Deep tectono-magmatic setting for metallogenesis of large porphyry copper deposits

Abstract：Based on the results of deep geophysical exploration, combined with geological and geochemical data, this paper analyzes the Oligocene tectono-magmatic settings of deep-seated mineralization in the Andean porphyry copper belt in the South America stable ocean-continent subduction regime, the Gangdise porphyry copper belt in the southern Tibet unstable continent-continent collision regime and the Jamda porphyry copper belt in the Sanjiang area in the unstable continental island-continent collision regime. Six basic conditions for mineralization have been summarized：(1) there was a good supply of upper mantle-derived high-temperature magmatic hydrothermal fluids; (2) a regional source for copper extraction was available; (3) there were a partial melting layer of the upper crust or magma chamber for circulation and deposition of copper-bearing hydrothermal fluids; (4) there were tensile faults in the upper crustal tectonic system for emplacement of magmatic hydrothermal fluids; (5) the chemical properties of the country rocks were important for the precipitation of ore materials; and (6) the relatively stable tectonic stage created conditions for the precipitation of ore materials. In the case of an unstable regime, it is necessary to look for a relatively stable time interval in the regime. The main differences in mineralization between the continent-continent collision regime and ocean-continent subduction regime lie in the long tectonically unstable stage, continental crustal thickening and tectonic complication, as well as the mechanism of crack and break of the mantle lithosphere. The author proposes new ore prospect areas in the Gangdise belt.