A Manto-type Cu deposit in the Central Asian Orogenic Belt: The Hongguleleng example (Xinjiang, China)

Abstract

Manto-type Cu deposits with relatively high grade (up to >8 wt% Cu) occurred widely around the Pacific Rim Belt and along the Himalayan–Tibetan Belt. However, so far, Manto-type Cu deposits have not been reported in the Central Asian Orogenic Belt (CAOB). Hongguleleng (also called Armuqiang), located in the West Junggar, Xinjiang, China, is the first recognized Manto-type Cu deposit. It is hosted in the Late Silurian–Early Devonian volcano-sedimentary sequence and associated with pale-volcanic apparatus. The Cu bodies are restricted to particular porous units (e.g. andesitic volcanic breccias, amygdale basalt and andesite) and are mostly controlled by the steep dipping fault zones.The host volcanic rocks have been overprinted by three alteration assemblages and associated copper mineralization. An early barren propylitic (chlorite-calcite) assemblage is widespread and is overprinted by epidote-chlorite assemblage associated with ores. They are cut by barren calcite veins. The major copper sulfides are chalcopyrite, bornite, and chalcocite that show disseminated, amygdale filling, breccias, vein-veinlet, massive and replacement textures. Only two fluid inclusion types were recognized in quartz, calcite and epidote: liquid-rich and vapor-rich inclusions. They have homogenization temperatures in the range 140–280 °C. Sulfur isotope compositions from ores have a positive δ34S values range from +0.5‰ to +3.4‰, suggesting a magma source. From the geology, alteration, mineralization, and fluid inclusion characteristics and sulfur isotopic compositions, we propose that the Hongguleleng deposit is classified as a typical Manto-type copper deposit.