Geological, Geochemical Characteristics And Genesis Of Qixing Lead-Zinc Deposit, Jinghe, Xinjiang

Xinjiang is one of the important nonferrous metals metallogenetic areas in China. The late Paleozoic is the most important metallogenetic period in Xinjiang. But in Mesozoic, especially in Yanshanian nonferrous metals mineralization was rare. At present, Xinjiang nonferrous metals mineralization in Yanshanian was found only in the Western Kunlun orogenic belt, Altun orogenic belt and Eastern Tianshan. There hasn't a report of Yanshanian mineralization in Western Tianshan.Qixing Pb-Zn ore deposit was recently discovered in Xinjiang, Western Tianshan. It was regarded as a part of the Lailisigao'er-3571 Hercynian metallogenetic system. In this paper, the author studied SHRIMP zircon U-Pb age of gabbro-diabase in Qixing Pb-Zn ore deposit, and obtained an age of 186.2±8.4Ma. The Zn-Pb sulfide ore-body, paragenied or associated with some basic dikes and cut through the basic dikes. Evidence shows that the Qixing Zn-Pb ore deposit is a product of the Yenshan period structure-magma- hydrothermal mineralization, rather than a part of the Lailisigao'er–3571 Hercynian metallogenetic system.Explaining the genesis of Qixing ore deposit is of great significance to understanding the mineralization and the geological evolution correctly and funding Yanshanian non-ferrous metals ore deposits in Xinjiang, Western Tianshan.The Zn-Pb sulfide ore-body in Qixing ore deposit is vein in silty mud of Silurian system. The Zn-Pb ore is composed by Quartz, Zn-Pb sulfide and many other minerals, and show a complex mineral composition. The minerals are middle-coarsely crystalline and replaced textures in the ores. The ore-forming is hydrothermal filling-replacing style.The ore-forming fluid was middle temperature, low salty and low density.δ¹⁸O_H2O andδD_H2O characteristics show that ore-forming fluid mainly from the magma, at later stage mixed rainfall.The oreδ³⁴S characteristics show that S mainly from the deep magma and mixed small stratigraphic S. The ore Pb-isotopic composition shows that the metals in the ore was from basic rocks in the ore deposit of Qixing ,or from lower crust associated with basic magmatic activities, and in the course of ore-froming it mixed small upper crust materials.Characteristics of trace and rare earth elements suggest that mafic dykes in Qixing ore deposit were most probably formed in rifted environment within plate basalts. The mafic dykes in Qixing ore deposit belongs to the cal-alkaline series.Qixing Pb-Zn ore deposit formed in Yanshanian.The Yanshan period tectonic extension– magma activity– Zn-Pb mineralization was a starting, developing and closely related geological process.