Geology, fluid inclusion geochemistry, and Ar-40/Ar-39 geochronology of the Wulasigou Cu deposit, and their implications for ore genesis, Altay, Xinjiang, China | |
Zheng, Yi ; Zhang, Li ; Chen, Yan-Jing ; Qin, Ya-Jing ; Liu, Chun-Fa | |
刊名 | ore geology reviews
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2012 | |
关键词 | Copper deposit Fluid inclusion Ar-40/Ar-39 geochronology Orogenic lode deposit Altay Xinjiang MASSIVE SULFIDE DEPOSITS GOLD DEPOSITS HYDROTHERMAL FLUIDS INNER-MONGOLIA OROGENIC BELT METALLOGENESIS CONSTRAINTS ORIGIN HENAN MINERALIZATION |
DOI | 10.1016/j.oregeorev.2012.09.005 |
英文摘要 | The Wulasigou Cu deposit occurs as veins controlled by a NW-trending structure in a Devonian volcano-sedimentary basin of the Altay orogenic belt, Xinjiang, China. Igneous and sedimentary rocks exposed in the area have undergone greenschist-facies metamorphism. The ore-forming process can be divided into early, middle, and late stages, represented by, respectively, pyrite-quartz, polymetallic sulfide-quartz, and carbonate-quartz veins, veinlets, and/or replacement bodies. The early veins were deformed and brecciated during a compressional or transpressional event. The middle-stage veinlets filled fractures in the early-stage vein and alteration assemblages, and are undeformed, suggesting a tensional shear setting. The late-stage veinlets are mainly open-space fissure fillings that cut veins and replacement bodies formed in the earlier stages. Four types of fluid inclusions (FIs), including aqueous (W-type), mixed carbonic-aqueous (M-type), purely carbonic (C-type) and daughter mineral-bearing (S-type), have been identified in copper-related quartz and calcite from the Wulasigou deposit The early-stage quartz contains M- and W-type primary FIs that completely homogenized at temperatures of 322-412 degrees C with low salinities of 0.9-6.5 wt.% NaCl equiv. In contrast, the late-stage quartz or calcite contains only the W-type FIs with homogenization temperatures of 101-234 degrees C, and salinities of 0.9-2.9 wt.% NaCl equiv. This indicates that the metallogenic system evolved from CO2-rich, metamorphic to CO2-poor, through input of meteoric fluids. All four types of FIs can only be observed in the middle-stage minerals, where they show evidence of vein formation during an episode of fluid immiscibility. These FIs homogenized at temperatures ranging mainly from 230 to 347 degrees C, with salinities clustering 2.7-10.2 wt.% NaCl equiv for the W-, M- and C-types, and 34.7-38.2 wt.% NaCl equiv for the S-type, respectively. The metal precipitation resulted from a decrease in copper solubility during the fluid immiscibility episode. The estimated trapping pressures for the middle-stage fluids are 1.55-3.55 kbar, suggesting an alternating lithostatic-hydrostatic fluid-system, controlled by fault-valve activity at a depth of 13-15.5 km. Muscovite separates from the middle-stage polymetallic-quartz veinlets yield a well-defined Ar-40/Ar-39 isotopic plateau age of 219.41 +/- 2.10 Ma, and an Ar-39/Ar-36 - Ar-40/Ar-36 isochron age of 219.73 +/- 2.17 Ma. This age postdates the final Paleo-Asia Ocean closure (at ca. 250 Ma) by about 30 Ma, and indicates that the Cu mineralization at Wulasigou has occurred in the Triassic continental collision setting. Hence, the Wulasigou Cu deposit may be the first example of orogenic lode Cu deposits formed in accretionary orogeny or continental collision. (C) 2012 Elsevier B.V. All rights reserved.; http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000312040900007&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701 ; Geology; Mineralogy; Mining & Mineral Processing; SCI(E); EI; 45; REVIEW; 128-140; 49 |
语种 | 英语 |
内容类型 | 期刊论文 |
源URL | [http://ir.pku.edu.cn/handle/20.500.11897/228834] ![]() |
专题 | 地球与空间科学学院 |
推荐引用方式 GB/T 7714 | Zheng, Yi,Zhang, Li,Chen, Yan-Jing,et al. Geology, fluid inclusion geochemistry, and Ar-40/Ar-39 geochronology of the Wulasigou Cu deposit, and their implications for ore genesis, Altay, Xinjiang, China[J]. ore geology reviews,2012. |
APA | Zheng, Yi,Zhang, Li,Chen, Yan-Jing,Qin, Ya-Jing,&Liu, Chun-Fa.(2012).Geology, fluid inclusion geochemistry, and Ar-40/Ar-39 geochronology of the Wulasigou Cu deposit, and their implications for ore genesis, Altay, Xinjiang, China.ore geology reviews. |
MLA | Zheng, Yi,et al."Geology, fluid inclusion geochemistry, and Ar-40/Ar-39 geochronology of the Wulasigou Cu deposit, and their implications for ore genesis, Altay, Xinjiang, China".ore geology reviews (2012). |
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