The geology of the Arkose Lake area, north of Seal Lake, Labrador, Canada

Knight, I. (Ian) (1972) The geology of the Arkose Lake area, north of Seal Lake, Labrador, Canada. Masters thesis, Memorial University of Newfoundland.

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Abstract

The Proterozoic sediments of the Seal Lake Group in the Arkose Lake area are here subdivided into the Arkose Lake Formation and the Majoque Lake Formation. -- The Arkose Lake Formation is subdivided into a Lower Member of coarse sandstones and grits and subsidiary conglomerates and an Upper Member of fine to coarse red sandstones with subsidiary conglomerates and red siltstones. Field, petrographic and statistical evaluation indicate deposition, by braided streams upon an alluvial fan, of immature, fluviatile sediments derived from a gneissose and granitic terrane to the north of the present area. -- The Majoque Lake Formation consists predominantly of subaerial basaltic flows with some thin sediment bands. Thin, weathered basalt profiles separate the sediments from the underlying basalts. Mineralogically and chemically, the basalts are transitional between alkali and tholeiite basalts. The sediments are composed predominantly of conglomerate, grit and sandstone with local, fine,pink quartzites. Field, petrographic and statistical data suggests that they represent coarse, immature, gravel and sand deposited under semi-arid conditions on a braided outwash plain that periodically covered a volcanic 'pediment'. They were derived from a gneissic-granitic and in part acid-volcanic terrane to the north. -- The area has been deformed by one major phase of compression probably associated with the Grenville orogeny. This produced northward facing, major folds and thrust faults which trend east - west. The stratigraphy within the Arkose Lake area is significantly affected by these structures and suggests that the northern limb of the Seal Lake Basin is more complex than previous studies suggested. As a result, the stratigraphy of the Seal Lake Basin may be significantly different from that set up by Brummer and Mann (1961) and the thickness of the Seal Lake Group may be markedly less than the 42,000' suggested by the above authors.

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