Application of lead isotopes to mineral exploration using glacial till of the Halfmile Lake area, Bathurst, New Brunswick

Pb isotope ratios from till in the Halfmile Lake area have successfully identified a glacial dispersal train down ice from the sulphide outcrop. The sediments adjacent to and down-ice from the Upper AB Zone define a dispersal train that extends eastward for about 600 m. The Pb isotopic ratios of the till in the dispersal train are very low compared with till remote from mineralization. Pb abundance data also defined a primary and a secondary dispersal train trending in a south-southeasterly direction toward the Northwest Miramichi River.;Pb isotope and Pb abundance data have shown that the Pb in till from the Halfmile Lake area can be considered the product of binary mixing between Pb from the volcanogenic massive sulphide (VMS) outcrop and Pb from the surrounding country rocks. The most important finding to emerge from this study is that the Pb isotopes can be used to distinguish between Pb from a VMS deposit and Pb from other sources. This can not be done using Pb abundance data alone. The successful delineation of a Pb isotope dispersal train at Halfmile Lake shows that Pb isotopes can be used to target relatively young VMS deposits.