An Analysis and Interpretation of the Geoscience BC Trek Project Till Geochemical and Mineralogical Data to Determine the Surficial Geochemical Expression of Bedrock Au-Ag-Cu-Mo Mineralization on the Nechako Plateau, British Columbia, Canada.

Abstract: The mineral exploration in the interior of British Columbia is challenged by an extensive coverage of glacial sediments. The Geoscience British Columbia (GBC) Targeting Resources through Exploration and Knowledge (TREK) Survey has since 2013 collected till samples in the northern interior plateau of British Columbia, covering an area of approximately 25,000km2. The TREK area is largely covered by Miocene to Pleistocene age volcanic rocks that are underlain by older volcanic, sedimentary, and intrusive rocks of the Stikine Terrane, and also to a smaller extent in the east by rocks of the Cache Creek Terrane. Previous surficial mapping to aid mineral exploration has determined that the Pleistocene ice sheet advances have been mainly to the east-northeast. The British Columbia Geological Survey (BCGS) MINFILE database includes five developed prospects, seven prospects and 39 mineral showings in the TREK Project area. Styles of mineralization include late Cretaceous and Eocene epithermal Au and Ag deposits (e.g., Blackwater-Davidson, Capoose, Wolf, and 3T’s), lower Cretaceous sediment-hosted Carlin-type deposits (e.g. Bob) and Jurassic to Eocene porphyry Cu and Mo deposits (e.g., Endako and Chu). This report analyzes and interprets till digital data from three TREK Geoscience BC reports and one BCGS Open File to determine if there is a mineralogical and geochemical signature in the till of buried bedrock mineralization. Through statistical analysis, including scatter plots, probability plots, and box plots, populations of key ore indicators and pathfinder elements are compared, thresholds are established and anomalous samples queried. Spatial plots of samples with known pathfinder elements e.g. Au, Ag, Cu, and Mo values above established thresholds are created and compared with heavy mineral till concentrates such as pyrite and cinnabar. Major oxide element ratios from till sample whole rock analysis were also analyzed to identify hydrothermal alteration associated with the mineralization. The analysis has demonstrated that anomalous values reflect known bedrock mineralization and that there are two areas within the study area that do not appear to be related to already known mineral occurrences.