蛇绿岩研究新进展及其定义和分类的再讨论

Ophiolite:Some key aspects regarding its definition and classification

蛇绿岩保存于大陆造山带中,在地质历史上产于洋——陆过渡区多种构造背景(活动大陆边缘、被动大陆边缘、弧前、弧后、弧内、弧间、板块三联点、转换断层、大陆裂谷或它们的复合背景等)的洋盆扩张脊.蛇绿岩以超镁铁质岩、镁铁质岩为主,是一套彼此具有成因演化亲缘关系的、古洋壳+大洋地幔岩石的有机组合.我们把蛇绿岩概括为产于洋盆扩张脊的洋壳+大洋地幔岩石组合.蛇绿岩按构造背景有红海萌芽型洋壳和大洋中脊型洋壳两个端元,可三分为近陆的活动大陆边缘型——科迪勒拉型、东地中海型(新特提型)过渡型、西地中海型——大洋中脊古特提斯型.科迪勒拉型和东地中海型均属俯冲带(SSZ)上叠型,更近陆靠俯冲带;环太平洋型和被动大陆边缘型属特提斯型.

Ophiolite is a suite of mafic-ultramafic and relevant rocks with close affinity.It comprises the ancient oceanic crust ＋sub-ocean mantle assemblage and occurred in ocean ridges of various tectonic settings（active continent margin,passive continent margin,fore-arc,back-arc,intra-arc,inter-arc,triple junction,translation fault,intra-continental rift or their composite） during the geological history.Ophiolites may be classified as the Cordilleran-active continental margin type,the Neotethyan-eastern Mediterranean（transition） type,and the Paleotethyan—the western Mediterranean（mid-ocean ridge） type between the Red Sea type（embryogeny type） and the mid-ocean ridge type.The Cordilleran and eastern Mediterranean types were closely related to the suprasubduction zone type,closer to the continent and the subduction zone.The circumo-Pacific ophiolites and passive continental margin-type ophiolites are in close affinity with the Tethyan types.