摘要
蛇绿岩记录了地球特别是大洋演化的历史,是地球科学关注的热点。同时,蛇绿岩也是多种关键金属矿床的赋矿岩体,在铬铁矿、铂族矿产、贵金属找矿中地位突出。围绕蛇绿岩构造环境、地球化学、地质年代学、岩石学研究已取得重大进展,在地质固碳和地质氢新能源研究方面也有突破。但蛇绿岩的内部结构,特别是小尺度的内部结构,至今仍是蛇绿岩研究的薄弱环节。本文介绍了蛇绿岩内部结构研究方法与进展,依托矿床电磁学观测,结合地质、钻探结果,讨论了蛇绿岩的内部结构特征,特别是蛇绿岩内部超基性岩体的内部结构特征。矿床电磁学分析结果表明:从岩石物理分析到电磁法探测都发现西藏罗布莎、东巧蛇绿岩内部发育显著的高低阻电阻率异常分带。CSAMT探测结果表明新疆萨尔托海蛇绿岩内部也有类似的电性结构分带特征。依据罗布莎、东巧、萨尔托海、Semail蛇绿岩的地球物理探测和钻探结果以及乌拉尔一些矿区的剥露与深钻结果,我们提出了蛇绿岩电阻率-蚀变带结构模型。基于这一模型,蛇绿岩中的超基性岩主要发育高阻新鲜-弱蚀变方辉橄榄岩和低阻蚀变-强蚀变纯橄岩-蛇纹岩两个岩相结构带,两个岩相之间的过渡带是铬铁矿富集成矿的有利空间。电阻率-蚀变带模型可用于铬铁矿成矿预测以及蛇绿岩内部地质作用研究。
Ophiolites are the best archives of the evolutionary history of the Earth,especially the ocean basins from their rift-drift to subduction initiation and final closure.The studies of ophiolite have brought together diverse groups of scientists and professionals all through the world on a regular basis far more than any other topic in geology.Ophiolites have also been indispensable for human beings because of the endows of mineral and ore deposits they host,including the chromitite and precious minerals such as gold,silver and the platinum group metals.Great progresses have been achieved in the geo-structural environment,geochemistry,geochronology and petrology studies of ophiolites.Break outs have also been made in geological carbon cycle and new geological energy like natural hydrogen.Several geophysical approaches,such as gravity,magnetic survey,audio magnetotelluric sounding,have been employed for mineral exploration.However,understanding the internal structure of ophiolite,especially the detailed internal structure of the ultramafic rock masses remains unclear.In this paper,we reviewed the approaches and progress of the research on the internal structure of ophiolite.We then discussed the internal structure and geo-electrical properties especially the ultramafic rock mass inside the ophiolite based on the geophysical,geological observations and drilling boreholes.The electromagnetic studies to the mineral deposits and the petro-physical analysis of the ultramafic rocks show that the internal of the ultramafic rock mass in Luobusa and Dongqiao ophiolites in Xizang could be generally divided into an upper high resistivity domain and a lower low resistivity domain.CSAMT exploration results show that there have similar electrical structures in the Sartohay ophiolite in West Junggar,Northwest China.Based on the comprehensive analysis of the geophysical and drilling results of Luobusa,Dongqiao,Sartohay and Semail ophiolites,as well as some deep drilling results of Ural ultramafic belt,we propose a new model for understanding the internal structure of ophiolites based on resistivity and alteration rather than sole on the lithofacies.In this model,the ultramafic rocks in ophiolites are generally divided into two structural lithofacies domains,a relative fresh to weak altered harzburgite domain and an altered to intensively altered dunite-serpentinite domain.The transition zone between the two lithofaceis domains is a favorite area for the deposits of chromitite in relatively large scale.The resistivity-alteration ophiolite internal structure model could be used for predicting the deep-buried favorite areas of chromitite deposits as well understanding the geological process in ophiolites.
作者
何兰芳
王绪本
熊发挥
万阈
王军年
姚红春
陈儒军
秦克章
HE LanFang;WANG XuBen;XIONG FaHui;WAN Yu;WANG JunNian;YAO HongChun;CHEN RuJun;QIN KeZhang(Key Laboratory of Deep Petroleum Intelligent Exploration and Development,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Science,Beijing 100049,China;College of Geophysics,Chengdu University of Technology,Chengdu 610059,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Tacheng Geological Survey Team,Geological Bureau of Xinjiang,Wusu 833099,China;School of Geosciences and Info-Physics,Central South University,Changsha 410083,China;State Key Laboratory of Lithospheric and Environmental Coevolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)
出处
《岩石学报》
北大核心
2025年第2期657-668,共12页
Acta Petrologica Sinica
基金
第二次青藏高原科学考察研究项目(2019QZKK0801)
新疆重点研发计划(2023B03006-3)
国家自然科学基金项目(41774083)联合资助.
