Mid-late paleozoic metallogenesis and evolution of the Chinese altai and east junggar orogenic belt, NW China, Central Asia

Abstract

The Chinese Altai-East Junggar collage in southern Altaids is one of the largest and most important metallogenic provinces in China. It is composed of five major types of Middle to Late Paleozoic metal deposits: (1) VMS Cu-Pb-Zn, (2) porphyry Cu-Au, (3) magmatic Cu-Ni-sulfide, (4) skarn Cu-Mo-Fe and (5) orogenic Au. Tectonically, the development of these metal deposits was closely associated with accretionary and convergent processes that occurred along the southern margin of the Central Asian Orogenic Belt (CAOB). The formation of the deposits involved three main stages, briefly described as follows: (i) Those formed during extensional back-arc volcanism along the Paleozoic active margin of the CAOB. They are Late Devonian to Early Carboniferous polymetallic volcanogenic massive sulfide deposits, together with some broadly contemporaneous Fe-Cu skarns, located in the accreted Qiongkuer-Talate Terrane in the western Altai; (ii) Carboniferous to Permian terrane accretion and arc magmatism, resulting in widespread metalliferous ores of different types such as copper-bearing porphyries and Alaskan-type Cu-Ni-PGE zoned ultramafic bodies developed in arcs in the Buerjin-Ertai and Erqis terranes, and Cu-Fe skarns formed in the Erqis flysch basin; (iii) Continuing accretion in the Permian leading to the development of the Dulate arc in the southern Altai associated with the formation of Cu-Mo skarns and orogenic-type gold vein systems. The Chinese Altai-East Junggar collage typically demonstrates the various classic metalliferous ores formed during the processes of subduction-accretion and arc generation.