Helicopter AFMAG (ZTEM) EM and magnetic results over sedimentary exhalative (SEDEX) lead-zinc deposits at Howard?s Pass in Selwyn Basin, Yukon

Abstract

In 2008 Geotech flew a regional scale 24,675 line-km survey covering a 25,000 km2 area (1 km line spacing) in the Selwyn Basin. The survey footprint straddles east-central Yukon and overlaps into the western Northwest Territories. In March 2013 Yukon Geological Survey purchased the survey data, and in November 2013, released the data publicly. The Selwyn Basin area is prospective for SEDEX-style Pb-Zn-Ag mineralization and the ZTEM survey data provide insights into regional structures and plutons in the region. The Howard's Pass SEDEX deposits at the southeastern edge of the Selwyn Basin survey area host a combined ~250 million tonne resource with ~4.5% Zn and ~1.5% Pb. Major NW-SE to ESE and minor NNW-SSE linear conductive trends correlate with known regional geologic, structural and inferred mineral trends. Circular conductive anomalies surrounding resistivity highs reflect po-rich hornfels surrounding intrusive plutons. 2D-3D computer inversions reveal a correlation between enhanced conductivity along strike and the clustering of deposits at Howard's Pass.