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Ore-Forming Fluid Geochemistry And Genisis Of The Huanxiangwa Gold Deposit In Western Henan, China

Posted on:2008-12-10Degree:MasterType:Thesis
Country:ChinaCandidate:C J DuanFull Text:PDF
GTID:2120360212483554Subject:Geological Engineering
Abstract/Summary:PDF Full Text Request
The Huanxiangwa gold deposit, located at Xiong'er Mountain area of western Henan, occurs in the Mesoproterozoic volcanic rock formation of the Xiong'er Group on the southern margin of the North China plate. Homogeneous fluid derived mostly from the deep fluids and multi-periodic activity of the fracture structures are main ore-controlling factors. Rock-fluid reaction and the activity of the fracture structures resulted in various types of alterations, mineralizations. The main mineralization is pyrite-sericite-quartz-potash feldspar alteration type. Five mineralizing stages are divided, among them the quartz-potash feldspar-pyrite mineralization is the main stage. Based on the geochemical characteristics of trace elements, fluid inclusions and stable isotopes, the folloing is indicated that: Au is correlative to Ag, Pb , As, etc. and relative to the activity of the ore-forming fluids, and the distributive characteristics of the metallogenic elements especially Au indicate multiple characteristics of mineralization's superimposing in the main metallogenic epoch. There are six types of fluid inclusions among them LH2O type and (LH2O + VCO2) type are the main ones. The ore-forming fluids is of CO2-H2O-NaCl system, with homogenezation temperature from 130 to 265℃, formation pressure from 200 ×105 to 230 × 105Pa, fluid salinity from 0.9 to 7.5 wt%NaCl, pH volume from 6.6 to 7.10. The metallogenic substances derived mostly from the deep upper mantle and partly from mantle-related lower crust materials might absorbe part minerogenic substances from the upper crust in the process of migration of the ore-forming fluids, thus they had characteristics of mantle-crust-mixed resource mainly mantle-derived. As the earlier ore-forming fluids from the subterranean depth(mainly from mantle) mixed with large amounts of fluids related to intracontinental subduction associated with Indosinian-Yanshanian collision, resultingly, the homogeneous extensively fluid formed before the ore-forming and mixed or hybridized gradually by precipitate water with the ore-forming processes. Au of the ore-forming fluids migrated mainly in the form of [Au(HS)2]-, [Au2(HS)2S]2- and/or [AuH3SiO4]0. Fluid and rock interaction (rock and water reaction), the mixing of fluids, and lowing temperature and press probably is a valid depositional mechanism of Au from the ore-forming fluids of Huangxiangwa gold deposit. The metallogenic epoch of this deposit is in Indosinian-Yanshanian epoch , whereas the metallization might mainly take place in Yanshanian epoch. The metallogenic mechanism is elementarily set up for this gold deposit in this paper, that's the ore-forming process were jointly controlled by the homogeneous fluid mainly from thesubterranean depth and multi-periodic tectonic activity associated with Indosinian-Yanshanian intracontinental subduction. The deposit belongs to mesothermal-epithermal structural altered-rock type in genesis.
Keywords/Search Tags:ore-forming fluid, geochemistry, fluid inclusion, stable isotope, ore genesis, Huanxiangwa gold deposit, western Henan
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