Analyzing the data in MOROCCAN.WK1 using NEWPET
You have been provided with 61 analyses of samples collected from the Late Precambrian volcanic complex of Bou Azzer in the Anti-Atlas Mountains of southern Morocco, and two standard oceanic basalts. The Moroccan data is taken from papers by Bodinier et al. 1984, and Naidoo et al 1991, and is contained in the Lotus 1-2-3 file 'MOROCCAN.WK1' created by importing the ascii file ANAL.DAT into EXCEL. MOROCCAN.WK1 was then converted to the NEWPET .ROC file format using the Newpet conversion program.
The data has been selected on the basis of location, and has been symbol and colour coded as follows. (The locations and sample numbers are also shown on the accompanying sheet andmap (created from FIELDLOG)):
Symbol# colour# symbol colour Area Samples:
1 1 circle black Atlantic 3-18 (oceanic basalt)
2 2 half filled circle green Atlantic 210 (oceanic basalt)
3 3 filled circle lt blue Menissi 8-1, 2, 13, 19 (basalt, andesite)
4 4 open square red Diorites 1273; 1172; 285; 701 (diorites)
5 5 half filled square pink Oumarou 1200 (M-G); 1199 (diab); A8 (diab);
1K13D1C etc. (diab); 1-8, 9, 11 (diab)
1179 (pillow lava); 575 (M-G); 569 (M-G);
1403 (diab)
6 6 filled square orange Bleida 9-2, 11; 10-1, 5, 7; 14-8, 10 (basalt)
7 7 open triangle white Ousdrat 1167 (basalt/spilite); 2-6 (and),11 (rhy);
4-11, 13 (basalt); 6-5 (rhy), 9 (basalt);
11-5a, 11, 13, 14, 24 (andesite); 12-4 (and),
9 (dacite),14 (dacite),17 (and)
8 8 filled triangle grey Skouraz 734, 1184, 736 (spilite); 7-4,12,15 (basalt)
9 9 triangle blue Dwaissat 3-7; 13-2, 3, 14 (basaltic);743 (diab);
10 10 triangle green Bou Azzer 311 (cpxite)
The data points in all plots made in NewPet will therefore be recognisable in terms of symbol and colour.
The exercise involves establishing, where possible, the tectonic affiliation or environment of formation of individual or sets of related samples, as the case may be, through an analysis of the plots of the data made by NewPet. Bear in mind that that at any given location there may be several tectonic environments represented e.g. oceanic and island arc rocks.
PROCEDURE
The NewPet program and the data files are located in the folder ‘Mapped drive\Public\Es300b\Newpet on Earthnt’. Make a note of the drive letter attributed to the mapped drive. Click the ‘My Computer’ icon (or NT Explorer) and select Public\Es300b on Earthnt, and then the subdirectory (folder) ‘NewPet’. To implement ‘NewPet’ double click the ‘NewPet.exe’ file. The NewPet DOS window will appear. Press any key to continue.
Cursor to the plot option ‘3 NewDisc discrimination X-Y, Ternary plots’ and press ENTER. A 'Discrimination Plots' menu will appear. Cursor down to the 'Get a data file' line and press the ENTER key. If the mapped drive letter does not correspond to the default data directory indicated on the screen, enter the mapped drive letter for 'Earthnet\Public', and then add the path 'Es300\newpet', e.g. G:\Es300\newpet. In the NewPet folder select ‘moroccan.roc’ and press the ENTER key.
To change the plot symbols select 'Change Plot Symbols' and then 'Individual Samples'. A table of sample names and their symbol and colour attributes will appear on the screen. Cursor down to sample 701 and press Enter. A symbol box will appear. Cursor down to number 4 (Box-open) and press ENTER. Cursor down to 4 (red) in the colour box that now appears. Press ENTER. Carry out the same procedure to change sample 1179 to symbol and colour value 11, and sample 743 to value 9. Upon completion, press ESC to return to the Discrimination Plots menu.
Select Majors Discrimination Plots and then SiO2 - Na2O + K2O to see alkali - silica rock classification. Note that most samples range from basalt to rhyolite, but that some samples are enriched in alkalies and fall in the trachyandesite field, others are almost devoid of alkalies, and that one of the Dwaissat samples is particularly enriched in Na+K. These variations may indicate that alkalies have been mobile during the low-grade metamorphism of the rocks, and that the use of alkali plots is suspect. Systematically examine the information provided for each region (choose data by symbol) using the various plots listed in the 'Major Discrimination Plot' menu and the 'Traces Discrimination Plots' menu. In particular examine the FeO/MgO v TiO2 plot and the Ti/100-Zr-3*Y diagrams, and write down your observations concerning the spacial distribution of the colour coded samples. Identify the various tectonic environments (WP, MORB, LKT, CA) represented by the samples, on the map provided. Look at some of the samples as SPIDERGRAMS.
SAMPLES
COORDS
SAMPLE NAME,
X, Y SYMBOL
COLOUR ROCK TYPE
3-18 (9), 1, 1, depleted MORB
2-10 (2), 2, 2, enriched MORB
8-1 MENISSI N, 3960, 3775, 3, 3, ANDESITE
8-13 MENISSI N, 3960, 3775, 3, 3, BASALT
8-19 MENISSI N, 3960, 3775, 3, 3, BASALT
8-2 MENISSI N, 3960, 3775, 3, 3, BASALT
1273 OUS DIOR B, 3870, 3890, 4, 4, DIORITE
701 GRAARA OPH B, 3900, 3840, 4, 4, DIORITE
1172 OUM OPH DIOR B, 3350, 3865, 4, 4, DIORITE
285 OUM OPH DIOR B, 3485, 3950, 4, 4, DIORITE
1200 OUM OPH MGB B, 3867, 3858, 5, 5, MASS_GABBRO
1199 OUM OPH SD B, 3867, 3858, 5, 5, DIABASE
A8 OUM OPH SD B, 3867, 3858, 5, 5, DIABASE
IK13D1C OUM DINSERP N, 3850, 3867, 5, 5, BASALT
IK20DY1B OUM DINSERP N, 3850, 3867, 5, 5, ANDESITE
IK23F4C OUM DINSERP N, 3850, 3867, 5, 5, BASALTIC
IK38DB2 OUM DINSERP N, 3850, 3867, 5, 5, BASALT
IK40FSC OUM DINSERP N, 3850, 3867, 5, 5, BASALT
IK52F3C OUM DINSERP N, 3850, 3867, 5, 5, BASALT
IK8D1C OUM DINSERP N, 3850, 3867, 5, 5, BASALT
1-11 OUM DINSERP N, 3850, 3867, 5, 5, BASALT
IK1CF3BC OUM SD N, 3850, 3867, 5, 5, BASALTIC
IK37CF2C OUM SD N, 3850, 3867, 5, 5, ANDESITE
IK4CF1DC OUM SD N, 3850, 3867, 5, 5, BASALT
1-8 OUM SD N, 3850, 3867, 5, 5, BASALT
1-9 OUM SD N, 3850, 3867, 5, 5, BASALT
1179 GRAA C OPH P B, 3932, 3815, 5, 5, PILLOW_LAVA
575 GRAA C OPH D B, 3850, 3870, 5, 5, DIABASE
569 GRAA C OPH G B, 3860, 3860, 5, 5, MASS_GABBRO
1403 GRAA C OPH D B, 3830, 3880, 5, 5, DIABASE
9-11 BLEIDA N, 4020, 3728, 6, 6, BASALT
9-2 BLEIDA N, 4020, 3728, 6, 6, BAS-ANDESITE
10-5 BLEIDA N, 4000, 3725, 6, 6, BASALT
10-7 BLEIDA N, 4000, 3725, 6, 6, BASALT
10-1 BLEIDA N, 4000, 3725, 6, 6, BASALT
14-10 BLEIDA N, 4025, 3715, 6, 6, BASALT
14-8 BLEIDA N, 4025, 3715, 6, 6, BASALTIC
1167 OUS B, 3890, 3876, 7, 7, SPILITE
2-11 OUS N, 3900, 3875, 7, 7, RHYOLITE
2-6 OUS N, 3900, 3876, 7, 7, ANDESITE
4-11 OUS N, 3950, 3837, 7, 7, BASALT
4-13 OUS N, 3935, 3845, 7, 7, BASALT
6-5 OUS N, 4055, 3765, 7, 7, RHYOLITE
6-9 OUS N, 4055, 3765, 7, 7, BASALT
11-5A OUS N, 3940, 3840, 7, 7, RHYOLITE
11-11 OUS N, 3940, 3840, 7, 7, BAS-ANDESITE
11-13 OUS N, 3940, 3840, 7, 7, ANDESITE
11-14 OUS N, 3940, 3840, 7, 7, ANDESITE
11-24 OUS N, 3940, 3840, 7, 7, ANDESITE
12-4 OUS N, 3875, 3872, 7, 7, ANDESITE
12-9 OUS N, 3875, 3872, 7, 7, DACITE
12-14 OUS N, 3875, 3872, 7, 7, DACITE
12-17 OUS N, 3875, 3872, 7, 7, ANDESITE
734 SKOURAZ B, 3900, 3810, 8, 8, SPILITE
1184 SKOURAZ B, 3900, 3810, 8, 8, SPILITE
736 SKOURAZ B, 3900, 3810, 8, 8, SPILITE
7-12 SKOURAZ N, 3930, 3790, 8, 8, BASALT
7-15 SKOURAZ N, 3930, 3790, 8, 8, ANDESITE
7-4 SKOURAZ N, 3930, 3790, 8, 8, BASALT
3-7 DWAISSAT N, 3932, 3815, 9, 9, BASALT
13-2 DWAISSAT N, 3943, 3812, 9, 9, BAS-ANDESITE
13-3 DWAISSAT N, 3943, 3812, 9, 9, BASALT
13-14 DWAISSAT N, 3943, 3812, 9, 9, BASALT
743 W GRAA C B, 3945, 3810, 9, 9, DIABASE
311 BOU B, 3500, 3950, 10, 10, CPYROXENITE
B = Boudier et al.; N = Naidoo et al; oph = ophiolite; SD - sheeted diabase;
DINSERP = diabase intruding serpentine; DIOR = diorite