<p> A sequence of metasedimentary rocks comprising the Prince Albert
Group, within and to the southwest of the Ellice Hills, District of
Keewatin, N.W.T., was studied. Petrographic examination of the four
major facies present -- quartzites, greywacke-paragneisses, metaultrabasics
and iron formation was carried out and geochemical whole
rock data was obtained using X.R.F. methods. </p> <p> Metamorphism occurred during the Hudsonian orogeny and came in
three distinct pulses. These pulses are evident in thin section. The
first pulse is characterized by the fonnation of garnet poikiloblasts
and a biotite foliation; the second by a stronger biotite and hornblende foliation accompanied by quartz and muscovite porphyroblasts, and the
third pulse is characterized by the growth of fibrolite needles. The
last pulse of metamorphism shows that fibrolite and orthoclase formed
from the dehydration of muscovite in the presence of quartz. Thus, a
pressure and temperature regime for this event can be inferred from
published experimental studies. These indicate that PM2O ranged from
2.0 to 3.5 Kbars and that temperature ranged from 640° ± l0°C to
670° ± l0°C. Previous pulses may have had higher pressure ranges but
certainly lower temperature ranges prevailed. The present metamorphic
grade of the Prince Albert Group displays mineral assemblages indicative
of the Sillimanite-orthoclase-almandine Subfacies of the Almandineamphibolite
Facies as defined by Winkler (1967). </p> <p> Structural deformation is closely associated with metamorphism.
At least three periods of deformation have occurred. The first is evident
in thin section by the s1 foliation and parallel trains of sialic material
in garnet poikiloblasts. The second period of deformation caused the
rotation of the above garnets, plus formation of the F2 isoclinal folds,
s2 biotite foliation, crenulation of the s1 foliation and the formation
of muscovite-quartz porphyroblasts. The third period of deformation is
responsible for the F3 folding, warping of the F2 axial trace and the
antisotropic growth of fibrolite.</p> / Thesis / Bachelor of Science (BSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/20799 |
| Date | 04 1900 |
| Creators | Wolff, John |
| Contributors | McNutt, R. H., Grundy, H. D., Geology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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