镍同位素在高温岩浆系统中的研究进展和矿床学应用  

Research progress of nickel isotope in high-temperature magmatic system and its implications to ore deposit

作　　者：张泽 薛胜超 唐冬梅[2] 王路阳 王晓曼 田洪庆 张瑞麟 ZHANG Ze;XUE ShengChao;TANG DongMei;WANG LuYang;WANG XiaoMan;TIAN HongQin;ZHANG RuiLin(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing 100083,China;Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]中国地质大学,地质过程与矿产资源国家重点实验室,北京100083 [2]中国科学院矿产资源研究重点实验室,中国科学院地质与地球物理研究所,北京100029

出　　处：《岩石学报》2024年第6期1959-1971,共13页Acta Petrologica Sinica

基　　金：国家自然科学基金面上项目(42172076);求真学人计划项目(265QZ2022008)联合资助.

摘　　要：Ni同位素在高温岩浆系统中被识别出高达4‰的δ60/58 Ni变化范围,打破了传统元素质量数越大同位素分馏相对越小的观点,这种高温岩浆体系中产生的巨大的同位素分馏可能是多个平衡同位素分馏过程叠加和/或动力学分馏导致的,因而也被应用到岩浆铜镍硫化物矿床中。前人对高温岩浆过程Ni同位素分馏机理的认识包括:(1)玄武岩难以代表地幔的Ni同位素组成;(2)地幔部分熔融和壳源物质循环不会产生明显的Ni同位素分馏,地幔交代作用是导致地幔Ni同位素不均一的主要原因;(3)硫化物参与的过程是高温岩浆体系产生Ni同位素变化的主控因素,例如,硫化物的溶解、结晶、熔离以及和硅酸盐岩浆的相互作用。目前Ni同位素在高温地质过程中的研究与应用还处于发展阶段,同位素分馏系数和简约配分函数比等参数有待确定,需要结合更精确的模拟计算和更合理的高温高压实验来解决。查明地幔交代过程中Ni同位素分馏的具体机制,有望精准识别地幔源区的岩石性质和精细交代过程;Ni和Cu同位素的联合应用在岩浆铜镍矿床的金属富集机制和地球动力学环境研究方面显示出巨大潜力。The variations of Ni isotopes have been identified as high as 4‰in high-temperature magmatic systems,which breaks the traditional view that the larger the large number of elements,the smaller the relative isotopic fractionation.The massive isotopic fractionation generated in high-temperature magmatic system may be caused by the superposition of multiple equilibrium isotope fractionation processes and/or dynamic fractionation and therefore has also been applied to magmatic Ni-Cu sulfide deposits.The current understanding of the Ni isotope fractionation mechanism in high-temperature magmatic processes includes:(1)The Ni isotope composition of basalt cannot represent the mantle value.(2)Partial melting of the mantle and recycling of crustal materials result in limited Ni isotope fractionation,and mantle metasomatism is the main reason for the heterogeneity of Ni isotope in the mantle.(3)The involvement of sulfides in high-temperature magmatic systems is the main controlling factor for the Ni isotope changes,especially for the large Ni isotope fractionation identified in high-temperature magmatic sulfide ore-forming systems,for example,the dissolution,crystallization,segregation and interaction with silicate magma of sulfides.At present,the research and application of Ni isotopes in high-temperature geological processes are still in the development stage,and parameters such as isotopic fractionation coefficients and reduced partition function ratios need to be determined.This requires more accurate simulation calculations and more reasonable high-temperature and high-pressure experiments to solve the problem.Uncovering the isotopic fractionation mechanism during mantle metasomatism is expected to accurately identify the mantle rock type and the detailed metasomatic processes.The combination of Cu and Ni isotopes has great potential in the study of metal enrichment mechanisms and geodynamic environments in magmatic Ni-Cu sulfide deposits.

关 键 词：Ni同位素 同位素分馏 地幔交代 岩浆铜镍硫化物矿床 高温地质过程 

分 类 号：P597.2[天文地球—地球化学] P618.63[天文地球—地质学]