蛇绿岩研究进展、存在问题及思考  

Comment on the Progress in and Problems on Ophiolite Study

作　　者：史仁灯[1] 

机构地区：[1]中国科学院壳幔物质和环境重点实验室

出　　处：《地质论评》2005年第6期681-693,共13页Geological Review

基　　金：国土资源部十五重点项目(编号20010201);国家自然科学基金重大国际合作项目(编号49732070)资助的成果

摘　　要：20世纪70年代建立的蛇绿岩(Ophiolite)概念认为出露在缝合带中的一套镁铁—超镁铁岩组合是大洋岩石圈的残留,其岩性单元可以与现代大洋岩石圈各个层圈一一对应,所以蛇绿岩是确定古板块边界的重要证据,该认识促进了板块构造学说的发展。近年来完善的MOR型和SSZ型蛇绿岩理论体系认为MOR型蛇绿岩形成于洋中脊(MOR),SSZ型蛇绿岩形成于俯冲带上(Supra-SubductionZone),二者的地幔橄榄岩、堆晶岩组合及上部熔岩在岩石学、矿物学和地球化学方面均有不同的特征,洋—陆俯冲和洋内俯冲是形成SSZ型蛇绿岩的两种机制,较为合理地解释了蛇绿岩的多样性及其与大洋岩石圈的差异。由于大洋板块的俯冲作用,在缝合带中MOR型蛇绿岩很少被保存下来,保存较好的大多数为SSZ型蛇绿岩。本文探讨了蛇绿岩研究中经常遇到的问题并提出了解决的思路,同时认为Rodinia超大陆前是否存在蛇绿岩、太古宙绿岩是否为蛇绿岩均为有待深入研究的问题。According to the concept of ophiolite in 1970s, exposure of been interpreted to represent the relic of fossil ocean lithosphere based on its lithology units consisting with oceanic crust and upper mantle. So the ophiolite is a key eyidence of boundary between the fossil plates, and has been played an important role on the formulation and advancement of the plate tectonic theory. Recently, ophiolite is divided into MOR- and SSZ- types based on the formation tectonic setting. MOR-type ophiolite formed at Mid-ocean ridges （MOR）, and SSZ-type ophiolite formed on the supra-subduction zone caused by the ocean-continent subduction or intra-ocean subduction, and there are obvious difference in mantle sequence, cumulated assemblage and lavas in petrology, mineralogy and geochemistry between MOR- and SSZ-type ophiolites. This classification explains well the various ophiolites and the difference between the ophiolite and oceanic lithosphere. During the subduction of oceanic lithosphere, the MOR-type ophiolite was subducted, or is preserved only as dismembered thrust sheets or blocks in ophiolitic melange, while SSZ-type ophiolite, as fragments of modified oceanic or rebirth lithosphere caused by fossil oceanic plate subduction, is commonly preserved in the orogenic zone due to it formed above subduction zone. Therefore, SSZ-type ophiolite is major one preserved well in the orogenic zone. Also discussed in this paper are the problems in the ophiolite study, such as the difference between the ophiolite and ocean lithosphere in peridotites, and the methods to solve these problems. And the pre-Rodinia super-continent ophiolite record is still considered poorly understanding, and whether Archean greenstone is ophiolite or not. These are all questions to answer.

关 键 词：MOR型蛇绿岩 SSZ型蛇绿岩 RODINIA超大陆 太古宙绿岩 板块构造学 

分 类 号：P588.1[天文地球—岩石学] P542[天文地球—地质学]