Pyrite trace element halos to northern Australian sediment-hosted Zn-Pb-Ag deposits

Abstract

Subtle primary halos form around many sedimenthosted Zn-Pb deposits. Northern Australian deposits may also have pyrite halos, representing the first paragenetic stage of the mineralising fluids. The occurrence of trace elements within this pyrite has potential toprovide vectors to the orebody or delineate mineralised from batten systems. Pyrite trace element compositions from rocks surrounding the McArthur River sediment-hosted Zn-Pb deposit. Northern Territory, Australia have been analysed by LA-ICPMS. Analysis was conducted for 25 elements. Over 95% of all pyrite analysed contained_> 0.10 wt% of trace elements, of which, Co, Ni, Cu, Zn, As, Sb, Ba, Tl, Pb, Mn, Mo, Ag, Bi and Sn are found in abundances significantly greater than detection limits. The host sediments contain no significant levels of Cu, Co, Ni, Pb, Zn. Concentrations of Co, Cu, Ni, Tl and Zn are significantly elevated at the orebody and hangingwall equivalent stratigraphy. As, Ba, Mo, Sb, Sn are slightly elevated at the orebody equivalent stratigraphy. Spatial distribution patterns of the trace elements are erratic, possibly reflecting variations in pH, oxidation state, or temperature across the basin at the time of formation.