UBC Theses and Dissertations
Surficial and geochemical evolution of periglacial soils : applications to mineral exploration in Yukon Cox, David
Exploration geochemistry is a powerful tool when exploring for gold deposits in periglacial environments, such as west-central Yukon. However, this study identified two main challenges to using soils as indicators of bedrock mineralization: 1) the variability of sample material over the scale of hundreds of meters and 2) The dilution of metal concentration in soil caused by the addition of loess. Herein, a study into the distribution of surficial materials is presented, the outcome of which is the mapping of surficial units whereby the terrain is divided into domains based on topography, surficial material and surficial processes. Furthermore, a study into the distribution of metals, specifically gold, within a selection of domains concludes that there is considerable geochemical variation between domains and that no single optimum sample material occurs throughout west-central Yukon. Hence, a tailored sampling protocol, based on surficial mapping is recommended. Results of scoping studies to the development of two methods to aid in exploration for gold deposits in west-central Yukon are presented: 1) a method for approximating the proportions of loess in a soil sample; proportion of loess in the Bdm horizon and Bm horizon from a selection of exposures from the Golden Saddle deposit were calculated. 2) A method for detecting bedrock alteration by the analysis of the mineralogy of surficial material; Well-crystalized illite, which forms specifically under hydrothermal conditions is identified in surficial material overlying the Golden Saddle deposit. This demonstrates that bedrock alteration minerals remain stable under surficial conditions. The two methods outlined above are demonstrated to be plausible and applicable to exploration in this area.
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