Geochemistry of till in perennially frozen terrain of the Canadian shield— application to prospecting

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Abstract
Shilts, W. W. 1977 06 01: Geochemistry of till in perennially frozen terrain of the Canadian shield ‐ application to prospecting.Geomorphological (drumlins, ribbed moraine) and geochemical features associated with till in the District of Keewatin are arranged in belts or dispersal trains paralleling the main direction of ice flow. Both types of features can be related to chemical and physical characteristics of specific types of source rocks.For dispersal studies in perennially frozen terrain, till samples were collected from mudboils at spacings of approximately 1.6 km. The texture of till samples varies significantly from sample site to sample site because of varying source‐rock lithologies and periglacial processes. Thus, because fractions coarser than clay are mostly quartz and feldspar and contain very little metal after weathering in the active layer, they were removed by centrifugation so as not to mask the ‘true’ relative metal contents of samples. The clay‐sized fraction was separated from till samples and analyzed on the assumption that it contained scavenging phases that adsorb cations in proportion to those released by weathering of mineralized particles that were originally physically dispersed by glacial action.Dispersal patterns of copper, zinc, nickel, and uranium were derived for approximately 1000 samples evenly distributed over a 2500 km2 grid. From these maps, large dispersal trains of copper and nickel were found, and known areas of high potential for uranium and Cu‐Zn mineralization were clearly indicated.

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