Using Platinum Group Element geochemistry to determine magma fertility of Mount Hagen, Papua-New Guinea

Abstract

Mount Hagen is a Mid-Pleistocene stratovolcano located in Papua-New Guinea Highlands. The tectonic setting of the volcano has been a matter of considerable debate, with its complexity leading to different conclusions regarding magma source and classification. Two key questions remain unanswered: (i) is this "arc-like" magma related to a subduction zone and therefore part of an arc system? and, (ii) can it be related to potential porphyry style economic mineralisation?

Occurrence of porphyry deposits is strongly related to subduction zones, so the identification of tectonic setting is important for mineral exploration. If Mount Hagen is part of an arc system, is it barren or ore-bearing?

Assuming that sulfide saturation, relative to volatile saturation, is one of the main factors controlling magma fertility, PGE, Re and Au concentrations were measured by fire-assay isotope dilution method in 18 samples, to determine its potential to form an Au-Cu deposit. PGE were chosen to investigate the timing of S saturation because of their low solution mobility in hydrothermal fluids and their high partition coefficient into sulfide melts. Analyses showed that S saturation occurred early in the system (at 8 MgO wt%), which make it unlikely that the system will produce an Au-Cu deposit. Show more