Sub-volcanic epithermal mineralization of Jiulongwan silver-polymetal deposit, Eastern Daqingshan, Inner Mongolia, China: evidence from fluid inclusions

摘要

Silver deposits occurring in volcanic rocks are most important in the world, with 50% of reserves and production in total. Jiulongwan silver deposit, located in eastern Daqingshan Mountains, Inner Mongolia, is a potential silver-polymetal deposit discovered recently. Strata distributed in mine area are Archean Upper Jining group, Mesozoic and Cenozoic volcanic rocks, The Upper Jining group is lithologically composed of gneiss, granulite and marble, and faults are developed. Ore bodies occur in altered fractured zones within Archean metamorphic rocks, which surround Yenshanian quartz-porphyry. Wall rock alterations are mainly silicification, sericitization, kaolinization, chloritization and carbonization. Ore assemblages are dominated by sphalerite, galena, chalcopyrite and argentite. Mineralization can be divided in to three stages: 1) silicification stage; 2) polymetallic stage, which is the main silver stage; 3) carbonization stage.