机构地区:[1]中国科学院地质与地球物理研究所,深层油气理论与智能勘探开发重点实验室,北京100029 [2]中国科学院大学地球与行星科学学院,北京100049 [3]成都理工大学地球物理学院,成都610059 [4]中国地质科学院地质研究所,北京100037 [5]新疆地质局塔城地质大队,乌苏833099 [6]中南大学地球科学与信息物理学院,长沙410083 [7]中国科学院地质与地球物理研究所,岩石圈演化与环境演变全国重点实验室,北京100029
出 处:《岩石学报》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.
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 Tibet 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 under
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