Vectors to mineralization in the carbonate-hosted Grasberg-Ertsberg porphyry district from calcite C-O isotope and trace element geochemistry

Trace element analyses of calcite veins, marbles, and skarn in the Grasberg-Ertsberg district reveal distinctive characteristics in distal and proximal skarn and porphyry environments. C-O isotopic values correlate with trace element variations and both can be attributed to magmatic fluid mixing with rock-buffered meteoric waters. A negative correlation is observed between δ18O and Mn:Mg values, which change systematically towards the center of the Grasberg Intrusive Complex (GIC). Evidence for fluid migration for up to 5km away from the GIC along permeable fracture and fault networks is indicated by magmatic-hydrothermal signatures in distal calcite vein chemistry. Isotopic and trace element analyses of calcite present a new and potentially effective tool for the detection of porphyry deposits in carbonate-hosted terrains which to date have proven challenging to explore.