Metallogeny and tectonic setting of Paleozoic porphyry copper deposits in the East Tianshan

The East Tianshan copper metallogenic belt is an important part of the Central Asian metallogenic belt, which mainly includes large-scale Tuwu and Yandong, medium-scale Sanchakou and Yuhai, and small-scale Chihu, Fuxing, Linglong, Yudai and Sidingheishan porphyry copper deposits. The porphyry copper belt is distributed along the Dananhu-Tousuquan island arc in a nearly EW direction. Magmatic activities related to this metallogenic belt mainly include two peak periods of the Silurian and Carboniferous periods, while the peak period of mineralization is the Carboniferous. The host rock strata of the porphyry copper belt are mainly Paleozoic volcanic rocks, granites and sedimentary rocks. The wall rock alteration mainly includes biotite-magnetite alteration, phyllic and propylitization, with a relatively weak potassium alteration. The ore-forming rocks are mainly intermediate-acid calc-alkaline granites with typical island arc magmatic and adakite characteristics, which are enriched in large ion lithophile elements and depleted in high field strength elements with high Sr/Y ratios. In the early stage of ore-forming fluid, a large number of daughter bearing high salinity inclusions are developed, which is an H2O-NaCl +/- CO2 system. H-O-S isotopes show obvious magmatic hydrothermal characteristics. Sr-Nd-Hf isotopic characteristics indicate that the ore-bearing rocks have a mixed source of juvenile crust and depleted mantle. The East Tianshan orogenic belt experienced a multi-directional and multi-stage arc basin transformation in the Paleozoic and experienced multiple magmatic hydrothermal activities, as a result, it has the characteristics of multi-stage superimposed mineralization. The Carboniferous calc-alkaline magmatic rocks are the main target for ore prospecting in the next step, and the late structural superposition may lead to the formation of rich ore bodies.

Automated summary

The East Tianshan copper metallogenic belt is a part of the Central Asian metallogenic belt and includes large, medium, and small-scale copper deposits. The belt is distributed along an island arc and experienced magmatic activities during the Silurian and Carboniferous periods. The host rocks are mainly Paleozoic volcanic rocks, granites, and sedimentary rocks. The ore-forming rocks are intermediate-acid calc-alkaline granites with island arc magmatic characteristics. The fluid inclusions indicate a high salinity H2O-NaCl +/- CO2 system, and the isotopic characteristics suggest a mixed source of juvenile crust and depleted mantle. The East Tianshan orogenic belt has gone through multiple transformations and magmatic activities, resulting in multi-stage mineralization.