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Stratigraphy, petrology, and geochemistry of the North Touak-Cape Dyer volcanic belt, and implications for the tectonic setting of the Paleoproterozoic Hoare Bay group, eastern Baffin Island2012 September 1900 (has links)
During the Geological Survey of Canada’s Cumberland Peninsula Integrated Geoscience project a ~150km long NE-SW trending volcanic belt, now termed the North Touak-Cape Dyer volcanic belt, was mapped.
The volcanic rocks that comprise the belt are dominantly green weathering komatiitic rocks with some black weathering tholeiitic occurrences. Given the similar stratigraphic position, textures, mineralogy, and geochemical characteristics of the volcanic rocks throughout the belt they have been termed the Totnes Road formation, after the locality from which they were first described. The komatiitic rocks possess numerous unusual characteristics for ultramafic volcanic rocks including: fragmental textures, lack of spinifex texture, young eruption age (Paleoproterozoic), eruption through ancient continental crust, and enrichment in the HFSEs including the REEs. This places them in the uncommon and poorly understood sub-type of komatiites termed Karasjok-type komatiites. Given the ultramafic nature of the rocks and their within-plate geochemical signatures, a mantle plume is the most likely source of these rocks, with the komatiites being sourced from the hot plume axis and the tholeiites from the cooler plume head. Incorporation and melting of mantle enriched by the addition of subduction zone recycled, garnet-bearing eclogitic material, beneath thick lithosphere could cause the rocks geochemical enrichment.
Stratigraphically overlying the Totnes Road formation is a variety of chemical sedimentary rocks including chert, sulphide and silicate facies iron formation, and sulphide-rich boulders. Given their consistent stratigraphic position and parallel REE patterns, these rocks have been interpreted as a co-genetic suite and are grouped under the Clephane Bay formation, after a locality that exposes a spectacular section of the chemical rocks. The variety of lithologies is believed to be due to mixing of hydrothermal and detrital inputs during deposition within an anoxic basin.
Regional correlations in the area are tentative due to the lack of available geochronological and geochemical data. Mafic-ultramafic volcanic occurrences to both the north and the south of the Cumberland Peninsula show remarkably similar geochemical characteristics to the Totnes Road formation. Thus it is possible that one plume was the source for numerous volcanic occurrences within in the region but more detailed study is required to prove or disprove this possibility.
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An examination of the Pre-Dorset caribou hunters from the deep interior of Southern Baffin Island, Nunavut, CanadaMcAvoy, Deanna Grace 21 April 2014 (has links)
The faunal remains from four archaeological sites on the northwest shore of Mingo Lake, in the interior of Southern Baffin Island, are examined in this thesis. All four sites are radiocarbon dated to Pre-Dorset times (4500 – 2700 BP). The faunal assemblage is dominated by caribou remains. As such, this study is the first, large-scale faunal analysis of an interior Pre-Dorset site with caribou as a main subsistence resource. In total 18,710 faunal bones were examined. Elemental frequencies, fracture patterns, bone burning, and butchering patterns will provide important insights into the lifeway of the Pre-Dorset. The results of the thesis indicate that the Pre-Dorset were utilizing the Mingo Lake area during the late summer into early fall. The main activity at all four sites was caribou hunting with a focus on marrow extraction. The sites served dual purposes as habitation and butchering sites and were occupied for varying lengths of time.
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