An Analysis of Glacial Sediment Dispersion with Applications to Diamond Exploration, Lac de Gras, Northwest Territories

• Main Author: Janzen, Robert
• Format: Master Thesis
• Language: English
• Published: University of Waterloo 2020
• Subjects: Diamond; Exploration; Quaternary; Geology; Lac de Gras; indicator minerals; kimberlite; Canada; Northwest Territories
• Online Access: http://hdl.handle.net/10012/16339

Diamond exploration is important to the economy of the Northwest Territories and Canada. In recent years, however, there has been a marked decline in the discovery rate of large diamond deposits. Emphasis is being put on improving geological models and developing new approaches of exploration in the hope of finding previously overlooked deposits. A proven approach in diamond exploration in the Northwest Territories and other similarly glaciated terrains has been to characterize the glacial cover to reveal secondary detrital dispersion of indicator minerals and geochemical pathfinders, which can help vector towards a buried kimberlitic source. Typically, only the surficial indicator mineral expression of a kimberlitic signature is known and mapped, which may lead to missed targets, especially in places with shifting ice flows and a complex glacial sedimentary record. This research, in the Lac de Gras area of Northwest Territories, uses a dataset containing both surface and subsurface data, from hand sampling and RC drilling, to bring new knowledge about the glacial geology and to improve our understanding of till production and related detrital dispersion in this prospective region. Erosional outcrop-scale paleo-ice flow indicators show an evolving history of ice-flow in a clockwise sequence starting in the southeast, then west, and finally to the northwest. The ice-flow indicators in the study area show that the northwest ice-flow phase is prominent accounting for 77% of all observations. The particle size distribution of surficial till samples is relatively homogenous, which lends support to the interpretation that the surface till forms a single till unit. The clast lithological analysis shows that the till contains all the different lithologies present in the study area in variable proportions, which appears to reflect a combination of processes and factors, such as bedrock hardness in the up-ice area versus in the dispersion area. The principal component analysis (PCA) of the major oxides shows the till is a ...