Numerical Simulation of Hydrothermal Alteration Chemical Reactions During Ore-forming Process of the Jiaojia Gold Deposit, Jiaodong Peninsula, China

被引：0
作者：
Zou Y. [1 ,2 ]
Zhang W. [1 ,2 ]
Mao X. [1 ,2 ]
Liu Z. [1 ,2 ]
机构：
[1] Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, Central South University, Hunan, Changsha
[2] School of Geosciences and Info-Physics, Central South University, Hunan, Changsha
来源：
Geotectonica et Metallogenia | 2023年 / 47卷 / 05期
关键词：
chemical reaction; hydrothermal alteration; Jiaojia gold deposit; numerical simulation; TOUGHREACT;
D O I：
10.16539/j.ddgzyckx.2022.01.010
中图分类号：
学科分类号：
摘要：
The Jiaojia gold deposit is featured by obvious alteration zonation, and is one of the typical altered-type gold deposits in the Jiaodong gold province. However, the formation conditions of hydrothermal alteration zonation and the spatial location of chemical reaction associated with gold precipitation are still unclear. To quantitatively discuss the hydrothermal process, we used the TOUGHREACT software to simulate the chemical reactions between ore-bearing fluids and wall rocks of the Jiaojia gold deposit. First, we constructed a conceptual mineralization model related to hydrothermal alteration by discussing the chemical reaction between ore-bearing fluids and wall rocks. Subsequently, we simulated the chemical equilibrium concentration of ore-forming fluids and pH changes under different temperature and pressure conditions, which was used to study the dissolution and precipitation mechanism of hydrothermal minerals during ore-forming processes. The simulation results show that the chemical equilibrium concentration of Au+ significantly decreased with temperature from 280 ℃ to 180 ℃, and the chemical equilibrium concentration of Fe2+ showed similar trend, indicating that the favorable gold metallogenic temperature range is 180 ℃ to 280 ℃, and Fe2+ in ore-forming fluids reacts with [Au(HS)2]− to promote gold precipitation. The temperature and pressure conditions influence the chemical equilibrium concentrations of ore elements, nevertheless, temperature is a more critical factor controlling gold precipitation, while the influence of pressure is relatively weak. The pH simulation results show that the pH values of ore-forming fluids increased during the hydrothermal alteration reaction, which means that the ore-forming environment changes from acidic to neutral and/or alkaline. The pH variation during the ore-forming process is consistent with conventional geological observations, and thus validated the simulation results. The above results indicate that the temperature driving lateral migration of ore-forming fluids along the fault resulted in the continuous overprinting alteration. The pyrite-sericite-quartz alteration in the footwall of the fault zone is conducive to gold precipitation and enrichment due to frequent overprinting of various alteration and changes of temperature and pH. © 2023 Science Press. All rights reserved.
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页码：1158 / 1172
页数：14
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