A synthesis of mineralization styles and geodynamic settings of the Paleozoic and Mesozoic metallic ore deposits in the Altay Mountains, NW China

摘要

The Allay Mountains within the Xinjiang region of northwestern China hosts major metallic ore deposits. Here we review the geological characteristics, metallogenic features and tectonic settings of these deposits. The metallic ore deposits in the Allay Mountains occur mainly within four regions: North Altay, Central Altay, South Altay and Ellis. We recognize seven types of metallic ore deposits in the Altay Mountains: VMS, submarine volcanogenic iron, magmatic, skarn, pegmatite, hydrothermal vein (Cu-Zn, Fe) and orogenic gold. Among these types, the VMS, pegmatite, orogenic gold and skarn deposits are the most common. Most of the rare metal pegmatite deposits are distributed in Central Altay, with only a few in South Altay. The VMS, submarine volcanogenic type iron and skarn-type deposits are distributed in South Altay, whereas the orogenic-type gold deposits are distributed in the Ergis Fault belt. The hydrothermal vein-type deposits occur in the Ergis Fault belt and Chonghu'er Basin in South Altay. Magmatic-type deposits are mostly in the Ergis Fault belt and Central Allay. Based on isotopic age data, the VMS, submarine volcanogenic-type Fe and skam-type Cu, Pb, Zn, Fe mineralization occurred during Early Middle Devonian (similar to 410-377 Ma), orogenic-type Au, magmatic-type Cu Ni, and a small number of skarn-type Fe, hydrothermal vein-type Cu Zn, pegmatite-type rare-metal deposits in Early Middle Permian (293-261 Ma), pegmatite-type rare-metal deposits, few skarn-type Fe deposit in Early Middle Triassic (248-232 Ma), and dominantly represented by pegmatite-type rare-metal deposits in Late Triassic Early Jurassic (223-180 Ma). The metallic ore deposits in the Altay Mountains formed in various tectonic settings, such as the Early Middle Devonian continental arc and oceanic island arc, Early Middle Permian post-collisional extensional setting, and Triassic Early Jurassic intracontinental setting.