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Kimberlite Indicator Minerals from the Central Mackenzie Valley, Northwest Territories, Canada: A Reconnaissance Geochemistry Survey
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- Author / Creator
- Poitras, Stephane P
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The Central Mackenzie Valley (CMV) area of Northwest Territories is underlain by Precambrian basement belonging to the North American Craton. The potential of this area to host kimberlitic diamond deposits is relatively high judging from the seismologically-defined lithospheric thickness, the age of basement rocks (2.2-1.7 Ga) and presence of kimberlite indicator minerals (KIMs) in Quaternary sediments. This study presents new major, minor and trace element chemistry data for kimberlite indicator mineral (KIM) grains collected from two regions within the Central Mackenzie Valley, Northwest Territories. The data, along with new kimberlite-related rutile U-Pb ages and ilmenite Hf isotopic compositions are used to constrain the composition and thickness of the lithospheric mantle sampled by the source kimberlite(s) and age of these kimberlites for these two regions. In the processed samples, peridotitic garnets dominate (> 25 % at each location) while eclogitic garnet is almost absent in both regions (< 1 % each).
KIM chemistry for the Horn Plateau indicates significant diamond potential, with a strong similarity to KIM systematics from the Central and Western Slave Craton. The most significant issue to resolve in assessing the local diamond potential is the degree to which KIM chemistry reflects local and/or distal kimberlite bodies. Radiogenic isotope analysis of detrital kimberlite-related CMV oxide grains requires at least two broad age groups for eroded source kimberlites. Statistical analysis of the data suggests that it is probable that some of these KIMs were derived from primary and/or secondary sources within the CMV area, while others may have been transported to the area from the east-northeast by Pleistocene glacial and/or glaciofluvial systems. At this stage, KIM chemistry does not allow the exact location of the kimberlitic source(s) to be constrained. -
- Graduation date
- Fall 2018
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.