Fluid Evolution of the Yaochong Porphyry Mo Deposit, Xinxian County, Henan Province, China
详细信息
- 责任者：Wang Pin (Key Laboratory of Mineralogy and Metallogeny ; Guangzhou Institute of Geochemistry ; CAS ; Guangzhou 510640 ; China) ; Yang Yongfei
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(1)
- 页码：p.107-120
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Yaochong porphyry Mo deposit in Xinxian County, Henan Province, China, is located in the Dabie orogenic belt. Mo mineralization formed in continental collision settings. The hydrothermal ore-forming process can be divided into the early, middle and late stages, characterized by mineral assemblages of quartz+potassic feldspar±pyrite±magnetite, quartz±potassic feldspar+molybdenum±other sulfides and quartz±calcite±fluorite, respectively. There are four fluid compositional types determined in hydrothermal quartz and fluorite from early to late: pure CO2, CO2-H2O, aqueous and solid-bearing fluid inclusions (FIs). The early-stage quartz contains three of the four types FIs other than the aqueous type. The middle-stage quartz has CO2-H2O, aqueous and solid-bearing FIs, without pure CO2 FIs. In the late stage, a small amount of CO2-H2O FIs can be observed in quartz of barren quartz veins, while in quartz-carbonate-(fluorite) veins, only the aqueous FIs are present. Fluid inclusions in the early-stage quartz are homogenized at temperatures of 277~380℃, clustering at 300~360℃, with salinities mainly ranging from 3.0% to 10.3% NaCleqv. Fluid inclusions in the middle stage quartz yield homogenization temperatures of 185℃ to 351℃, with most between 260℃ and 320℃, and salinities of 2.4% to 9.3% NaCleqv. Fluid inclusions in the late stage are totally homogenized at temperatures of 139~245℃, yielding salinities of 0.7%~6.3% NaCleqv. The estimated pressures decrease from a span of 47~131MPa in the early stage, to a range of 26~118MPa in the middle stage, corresponding to a change in depths from 4.7km to 2.6~4.2km. We conclude that the initial fluids forming the Yaochong deposit is high temperature, high salinity and CO2-rich, and predict that the deeper exploration is potential for ore prospecting.