基于TOUGHREACT的成矿过程化学反应数值模拟——以虎头崖铅锌多金属矿床为例  

The TOUGHREACT-based numerical simulation of chemical reactions in ore-forming process:A case study of Hutouya Pb-Zn polymetallic deposit

作　　者：张婉秋 邹艳红[1,2] ZHANG Wanqiu;ZOU Yanhong(Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;Computational Geosciences Research Center, Central South University, Changsha 410083, China)

机构地区：[1]中南大学有色金属成矿预测与地质环境监测教育部重点实验室,长沙410083 [2]中南大学地球科学与信息物理学院,长沙410083

出　　处：《地质找矿论丛》2020年第3期354-362,共9页Contributions to Geology and Mineral Resources Research

基　　金：国家自然科学基金项目(编号:41872249,41472302)资助。

摘　　要：虎头崖铅锌多金属矿床是青海省祁漫塔格成矿带中典型的矽卡岩型矿床。本文基于前人对该矿区地质特征、矿物学和地球化学特征等方面的研究成果,利用TOUGHREACT数值模拟软件,针对石英晚期硫化物成矿阶段进行成矿过程化学反应数值模拟研究。通过建立地质概念模型和网格化物化参数的设置,在设置的时间步长内对多相流体流动和热对流传导、溶质运移以及地球化学反应过程进行模拟计算,研究了矿区内不同温压条件下成矿元素化学平衡浓度变化的总体趋势以及对方铅矿和闪锌矿矿物溶解沉淀情况的影响。结果表明:当温度从250℃降至155℃时,Pb^2+的化学平衡浓度出现骤减;当温度从300℃降至100℃时,Zn^2+的化学平衡浓度出现骤减;由于矿物的沉淀需要消耗大量相关的成矿元素,方铅矿和闪锌矿最佳成矿温度范围分别为155℃~250℃和100℃~300℃;不同温度和压力对成矿元素化学平衡浓度影响不同,温度是控制方铅矿和闪锌矿沉淀化学反应的核心因素,压力的影响较小。模拟结果与传统地质解译结果相对符合,证明了模拟的有效性。The Hutouya Pb-Zn polymetallic deposit located in Qinghai,China,is a typical skarn-type deposit in the Qimantage mineralization belt.Combined with previous studies on the geological features,mineralogy and geochemical characteristics of the deposit we used the software of TOUGHREACT to simulate numerically the chemical reactions of quartz-late sulfide mineralization stage.Geological conceptual model was built,the physicochemical parameters set in the grids,thermal convection and conduction of the multiphase fluid,solute transportation,and geochemical reaction processes within a set time step simulated and calculated.The general trend of chemical equilibrium concentration of ore-forming elements under different temperature and pressure conditions and the influence on dissolution and precipitation of galena and sphalerite was studied.The results show that the chemical equilibrium concentration of Pb^2+decreased sharply when the temperature dropped from 250℃to 155℃,and the chemical equilibrium concentration of Zn^2+decreased sharply when the temperature dropped from 300℃to 100℃.Precipitation of minerals onsumes a large number of relevant ore-forming elements.The influence on chemical equilibrium concentration of ore-forming elements is different under different temperatutre and pressure.Temperature is the key factor controlling the chemical reaction of galena and sphalerite precipitation,and the influence of pressure is small.The simulation results are relatively consistent with the traditional geological interpretation results and prove the validity of the numerical simulation.

关 键 词：TOUGHREACT 虎头崖铅锌多金属矿床 地球化学反应 化学平衡浓度 数值模拟 

分 类 号：P618.4[天文地球—矿床学] P617.9[天文地球—地质学]