Tectonic setting and formation mechanism of the circum-Junggar porphyritic copper deposit belts.

Abstract

Tectonics, magmatism and mineralization belts in the Junggar area are circularly present around Junggar block, it was results of Paleozoic tectonic evolution of Junggar block. The Kasakhstan-Junggar plate was subducted by the Paleo-Asian oceanic plate at north side and by the South Tianshan oceanic plate at south side in Paleozoic era. Magmatic rock belts and associated volcanic rock- type Cu-Fe polymetallic deposit belts, porphyritic Cu-Mo-Au deposit belts and epithermal gold deposit belts were formed both in the south and north arc-basin systems. The Kasakhstan-Junggar plate was collided with Siberia plate and Tarim plate and intensively compressed, sheared and broken, resulting in anticlockwise rotation of Junggar block, dislocation of tectonics, magmatism and mineralization belts to surround the Junggar block. Porphyry copperitic Cu deposits around Junggar block were formed in four tectonic settings including continental arc, ocean island arc and backarc basin related to plate subduction and intraplate at post collision period, and the later Paleozoic era was the major main mineralization formation period.