, Clifford R. and Morrow, Jared R. and Nelson, Gabriel J. and Edwards, Cole T.},
doi = {10.1130/G23751A.1},
issn = {00917613},
journal = {Geology},
keywords = {Bolide,Ejecta,Impact,Meteorite,Michigan,Platinum group elements,Sedimentology,Sudbury},
pages = {827--830},
title = {{Physical and chemical evidence of the 1850 Ma Sudbury impact event in the Baraga Group, Michigan}},
volume = {35},
year = {2007}
}
@article{Boast2006,
abstract = {A \~{}2.0-km-wide metamorphic aureole has been mapped beneath the northern margin of the 2.5-km-thick Sudbury Igneous Complex of the 1.85 Ga Sudbury impact structure. The aureole is difficult to observe in the field because it overprints Archean granitoids and high-grade polydeformed gneisses, which do not yield diagnostic thermal minerals at the macroscopic scale. However, detailed petrography and electron microscopy reveal four zones: albite-epidote (1,000 m wide), hornblende (900 m), and pyroxene (200 m) hornfels facies, and an innermost zone of partial melting (25 m). Using metamorphic isograds as markers, we have revealed previously undetected thrust faults between the Sudbury Igneous Complex and the Archean footwall. We demonstrate that, in places, all or part of the aureole has been overthrust and obscured at surface. Thrust units are segmented by northwest-trending strike-slip faults, which together form thrust-transfer fault systems that were active after the impact melt sheet had solidified. This post-impact deformation is attributed to late Penokean (<1.85 Ga) and possibly Grenvillian (\~{}1 Ga) compression. Overthrusting of the footwall by the Sudbury Igneous Complex may conceal sublayer, footwall breccia, and embayment units that are traditionally the hosts of massive Ni-Cu sulfides and related platinum group element deposits. An example is provided by the Ministic offset dike located in the west of the Sudbury basin, which, as an intrusion derived from the impact melt, is atypical in not being associated with an exposed embayment structure.},
author = {Boast, M. and Spray, J. G.},
doi = {10.2113/gsecongeo.101.8.1583},
issn = {03610128},
journal = {Economic Geology},
pages = {1583--1594},
title = {{Superimposition of a thrust-transfer fault system on a large impact structure: Implications for Ni-Cu-PGE exploration at Sudbury}},
volume = {101},
year = {2006}
}
@article{Nriagu1998,
abstract = {Mining and resource recovery activities have not been kind to ecosystems in the Sudbury basin, Ontario. The combination of logging, smelting, fires and erosion resulted in an unusual anthropogenic ecosystem of denuded barren land with lifeless lakes, or a micro-desert. Since the 1970s, however, the concerted efforts made to reduce the emissions and rehabilitate parts of the degraded ecosystem have resulted in improvements in water quality, and recoveries in phytoplankton, zooplankton, zoobenthos and fish communities but have had little impact on toxic metal concentrations in many lakes. We show that most of the catchments in the Sudbury basin have become saturated with Cu and Ni, and some with Zn and Pb. It is estimated that mobilization of metals stored in soils and glacial overburden by surface runoff, groundwater drainage and wind re-working of tailings can sustain the high concentrations of Cu and Ni in many lakes for well over 1000 years. Strategies to immobilize the pollutant metals in the watershed rather than further emission controls may be required for dealing with high levels of toxic metals in surface waters of the saturated ecosystems. Copyright (C) 1998 Elsevier Science B.V. All rights reserved.},
author = {Nriagu, Jerome O. and Wong, H. K T and Lawson, Gregory and Daniel, Peter},
doi = {10.1016/S0048-9697(98)00284-8},
isbn = {0048-9697},
issn = {00489697},
journal = {Science of the Total Environment},
keywords = {Metal flux,Metal pollution,Metal yield,Saturated ecosystem,Soil pollution},
pages = {99--117},
pmid = {9861730},
title = {{Saturation of ecosystems with toxic metals in Sudbury basin, Ontario, Canada}},
volume = {223},
year = {1998}
}
@article{Lightfoot2001,
abstract = {The Sudbury Igneous Complex is widely believed to be the result of melt generation due to meteorite impact, and the Ni and Cu ores associated with the sublayer and offsets of the complex are considered to be a consequence of this event. The noritic and granophyric rocks of the main mass have similar yet elevated ratios of large ion lithophile elements (LILE) and light rare earth elements (LREE) relative to high field strength elements (HFSE) and heavy rare earth elements (HREE). This indicates that the magma was homogenized in terms of the incompatible trace element ratios and had a large chemical and isotopic contribution from an upper crustal source. Through the mafic and felsic norite there is an upward decline in MgO (14.6–4.4 wt \%) and a small increase in incompatible element abundance (Ce = 35–50 ppm). The granophyre becomes slightly more evolved from the top toward the base (MgO = 0.6–2 wt \%; Ce = 90–120 ppm). Some of these variations may be due to differentiation, but we believe that the crystallization of the original melt took place from the base upward and the top downward; this implies that the melt sheet was fundamentally density stratified into noritic and granophyric layers. Estimates of the bulk composition of the melt sheet are within the range of quartz diorite from the different Sudbury offsets, and we believe that all of these rocks are the products of impact- triggered melting of upper crustal rocks of the Sudbury region. Mafic norite from the base of the Sudbury Igneous Complex has 1 to 5 modal percent pyrrhotite, plus chalcopyrite and elevated Ni (40–1,000 ppm) and Cu (40–1,140 ppm); this is overlain by felsic norite, which contains trace pyrite, and low Ni (15–40 ppm) and Cu (7–40 ppm). For a similar range of MgO, the upper portion of the felsic norite unit has 5 to 10 times lower Ni and Cu than within-plate basalts and crustal rocks. There is an increase in Ni (1–5 wt \%) and Cu (1–5 wt \%) tenor of sulfide toward the base of the norite sequence. The depletion of the upper part of the felsic norite in Ni, Cu, and platinum group elements (PGE) is most likely due to equilibration of the magma with magmatic sulfide and accumulation of the dense sulfide liquid to the base of the melt sheet. The parental magmas giving rise to these disseminated sulfides contained \~{}210 ppm Ni and 109 ppm Cu based on realistic partition coefficients and magma/sulfide ratio; the process of sublayer and offset ore formation did not entirely strip the Ni, Cu, and PGE from the main mass. About 40 percent of the total Ni-Cu-PGE inventory of the Sudbury Igneous Complex is related to quartz diorite in offset dikes and Sudbury breccia belts. The marginal sulfide-free quartz diorite of the Worthington offset has a Ni and Cu abundance that is similar to crustal rocks over the same range in MgO content (3–6 wt \% MgO). We believe that the quartz diorite initially formed from an S-undersaturated magma that was injected downward away from the melt sheet. The Worthington offset quartz diorite averages 83 ppm Ni and 98 ppm Cu, which is similar to sulfide-poor quartz diorite from the other offsets (Lightfoot et al., 1997b). Saturation of the melt sheet in S was achieved shortly after the injection of the quartz diorite magmas but before the center of the offset had entirely crystallized. The presence of immense resources of magmatic sulfides in the Copper Cliff offset, with sulfide metal tenors of \~{}13 wt percent Cu, \~{}6 wt percent Ni, \~{}18 ppm Pt, and high Pd/Ni, indicates that these sulfides formed early and from a parental magma with a Ni/Cu ratio of \~{}1. The parental magma is calculated to have contained 310 ppm Ni and 311 ppm Cu, and this is not characteristic of the bulk crustal melt. Presumably density segregation accompanied or predated sulfide saturation in the melt sheet, and this mechanism provides a way to produce a more metal-rich parental magma with a Ni/Cu \~{}1. The formation of the geologically complex and heavily contaminated sublayer is believed to either accompany or postdate offset formation. The sublayer at the Whistle and Creighton mines occupies embayment structures at the base of the Sudbury Igneous Complex, which are directly connected to small offsets. Ores from the Creighton embayment have sulfide metal tenors of \~{}7 wt percent Cu, \~{}5 wt percent Ni, and a lower Pd/Ni than the offset ores. Calculated parental magmas would have 265 ppm Ni and 172 ppm Cu, which indicates that the metals were not all removed by the formation of offset ores. Mass-balance calculations show that there is more than enough Ni and Cu in the initial melt sheet to produce all of the known sulfide deposits at Sudbury. In this model there is no requirement for metal contributions from mantle sources or from protores. The mineral potential of offset and embayment structures appears to be empirically linked to the thickness of the overlying noritic rocks, and this is consistent with our model.},
author = {Lightfoot, Peter C. and Doherty, Will},
doi = {10.2113/gsecongeo.96.8.1855},
issn = {03610128},
journal = {Economic Geology},
pages = {1855--1875},
title = {{Chemical evolution and origin of nickel sulfide mineralization in the sudbury igneous complex, Ontario, Canada}},
volume = {96},
year = {2001}
}
@article{Gay1976,
abstract = {Spherical particles of silicate composition occur on the surface of some shatter cones from the collar rocks around the Vredefort structure, South Africa. They are best developed on shatter cones from a shale horizon but are also found on more arenaceous rocks and banded ironstones. They have not been found on shatter cones from the purer quartzites.},
author = {Gay, N C},
doi = {10.1126/science.194.4266.724},
issn = {0036-8075},
journal = {Science (New York, N.Y.)},
pages = {724--725},
pmid = {17832541},
title = {{Spherules on shatter cone surfaces from the vredefort structure, South Africa.}},
volume = {194},
year = {1976}
}
@article{Mungall2002,
author = {Mungall, James E.},
doi = {10.2113/gsecongeo.97.7.1563},
issn = {03610128},
journal = {Economic Geology},
pages = {1563--1576},
title = {{Late-stage sulfide liquid mobility in the main mass of the Sudbury Igneous Complex: Examples from the Victor Deep, McCreedy East, and Trillabelle Deposits}},
volume = {97},
year = {2002}
}
@misc{Grieve2000,
abstract = {Vredefort, Sudbury, and Chicxulub are the largest known terrestrial impact structures. All have been cited as multi-ring basins. The available data indicate that all have some form of multiple-ring attributes, most commonly structural features. Chicxulub, however, is the only example with morphological ring features. There are also commonalities in the structural and lithological features of Vredefort and Sud- bury, and it is possible to construct a generalized compilation of the character of 200– 300 km diameter impact basins on Earth. It is not clear, however, that any of these structures had the original morphological characteristics of large lunar multi-ring basins. Additional data and synthesis are required to fully characterize these structures in order to realize their potential to constrain large-scale cratering processes. If this is not sufficient incentive for further studies (the environmental effects of Chicxulub aside), the Vredefort, Sudbury, and Chicxulub impact events are also the reason for the existence of world-class mineral and hydrocarbon deposits.},
author = {Grieve, Richard and Therriault, Ann},
booktitle = {Annual Review of Earth and Planetary Sciences},
doi = {10.1146/annurev.earth.28.1.305},
isbn = {0084-6597},
issn = {0084-6597},
pages = {305--338},
pmid = {318},
title = {{Vredefort, Sudbury, Chicxulub: Three of a Kind?}},
volume = {28},
year = {2000}
}
@article{Riller2010a,
abstract = {Large-volume pseudotachylite bodies in impact structures are dike like and consist of angular and rounded wall-rock fragments enveloped by a microcrystalline and sporadically glassy matrix that crystallized from a melt. Knowledge of the formation of pseudotachylite bodies is important for understanding mechanics of complex crater formation. Most current hypotheses of pseudotachylite formation inherently assume that fragmentation and melt generation occur during a single process. Based on the structure of pseudotachylite bodies at Sudbury (Canada) and Vredefort (South Africa), we show that these processes differ in time and space. We demonstrate that the centimeter- to kilometer-scale bodies are effectively fragment- and melt-filled tension fractures that formed by differential rotation of target rock during cratering. Highly variable pseudotachylite characteristics can be accounted for by a single process, i.e., drainage of initially superheated impact melt into tension fractures of the crater floor.},
author = {Riller, Ulrich and Lieger, Daniel and Gibson, Roger L. and Grieve, Richard A F and St\"{o}ffler, Dieter},
doi = {10.1130/G30806.1},
issn = {00917613},
journal = {Geology},
pages = {619--622},
title = {{Origin of large-volume pseudotachylite in terrestrial impact structures}},
volume = {38},
year = {2010}
}
@article{Dreuse2010,
abstract = {Terra Nova, 00, 000 000, 2010Based on high-resolution topography data and the geometry of geological contact traces at the surface, we determined the orientation of layer interfaces of the Sudbury Igneous Complex (SIC). Our analysis provides, for the first time, quantitative structural evidence for the thickness variation of its layers, which supports an impact melt origin of the SIC. The present crater floor topography varies up to 400 m over distances of hundreds of metres to a few kilometres, and up to 1500 m over a distance of about 25 km. Crater floor depressions are spatially associated with economically important sulphide mineral deposits, which points to a viable exploration strategy. Finally, observed variations in the width of the thermal aureole imparted by the SIC on its host rocks are due to primary thickness variations of the SIC rather than post-impact deformation. © 2010 Blackwell Publishing Ltd.},
author = {Dreuse, Ren\'{e} and Doman, Daniel and Santimano, Tasca and Riller, Ulrich},
doi = {10.1111/j.1365-3121.2010.00965.x},
isbn = {1365-3121},
issn = {09544879},
journal = {Terra Nova},
pages = {463--469},
title = {{Crater floor topography and impact melt sheet geometry of the Sudbury impact structure, Canada}},
volume = {22},
year = {2010}
}
@article{Narendrula2012,
abstract = {DR-Congo is a main world producer of copper (Cu) and cobalt (Co). Several hydrometallurgical plants and smelters also produced zinc, arsenic, and cadmium as by-products. In Sudbury (Canada), the production of nickel, copper and other metals has been maintained at high levels while industrial SO emissions have been reduced by approximately 90\% through combination of industrial technological developments and legislated controls. Metal analysis in the present study revealed that the levels of copper and cobalt in soils from mining sites in the Lubumbashi (DR-Congo) were up to 200 fold higher compared to contaminated Sudbury sites and tailings. Zinc content in soil samples from some mining areas in Lubumbashi was at least 70 times higher compared to samples from the Sudbury area. Nickel content in soil samples from Lubumbashi were much lower compared to the Sudbury Region samples. Overall, this study confirms that the African Copper belt region is among the ten most polluted areas in the world. [ABSTRACT FROM AUTHOR]},
author = {Narendrula, R. and Nkongolo, K. K. and Beckett, P.},
doi = {10.1007/s00128-011-0485-7},
issn = {00074861},
journal = {Bulletin of Environmental Contamination and Toxicology},
keywords = {DR-Congo,Lubumbashi,Mining,Pollution,Soil metal content,Sudbury},
pages = {187--192},
pmid = {22139330},
title = {{Comparative soil metal analyses in Sudbury (Ontario, Canada) and Lubumbashi (Katanga, DR-Congo)}},
volume = {88},
year = {2012}
}
@article{Mungall2004,
abstract = {Deformation and melting of the crust during the formation of large impact craters must have been important during the Earth's early evolution, but such processes remain poorly understood. The 1.8-billion-year-old Sudbury structure in Ontario, Canada, is greater than 200 km in diameter and preserves a complete impact section, including shocked basement rocks, an impact melt sheet and fallback material. It has generally been thought that the most voluminous impact melts represent the average composition of the continental crust, but here we show that the melt sheet now preserved as the Sudbury Igneous Complex is derived predominantly from the lower crust. We therefore infer that the hypervelocity impact caused a partial inversion of the compositional layering of the continental crust. Using geochemical data, including platinum-group-element abundances, we also show that the matrix of the overlying clast-laden Onaping Formation represents a mixture of the original surficial sedimentary strata, shock-melted lower crust and the impactor itself.},
author = {Mungall, James E and Ames, Doreen E and Hanley, Jacob J},
doi = {10.1038/nature02577},
issn = {0028-0836},
journal = {Nature},
pages = {546--548},
pmid = {15175748},
title = {{Geochemical evidence from the Sudbury structure for crustal redistribution by large bolide impacts.}},
volume = {429},
year = {2004}
}
@article{Dixit1991,
abstract = {Stratigraphic changes in diatoms and chrysophytes from three manipulated Sudbury lakes were explored in an attempt to examine the influence of fertilization and/or neutralization on algal microfossil assemblages. Both diatom- and chrysophyte-inferred pH profiles indicate that the pH of Labelle Lake has remained fairly stable in the past. The study of Labelle and Middle lakes indicates that the addition of nutrients to acidic and non-acidic oligotrophic lakes did not directly influence diatom and chrysophyte species composition, perhaps because pH remained stable. The diatom and chrysophyte assemblages of Middle Lake only changed when the pH was raised. In Mountaintop Lake the recent shift in chrysophyte species composition and the resulting inferred pH declines is most likely related to a decline in mid-summer epilimnetic pH. Reliable paleolimnological inferences are difficult in lakes such as these because it is difficult to track limnological conditions in the absence of modern analogues.},
author = {Dixit, Sushil S. and Dixit, Aruna S. and Smol, John P.},
doi = {10.1007/BF00050957},
issn = {00188158},
journal = {Hydrobiologia},
keywords = {Sudbury,acidification,chrysophytes,diatoms,fertilization,inferred pH,neutralization},
pages = {245--252},
title = {{Paleolimnological investigation of three manipulated lakes from Sudbury, Canada}},
volume = {214},
year = {1991}
}
@article{Cawthorn2005,
abstract = {The Sudbury Igneous Complex (SIC) contains abundant sulphides, especially near the base, and hosts one of the world’s largest nickel and copper deposits. The Bushveld Complex (BC) contains relatively little sulphide, but hosts the world’s largest platinum-group element deposits. The most recent calculations of the sulphur solubility in magmas that produced the BC are based on the sulphur solubility of mid-ocean ridge basalts that have less SiO<sub>2</sub> than Bushveld magmas. Such a difference may lead to an overestimation of sulphur solubility by as much as 25\%. The revised sulphur solubility curve presented here for Bushveld magmas may also have relevance to the SIC in view of its siliceous nature. Sulphur solubility curves can be used to determine the proportion of sulphide expected in cumulate rocks once sulphur saturation is attained. These models are tested using observed sulphide contents in both intrusions. The observed decreasing sulphur contents (\&gt;0.3–0.05\% S) from the base of the SIC upward are broadly consistent with these sulphur solubility curves, and are consistent with sulphide saturation through the entire mafic portion. In contrast, the lower half of the BC contains extremely little sulphur (generally \&lt;0.02\% S), except for two thin layers, which is not consistent with sustained sulphide saturation at any level. Previous interpretations of the sulphur content of Bushveld rocks have suggested that the Lower and Critical Zones were sulphide saturated, but that they had then lost some of the sulphide due to various processes. The present sulphide content of the cumulates of the BC is so low that, if they had once been saturated, over 90\% of all the sulphide must have been removed. Mass balance calculations indicate that these large amounts of displaced sulphur remain unaccounted for in such models. Instead, the observed sulphur contents are in reasonable agreement with that expected in a cumulate sequence forming from a sulphur-undersaturated magma. Whereas the Merensky Reef and Bastard pyroxenite contain minor sulphides, the compositions of the immediate hanging wall rocks indicate sulphide undersaturation. Such an abrupt return to sulphide undersaturation is not consistent with models involving sulphide formation from large volumes of magma. One possible explanation for these two observations is that intermittent sulphur degassing occurred through a fractured roof of the BC, so that the magma was never continuously sulphur-saturated with respect to an immiscible sulphide liquid.},
author = {Cawthorn, R. Grant},
doi = {10.1007/s00126-005-0465-0},
isbn = {0026-4598},
issn = {00264598},
journal = {Mineralium Deposita},
keywords = {Bushveld Complex,Degassing,Sudbury Igneous Complex,Sulphide immiscibility},
pages = {1--12},
title = {{Contrasting sulphide contents of the Bushveld and Sudbury Igneous Complexes}},
volume = {40},
year = {2005}
}
@book{Card1976,
abstract = {Card, K.D. 1978. Geology of the Sudbury–Manitoulin area, districts of Sudbury and Manitoulin; Ontario Geological Survey, Geological Report 106, 238p.},
author = {Card, K D},
booktitle = {Geoscience report 138},
pages = {viii, 63 p.},
title = {{Geology of the McGregor Bay - Bay of Islands Area : Districts of Sudbury and Manitoulin}},
year = {1976}
}
@article{Szabo2006,
abstract = {Paleomagnetic results from fine-grained samples of Sudbury breccia, collected from 28 sites around the northern half of the 1.85 Ga Sudbury Igneous Complex (SIC), reveal the existence of two major components of magnetization, A and B. A, carried by magnetite, was formed close to the time of the SIC and has a direction that is related to the dip of the norite unit within the different ranges of the SIC. Component B, mainly carried by pyrrhotite, is a younger, secondary magnetization of more problematical origin, in part related to heating during the 1.24 Ga Sudbury magmatic event. In the northwest part of the SIC, A is found in breccia clasts, intermediate norite, sublayer, Levack Gneiss and Matachewan diabase, indicating that it is due to baking by the SIC. Tilt-correcting the West range by 36°, the North range by 22° and the northern East range by 36°, about axes parallel to local strike of the norite, minimises the dispersion of the paleomagnetic data to give a pre-folding direction of 199.4°/78.8°. The paleomagnetic data are similar to those obtained by Morris [Morris, W.A., 1984. Paleomagnetic constraints on the magmatic, tectonic, and metamorphic history of the Sudbury basin region. In: Pye, E.G., Naldrett, A.J., Giblin, P.E., (Eds.), The Geology and Ore Deposits of the Sudbury Structure, Special vol. 1. Ontario Geological Survey, pp. 411-427] on the SIC, suggesting for the first time that the SIC and the surrounding basement were deformed (probably during the 1.9-1.7 Ga Penokean Orogen) as a single unit. The un-folding of the paleomagnetic directions indicates that SIC limbs were already inclined, a result of the original intrusion configuration, or a syn-folding remanence. It is possible that the SIC was originally flatter if the distribution of paleomagnetic directions is the result of flexural flow folding. This explanation could also produce a similar distribution of paleomagnetic directions across the basin, but cannot be quantified due to the lack of measurable fold-related strain in breccia and SIC units around the northern half of the basin. © 2006 Elsevier B.V. All rights reserved.},
author = {Szab\'{o}, Erika and Halls, Henry C.},
doi = {10.1016/j.precamres.2006.07.010},
issn = {03019268},
journal = {Precambrian Research},
keywords = {Deformation,Paleomagnetism,Rock magnetism,Sudbury Structure,Sudbury breccia},
pages = {27--48},
title = {{Deformation of the Sudbury Structure: Paleomagnetic evidence from the Sudbury breccia}},
volume = {150},
year = {2006}
}
@inproceedings{Gunn1995,
abstract = {A case history is presented describing the ecosystem changes that accompanied the nearly 90\% reduction of SO2 and metal particulate emissions from Sudbury smelters during the past 25 years. The instances of severe ground-level fumigations that caused acute damage to vegetation in an area of approximately 1,000 km2 have been nearly completely eliminated. Significant improvements in water quality have also occurred in many of the estimated 7,000 acid-damaged lakes. Several species of acid-sensitive phytoplankton, Zooplankton and insects have invaded lakes where improvements have occurred. Epiphytic lichens have reinvaded the former “lichen desert” that once extended out 7 km from the smelters. Sensitive species such as Evernia mesomorpha and Usnea hirta now exist throughout the area. The vascular plant communities have been relatively slow to recover in the most severely damaged terrestrial areas. Metal-tolerant grasses (e.g. Agrostis scabra. Deschampsia caespitosa) were the first species to invade the barrens. Acid- and metal-contamination of soil, severe microclimate conditions, and the damaging effects of insect pests appear to delay recovery of terrestrial ecosystems. Recovery rates of aquatic ecosystems are also affected by a suite of physical, chemical and biotic interactions and many lakes remain severely damaged},
author = {Gunn, J. and Keller, W. and Negusanti, J. and Potvin, R. and Beckett, P. and Winterhalder, K.},
booktitle = {Water, Air, and Soil Pollution},
doi = {10.1007/BF00477238},
isbn = {0049-6979},
issn = {00496979},
keywords = {acidification,copper,nickel,recovery,smelter},
pages = {1783--1788},
title = {{Ecosystem recovery after emission reductions: Sudbury, Canada}},
volume = {85},
year = {1995}
}
@article{Cohen2000,
abstract = {Re-Os isotope analyses have been performed on a suite of 14 melanorite inclusions from the Sublayer of the Sudbury Igneous Complex (SIC) at Whistle Mine, 30 km NNE of Sudbury, Ontario, Canada. Six S-poor olivine melanorites have relatively unradiogenic present-day 
                        187Os/
                        188Os ratios of 0.16-1.2 and define an imprecise age of 1.97 Ga. Their 
                        187Os/
                        188Os((1.85)) ratios of 0.107-0.237 are compatible with derivation either from the mantle at the time of SIC formation 1.85 Ga ago, or from pre-existing crustal rocks with low Re/Os ratios and unradiogenic Os isotope compositions. In contrast, the relatively S-rich inclusions define much older ages of 2.46 Ga (melanorites) and 2.67 Ga (olivine melanorites), while 
                        187Os/
                        188Os((1.85)) ratios of 0.41-1.80 unequivocally demonstrate that their Os was largely derived from pre-existing crustal lithologies. The Os isotope compositions and S abundances of the inclusions are consistent with mixing at 1.85 Ga between an unradiogenic silicate fraction defined by the S-poor suite and a radiogenic sulphide-rich component with Re/Os ratios similar to those of pre-existing crustal lithologies. Attempts to evaluate the source of the Ni, Cu, S and PGE in the SIC through mass-balance calculations are not definitive because of the difficulties in estimating accurately both present-day and pre-SIC crustal abundances. However, crude estimates suggest that the overall levels of Ni and Cu in the pre-impact crust were probably sufficient to account for the budget of these elements in the present-day SIC, but do not rule out the possibility of significant late-Archaean/early-Proterozoic sulphide mineralisation in the pre-existing SIC target rocks. (C) 2000 Elsevier Science B.V. All rights reserved.},
author = {Cohen, A. S. and Burnham, O. M. and Hawkesworth, C. J. and Lightfoot, P. C.},
doi = {10.1016/S0009-2541(99)00162-X},
isbn = {1908655151},
issn = {00092541},
journal = {Chemical Geology},
keywords = {Impact,Osmium,Platinum group elements,Rhenium,Sudbury Igneous Complex,Ultramafic inclusions},
pages = {37--46},
title = {{Pre-emplacement Re-Os ages from ultramafic inclusions in the sublayer of the Sudbury Igneous Complex, Ontario}},
volume = {165},
year = {2000}
}
@misc{Darling2012,
abstract = {Laser-ablation (LA) multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) is ideally suited to in situ determination of isotope ratios in sulphide minerals. Using samples of magmatic sulphide ore from the Sudbury impact structure, we test LA-MC-ICPMS analytical protocols that aim to meet a range of analytical challenges in the analysis of Pb isotopes. These include: potential matrix sensitive isotopic fractionation; interferences on Pb isotopes; low melting points of many sulphide minerals; the availability of standards.Magmatic sulphides of wide ranging mineralogy (pyrrhotite, pentlandite, chalcopyrite, pyrite and sphalerite) were analysed for Pb isotopic composition, using the silicate glass NIST SRM 610 as an external standard to correct for instrumental mass-fractionation. Despite matrix sensitive melting and re-deposition around ablation pits, several lines of evidence indicate that all analyses are accurate, within typical analytical uncertainties of 0.003-2\% (2. ??), and that the defined approach is insensitive to compositional diversity in sample matrix: (a) laser ablation and dissolution based measurements of sulphide powders are in agreement; (b) analyses from each sample define isochron ages within uncertainty of the known crystallization age (1850. Ma); (c) the results of sulphide measurements by laser ablation are consistent with age-corrected feldspar analyses from the same samples.The results have important implications for ore formation in Sudbury. The Pb isotope data regressions are consistent with age corrected feldspar analyses from each respective sample, which together with time integrated Th/U ratios that match whole rock values (3.1, 4.0 and 6.1 for the Worthington, Copper Cliff and Parkin Offset Dykes, respectively) indicate chemical equilibrium between the silicate and sulphide systems during ore formation. The sulphides within each respective sample have indistinguishable model initial Pb isotope ratios ( 
                        207Pb/ 
                        204Pb 
                        m), irrespective of mineralogy or texture, indicating a common origin for ores within each of three different Offset Dykes. Furthermore, variations between Offset Dykes (e.g., 
                        207Pb/ 
                        204Pb 
                        m=15.514??0.012, 15.399??0.009 and 15.275??0.003) show that the ores have differing crustal sources on previously unrecognized scales. Mass balance considerations, particularly for MgO, Ni and Cu, indicate that the spatial distribution of mafic target rocks played a significant role in controlling the mineralization potential in different parts of the melt sheet. ?? 2012 Elsevier Ltd.},
author = {Darling, J. R. and Storey, C. D. and Hawkesworth, C. J. and Lightfoot, P. C.},
booktitle = {Geochimica et Cosmochimica Acta},
doi = {10.1016/j.gca.2012.09.028},
isbn = {0016-7037},
issn = {00167037},
pages = {1--17},
title = {{In-situ Pb isotope analysis of Fe-Ni-Cu sulphides by laser ablation multi-collector ICPMS: New insights into ore formation in the Sudbury impact melt sheet}},
volume = {99},
year = {2012}
}
@article{Karmiloff-Smith1998,
abstract = {Replies to R. Samuels (see record 1999-10156-005), A. Clark (see record 1999-10156-006), M. Harris (see record 1999-10156-007), and D. W. Lightfoot (see record 1999-10156-008)},
author = {Karmiloff-Smith, Annette U London University Coll Inst of Child Health Neurocognitive Development Unit London U S and Plunket, Kim and Johnson, Mark H and Elman, Jeffrey L},
doi = {10.1111/1468-0017.00095},
isbn = {0268-1064 (Print); 1468-0017 (Electronic)},
issn = {0268-1064},
journal = {Mind \& Language},
pages = {588--604},
title = {{What does it mean to claim that something is "innate"? Response to Clark, Harris, Lightfoot and Samuels}},
volume = {13},
year = {1998}
}
@article{McCormick2002,
abstract = {The footwall breccia is one of the main Ni-Cu-(PGE) ore-hosting units of the Sudbury camp. This polymict, matrix-supported, contact-metamorphosed breccia occurs between the Sudbury Igneous Complex and the footwall rocks along the west, north, and east margins of the Sudbury structure. In areas where there are depressions or embayments in the footwall, the footwall breccia and basal units of the Sudbury Igneous Complex are thickened, and the footwall breccia is variably mineralized. Mineralogical and textural variations of footwall breccia samples from the Strathcona embayment in proximity to the Fraser mine suggest that the mineralogy and texture of this unit vary as a function of proximity to the Sudbury Igneous Complex, proximity to ore, and location within the embayment. The most mafic footwall breccia mineralogy is present proximal to the base of the Sudbury Igneous Complex within a transition zone. The presence of relatively mafic, hydrous, and Cl-rich silicate minerals (e.g., biotite and amphibole) characterize the footwall breccia matrix around ore zones and form an alteration halo of up to 5 m thick. Textural variations include a coarsening of quartz and feldspar grains with increasing proximity to the Sudbury Igneous Complex contact. Textural coarsening also occurs from the margins of the Strathcona embayment to the center. Together, these mineralogical and textural variations influence the color of the footwall breccia matrix and can explain some of the gray colors that are typical of mineralized footwall breccia. These variations also constrain the timing of formation of this unit and suggest that at least three phases of footwall breccia exist.},
author = {McCormick, Kelli A. and Fedorowich, John S. and McDonald, Andrew M. and James, Richard S.},
doi = {10.2113/gsecongeo.97.1.125},
issn = {03610128},
journal = {Economic Geology},
pages = {125--143},
title = {{A textural, mineralogical, and statistical study of the footwall breccia within the strathcona embayment of the Sudbury structure}},
volume = {97},
year = {2002}
}
@article{Shott1989,
abstract = {Shovel-test sampling is the most common site-discovery technique used in vegetated areas, but its effectiveness is questionable. Recent papers in American Antiquity by Nance and Ball and by Lightfoot discuss the technique at length. The papers are welcome additions to the literature, but both contain deficiences that require comment and clarification.},
author = {Shott, Michael J. and Anonymous},
doi = {10.2307/281714},
isbn = {00027316},
issn = {1095-9203},
journal = {American Antiquity},
pages = {396--404},
pmid = {49},
title = {{Shovel-Test Sampling in Archaeological Survey: Comments on Nance and Ball, and Lightfoot}},
url = {http://links.jstor.org/sici?sici=0002-7316(198904)54:2<396:SSIASC>2.0.CO;2-4},
volume = {54},
year = {1989}
}
@article{Prevec2000,
abstract = {The mineralized sublayer at the base of the Sudbury Igneous Complex (SIC) consists of two variants, the noritic contact sublayer and radial and concentric quartz dioritic offset dykes. Both are characterized by the presence of significant quantities of Ni-Cu-PGE sulphides and by a prominent population of recrystallized diabasic-textured and melanocratic to ultramafic fragments. The two variants of the sublayer contain compositionally distinct inclusion populations and inclusion-bearing matrices. Contact sublayer and offset dykes hosted by north range granitoid footwall can be distinguished from those hosted by south range basaltic and metasedimentary footwall environments. The compositional variation in SIC rocks can be described in terms of contributions from exposed crustal rocks and differentiation of the resultant melt(s). The basaltic inclusion population is characterized by hornfels recrystallization of the plagioclase, and is geochemically and isotopically identified with Huronian basalts which comprise the south range footwall, with (Ce/Yb)(N) ratios of around 2.5 and ??(Nd)1850 between -2 to -5. The melanocratic inclusions in the sublayer are typically coarse-grained and undeformed, with incompatible element contents and radiogenic isotopic compositions intermediate between those of the basaltic inclusions and those of the melt sheet, which has (Ce/Yb)(N) ratios of around 10 and ??(Nd)1850 around -9. Calculated crystallization models are consistent with derivation of the ultramafic inclusions by crystallization from a magma produced by mixing of molten basaltic footwall with basal melt sheet. It is proposed that the sublayer appeared as the marginal facies of a meteorite impact melt sheet as a result of footwall melting following the impact. This basal layer was progressively enriched in sulphides and mafic cumulates from above through differentiation during cooling. Offset dykes were emplaced and the magmas effectively removed from the system. Subsequently, continued evolution of the marginal facies produced the more mafic inclusions in the contact sublayer. No extracrustal (e.g., mantle) component is envisioned in this model to explain the silicate compositional distributions in the SIC, and mafic crustal rocks in the target zone are implicated as the metal source for the SIC deposits. (C) 2000 Published by Elsevier Science B.V. All rights reserved.},
author = {Prevec, S. A. and Lightfoot, P. C. and Keays, R. R.},
doi = {10.1016/S0024-4937(00)00005-0},
issn = {00244937},
journal = {Lithos},
keywords = {Geochemistry,Meteorite impact,Mineral deposits,Neodymium isotopes},
pages = {271--292},
title = {{Evolution of the sublayer of the Sudbury Igneous Complex: Geochemical, Sm-Nd isotopic and petrologic evidence}},
volume = {51},
year = {2000}
}
@incollection{Dietz1971,
abstract = {Global distribution, force field vectoring, explosion focus, total energy of input.},
author = {Dietz, Robert S},
booktitle = {Planetology--Planetologie, Section 15.},
issn = {1023-3210, 1023-3210},
keywords = {23 Geomorphology,astroblemes,cryptoexplosion features,distribution,geomorphology,global,impact craters,impact features,meteor craters,shatter cones},
pages = {112--118},
title = {{Shatter Cones (Shock Fractures) in Astroblemes}},
volume = {24; 14},
year = {1971}
}
@misc{Stesky1983,
abstract = {Shatter cones produced by intense shock are found widespread on these islands, which have been interpreted as the central uplift of an eroded meteoritic impact crater approx 30 km in diameter. The cones are best developed in Keweenawan basalt flows and chilled margins of associated feeder dykes, and in Archaean diorite and foliated feldspar porphyry. At certain sites cones show an elongate cross-section and anomalous orientation caused by foliation- induced clastic anisotropy in the host rock. In general the cones point upward and inward towards the centre of the Slate Islands group. There is increased convergence of cone axes to a central focus (the inferred impact point) that occurs approx 1 km above the present land surface.},
author = {Stesky, R. M. and Halls, H. C.},
booktitle = {Canadian Journal of Earth Sciences},
doi = {10.1139/e83-001},
issn = {0008-4077},
pages = {1--18},
pmid = {264},
title = {{Structural analysis of shatter cones from the Slate Islands, northern Lake Superior}},
volume = {20},
year = {1983}
}
@misc{Bray1966,
abstract = {The Sudbury structure has been interpreted by R. S. Dietz as an astrobleme. Fieldwork indicates that shatter cones are locally developed in a belt up to 11 miles wide around the outer contact of the nickel intrusive, and are confined to preintrusive rocks. Although apparently modified by folding, the cones show a strong preferred orientation toward the Sudbury Basin. Such a distribution and orientation are not incompatible with the astrobleme theory as expounded by Dietz. However, shatter-coning may not be uniquely characteristic of meteor impact, and it is hoped that further evidence will be forthcoming by which the theory may be properly evaluated.},
author = {Bray, J. Guy},
booktitle = {The Journal of Geology},
doi = {10.1086/627158},
isbn = {00221376},
issn = {0022-1376},
pages = {243--245},
title = {{Shatter Cones at Sudbury}},
volume = {74},
year = {1966}
}
@misc{Dietz1959,
abstract = {A review of the characteristics of shatter cones associated with cryptoexplosion structures at various localities throughout the world and with the Bosumtwi (Ghana) and Kaalijarv (Estonia) meteorite craters supports the conclusion that shatter cones are diagnostic criteria for identification of ancient meteorite impact scars (astroblemes). Data on the characteristics and orientation of shatter cones are summarized, together with data on conical geologic structures resembling shatter cones, whose formation was not due to shock-loading.},
author = {Dietz, Robert S.},
booktitle = {The Journal of Geology},
doi = {10.1086/626603},
issn = {0022-1376},
pages = {496--505},
pmid = {513},
title = {{Shatter Cones in Cryptoexplosion Structures (Meteorite Impact?)}},
volume = {67},
year = {1959}
}
@article{Pattison1979,
author = {Pattison, Edward F},
journal = {Canadian Mineralogist},
pages = {257--274},
title = {{Canadian Mineralogist Vol. 17, pp. 257-2J74 (1979)}},
volume = {17},
year = {1979}
}
@misc{Prevec2005,
abstract = {New filtering of aeromagnetic images of the Sudbury area indicates the existence of a large, elliptical feature that appears to underlie the deformed Sudbury Structure in the region of the exposed Levack Gneiss Complex, such that the two features have long axes which are significantly orthogonal to one another. A north–south-oriented ellipse appears to be crosscut by that of the Sudbury Structure and does not correspond to known local lithological or structural trends. The magnetic images, combined with existing tectonic, petrological, geothermometric and geobarometric, and geochronological data, are used to suggest the existence of a pre-impact crustal dome in the southernmost Abitibi subprovince, probably related to ca. 2450 Ma rifting and magmatism in the area. This is consistent with existing petro logical and tectonic evidence from a variety of sources. Although the doming is itself unrelated to the ca. 1850 Ma Sudbury event, it may have affected the thermal regime existing at the time of impact, which would have profound implications for the subsequent evolution of the Sudbury Igneous Complex.},
author = {Prevec, Stephen A and Cowan, Duncan R and Cooper, Gordon RJ},
booktitle = {Canadian Journal of Earth Sciences},
doi = {10.1139/e04-097},
issn = {0008-4077},
pages = {1--9},
title = {{Geophysical evidence for a pre-impact Sudbury dome, southern Superior Province, Canada}},
volume = {42},
year = {2005}
}
@incollection{IvanovB.A.Deutsch1999,
abstract = {The Sudbury Igneous Complex (SIC) is interpreted as the solidified impact melt body of the 1.850-g.y.-old Sudbury impact structure. First results of cratering and thermal modeling for this approximately 250-km sized multi-ring structure are presented. The numerical calculations were done for the vertical impact of a stony (granite) body (cylindrical projectile, 12.5 km in diameter and height) impacting at a granite target with a velocity of 20 km s (super -1) . These simulations yield estimates of the transient cavity dimensions and the temperature field below the impact structure just after the modification stage. One-dimensional heat transfer modeling sets constraints for the thermal history of the impact melt. Cooling of the melt sheet, the present SIC, from the initial temperature of 2,000 degrees K to the liquidus at 1,450 degrees K lasted several 100 k.y, and below the solidus at 1,270 degrees K, about 300 k.y to 2 m.y., depending on the initial melt thickness H(SIC). The cooling sequence was modeled for H(SIC) of 2.5, 4, and 6 km. Given this long duration of cooling, postimpact tectonic processes during the Penokean orogeny may well have deformed the melt sheet prior to its final solidification. Prolonged cooling as well as this large-scale deformation may explain the present structural position and the composition of the Offset Dikes, consisting of differentiated impact melt.},
author = {{Ivanov, B. A., Deutsch}, A.},
booktitle = {Large meteorite impacts and planetary evolution; II.},
doi = {10.1130/0-8137-2339-6.389},
issn = {00721077},
keywords = {23 Geomorphology,Canada,Eastern Canada,Ontario,Sudbury Irruptive,Sudbury Structure,cooling,deformation,granites,heat flow,heat transfer,igneous rocks,impact craters,impact features,melts,models,one dimensional models,plutonic rocks,simulation,temperature,thermal history},
pages = {389--397},
title = {{Sudbury impact event; cratering mechanics and thermal history}},
volume = {339},
year = {1999}
}
@article{Ames2002,
abstract = {The 1.85 Ga Sudbury structure is the largest, well-preserved, exposed example of a terrestrial impact crater; it contains world-class Ni-Cu-platinum-group element (PGE) ores associated with the igneous component. A new understanding of the geology and geochemistry of the vitric crater-fill sequence, the Onaping Formation, provides constraints on the evolution of 1.85 Ga igneous rocks in the Sudbury structure. The Onaping Formation has a well-defined mappable stratigraphy composed of three members, seven stratigraphic units, and two types of intraformational dikes that are overprinted by an impact-generated hydrothermal system. Stratigraphic and alteration mapping provided a basis for well-constrained sampling and allowed the definition of the geochemical characteristics of the less altered rocks from each unit, including vitric bombs and blocks and intraformational vitric dikes. Significantly, the identification of a least altered composition of the vitric Onaping Formation enabled an investigation of the link between the early formed vitric melt phase in the impact crater-fill sequence and the Sudbury Igneous Complex and offset dikes. The least altered vitric Onaping Formation, represented by the massive, xenolith-poor cores of vitric bombs, blocks, and intraformational dikes, is andesitic in composition, consistent with a crustally derived melt. The melt composition (61.6 wt \% SiO2, 4.28 MgO, 60 ppm Ni) is remarkably uniform throughout the Onaping Formation with a typical enrichment of large ion lithophile and light rare earth elements and pronounced negative Nb and Ti anomalies. Incompatible trace element ratios and bulk concentrations of the Onaping Formation coincide with the main mass norite and offset quartz diorite compositions of the underlying Sudbury Igneous Complex but differ distinctly from the granophyre and quartz gabbro. Root mean squared differences in composition of the vitric Onaping Formation with the units of the Sudbury Igneous Complex and quartz diorite offset dikes show that the vitric Onaping Formation does not directly match any of these igneous units but more closely resembles the composition of the Ministic and Manchester offset dikes. The quartz diorite offset dikes have been proposed as representative of the bulk composition of the original melt of the Sudbury Igneous Complex. In detail, there are small compositional differences between North and South Range offset dikes and between these offset dikes and the concentric Manchester offset dike; however, such differences are lacking in the Onaping Formation. We propose that the least altered vitric composition of the Onaping Formation represents the best estimate of the bulk composition of an initial quenched melt, or shock melt, formed early in the evolution of the Sudbury structure and is a logical starting liquid to model the evolution of the Sudbury main mass and offset dikes. The offset dike compositions can be derived from Onaping Formation vitric shock melt by assimilation of progressively greater amounts of mafic material at deeper levels in the crater. This mafic-contaminated melt, or impact melt, developed at the base of the melt sheet and was injected into the offset dikes both prior to and contemporaneously with the earliest stages of sulfide precipitation from the Sudbury Complex. Fractionation of the mafic-contaminated melt by plagioclase and pyroxene accumulation produced the North Range felsic and mafic norite and the South Range norites. The chalcophile metal content of the Onaping Formation vitric phase closely reflects the overall metal ratios of the magmatic sulfide ores. The vitric Onaping Formation and unmineralized offset dikes have low liquidus temperatures (1,115°–1,125°C) and, if these units represent the source of metals in the sulfide deposits, unusually high mass distribution coefficients for Cu and Ni and high R factors are necessary to account for the metal endowment.},
author = {Ames, D. E. and Golightly, J. P. and Lightfoot, P. C. and Gibson, H. L.},
doi = {10.2113/gsecongeo.97.7.1541},
isbn = {0361-0128},
issn = {03610128},
journal = {Economic Geology},
pages = {1541--1562},
pmid = {823},
title = {{Vitric compositions in the Onaping Formation and their relationship to the Sudbury Igneous Complex, Sudbury structure}},
volume = {97},
year = {2002}
}
@article{Rousell2003,
abstract = {The Sudbury Structure, formed by meteorite impact at 1850 Ma, consists of three major components: (1) the Sudbury Basin; (2) the Sudbury Igneous Complex, which surrounds the basin as an elliptical collar; and (3) breccia bodies in the footwall known as Sudbury Breccia. In general, the breccia consists of subrounded fragments set in a dark, fine-grained to aphanitic matrix. A comparison of the chemical composition of host rocks, clasts and matrices indicates that brecciation was essentially an in-situ process. Sudbury Breccia forms irregular-shaped bodies or dikes that range in size from mm to km scale. Contacts with the host rocks are commonly sharp. The aspect ratio of most clasts is approximately 2 with the long axes parallel to dike walls. The fractal dimension (Dr) = 1.55. Although there appears to be some concentration of brecciation within concentric zones, small Sudbury Breccia bodies within and outside these zones have more or less random strikes and steep dips. Sudbury Breccia bodies near an embayment structure tend to be subparallel to the base of the Sudbury Igneous Complex. Sudbury Breccia occurs as much as 80 km from the outer margin of the Sudbury Igneous Complex. In an inner zone, 5 to 15 km wide, breccia comprises 5\% of exposed bedrock with an increase in brecciation intensity in embayment structures. Sudbury Breccia may be classified into three types based on the nature of the matrix: Clastic, pseudotachylite and microcrystalline. Clastic Sudbury Breccia, the dominant type in the Southern Province, is characterized by flow-surface structures. Possibly, a sudden rise in pore pressure caused explosive dilation and fragmentation, followed by fluidization and flowage into extension fractures. Pseudotachylite Sudbury Breccia, mainly confined to Archean rocks, apparently formed by comminution and frictional melting. Microcrystalline Sudbury Breccia formed as a result of the thermal metamorphism, of the North Range footwall, by the Sudbury Igneous Complex. This produced a zone, approximately 1.2 km wide, wherein the matrix of the breccia either recrystallized or, locally, melted. An overprint of regional metamorphism obliterated contact effects in the South Range footwall. The Ni-Cu- PGE magmatic sulphide deposits may be classified into four types based on structural setting: Sudbury Igneous Complex- footwall contact, footwall, offset, and sheared deposits. Sudbury Breccia is the main host for footwall deposits (e.g., McCreedy East, Victor, Lindsley). Sudbury Breccia locally hosts mineralization in radial (e.g., Parkin and Copper Cliff) and concentric (e.g., Frood-Stobie) offset dikes. ?? 2002 Elsevier Science B.V. All rights reserved.},
author = {Rousell, Don H. and Fedorowich, John S. and Dressler, Burkhard O.},
doi = {10.1016/S0012-8252(02)00091-0},
isbn = {1705675115},
issn = {00128252},
journal = {Earth-Science Reviews},
keywords = {Cu-Ni-PGE deposits,Flow surface,Friction,Impact,Pore fluid,Pseudotachylite},
pages = {147--174},
title = {{Sudbury Breccia (Canada): A product of the 1850 Ma Sudbury Event and host to footwall Cu-Ni-PGE deposits}},
volume = {60},
year = {2003}
}
@article{Wright2010,
abstract = {The formation of Sudbury's economically important magmatic Ni-Cu-PGE sulphide deposits is attributed to superheating of crustal rocks, following meteorite impact at 1.85 Ga. Crustal contamination of magmatic sulphide deposits is thought to be important in the mineralization process and this paper documents the first occurrence of sedimentary carbon in the Sudbury Ni-Cu-PGE sulphides near the base of the Sudbury Igneous Complex (SIC). Spherules of graphitic and more disordered carbon inclusions were found in chalcopyrite crystals, suggesting that carbon has behaved as a chalcophilic element in the impact melt. Samples from the impact structure have been subjected to carbon isotopic analysis and Raman microspectroscopy in order to investigate the relationship between carbonaceous strata of the Huronian basement, the crater-fill impact breccias, and the mineral deposits associated with the Sudbury impact. Carbonaceous material occurs in the impact breccias of the Onaping Formation and this study presents stratigraphically constrained carbon isotopic analysis of the impact breccias. Sulphides from the hydrothermal Zn-Pb-Cu Vermilion-Errington deposits 1.5 km above the SIC were found to contain both carbon spherules and larger irregular carbonaceous flakes, suggesting a genetic link between the Ni-Cu-PGE deposits and the hydrothermal Zn-Pb-Cu mineralization. A shared source of carbon for the Vermilion-Errington mineralization and the cross-cutting anthraxolite veins 100m above the deposits in post-impact carbonaceous shales of the Onwatin Formation is indicated by the similarity in their Raman spectra. This is considered to be carbon remobilized by metamorphic hydrothermal fluids preferentially scavenging disordered carbon from within the Onaping Formation breccias. The occurrence of carbon in the Sudbury Ni-Cu-PGE massive sulphide deposits indicates that carbon from the target rocks played a role in the mineralization process, hitherto unrecognized. Crown Copyright ?? 2009.},
author = {Wright, A. J. and Parnell, J. and Ames, D. E.},
doi = {10.1016/j.precamres.2009.11.002},
isbn = {0301-9268},
issn = {03019268},
journal = {Precambrian Research},
keywords = {Carbon,Graphite,Impact breccia,Ni-Cu mineralization,Raman microspectroscopy,Sudbury impact structure},
pages = {23--38},
title = {{Carbon spherules in Ni-Cu-PGE sulphide deposits in the Sudbury impact structure, Canada}},
volume = {177},
year = {2010}
}
@article{Abramov2004,
abstract = {Large impact events, like the one that formed the Sudbury crater in Ontario, Canada, at 1.85 Ga, significantly increase the temperature of target rocks. The heat sources generated by such an impact event can drive the circulation of groundwater, establishing a hydrothermal system. We report on the results of numerical modeling of postimpact cooling with and without the presence of water at the Sudbury crater. A hydrothermal system is initiated in the annular trough between the peak ring and final crater rim, perhaps venting through faults that bound blocks of the crust in the modification zone of the crater. Although circulation through the overlying breccias may occur in the center of the crater, the central melt sheet is initially impermeable to circulating fluids. By 10 5 years the central melt sheet crystallizes and partially cools, allowing fluids to flow through it. Host rock permeability is the main factor affecting fluid circulation and lifetimes of hydrothermal systems. High permeabilities lead to a rapid system cooling, while lower permeabilities allow a steady transport of hot fluids to the surface, resulting in high surface temperatures for longer periods of time than cooling by conduction alone. The simulations presented in this paper show that a hydrothermal system at a Sudbury-sized impact crater can remain active for several hundred thousand to several million years, depending on assumed permeability. These results suggest that a hydrothermal system induced by an impact event can remain active for sufficiently long periods of time to be biologically significant, supporting the idea that impact events may have played an important biological role, especially early in Earth’s history.},
author = {Abramov, Oleg and Kring, David A.},
doi = {10.1029/2003JE002213},
issn = {01480227},
journal = {Journal of Geophysical Research E: Planets},
keywords = {Astrobiology,Crater cooling,Hydrothermal systems,Numerical modeling,Sudbury, impact cratering},
title = {{Numerical modeling of an impact-induced hydrothermal system at the Sudbury crater}},
volume = {109},
year = {2004}
}
@misc{Wu1994,
abstract = {The paper presents new high-resolution seismic images of the Sudbury Impact Structure, acquired across the Sudbury Igneous Complex and its environs, which provide evidence for the relative timing of the deformation events that reshaped the initial Sudbury Structure. The seismic images show that the lower unit of the Sudbury basinal fill sediments is penetrated by a set of blind, imbricated thrusts, whereas the overlying Chelmsford turbidites are unaffected by faulting. This observation is interpreted to mean that the deposition of the Chelmsford sediments postdates the latest major deformation of the Sudbury Structure, suggesting that the uniform paleocurrent trends observed in the Chelmsford turbidites are not related to the initial shape of the Sudbury Structure. -Authors},
author = {Wu, Jianjun and Milkereit, Bernd and Boerner, David},
booktitle = {Canadian Journal of Earth Sciences},
doi = {10.1139/e94-147},
issn = {0008-4077},
pages = {1654--1660},
title = {{Timing constraints on deformation history of the Sudbury Impact Structure}},
volume = {31},
year = {1994}
}
@article{Anders2013,
abstract = {The results of this study provide evidence that the Onaping Intrusion from the Sudbury impact structure is an impact melt and might be the roof rock of the SIC.},
author = {Anders, D and Osinski, G R and Grieve, R A F},
journal = {44th Lunar and Planetary Science Conference},
pages = {Abstract \#1637},
title = {{The Onaping Intrusion, Sudbury, Canada: An Impact Melt Origin and Relationship to the Sudbury Igneous Complex}},
url = {http://www.lpi.usra.edu/meetings/lpsc2013/pdf/1637.pdf},
year = {2013}
}
@article{Mossman2003,
abstract = {Fullerenes have been reported from diverse geologic environments since their discovery in shungite from Karelian Russia. Our investigation is prompted by the presence of onionskin-like structures in some carbonaceous substances associated with the fossil nuclear fission reactors of Oklo, Gabon. The same series of extractions and the same instrumental techniques, laser desorption ionization and high-resolution mass spectroscopy (electron-impact mass spectroscopy), were employed to test for fullerenes in samples from three different localities: two sites containing putative fullerenes (Sudbury Basin and Russian Karelia) and one new location (Oklo, Gabon). We confirm the presence of fullerenes (C60 and C70) in the Black Tuff of the Onaping Formation impact breccia in the Sudbury Basin, but we find no evidence of fullerenes in shungite samples from various locations in Russian Karelia. Analysis of carbonaceous substances associated with the natural nuclear fission reactors of Oklo yields no definitive signals for fullerenes. If fullerenes were produced during sustained nuclear fission at Oklo, then they are present below the detection limit ([\~{}]100 fmol), or they have destabilized since formation. Contrary to some expectations, geologic occurrences of fullerenes are not commonplace.},
author = {Mossman, David and Eigendorf, Guenter and Tokaryk, Dennis and Gauthier-Lafaye, Fran\c{c}ois and Guckert, Kristal D. and Melezhik, Victor and Farrow, Catharine E G},
doi = {10.1130/0091-7613(2003)031<0255:TFFIGM>2.0.CO;2},
isbn = {00917613},
issn = {00917613},
journal = {Geology},
keywords = {Fullerenes,Geologic materials,Karelia,Oklo,Sudbury},
pages = {255--258},
title = {{Testing for fullerenes in geological materials: Oklo carbonaceous substances, Karelian shungites, Sudbury Black Tuff}},
volume = {31},
year = {2003}
}
@misc{Heath2007,
abstract = {Shorelines of Lake Algonquin, the largest of the glacial lakes of the Great Lakes area, are well known in southern Ontario, but are sporadic and difficult to trace northward onto the Precambrian shield. Improved knowledge of the extent and uplift pattern for Algonquin shorelines is needed to support geophysical models of isostatic response, interpretation of glacial and glacial lake history, and the search by archeologists for evidence of Paleoindian activity, shown to be localized along its shoreline. The Sudbury basin is one of the few areas of mapping of Quaternary geology on the Canadian shield that provides a record of Algonquin lake phases. Meltwaters from the northward-receding ice front formed a series of deltas southward into the Sudbury basin in central Ontario around the time the Cartier I moraine was deposited. Instrumental surveys of deltas, bars, and shorebluffs carried out in the northern Sudbury basin delineate several discrete water planes. Correlation with previously surveyed and correlated shorelines on Manitoulin Island, southwest of Sudbury, indicates the presence of an upper Algonquin shoreline and features correlated to the Cedar Point, Payette, Sheguiandah, and Korah levels. Features southwest of the Sudbury basin at Nairn correlate with Korah and post-Korah water levels. Land between Nairn and Sudbury is too elevated to have been reached by the later Nipissing transgression. Similar shoreline sequences have been surveyed near North Bay, with results supporting the findings of this study.},
author = {Heath, Andrew J. and Karrow, Paul F.},
booktitle = {Journal of Great Lakes Research},
doi = {10.3394/0380-1330(2007)33[264:NGLASS]2.0.CO;2},
isbn = {0380-1330},
issn = {0380-1330},
pages = {264--278},
title = {{Northernmost (?) Glacial Lake Algonquin Series Shorelines, Sudbury Basin, Ontario}},
volume = {33},
year = {2007}
}
@article{Klimczak2007,
abstract = {Structural analysis of the Onaping Formation, a heterolithic impact melt breccia, and the Granophyre in the NE-lobe of the 1.85 Ga Sudbury Igneous Complex (SIC) assist in understanding the formation of the Sudbury Basin. Previously, the lack of mesoscopic strain fabrics in the SIC, in contrast to pervasive fabrics in the Onaping Formation of the NE-lobe, led to interpretations of the shape of the NE-lobe as primary. We demonstrate that the structures of the Onaping Formation are consistent with deformation in a fold core controlled by the mechanically stronger Granophyre of the NE-lobe. Evidence for this interpretation includes the (1) presence of open structural domes and basins, (2) geometry of planar mineral shape fabrics, (3) variation in shape fabric intensity, and (4) kinematics of prominent faults. Folding of the Onaping Formation affected the SIC because fold geometry is based on dip data in the SIC and fold-related faults cut both the Onaping Formation and Granophyre. Microstructural observations point to different temperatures during deformation in both units that are consistent with initiation of folding during cooling of the SIC upon reaching middle greenschist-facies metamorphic conditions. ?? 2007 Elsevier Ltd. All rights reserved.},
author = {Klimczak, Christian and Wittek, Andrea and Doman, Daniel and Riller, Ulrich},
doi = {10.1016/j.jsg.2007.09.003},
issn = {01918141},
journal = {Journal of Structural Geology},
keywords = {Faults,Folds,Heterogeneous deformation,Mineral fabrics,Sudbury Basin},
pages = {1744--1756},
title = {{Fold origin of the NE-lobe of the Sudbury Basin, Canada: Evidence from heterogeneous fabric development in the Onaping Formation and the Sudbury Igneous Complex}},
volume = {29},
year = {2007}
}
@misc{Dixit1992,
abstract = {Surface (recent) and bottom (pre-1880s) sediment samples from each of 72 Sudbury area lakes were analyzed for diatom valves and chrysophyte scales, and using these microfossils, we inferred changes in lake water pH, [Al], [Ni], conductance, and [Ca]. The study shows that extensive acidification has occurred in presently acidic (pH < 6.0) Sudbury lakes. Inferred [Al] has also increased in these lakes. The region also contains a few naturally acidic lakes; however, even these lakes have acidified further since the bottom sediments were deposited. Lakes that have current measured pH between 6.0 and 7.0 have either declined or increased in inferred pH in the past, whereas all lakes that are presently alkaline (pH > 7.0) have become more alkaline. The increase in inferred [Ni] in most of the study lakes indicates that Ni inputs are mainly atmospheric. Our data suggest that, in general, ion concentrations have increased in Sudbury lakes. The extent of acidification or alkalification in Sudbury lakes was primarily a function of proximity of the lakes to the smelters, orientation of prevailing wind patterns, and differences in watershed geology.},
author = {Dixit, Sushil S. and Dixit, Aruna S. and Smol, John P.},
booktitle = {Canadian Journal of Fisheries and Aquatic Sciences},
doi = {10.1139/f92-295},
issn = {0706-652X},
pages = {8--16},
title = {{Assessment of Changes in Lake Water Chemistry in Sudbury Area Lakes since Preindustrial Times}},
volume = {49},
year = {1992}
}
@misc{Keller1991,
abstract = {Temporal patterns in the species richness of crustacean zooplankton communities were assessed in eight Sudbury area lakes based on data collected between 1973 and 1986. Excluding a consistently nonacidic reference lake, the study lakes showed general reductions in acidity and trace metal concentrations during this period, related to reduced contaminant emissions from the Sudbury smelters. Despite water quality improvements, several of the study lakes continue to have low pH and elevated trace metal concentrations which have inhibited recovery of zooplankton species richness. However, in lakes with more favourable current pH and lower trace metal concentrations, substantial increases in the average species richness of crustacean plankton communities have occurred, apparently due to both invasion of new species and more frequent occurrence of existing species. These results clearly demonstrate that reductions in acid-forming emissions lead to both chemical and biological improvements in some aquatic systems},
author = {Keller, W. and Yan, N. D.},
booktitle = {Canadian Journal of Fisheries and Aquatic Sciences},
doi = {10.1139/f91-194},
isbn = {0706-652X},
issn = {0706-652X},
pages = {1635--1644},
title = {{Recovery of Crustacean Zooplankton Species Richness in Sudbury Area Lakes following Water Quality Improvements}},
volume = {48},
year = {1991}
}
@article{McCormick2002a,
abstract = {The Ni-Cu-platinum-group element ores in the sublayer and footwall breccia of the Sudbury structure have distinctive geochemical halos. In the Fraser mine, F/Cl ratios of the sublayer rocks appear to decrease, Na2O/K2O ratios of the footwall breccia samples decrease, and Cl in both units increases with proximity to mineralization. These halos are interpreted to result from interaction of residual magmatic fluids with host rocks, which altered the host-rock mineralogy and precipitated Cl-bearing minerals. The results of this study, together with the results of previous studies, suggest that most ores at Sudbury, including sublayer- and footwall breccia-hosted contact ores and Sudbury breccia-hosted footwall ores, are surrounded by Cl and possibly alkali halos and that these geochemical signatures may be used to identify rocks that are proximal to mineralization.},
author = {McCormick, K. A. and Lesher, C. M. and McDonald, A. M. and Fedorowich, J. S. and James, R. S.},
doi = {10.2113/gsecongeo.97.7.1509},
issn = {03610128},
journal = {Economic Geology},
pages = {1509--1519},
title = {{Chlorine and alkali geochemical halos in the footwall breccia and sublayer norite at the margin of the Strathcona Embayment, Sudbury structure, Ontario}},
volume = {97},
year = {2002}
}
@article{Olaniyan2013,
abstract = {The Sudbury Structure is one of the most studied geologic structures in the world due to its enigmatic nature and mineral wealth. The available geologic work from the literature and mining industry operations accumu- lated for more than a century was recently assessed and compiled into a bedrock geologic map. Most regional geophysical investigations of the Sudbury Structure have been quantitative — modeling and depth estimation without a clear definition of surface control. Airborne total magnetic intensity data over the Sudbury Structure were compiled, processed, and interpreted, to define magnetic stratigraphy boundaries and near-surface linea- ments. Traditional directional and normalized derivatives were computed to enhance the high-frequency infor- mation in the magnetic field. Available airborne frequency-domain electromagnetic (EM) data were also interactively interpreted along profiles and in a gridded format to isolate conductive structures. On-screen geo- graphic information system-based information extraction from multiple derivatives was used to interpret the magnetic contacts, dykes, and lineaments. The magnetic interpretation was compared with published bedrock maps of the Sudbury Structure. Magnetic contacts based on the qualitative classification of the magnetic texture did not always correspond to the geologic boundaries on the existing maps. Some magnetic lineaments cor- responded with well-defined geologic structures, some were further extensions of partially mapped structures, and others are newly identified linear structures. Conductive locations identified from the EM profiles were probably due to responses from conductive ore bodies, faults, dykes, lithological contacts, and cultural objects.},
author = {Olaniyan, Oladele and Smith, Richard S. and Morris, Bill},
doi = {10.1190/INT-2012-0010.1},
issn = {2324-8858},
journal = {Interpretation},
keywords = {electromagnetic, interpretation, magnetics, mining},
pages = {25--43},
title = {{Qualitative geophysical interpretation of the Sudbury Structure}},
volume = {1},
year = {2013}
}
@inproceedings{Staecker2011,
abstract = {This talk will continue the discussion of Roger's contributions as a volunteer leader within the MTT Society as well as for all of Technical Activities within IEEE. Roger's wisdom, honesty, and energy were widely respected by all who worked with him.},
author = {Staecker, P. W. and Delaney, W. P. and Gopinath, A. and Gelnovatch, W. and McQuiddy, D. and Sudbury, D. M. and Sudbury, A. and Cohen, E. and Lyons, W. G. and Gouker, M. A.},
booktitle = {IEEE MTT-S International Microwave Symposium Digest},
doi = {10.1109/MWSYM.2011.5972908},
isbn = {9781612847566},
issn = {0149645X},
keywords = {GaAs MMICs,MMW MMICs,microwave modules,phased array},
title = {{IMS2011 memorial session for Roger W. Sudbury}},
year = {2011}
}
@article{Dietz1960,
abstract = {Shatter cones, related brecciation, and shatter and chaotic circularly disturbed structures have been laid to possible meteoric impact. These structures have previously been ascribed to volcanic origins but are now considered shock wave reactions of nonvolcanic impacts, and possibly extraterrestrial. Three possible sites were visited and identified; however Meteor Crater yielded no similar structures. On the other hand, a lake of meteoric origin did yield the 8th known locality for the distinctive shatter cones.},
author = {Dietz, R S},
doi = {10.1126/science.131.3416.1781},
issn = {0036-8075},
journal = {Science (New York, N.Y.)},
pages = {1781--1784},
pmid = {17753204},
title = {{Meteorite Impact Suggested by Shatter Cones in Rock.}},
volume = {131},
year = {1960}
}
@article{Sagy2004,
abstract = {Shatter cones are rock discontinuities known only from sites of extraterrestrial impacts, and they are assumed to be formed by impact-induced shock waves. Here we characterize the structure of shatter cones by field and microanalyses and explain their formation by dynamic fracture mechanics. Our analyses reveal that shatter cones always occur as multilevel, three-dimensional networks, 0.01–100 m in size, with hierarchal branched fractures. A typical, individual shatter cone is a curved, oblate branch that bifurcates from its parent fracture (e.g., a larger shatter cone) and expands to form a spoon-like surface. The unique shatter cone striations are arranged in V-shaped pairs whose enclosed angle is constant for a given sample. We propose that shatter cones are the natural consequence of tensile rock fracturing at extreme velocities. First, the structure of shatter cone networks is strikingly similar to the structure of branched networks of experimental dynamic fractures that propagate at high velocities (velocities that approach the Rayleigh wave speed, VR). Second, ‘‘fracture front waves,’’ generated experimentally by the interaction of a rapidly moving tensile fractures and material inclusions, create tracks on the fracture surface that correspond to the V-shaped striations of shatter cones. Third, applying the front wave concept to our field measurements (Vredefort impact, South Africa) shows that the shatter cones propagated at velocities of 0.98–0.90 VR, with a systematic velocity decrease from the impact center. These extreme asymptotic velocities require the intense energy flux of impacts. Our model explains all of the structural features of shatter cones (curved surfaces, cone directivity, unique striations, hierarchic, multilevel structure) and their exclusive occurrence at impact sites.},
author = {Sagy, Amir and Fineberg, Jay and Reches, Ze'ev},
doi = {10.1029/2004JB003016},
issn = {01480227},
journal = {Journal of Geophysical Research B: Solid Earth},
keywords = {Deformation,Dynamic,Fracture,Impact,Shatter cones,Shock},
title = {{Shatter cones: Branched, rapid fractures formed by shock impact}},
volume = {109},
year = {2004}
}
@article{Sagy2002,
abstract = {A large impact by a comet or meteorite releases an enormous amount of energy, which evaporates, melts and fractures the surrounding rocks. Distinctive features of such impacts are 'shatter cones', deformed rocks characterized by hierarchical striated features. Although such features have been used for decades as unequivocal fingerprints of large-body impacts, the process by which shatter cones form has remained enigmatic. Here we show that the distinctive shatter-cone striations naturally result from nonlinear waves (front waves) that propagate along a fracture front. This explains the observed systematic increase of striation angles with the distance from the impact. Shatter-cone networks, typically spanning many scales, can be understood as hierarchical bifurcations of the fracture front, which is generated by the immense energy flux carried by the initial, impact-generated, shock waves. Our quantitative predictions based on this theory are supported by field measurements at the Kentland and Vredefort impact sites. These measurements indicate that shatter cones near to the impact site were formed by fractures propagating at nearly the Rayleigh wave speed of the host rocks, whereas the furthest shatter cones observed (about 40 km from the impact site) were formed by fronts moving more slowly. These results provide insight into impact dynamics as well as dissipative mechanisms in solids subjected to sudden, extremely intense fluxes of energy.},
author = {Sagy, Amir and Reches, Ze'ev and Fineberg, Jay},
doi = {10.1038/nature00903},
issn = {0028-0836},
journal = {Nature},
pages = {310--313},
pmid = {12124620},
title = {{Dynamic fracture by large extraterrestrial impacts as the origin of shatter cones.}},
volume = {418},
year = {2002}
}
@misc{Roach1993,
abstract = {The branching patterns of radiating ridges on surfaces of tensile joints and shatter cones were simulated and quantified, and their scaling properties were examined in three dimensions by means of a technique new to geology, the slit-island method. Results show that the textures are fractal over a wide range of scales. Accordingly, an algorithm simulates growth of tensile fracture-surface features by combining a set of rules with an element of randomness. The simulated surfaces are fractal and strikingly similar to natural fracture surfaces. These and other complex branching patterns observed in geology are likely due to an interplay of deterministic and random processes.},
author = {Roach, D. E. and Fowler, A. D. and Fyson, W. K.},
booktitle = {Geology},
doi = {10.1130/0091-7613(1993)021<0759:FFOJAS>2.3.CO},
issn = {00917613},
pages = {759--762},
title = {{Fractal fingerprinting of joint and shatter-cone surfaces}},
volume = {21},
year = {1993}
}
@article{Amstutz1965,
abstract = {The geometric space of possible isomorphism of cones in different rocks is subdivided into aggregate properties or relations between individual cones or groups of cones, external shape and size of individuals, and internal properties of their microtextures. A list of the most important theories of origin includes syndiagenetic and genetic formation; cones cannot be explained in only one way. Cones from two polygonal structures in Missouri are compared. In the Crooked Creek structure cone patterns in carbonate rocks show no relation to the numerous carbonate-filled fractures. Observations on outcrop, hand-specimen, and thin-section scales suggest a gradual growth process. At Decaturville the observed details call for a mechanical, tectonic origin--formation by rupture, not growth.},
author = {Amstutz, G C},
doi = {10.1111/j.1749-6632.1965.tb20416.x},
isbn = {1749-6632},
issn = {0077-8923, 0077-8923},
journal = {Annals of the New York Academy of Sciences},
keywords = {06:Sedimentary petrology,Cone structures,Decaturville cf. Crooked Creek,Missouri,Morphologic comparison with shatter cones,United States,carbonate rocks,cone-in-cone,cryptoexplosion features,diagenesis,diagenetic cone-in-cone,explosion phenomena,morphology,petrofabrics,products,secondary structures,sedimentary petrology,sedimentary rocks,sedimentary structures,shatter cones},
pages = {1050--1056},
title = {{A morphological comparison of diagenetic cone-in-cone structures and shatter cones}},
url = {https://www.lib.uwo.ca/cgi-bin/ezpauthn.cgi/docview/52912860?accountid=15115 LA  - English},
volume = {123},
year = {1965}
}
@misc{DIETZ1967,
abstract = {Shatter cones caused by shock fracturing are widely developed at the Gosses Bluff cryptoexplosion ring structure in central Australia. The force field can be reconstructed whereby the applied shock arrived centrally and from above, which is consistent with a cosmic impact. For this and other reasons, Gosses Bluff is an astrobleme.},
author = {DIETZ, ROBERT S.},
booktitle = {Nature},
doi = {10.1038/2161082a0},
issn = {0028-0836},
pages = {1082--1084},
title = {{Shatter Cone Orientation at Gosses Bluff Astrobleme}},
volume = {216},
year = {1967}
}
@misc{Stewart1987,
abstract = {The Lawn Hill circular structure is a ring of low hills 18 km in external diameter composed of brecciated Cambrian limestone and chert. It surrounds a plain approx 8 km across of fractured Proterozoic siltstone, sandstone and, at the centre of the ring, flow-folded igneous rock containing abundant devitrified glass. The Proterozoic rocks crop out also outside the ring, and their macroscopic geometry indicates approx 2 km of uplift inside the ring. The centre of the structure is located 7 km from the intersection of two major faults. An aeromagnetic dipole anomaly indicates a magnetic body beneath the NE part of the ring. Well-formed radially striated shatter cones of Proterozoic siltstone and sandstone are present inside the ring, mostly as colluvial float, although five in situ outward-pointing cones are also known. Intersecting sets of closely spaced planar lamellae are present in quartz grains in the cones, but anomalous birefringence, vitreous phases, reduced refractive index, crystal cleavage, crystal faults and mosaic extinction have not been observed. Breccia in the limestone ring forms massive cross-cutting bodies; its clasts are angular to subangular, consist of chert and limestone, and range in size from sand grains to boulders. No shatter cones have been observed in the limestone or breccia. The shatter cones show that the Lawn Hill circular structure originated by shock. The proximity to faults and presence of a subsurface magnetic body suggest the possibility of an intraterrestrial source for the shock energy but, because of the intersecting planar lamellae, central uplift, and melt rock at the centre of the structure, an origin by extraterrestrial impact is favoured. The absence of shatter cones in the Cambrian limestone suggests that the impact occurred before its deposition; the limestone ring is a palimpsest of the original crater.},
author = {Stewart, Alastair and Mitchell, Ken},
booktitle = {Australian Journal of Earth Sciences},
doi = {10.1080/08120098708729427},
issn = {0812-0099},
pages = {477--485},
title = {{Shatter cones at the Lawn Hill circular structure, northwestern Queensland: presumed astrobleme}},
volume = {34},
year = {1987}
}
@article{Ames2007,
abstract = {MDD/GAC Volume},
author = {Ames, D and Farrow, C},
journal = {Mineral Deposits of Canada},
pages = {329--350},
title = {{METALLOGENY OF THE SUDBURY MINING CAMP, ONTARIO}},
url = {papers://32862730-33e4-4f24-9997-a2585c9ed6b6/Paper/p482},
volume = {5},
year = {2007}
}
@incollection{French1972,
abstract = {Features in footwall rocks, in Onaping Formation, history of structure, volcanism, Ontario.},
author = {French, Bevan M},
booktitle = {New developments in Sudbury geology.},
keywords = {16 Structural geology,Canada,Eastern Canada,Ontario,Sudbury,concepts,cryptoexplosion features,geomorphology,impact features,interpretation,metamorphic rocks,metamorphism,preferred orientation,shatter cones,shock,structural analysis,structural geology,structure,tectonics,textures,volcanism,volcanology},
pages = {19--28},
title = {{Shock-metamorphic features in the Sudbury structure, Ontario; a review}},
volume = {10},
year = {1972}
}
@article{Dressler1996,
abstract = {The origin of the Sudbury Structure and of the associated heterolithic breccias of the Onaping Formation and the Sudbury Igneous Complex have been controversial. While an impact origin of the structure has gained wide acceptance over the last 15 years, the origin of the recrystallized Onaping Formation glasses and of the igneous complex is still being debated. Recently the interpretation of the breccias of the Onaping Formation as suevitic fall-back impact breccias has been challenged. The igneous complex is interpreted either as a differentiated impact melt sheet or as a combination of an upper impact melt represented by the granophyre, and a lower, impact-triggered magmatic body consisting of the norite-sublayer formations. The Onaping Formation contains glasses as fluidal and nonfluidal fragments of various shapes and sizes. They are recrystallized, and our research indicates that they are petrographically heterogeneous and span a wide range of chemical compositions. These characteristics are not known from glasses of volcanic deposits. This suggests an origin by shock vitrification, an interpretation consistent with their association with numerous and varied country rock clasts that exhibit microscopic shock metamorphic features. The recrystallized glass fragments represent individual solid-state and liquid-state vitrified rocks or relatively small melt pods. The basal member lies beneath the Gray and Black members of the Onaping Formation and, where not metamorphic, has an igneous matrix. Igneous-textured melt bodies occur in the upper two members and above the Basal Member. A comparison of the chemical compositions of recrystallized glasses and of the matrices of the Basal Member and the melt bodies with the components and the bulk composition of the igneous complex is inconclusive as to the origin of the igneous complex. Basal Member matrix and Melt Bodies, on average, are chemically similar to the granophyre of the Sudbury Igneous Complex, suggesting that they are genetically related. Our chemical results allow interpretation of the entire igneous complex as a differentiated impact melt. However, they are also consistent with the granophyre alone being the impact melt and the norite and quartz gabbro beneath it representing an impact-triggered magmatic body. This interpretation is preferred, as it is consistent with a number of field observations. A re-evaluation and extension of structural field studies and of geochemical data, as well as a systematic study of the contact relationships of the various igneous phases of the igneous complex, are needed to establish a Sudbury impact model consistent with all data and observations.},
author = {Dressler, B. O. and Weiser, T. and Brockmeyer, P.},
doi = {10.1016/0016-7037(96)00067-1},
issn = {00167037},
journal = {Geochimica et Cosmochimica Acta},
pages = {2019--2036},
pmid = {507},
title = {{Recrystallized impact glasses of the Onaping Formation and the Sudbury Igneous Complex, Sudbury Structure, Ontario, Canada}},
volume = {60},
year = {1996}
}
@article{French1967,
abstract = {Unusual deformation structures, similar to those observed in rocks from known and suspected meteorite impact craters, are observed in inclusions of basement rock in the Onaping formation at Sudbury, Ontario. These features, which include planar sets in quartz parallel to the (0001) and (10ī3) planes, suggest that the Onaping formation consists of shocked and melted material deposited immediately after a meteorite impact which formed the Sudbury basin.},
author = {French, B M},
doi = {10.1126/science.156.3778.1094},
isbn = {9780470114735},
issn = {0036-8075},
journal = {Science (New York, N.Y.)},
pages = {1094--1098},
pmid = {17774054},
title = {{Sudbury structure, ontario: some petrographic evidence for origin by meteorite impact.}},
volume = {156},
year = {1967}
}
@misc{Thompson1996,
abstract = {Pseudotachylytes and their host rocks from the North Range of the 1.85 Ga Sudbury impact struc- ture have been investigated using analytical scanning electron microscopy, electron microprobe analysis and XRF spectrometry. The results show that the pseudo- tachylytes were produced in high-speed slip zones by the frictional comminution and selective melting of wall rock lithologies. The preferential assimilation of hydrous ferromagnesian phases during frictional melting pro- duced relatively basic melts, leaving the more mechani- cally resistant quartz and, to a lesser extent, plagioclase as included mineral clasts. Three distinct assemblages are identified within the pseudotachylytes: (a) pre-im- pact (?1.85 Ga) rock and mineral clasts derived from host lithologies; (b) a syn- to immediately post-impact (1.85 Ga), rapidly cooled, quartz?sanidine?labrador- ite ? phlogopitic biotite matrix assemblage, formed due to crystallization from a melt at 800–900?C and (c) a post-impact (?1.85 Ga) retrograde assemblage which overprints both clasts and matrices. Field evidence indi- cates that most pseudotachylyte formed in large-dis- placement fault systems during gravitational collapse of the impact-generated transient cavity. The Sudbury pseudotachylytes, like endogenic pseudotachylytes, were generated by frictional melting on fault surfaces. The difference is primarily one of scale. Large (km) dis- placements occurring on impact-induced ring faults can generate immense volumes of friction melt resulting in spectacular pseudotachylyte bodies up to 0.5 km thick and more than 10 km long. Introduction},
author = {Thompson, Lucy M. and Spray, J. G.},
booktitle = {Contributions to Mineralogy and Petrology},
doi = {10.1007/s004100050228},
issn = {0010-7999},
pages = {359--374},
title = {{Pseudotachylyte petrogenesis: constraints from the Sudbury impact structure}},
volume = {125},
year = {1996}
}
@article{Deutsch1995,
abstract = {The occurrence of shock metamorphic features substantiates an impact origin for the 1.85 Ga old Sudbury Structure, but this has not been universally accepted. Recent improvements in knowledge of large-scale impact processes, combined with new petrographic, geochemical, geophysical (LITHOPROBE) and structural data, allow the Sudbury Structure to be interpreted as a multi-ring impact structure. The structure consists of the following lithologies: Sudbury Breccia - dike breccias occurring up to 80?km from the Sudbury Igneous Complex (SIC); Footwall rocks and Footwall Breccia - brecciated, shocked crater floor materials, in part thermally metamorphosed by the overlying SIC; Sublayer and Offset Dikes, Main Mass of the SIC and Basal Member of the Onaping Formation (OF) - geochemically heterogeneous coherent impact melt complex ranging from inclusion-rich basal unit through a dominantly inclusion-free to a capping inclusion-rich impact melt rock; Grey Member of OF - melt-rich impact breccia (suevite); Green Member of OF - thin layer of fall back ejecta; Black Member of OF - reworked and redeposited breccia material; Onwatin and Chelmsford Formations - post-impact sediments. Observational and analytical data support an integrated step-by-step impact model for the genesis of these units. Analysis of the present spatial distribution of various impact-related lithologies and shock metamorphic effects result in an estimated original rim-to-rim diameter of the final crater of 200 or even 280?km for the Sudbury Structure, prior to tectonic thrusting and deformation during the Penokean orogeny.  },
author = {Deutsch, A. and Grieve, R. A F and Avermann, M. and Bischoff, L. and Brockmeyer, P. and Buhl, D. and Lakomy, R. and M\"{u}ller-Mohr, V. and Ostermann, M. and St\"{o}ffler, D.},
doi = {10.1007/BF00240561},
issn = {00167835},
journal = {Geologische Rundschau},
keywords = {Impact crater,Multi-ring basin,Penokean orogeny,Rare earth elements,Rb/Sr Sm/Nd,Sudbury Structure},
pages = {697--709},
pmid = {874},
title = {{The Sudbury Structure (Ontario, Canada): a tectonically deformed multi-ring impact basin}},
volume = {84},
year = {1995}
}