Fluids Inclusion Constraints on the Origin of the Shiduolong Hydrothermal Vein-Type Mo-Pb-Zn Deposit, Qinghai Province
详细信息
- 责任者：Li Gongjian (State Key Laboratory of Geological Processes and Mineral Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Wang Qingfei
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(4)
- 关键词：钼矿 ; molybdenum ores ; 铅锌矿床 ; lead-zinc deposit ; 流体包裹体 ; fluid inclusions ; 青海 ; Qinghai Province
- 页码：p.1377-1391
- 图表：illus., 3 tables, 58 refs.
- 分类号：1001
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Shiduolong hydrothermal Mo-Pb-Zn deposit is located in the Xinghai County, northeast of the Qinghai Province. Mineralization is controlled by NNW faults formed in the Indosinian, and closely associated with simultaneous granitoid intrusions. Four stages of hydrothermal ore-forming process are recognized, characterized by mineral assemblages of quartz-molybdenite (Ⅰ), quartz-pyrite-sphalerite (Ⅱ), quartz-polymetallic sulfides (Ⅲ) and quartz-carbonate (Ⅳ), respectively. Two main types of fluid inclusions are distinguished in the hydrothermal quartz, aqueous-rich CO2-H2O inclusions and aqueous inclusions. The later can be further divided into vapor-rich, liquid-rich and pure liquid inclusions. Microthermometic data show that the homogenization temperatures of the fluid inclusions from the stage Ⅰto the Ⅲ are gradually decreased, from 317～397℃, through 226～342℃, to 131～247℃, and the corresponding salinities followed by 9.98%～12.28% NaCleqv, 4.34%～10.98% NaCleqv and 2.07%～5.41% NaCleqv. Plenty of secondary fluid inclusions could be observed in the quartz from the Ⅰand the Ⅱ stage, implying intensive fluid superposition subsequently. Study of gas-liquid components of fluid inclusions from different mineralization stages indicates that the ore-forming fluid belongs to K+-Na+-SO42- type, and the content of total ions reduced rapidly from early to late. The gas component contains a relatively high N2, CH4 and other gases in addition to H2O and CO2. The stage Ⅰ ore-forming fluid is mainly of magmatic water, hybrid with certain amount of meteoric water. Fluid mixing occurs in the stage Ⅱ, abundant meteoric water with some formation water mixed into the early stage fluid. Ore-forming fluid of the stage Ⅲ is mainly of meteoric water and/or formation water. Influence by surface water system is more and more obvious as the evolution of ore-forming fluid. The mixing of fluids and accompanying decrease of temperature and pressure are the dominant mechanisms for deposition and enrichment of Pb-Zn and other mineralizing elements.
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