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Phase equilibria, thermodynamic properties, and solubility of quartz in saline -aqueous -carbonic fluids: Application to orogenic and intrusion -related gold deposits

文献类型：期刊论文

作者Li, Xing-Hui2,3,4; Klyukin, Yury, I4,5; Steele-MacInnis, Matthew4; Fan, Hong-Rui2,3,6; Yang, Kui-Feng2,3,6; Zoheir, Basem1
刊名GEOCHIMICA ET COSMOCHIMICA ACTA
出版日期2020-08-15
卷号283页码:201-221
ISSN号0016-7037
关键词H2O-NaCl-CO2 Thermodynamic properties Quartz solubility Fluid inclusions Mesothermal gold deposits
DOI10.1016/j.gca.2020.06.008
英文摘要Hydrothermal fluids in orogenic and intrusion-related (mesothermal) gold deposits are dominated by saline-aqueous- carbonic fluids, commonly represented by the ternary system H2O-NaCl-CO2. The phase equilibria, thermodynamic proper- ties (PVTx , density, compositions of fluid phases) and quartz dissolution-precipitation behavior in the H2O-NaCl-CO2 sys- tem, which are still poorly constrained, are of great importance to understanding the process of hydrothermal gold mineralization. Here, we conducted thermodynamic modeling to constrain the fluid properties under single- and two-phase conditions in the H2O-NaCl-CO2 system at temperatures of 300 to 500 degrees C and pressures of 0.001 to 3.5 kbar. Our results illus- trate thermodynamic controls rooted in the equilibria of the H2O-NaCl-CO2 system. Increasing CO2 and/or NaCl contents shift the solvus to higher pressures and temperatures, expanding the pressure & ndash;temperature region of L + V immiscibility. Cal- culated isopleths of CO2 content in coexisting, immiscible vapor and liquid describe the maximum amount of CO2 that may be present in fluid inclusions through the studied P-T-x ranges. Quartz solubility in the H2O-NaCl-CO2 fluids shows strong dependence on temperature, pressure, and CO2 content, with several potential triggers for vein mineral deposition. Specifi- cally, solubility of quartz generally decreases with decreasing temperature, pressure, and increasing CO2 content both in the single- and two-phase fluids, but exhibits retrograde behavior in the L + V field or at the phase-transition boundary. In detail, the dependence of quartz solubility on pressure is weak at low temperatures (300 degrees C), and becomes progressively stronger at high temperatures (400 degrees C and 500 degrees C), vice versa for temperature dependency at different pressures. The present study reviews two mechanisms of fluid immiscibility and constrain the conditions at which distinct fluid inclu- sion types, bedding-parallel shear veins and fault-related extension veins are formed in mesothermal gold deposits. Thermo- dynamic modeling of the solvus of the H2O-NaCl-CO2 system is consistent with the hypothesis that decompression is an efficient mechanism driving fluid immiscibility at specific ranges of temperature and composition, producing coexisting liquid- and vapor-phase fluids, both with low density and relatively low content of CO2 . For fluids with high CO2 contents (>10 mol. %), cooling at relatively high pressure may also lead to fluid immiscibility, producing a liquid with low CO2 content in equilibrium with a vapor of medium to high CO2 content. Very CO2-rich, or & ldquo;pure CO2 & rdquo; fluid inclusions (>90 mol. % CO2 , type I) cannot be produced by immiscibility under these conditions, but may rather be the result of decrepitation of primary H2O-NaCl-CO2 fluid inclusions. Within the P-T-x ranges studied here, cooling-dominated phase separation accounts for the formation of fluid inclusions with moderate to high CO2 contents (50-80 mol. % CO2 , type IIa). Fluid inclusions with low to moderate CO2 contents (5-30 mol. % CO2 , type IIb) can represent the original ore-forming fluids, or can be produced by decompression-dominated phase separation. And H2O-NaCl fluid inclusions (type III) generally represent the latest-stage ore-forming fluids, or can be produced by decompression-induced immiscibility at high temperature. In orogenic (mesother- mal) gold deposits, decompression-induced quartz precipitation during pressure fluctuation is dominant in bedding-parallel shear veins. Fault-related extension veins are associated with initial decompression-induced quartz precipitation and subse- quent cooling-dominated deposition.
WOS关键词FAULT-VALVE BEHAVIOR ; ORE-FORMING FLUIDS ; EQUATION-OF-STATE ; HIGH CO2 CONTENT ; PREDICTIVE MODEL ; SYSTEM H2O-NACL-CO2 ; PVTX PROPERTIES ; ASHANTI BELT ; INCLUSIONS ; MINERALIZATION
资助项目UCAS Joint PhD Training Program ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP)[2019QZKK0801] ; National Key Research and Development Program[2016YFC0600105] ; China Postdoctoral Science Foundation[2019M660788] ; NSERC
WOS研究方向Geochemistry & Geophysics
语种英语
出版者PERGAMON-ELSEVIER SCIENCE LTD
WOS记录号WOS:000546451400013
资助机构UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; NSERC ; NSERC ; NSERC ; NSERC ; UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; NSERC ; NSERC ; NSERC ; NSERC ; UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; NSERC ; NSERC ; NSERC ; NSERC ; UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; UCAS Joint PhD Training Program ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; National Key Research and Development Program ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; China Postdoctoral Science Foundation ; NSERC ; NSERC ; NSERC ; NSERC
源URL[http://ir.iggcas.ac.cn/handle/132A11/97128]  
专题地质与地球物理研究所_中国科学院矿产资源研究重点实验室
通讯作者Fan, Hong-Rui
作者单位1.Benha Univ, Fac Sci, Dept Geol, Banha 13518, Egypt
2.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China
3.Chinese Acad Sci, Innovat Acad Earth Sci, Beijing 100029, Peoples R China
4.Univ Alberta, Dept Earth & Atmospher Sci, Edmonton, AB T6G 2E3, Canada
5.Univ Calgary, Dept Geosci, Calgary, AB T2N 1N4, Canada
6.Univ Chinese Acad Sci, Coll Earth & Planetary Sci, Beijing 100049, Peoples R China
推荐引用方式
GB/T 7714		 Li, Xing-Hui,Klyukin, Yury, I,Steele-MacInnis, Matthew,et al. Phase equilibria, thermodynamic properties, and solubility of quartz in saline -aqueous -carbonic fluids: Application to orogenic and intrusion -related gold deposits[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2020,283:201-221.
APA Li, Xing-Hui,Klyukin, Yury, I,Steele-MacInnis, Matthew,Fan, Hong-Rui,Yang, Kui-Feng,&Zoheir, Basem.(2020).Phase equilibria, thermodynamic properties, and solubility of quartz in saline -aqueous -carbonic fluids: Application to orogenic and intrusion -related gold deposits.GEOCHIMICA ET COSMOCHIMICA ACTA,283,201-221.
MLA Li, Xing-Hui,et al."Phase equilibria, thermodynamic properties, and solubility of quartz in saline -aqueous -carbonic fluids: Application to orogenic and intrusion -related gold deposits".GEOCHIMICA ET COSMOCHIMICA ACTA 283(2020):201-221.

入库方式： OAI收割

来源：地质与地球物理研究所

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