Paleotectonic setting of basaltoid volcano-plutonic belts with porphyry copper deposits

Abstract

The article considers geotectonic position and geological features of basaltoid volcano-plutonic belts (VPBs) associated with porphyry copper and gold-copper deposits. Three types of the belts, the oceanic, perioceanic, and riftogenic ones, are distinguished among these VPBs. The oceanic and perioceanic belts were incorporated into the composition of ensimatic island arcs and formed at a late stage of their development, after inversion of the basaltoid troughs. The riftogenic belts appeared in island-arc oceanic settings at a late stage of filling the spreading zones. VPBs of the first two types with porphyry gold-copper deposits are located over the convergent boundaries of tectonic plates in an above-subduction position, while belts of the third type form extended linear zones within individual rift structures and contain small-scale porphyry copper objects with poor gold and molybdenum contents. As examples of the structures, the Sunda, Philippine archipelago, New British, Solomon, Alaska, and Antilles ensimatic island arcs and the Irendyk and Novoalekseevsky belts of rift zones of the Southern Urals are described. Volcanic-plutonic associations participating in the structure of these VPBs (including those productive for porphyry copper mineralization), as well as structural-lithological complexes of their basement, are characterized. It is noted that repeated magmatism manifestations during the long-term development of the ensimatic island arcs lead to appearance of several basaltoid VPBs with porphyry gold-copper deposits, while basaltoid belts with porphyry copper objects in the rift settings are formed only once.

Keywords

• porphyry copper deposits
• volcano-plutonic belts
• ensimatic island arcs
• riftogenic structures
• magmatic series
• associations
• formations