铬同位素体系及其在铬铁矿成矿过程中的应用  

Chromium isotope systematics and its applications in chromite deposits

作　　者：白洋 苏本勋[2,3] 肖燕 史仁灯[3,5,6] 潘旗旗 袁庆晗[2,3] 崔梦萌 王静 BAI Yang;SU Benxun;XIAO Yan;SHI Rendeng;PAN Qiqi;YUAN Qinghan;CUI Mengmeng;WANG Jing(College of Mining Engineering,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Key Laboratory of Continental Collision and Plateau Uplift,Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China;Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences,Beijing 100101,China)

机构地区：[1]太原理工大学矿业工程学院,山西太原030024 [2]中国科学院地质与地球物理研究所,中国科学院矿产资源研究重点实验室,北京100029 [3]中国科学院大学,北京100049 [4]中国科学院地质与地球物理研究所,岩石圈演化国家重点实验室,北京100029 [5]中国科学院青藏高原研究所,大陆碰撞与高原隆升重点实验室,北京100101 [6]中国科学院青藏高原地球科学卓越中心,北京100101

出　　处：《地质学报》2023年第11期3637-3650,共14页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41973012);优秀博士毕业生来晋工作奖励(编号DC2100004358);中国科学院青年创新促进会联合资助的成果。

摘　　要：近年来铬(Cr)同位素体系在示踪地幔部分熔融、岩浆结晶分异及俯冲带流体相关的地质过程中均取得了重要进展。本文通过实例研究综述了Cr同位素在铬铁矿成矿作用方向的主要进展,包括:(1)Stillwater层状岩体橄榄岩带和Kizildag蛇绿岩壳幔过渡带内铬铁矿及共生硅酸盐矿物的Cr同位素研究,揭示了层状/似层状铬铁矿成矿过程中可能发生明显的Cr同位素分馏,且主要受结晶分异和岩浆补给过程控制;(2)Kizildag蛇绿岩豆荚状铬铁矿床的Cr同位素研究,证明了俯冲带地幔橄榄岩中尖晶石的部分熔融,可能是豆荚状铬铁矿床主要的成矿物质来源之一,同时俯冲带流体也可能直接参与成矿;(3)层状岩体及蛇绿岩中普遍存在矿物间的Cr同位素不平衡分馏现象,不仅可用以记录岩浆作用的冷却时间,同时也证明了铬铁矿成矿过程中释放的流体对矿物间的元素交换具有明显促进作用。In recent years,chromium(Cr)isotope systematics have been widely used in tracing geological processes related to mantle partial melting,magma differentiation,and subduction fluid-related processes.This study summarizes the main advances in using Cr isotope geochemistry in chromite deposits in maficultramafic rocks,including:①Cr isotope compositions of chromite and coexisting silicates in the peridotite zone of the Stillwater complex and crust-mantle transition zone of the Kizildag ophiolite reveal that Cr isotopes had been significantly fractionated during formation of both stratiform and stratiform-like chromitite,which was mainly controlled by fractional crystallization and magma replenishment;②Cr isotope compositions of the podiform chromitite from Kizildag ophiolite suggested that spinel in the mantle peridotites in the subduction zone is one of the mainly Cr sources in podiform chromitite,and the subduction zone fluids may also directly participate in mineralized formation;③diffusion-driven intermineral Cr isotope fractionation in ophiolite and layered intrusion can not only be used to estimate cooling time of magmas,but also reveal critical medium role of hydrous fluids in chemical exchange between minerals.

关 键 词：蛇绿岩 层状岩体 铬铁矿 铬同位素 铬矿床 

分 类 号：P618.31[天文地球—矿床学] P618.33[天文地球—地质学]