APPLICATION OF LEAD ISOTOPES TO MINERAL EXPLORATION IN GLACIATED TERRAINS

The Pb-206/Pb-204 ratios of fine-grained fractions from glacial tills indicate the presence of known Proterozoic volcanogenic massive sulfid e deposits at Chisel Lake, near Snow Lake, Manitoba, Canada. Data from <2 mum and other size fractions define a linear array on a Pb-207/Pb- 204 VS. Pb-206/Pb-204 diagram, with a slope that yields an age similar to the age of the deposits and the surrounding country rocks. Some of the least radiogenic till samples were found down ice from the deposi ts, suggesting that the Pb isotopic compositions from till may provide a new approach to mineral exploration for massive sulfide deposits in glaciated terrains.