Geological Structural Characteristics and Ore-controlling Structures of the West 509-Daoban Li Deposit, Hetian, Xinjiang

The west 509-Daoban Li deposit is located in the eastern section of the West Kunlun and karakunlun mountain ranges, at the northern edge of the Tethys tectonic domain, and is a newly identified ultra-large pegmatitic Li deposit. Through the study of the geological structure and ore-control structure of the mine area, the tectonic features and ore-control pattern of the mine area have been clarified. The deposit is exposed in the shallow metamorphic clastic rocks of the Triassic Bayankhara Mountain Group, and is located between the Dahongliutan-Guozhazhong Fault and the Qitai Daban Fault, with the magmatic rocks in and around the mine area being more developed and controlled by fracture structures, with the main tectonic direction being NW-SE. Combined with the regional evolutionary events, the study of tectonic-magmatic ore-control model reveals that the formation, seating of the ore body and its later transformation are mainly controlled by three phases of tectonics. ① Pre-Mineralization: The Permian-Triassic NE-SW directional extrusion formed a ductile retrograde slip fault, which provided space for the ore body to be transported into position. ② Ore-forming period: A series of tensional fissures (joints) formed at the end of the Late Triassic with the intrusion of magmatic rocks provided favorable space for hydrothermal transport and mineral enrichment of mineral-bearing magma, resulting in the formation of mega lithium ore. ③ After the metallogenic period, the ore body was limitedly damaged by the impact of the collision between the Indian Ocean plate and the Asian-European plate in the Cretaceous-Quaternary period, and brittle ore-breaking structures were developed in the mine area. These understandings are of great significance in guiding the search for mineralization at the periphery and depth of the mine.