Abstract
Weakly metamorphosed metasedimentary rock samples used in this study belong to Ramah group of Proterozoic. The Ramah group, consisting chiefly of sedimentary rocks distribites along north-south trending synclinal axis in northern Labrador. The Ramah group is considered early Proterozoic on the basis of a Rb-Sr whole rock age of 1.89 Ga (Morgan, 1978), obtained from a basalt lava and related feeder dyke near the base of the group. Approximate total thickness of the group is 1700 m, most component of the group are sedimentary rocks. Volcanic rocks are minor component of the lower sequencre, but numerous diabase sills which intruded the group are known. The group is subdivided in to six formations (Morgan, 1975; Knight and Morgan, 1977, 1981), Rosell Harbour, Reddick Bight, Nullataktok, Warspite, Typhoon Peak and Cameron Brook formations in ascending order, the dominant lithologies are quartzite, sandstone, mudstone and carbonate rocks. Samples used in this study are grouped into three categories, black shale, grey shale, and graywacke, from the observation of hand specimens, thin sections as well as from their chemical compositions.
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