Explanatory Notes
    These are the explanatory notes that accompany Geological Survey of Canada Map 1860A.
    Notes concerning the Database structure and the Files, Directories, and Formats are contained in c:\aacrse\505\gscmap\DB_E.RTF and FILESDF.RTF, respectively.

    Map Projection Parameters
                                   Parameter                                                                        Value
                                     Type                                                         Lambert Conformal Conic projection
                                     Datum                                                       North American Datum 1927 (NAD27)
                                     Units                                                         metres
                                     Spheroid                                                  Clarke, 1866
                                     Lambert standard parallels                         49 00 00 N
                                                                                                      77 00 00 N
                                     Projection origin                                        95 00 00 W (central meridian)
                                                                                                      49 00 00 N
                                     False origin                                                (easting, northing)=(0, 0)

    Time Scale
    A variety of time scales has been used for assigning isotopically dated rocks to the appropriate subdivision or time unit of the Phanerozoic and Precambrian time scales. Phanerozoic isotopic ages have been codified according to the Geologic Time Scale 1989 (Harland et al., 1990) with the modification that the Phanerozoic-Precambrian boundary is now placed at 544 Ma as a result of recent U-Pb zircon geochronology (Bowring et al., 1993).

    Isotopic ages of Precambrian rocks have been classified according to the new Precambrian time scale and its subdivision of the Proterozoic (Plumb, 1991) and Archean eras (Lumbers and Card, 1991).

    The Proterozoic eras have been subdivided following the boundaries outlined by Plumb and James (1986), with three subsequent modifications: 1) the boundary at 700 Ma is not applicable in Canada, 2) the boundary between the Neoproterozoic and Mesoproterozoic has been changed subsequently from 900 Ma to 1000 Ma (Plumb, 1991), and 3) the subdivision boundary at 1400 Ma is hereby adjusted to 1350 Ma. The last permits a clear separation of ages older than 1350 Ma, related to widespread rhyolite volcanism in the mid-continent region of U.S.A. and bimodal magmatism in the Grenville Province, from younger ages associated with extensive calc-alkaline magmatism in the Grenville (A. Davidson, pers. comm., 1996).

    Finally, the alphabetical (U, V, W, X, Y, Z) divisions of the Precambrian adopted by the United States Geological Survey (James, 1972) are retained for simple and unambiguous labelling. Designation of further subdivisions is achieved by additional numerical labelling, such as X1, X2, X3, Y1, Y2, and Y3. In cases where units straddle sub-era boundaries, units may be designated X12, meaning the unit includes all or parts of X1 and X2 or, in cases such as X3Y1, the unit contains all or parts of X3 and Y1.

    Abbreviations -   a = anorthosite; f = felsic; g = granite;  i = intermediate; m = mafic; n = undivided gneiss; gn = orthogneiss; sgn = paragneiss; s = sedimentary;
     v  = volcanic; vk = alkaline volcanics; y = syenite; no suffix means sedimentary rocks.

Un PaleoArchean undivided gneiss
Ugn PaleoArchean orthogneiss

UWn PaleoArchean-NeoArchean undivided gneiss

Vn MesoArchean orthogneiss
Vsv MesoArchean sedimentary/volcanic rocks

VWn MesoArchean-NeoArchean undivided gneiss
VWsv Meso-NeoArchean sedimentary/volcanic rocks

Wma NeoArchean gabbro-anorthosite
Wa NeoArchean anorthosite
Wy NeoArchean syenite
Wm NeoArchean mafic intrusive rocks
Wg NeoArchean undivided intrusive granite
Wgn NeoArchean orthogneiss
Wsgn NeoArchean paragneiss
Wsn NeoArchean paragneiss
Wsv NeoArchean sedimentary/volcanic rocks
W NeoArchean sedimentary rocks
Wv NeoArchean volcanic rocks
Wvm NeoArchean mafic volcanic rocks
Wvi NeoArchean intermediate volcanic rocks
Wvfi NeoArchean intermediate to felsic volcanic rocks
Wvf NeoArchean felsic volcanic rocks

WXa NeoArchean-PaleoProterozoic anorthosite
WXm NeoArchean-PaleoProterozoic intrusive mafic rocks
WXg NeoArchean-PaleoProterozoic granites
WXn NeoArchean-PaleoProterozoic undivided gneiss
WXgn NeoArchean-PaleoProterozoic undivided granite
WXsv NeoArchean-PaleoProterozoic sedimentary/volcanic rocks
WX NeoArchean-PaleoProterozoic sedimentary rocks
WXv NeoArchean-PaleoProterozoic volcanic rocks

X1 Lower PaleoProterozoic
X2 Middle PaleoProterozoic
X3 Upper PaleoProterozoic

X3Y Paleoproterozic-Mesoproterozoic

Y1 Lower MesoProterozoic
Y2 Middle MesoProterozoic
Y3 Upper MesoProterozoic

Y3Z Mesoproterozoic-Neoproterozoic

Z1 Lower Neoproterozoic
Z2 Middle Neoproterozoic
Z3 Upper Neoproterozoic

      Colour Design
      Onshore geology
    The colour design of the map follows, in a general way, that of the previous edition (Douglas, 1969). Shades of blue are used for the lower Paleozoic, grey for the upper Paleozoic, green for the Mesozoic, and yellow for the Cenozoic. Mesozoic and Cenozoic granitoid rocks are shown in shades of red; Paleozoic plutons in rose, pink, and purple. A dark blue colour is introduced to highlight lower Paleozoic offshelf units in the Phanerozoic orogens surrounding the Precambrian craton. The darker colour helps to emphasize the embayments and promontories in the early Paleozoic continental margin.

    An effort has been made to choose colours for Precambrian units not used for the Phanerozoic: violet and lavender for Paleoproterozoic supracrustal rocks; yellowish-green for a Paleo-Mesoproterozoic unit; orange hues for the Mesoproterozoic; and shades of brown for the Neoproterozoic. Some colours, however, are repeated. Shades of rose and pink are used for the Archean plutonic rocks that dominate the Canadian Shield but, in general, are paler than the colours of the Paleozoic granitoid units. Grey is repeated in representing Archean sedimentary and paragneiss units but the green colours showing Archean greenstone belts are different from those depicting Mesozoic units. The most obvious colour repetition is the use of bold red colours for both the Mesozoic and Paleoproterozoic granitoid units. Bold red colours are important for the latter to highlight the magmatism associated with the Paleoproterozoic zones of convergence which resulted in the present assembly of Canadian Shield, except for the Grenville Province (Hoffman, 1989).

    Ice caps are shown only locally, as on Baffin Island and in the eastern Arctic islands. Elsewhere icefields are not shown because they interfere with a clear portrayal of the bedrock geology.

          Offshore geology
    Offshore units are designated by labels and dashed boundaries. In order that the onshore bedrock geology clearly stands out, the offshore units are coloured in pale shades of pink, blue, grey, green, and yellow, for Precambrian, lower Paleozoic, upper Paleozoic, Mesozoic, and Cenozoic, respectively. Special blue-green is used for Paleozoic and/or Mesozoic and pinkish colour for Paleozoic granitoid units. A white buffer zone along the coast line serves to further highlight the distinction between land and the offshore.

    Beyond the limit of continental crust, the offshore geology is represented by age of oceanic crust rather than the sedimentary cover, although a few isopachs are shown to indicate the thickness of the cover (Tucholke, 1986; Jackson and Oakey, 1988). The intention is to highlight the plate tectonic framework within the oceans surrounding Canada, thereby displaying the contrasting relations between the convergent and transform margin of the Pacific Ocean with the passive continental margins of the North Atlantic and Arctic oceans which formed during ocean opening and crustal spreading.

    Rifting between North America and Africa began in the Late Triassic resulting in a rifted margin off Nova Scotia and a transform margin south of Grand Banks. Seafloor spreading, thereafter, produced Jurassic and Cretaceous oceanic crust south of Grand Banks (Keen et al., 1990). Stretching and rifting of the crust between North America and Greenland began in the Early Cretaceous accompanied by formation of fault troughs, some of which contain Cretaceous sediments, in the region surrounding Labrador Sea and Baffin Bay (Balkwill et al., 1990). East-northeast seafloor spreading in Labrador Sea began in Late Cretaceous time but changed to north-northeast in the Early Eocene. Seafloor spreading is thought to have started in Baffin Bay in the latest Cretaceous or Paleocene, but it ceased in both Baffin Bay and Labrador Sea in the Late Eocene (Roest and Srivastava, 1989). On the other hand, seafloor spreading continued during the Cretaceous and Cenozoic in the North Atlantic where the Mid-Atlantic Ridge remains an active spreading centre today.

    By contrast, the Neogene and younger Pacific margin is complex and variable. A convergent margin now exists west of Vancouver Island where the Juan de Fuca and Explorer plates, bounded on the west by actively spreading ridges, are being subducted beneath the North American Plate. Subduction is manifested by the deformation front offshore at the leading edge of an accretionary prism whose southern part emerges onto the Olympic Peninsula south of Vancouver Island. Subduction is also reflected in the chains of Neogene and younger calc-alkaline volcanic centres in the Coast Belt and by extensive, more easterly, correlative back-arc mafic lavas (Wheeler and McFeely, 1991).

    A mainly transform margin extends from west of the Queen Charlotte Islands to the submergent Yakutat Terrane in the Gulf of Alaska. Along this segment the Pacific Plate continues to move northward relative to North America along dextral strike-slip faults.

    North of the Yakutat Terrane the Pacific margin becomes convergent again where the Cordillera swings westward around the Gulf of Alaska. During the Neogene and Quaternary the Yakutat Terrane was carried northward by the Pacific Plate and was partially subducted beneath southern Alaska. This led to rapid uplift of the mountain ranges bounding the Gulf of Alaska, accompanied there by calc-alkalic magmatism and volcanism (Plafker et al., 1994).

            Patterns and Symbols

    Mainly nonmarine sedimentary rocks, shown by red stipple, are widespread in Carboniferous-Permian basins in the Appalachian Orogen, in the Upper Cretaceous-Paleogene clastic wedge and Neogene gravels of Western Canada Basin, and in the Devonian clastic wedge in the Arctic Islands. They are also prominent in the Mesozoic Sverdrup Basin in the Arctic Islands where they reflect times of increased sedimentary supply, subsidence, and lowering of sea level resulting in progradation of deltaic sediments around the edge of the basin (Embry, 1991). Similarly, Upper Cretaceous-Paleogene nonmarine deposits manifest uplifts related to the Eurekan Orogeny whereas Neogene sediments along the Arctic coast reflect uplift of the northern rim of Sverdrup Basin. Nonmarine deposits are locally developed across the Cordillera in a small Cretaceous clastic wedge northeast of the Jurassic-Cretaceous Bowser Basin, in Paleogene fault-bounded basins, as Neogene fill within the partly intermontane, extensional Queen Charlotte Basin, and as Neogene remnants of the ancestral Fraser River.

    Patterns are also used to display the distribution of evaporites within Meso- to Neoproterozoic strata within Minto Inlier on Victoria Island and in the southern part of Brock Inlier north of Great Bear Lake. Patterns also show the relationships of Devonian evaporites, carbonate, and shale near Great Slave Lake.

    Elsewhere letters only are used to designate special types of sedimentary rocks such as Mesoproterozoic marble in the southwestern Grenville Province north and south of Ottawa, Paleoproterozoic conglomerate and sandstone west and north of Hudson Bay, and mélange in the Appalachian and Cordilleran orogens.

    Volcanic rocks are generally shown by darker shades of colours of the equivalent sedimentary assemblages. Their composition is designated by letters. The composition of intrusive rocks is similarly noted by letters. Ultramafic mélange units are coloured the same as ultramafic intrusive rocks and are included with them in the legend because they represent proximal erosional products of oceanic ultramafic rocks and are therefore important in identifying the leading edge of oceanic accreted terranes.

    Metamorphic rocks are most widespread in the Canadian Shield. There, medium grade metamorphic rocks (upper amphibolite facies), chiefly of Archean age, are designated by the letter "n" and for supracrustal rocks by letters denoting related compositions. Areas of granulite facies are shown by a "peck" pattern. Phanerozoic metamorphic rocks of upper amphibolite facies are shown in black stipple. They are most prominent on the west coast of Vancouver Island, in the Coast and Omineca belts of the Cordillera and in the Gander Zone of east-central Newfoundland. Metamorphic rocks in the Coast Belt whose protoliths are of uncertain age are shown in violet and designated by the letters "n" and "gn".

    Attention is drawn to certain aspects of the following onshore geological features:

    1. Volcanic centres represent volcanoes, vents, and plugs;

    2. Clusters of Mesoproterozoic mega-breccias or diatremes cut Paleoproterozoic units north and east of Dawson, Yukon. A few Ordovician-Silurian diatremes occur in Mackenzie Mountains southwest of Norman Wells, another lies just west of the Rocky Mountain Trench in northern British Columbia, and one is associated with a Mississippian carbonatite in the Rocky Mountains north of Peace River. Additional clusters of diatremes mostly of Ordovician-Silurian age but including one of Devonian- Mississippian age are scattered over the southernmost Rocky Mountains in easternmost British Columbia.

    3. Alaskan-type ultramafic bodies are roughly circular, comprising a dunite or wehrlite core surrounded by clinopyroxenite, hornblendite, and hornblende gabbro or diorite. Orthopyroxene is typically absent and plagioclase rare (Woodsworth et al., 1991). Those of Late Triassic age occur east and northeast of Bowser Basin and in southernmost Intermontane belt. Mid-Cretaceous bodies extend from near Prince Rupert northwest through southeastern Alaska.

    4. Although few of the kimberlites have been well dated they range considerably in age. Kimberlites around Lac de Gras in central Slave Province have yielded Eocene and Late Cretaceous ages (Pell, 1995). Kimberlites in the Fort à la Corne area are late Early Cretaceous (Lehnert-Thiel et al., 1992) whereas the Cross kimberlite near latitude 50oN in the Rocky Mountains is Permian-Triassic (Smith et al., 1988). A cluster in the Superior Province close to the Ontario-Quebec border yield Late Jurassic ages (Brummer et al., 1992).

    5. A special symbol shows the leading or inboard edge of terranes accreted to ancestral North America during the Phanerozoic. In the Appalachian Orogen this boundary is the Baie Verte-Brompton Line (Williams and St-Julien, 1982; Malo et al., 1992) separating the lower Paleozoic passive continental margin sequence of the Humber Zone in the northwest from the Cambrian-Ordovician oceanic, ophiolite-bearing assemblage of the Dunnage Zone to the southeast. Accretion took place during the Early and Middle Ordovician Taconic Orogeny accompanied by emplacement of ophiolitic oceanic thrust slices onto the Humber Zone (Williams, 1995). Some parts of the accreted terrane boundary have been engulfed by plutons and overlapped by Silurian, Devonian, and upper Paleozoic cover rocks.

    Pearya Terrane on northernmost Ellesmere Island in the Arctic is a fault-bounded composite continental fragment probably derived from the Caledonides. It is made up of Mesoproterozoic to Silurian rocks and contains an early Middle Ordovician suture coeval with the Taconic Orogeny. Pearya docked against the Franklinian deep water basin along sinistral faults, probably during Late Silurian-Early Devonian (Trettin, 1991).

    The leading edge of accreted terranes in the Cordillera generally forms the boundary between the Devonian to Triassic oceanic Slide Mountain Terrane and the Neoproterozoic to Triassic pericratonic Kootenay Terrane. Locally, where these terranes are thin or missing the neighbouring Quesnel Terrane in the west is juxtaposed against the Neoproterozoic and younger continental margin assemblages in the east.

    In the Yukon the leading edge of the accreted terranes is truncated by the through-going, northwest-trending Tintina Fault. Restoration of its dextral displacement of between 425 to 500 km (Gabrielse, 1991) permits the leading edge southwest of the fault to merge with the leading edge of the accreted terranes in a salient northeast of the fault.

    The Slide Mountain and Quesnel terranes accreted to ancestral North America and its proximal pericratonic Kootenay Terrane in early Middle Jurassic time (Gabrielse and Yorath, 1991). At that time, thrust sheets now lying east of the leading edge of the accreted terranes, were emplaced tens of kilometres onto the carbonate continental shelf in a manner similar to that in the Appalachian Orogen.


    Click the ‘My Computer’ file manager, followed by ‘MAP on ‘U171’ (J:). [NOTE: 'U171' must be mapped to a drive]

    Double click INTRO.EXE to load the GSC Map file.

    When the GSC Map windows appears, click the WINTOUR button.

    Read the files loaded through the hypertext links ‘OVERVIEW’, ‘USAGE’, and ‘The GEOLOGICAL MAP OF CANADA files’. Make notes on the abbreviations used in the file names to indicate the information contained in the map layer.

    Return to the GSC Map Window and click the hypertext link ‘THE TOUR’.

    From the file listing, click roxappPE.asc to display the digital map of the Appalachians.

    Click FILE on the Tool Bar followed by FILE DISPLAY LIST.

    Click the ADD button, and in ‘Select Data File for Map Display', select the file \canada\shp\can\ctycan.bob. The file name ctycan.bob will appear at the bottom of the file list in the display list box.

    Remove the ‘x’ in the 'Adjust view on return’ button, and click ‘OK’ to display the map layer overlain by a layer containing the locations of the major Canadian cities and towns.

    Click VIEW on the Tool Bar and then Zoom/Pan. Move the mouse to the left to adjust the size of the zoom box to your requirements. Click the left mouse button and move the zoom box until it is centered on the town of Fredericton. Then press the right mouse button.

    Examine the map using the map legend.

    To determine distances, place the cursor on the beginning location; click and hold the left mouse button, and drag the cursor to the end location without releasing the mouse button. The ‘Map Distance’ (in metres) can be read off at the top left of the window.

    Click File -> File Display List.

    Click /ctycan.bob and then the REMOVE button. Click OK.

    Place the airplane cursor on any of the displayed rock units and click the right mouse button. A RECORD box containing information about the rock unit will be displayed. Click the CLOSE button to return to the map display. (NOTE: this function cannot be used when there is more than one layer in the FILE DISPLAY LIST); therefore the necessity to remove ctycan.bob from the list as requested above.)

    Return to the File List Display dialog box, remove the roxappPE.asx layer and ADD and examine the roxappRC.asx layer. Repeat this procedure for each of the RS, UN and RA layers.

    Lab Exercise:

    (Optional: make a print of the Geological Provinces of Canada with an overlay of city names by removing all files from the FILE DISPLAY LIST, and then adding geoprov.asx first and ctycan.bob second from the Canada/shp/can folder. When printing select 'Landscape'.)

    Locate the structural province in which each of the following cities resides, and determine the nature and age of the rocks within 10-15 kilometres of each city:

    1) Sudbury

    2) Yellowknife

    3) Timmins

    4) Whitehorse

    5) Gander

    6) Baker Lake

    7) Edmonton

    8) Flin Flon

    9) St. John, New Brunswick

    10) Vancouver

         Find the oldest rocks in the Slave (Churchill) structural province (roxchuUN.asx).


    This atlas is a compilation of crustal seismic reflection data acquired by LITHOPROBE, Canada's national multidisciplinary geoscience project. This web site at:


allows you to view images of these data and their interpretations.

Click  LithoProbe Seismic Atlas of Canada to access the site.

    To  navigate the site, select a transect (study area) from the transect map or the menu bar on
the left. This will take you to a menu for that particular transect where you can select a seismic
line to view or a transect summary. If there is no data available, the transect summary will
come up by default. The data presented in this atlas are for public use. Feel free to download
images and use them in any way you want.

    Seismic data preparation and layout by Arie van der Velden. Maps by Elissa Lynn.
The transect summaries have been taken from the LITHOPROBE phase V proposal, edited by
R.M. Clowes.