Geotectonic setting of western Pacific gold deposits

Abstract

Fifty-six principal gold deposits in the western Pacific region were generated in multiple volcanoplutonic arcs during the last 25 million years. At least 75% of the contained gold was introduced in association with intrusive stocks, commonly porphyries. The gold-bearing magmatic arcs were all constructed in response to subduction of oceanic lithosphere. However, the nature of the magmatism and the style of associated gold mineralization depend to some degree on the arc setting. Determination of the precise geotectonic settings of gold-bearing arcs is controversial even in the youthful western Pacific region, and the difficulties involved are compounded in older island-arc terranes. Moreover, Mesozoic and older arcs are likely to have lost most of their epithermal and subvolcanic gold deposits as a result of uplift and erosion, as witnessed by the accreted Mesozoic arc terranes of western North America. from Author