Spelling suggestions: "subject:"precambrian rocks"" "subject:"precambriano rocks""
1 |
An Estimate of the Composition of Part of the Canadian Shield in Northwestern OntarioReilly, George Alexander 05 1900 (has links)
<p> An attempt has been made to estimate the abundance of trace and major constituents in the Precambrian surficial rocks in a large part (43,000 square miles) of the Red Lake - Lansdowne House area in northwestern Ontario. The area has an average composition which is
close to that of granodiorite, more silicic than most estimates of crustal abundance, close to other estimates for continental shield areas, but possibly deficient in K2O relative to Poldervaart's (1955) estimate. The rocks of this area appear to be low in Be, Ti, V, Cu, Y, Sc and Zr, and high in Sr, relative to crustal abundances based on the proportion of exposed rocks on the surface of the continents (Turekian and Wedepohl, 1961). Analysis of variance techniques have detected significant regional variations of Cr, Mn, Sr and Ba. Significant
variation exists between rock types for all trace elements analyzed except Cu.</p> / Thesis / Master of Science (MSc)
|
2 |
Petrology, geochemistry, and geochronology of some Precambrian rocks of the north-western Melville Peninsula, Northwest TerritoriesPrevec, Stephen 04 1900 (has links)
<p> The northwestern Melville Peninsula in the area of
69°34'N/84°50'W consists of Precambrian Shield rocks
that have suffered multiple metamorphic events,
including a high grade metamorphic event in the late
Archean, ranging from upper amphibolite to granulite
grade locally. The oldest unit present is a
tonalite-granodiorite-granite suite showing both
foliation and lineation and a somewhat migmatic texture.
This biotite-hornblende orthogneiss has produced a Rb-Sr
whole rock age date of 2.55 +/- 0.2 Ga. Field
relationships indicate that this is a metamorphically
induced age rather than an emplacement age. A coarse
grained granitic pegmatite associated with the
orthogneiss has produced a Rb-Sr isochron indicating an
age of 1.83 +/- 0.06 Ga. Petrographic and field evidence
indicate that this represents the emplacement age of the
pegmatite. </p> / Thesis / Bachelor of Science (BSc)
|
Page generated in 0.0436 seconds