辽吉成矿带热液型铅锌矿床矿物组合共生分异的热力学制约——以岫岩红旗铅锌矿床为例

辽吉成矿带上广泛分布着热液型铅锌矿床,对于该类型矿床中矿物共生组合特征和成矿物质迁移沉淀机制的研究是矿床学研究的核心问题之一。通过共生矿物热力学平衡的相关计算,绘制热力学lgCu2+]-pH、lgHS?]-pH和Eh-pH相图,可以有效地诠释成矿流体中成矿元素在迁移、沉淀过程中的物理化学条件。本文以辽吉成矿带上典型的热液型铅锌矿床——岫岩红旗铅锌矿床为例,在对该矿床进行镜下典型矿物共生组合研究的基础上,选取了黄铁矿、黄铜矿、方铅矿和闪锌矿四种矿物进行热力学平衡的相关计算,选取473 K、549 K、648 K三个温度截面绘制了热力学lgCu2+]-pH、lgHS?]-pH和Eh-pH相图,结果显示成矿流体中矿物迁移沉淀机制和矿物共生组合的形成主要受成矿流体的温度、离子活度、pH、Eh多因素制约。此研究对于解释辽吉成矿带上典型热液型铅锌矿床的运移沉淀机制和矿物组合特征具有重要的指导意义。

Thermodynamic Constraints on Mineral Assemblages and Differentiation of Hydrothermal Pb-Zn Deposits in the Liaoji Metallogenic Belt——A Case Study of the Hongqi Pb-Zn Deposit in Xiuyan

Hydrothermal Pb-Zn deposits are widely distributed in the Liaoji metallogenic belt.The mineral assemblages and mechanism of ore metal migration and precipitation are key issues in metallogenetic study of this type of deposits.The lgCu2+]-pH,lgHS?]-pH and Eh-pH phase diagrams established on the basis of thermodynamic equilibrium calculation of the mineral assemblages can effectively explain the physical and chemical conditions of ore-forming fluids and the process of migration and precipitation.This study took a typical hydrothermal Pb-Zn deposit,i.e.,the Xiuyan Hongqi Pb-Zn deposit in the Liaoji metallogenic belt as an example,and calculated the thermodynamic equilibrium of the pyrite,chalcopyrite,galena and sphalerite ore mineral assemblage.The thermodynamic lgCu2+]-pH,lgHS?]-pH and Eh-pH phase diagrams were established for three different temperatures,i.e.,473 K,549 K,and 648 K.The phase diagrams showed that the mechanism of ore metal migration and precipitation and the formation of the mineral assemblages are mainly controlled by temperature,ionic activity,pH and Eh of ore-forming fluids.This study is of great significance to explain the migration and precipitation mechanism and mineral assemblages of typical hydrothermal Pb-Zn deposits in the Liaoji metallogenic belt.