今天是2018年10月18日

豆荚状铬铁矿床研究回顾与展望

DOI:10.3799/dqkx.2018.704

作者:陈艳虹,杨经绥

联系地址:中国地质大学地球科学与资源学院,北京 100083

摘要:豆荚状铬铁矿是蛇绿岩的特征性矿产,对其成因的认识还存在较大的分歧,包括:(1)早期岩浆熔离;(2)地幔熔融残余;(3)熔体-岩石反应.豆荚状铬铁矿及其围岩地幔橄榄岩中大量异常地幔矿物群的发现,引起了地质学家对其形成过程的重新思考.回顾了铬铁矿的研究,借助pMELTS热力学软件模拟浅部地幔过程,使用定量化的方法限定这些过程对豆荚状铬铁矿形成的贡献,通过一个新的角度讨论其形成.初步模拟结果显示,单独的地幔部分熔融、熔体分离结晶以及拉斑质熔体与亏损地幔的反应等过程形成的铬铁矿,无论在数量还是品位上都难以达到矿床水平,暗示豆荚状铬铁矿的形成可能为多种作用耦合的结果,或与深部地幔作用有关.

关键字:结晶分异作用;部分熔融作用;熔体岩石反应;豆荚状铬铁矿;蛇绿岩;岩石学

Formation of Podiform Chromitite Deposits: Review and Prospects

Author:Chen Yanhong, Yang Jingsui

Author Address:School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China

Abstract:As the characteristic ore deposits in ophiolites, podiform chromitite deposits mainly formed in the ultramafic section of an ophiolite complex. However, the following issues on podiform chromitite remain controversial: (1) crystal melt separation; (2) residual of mantle partial melting; (3) melt rock interaction. It is of particular importance to study the formation processes of podiform chromitite when large amounts of unusual minerals are found in podiform chromitite and its host rock peridotite. Petrogeneses of chromitite are reviewed in this paper. The pMELTS thermodynamic software was used to calculate the contribution of shallow mantle processes to the formation of podiform chromitite. Preliminary simulation results show that it is impossible to explain the formation of large scale podiform chromitite deposits by individual mantle partial melting, mantle melt separation or tholeiitic melt depleted mantle interaction processes, which implies that the podiform chromitite deposits may have been formed by multi stage or deep mantle processes. Further researches are needed to be conducted on the origin of podiform chromitite deposits.

Keyword:crystal melt separation; partial melting; melt rock reaction; podiform chromitite; ophiolite; petrology

 

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作者简介:陈艳虹(1990-),女,博士研究生,主要从事岩石学研究.ORCID: 0000-0003-3835-0164. E-mail: chenyhlicht@126.com

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