GRADE DISTRIBUTION OF THE GIANT OK TEDI Cu-Au DEPOSIT, PAPUA NEW GUINEA—A DISCUSSION

摘要

Van Dongen et al. (2013) provide a useful picture of copper and gold grade distribution at Ok Tedi based on diamond drill hole and blast hole information. Among their conclusions is that fluids evolved from a deeper magma chamber used shallow stocks as their preferred permeable pathway to form skarns where limestone was present, and porphyry-style mineralization within the Fubilan monzonite porphyry because it is encapsulated within impermeable silicified silt-stone. It is also argued that the Fubilan monzonite porphyry is an altered equivalent of a rock essentially identical to the Sydney monzodiorite and that skarn and porphyry mineralization occurred contemporaneously from the same fluid exsolution event. These conclusions are not consistent with observations of the geology and mineralization at Ok Tedi that reveal a very different picture of the relationships between intrusive rocks, host rocks, and mineralization.