矿床地质2023，Vol.42Issue(6)：1214-1228,15.DOI:10.16111/j.0258-7106.2023.06.008
岩浆-热液成矿系统中铁同位素地球化学研究现状
Status and progress on geochemical behavior of iron isotope in magmatic-hydrothermal system
摘要
Abstract
Iron element is one of the important metal elements involved in mineralization in the magmatic-hydrother-mal metallogenic system.The δ 56Fe values of iron-rich minerals(pyrite,magnetite,chalcopyrite,pyrrhotite,bornite,arsenopyrite,siderite)in magmatic-hydrothermal deposits vary considerably(-2.07‰～+1.58‰),indica-ting that the iron isotope has obvious fractionation during the magmatic evolution,fluid exsolution and hydrother-mal evolution,therefore,it has great application potential in constraining the migration-enrichment-precipitation process of ore-forming metals and tracing the source of ore-forming materials in the magmatic-hydrothermal metallogenic system.Based on sorting out and analyzing the data of previous studies,this paper summarizes the research status of iron isotope geochemical behavior in magmatic evolution,fluid exsolution and hydrothermal evolution of magmatic-hydrothermal metallogenic system.The iron isotope will undergo significant fractionation in the process of magmatic evolution,and the melt phase is enriched in heavy iron isotope than the residual solid phase during partial melting;the iron isotope composition of the residual melt is changed due to the separation and crystallization of minerals,which are mainly affected by the crystallization of minerals containing Fe2+ or Fe3+,for example,separation and crystallization of magnetite will lead to enrichment of light iron isotope compo-sition in the residual melt,which generally reflects the main control of the redox state of magma on the fraction-ation of iron isotopes.Therefore,the composition and variation of iron isotope in ore-bearing rocks can be used to determine the redox state of magma.Fluid exsolution is a key process in the evolution of ore-bearing magma into magmatic hydrothermal deposits,the exsolution fluid is rich in light iron isotope relative to the host rock,howev-er,the experimental studies show that the iron isotope composition of the exsolution fluid may be affected by many factors,such as the migration form of iron,the proportion of Fe2+ or Fe3+ containing minerals in equilibrium with the fluid,the phase separation and the fluid mixing.During the hydrothermal evolution,the precipitation of iron bearing hydrothermal minerals will cause changes in the iron isotope composition of the fluid,the magnetite precipitation will cause the fluid to enrich the light iron isotope,and the precipitation of iron-bearing sulfides(such as pyrrhotite)makes the fluid gradually enrich the heavy iron isotopes,which shows that the redox state of hydrothermal fluid controls the fractionation of iron isotopes.Since chalcopyrite is considered to be able to effec-tively record the iron isotope composition of the fluid,its iron isotope value is used to distinguish the redox state of hydrothermal fluid.As an element directly involved in mineralization in the magmatic hydrothermal metallo-genic system,iron provides a possibility for direct tracing of the source of ore-forming materials,however,the ob-vious fractionation of iron isotopes in magmatic evolution,fluid dissolution and hydrothermal evolution leads to the particularity of tracing the source of ore-forming materials with iron isotopes.It is the key to trace the source of ore-forming materials by iron isotopes to further clarify the fractionation rules in the geological processes such as fluid dissolution and hydrothermal evolution.关键词
Fe同位素/岩浆-热液成矿系统/地球化学行为/应用研究现状Key words
Fe isotope/magmatic-hydrothermal metallogenic system/geochemical behavior/application research status分类
天文与地球科学引用本文复制引用
王续文,李宇轩,安芳..岩浆-热液成矿系统中铁同位素地球化学研究现状[J].矿床地质,2023,42(6):1214-1228,15.基金项目
本文得到国家自然科学基金项目(编号:42273062、42130102)和西北大学地质学系科研基金项目的联合资助 （编号:42273062、42130102）
