喜马拉雅碰撞造山带不同类型部分熔融作用的时限及其构造动力学意义

发布时间：2018-02-24 22:27

本文关键词： 喜马拉雅造山带淡色花岗岩深熔作用构造转换　出处：《地质学报》2016年11期 　论文类型：期刊论文

【摘要】：喜马拉雅新生代淡色花岗岩,是世界上S型花岗岩的典例,主要分布于两条近平行排列的东西向构造带内,特提斯喜马拉雅带和高喜马拉雅带。实验岩石学和理论研究表明:这些淡色花岗岩是中—下地壳岩石进行不同性质的地壳深熔作用的产物,部分熔融类型与构造变形密切耦合。具体表现在:146~35 Ma,在增厚地壳条件下,以角闪岩部分熔融作用为主,形成了具有高Sr/Y比值的二云母花岗岩;228~9 Ma,减压条件下,俯冲物质快速折返,白云母发生脱水部分熔融,形成具有较高Rb/Sr比值的花岗岩;3其中,在21~16 Ma期间,与藏南裂谷系E—W向伸展作用开启密切相关,变泥质岩发生水致白云母部分熔融作用,形成Rb/Sr比值较低,Sr和Ba含量较高的花岗岩;4在25~27 Ma期间,局部地区发生高压水致部分熔融作用。
[Abstract]:The Himalayan Cenozoic pinkish granite is a typical example of S-type granite in the world. It mainly distributes in two nearly parallel EW tectonic belts. Experimental petrology and theoretical studies show that these pallor granites are the product of the deep melting of the earth's crust by different properties of the middle and lower crust rocks, the Tethys Himalayan belt and the high Himalayan belt. The partial melting type is closely coupled with tectonic deformation, which is manifested in the thickening crustal conditions and the partial melting of amphibolite, resulting in the formation of a bimica granite with a high Sr/Y ratio of 2289 Ma and a decompression condition, respectively, under the condition of thickening the crust, and the partial melting of amphibolite. Due to the rapid exhumation of subduction materials, Muscovite dehydrates and partially melts, forming granitoids with high Rb/Sr ratio. During the period of 21 ~ 16 Ma, it was closely related to the opening of E-W extension in the southern Tibetan rift system. Water induced partial melting of Muscovite from argillaceous rocks resulted in partial melting of Muscovite by high pressure water during 2527 Ma, resulting in the formation of granitoids with lower Rb/Sr ratio and higher content of Sr and Ba.
【作者单位】：中国地质科学院地质研究所大陆构造与动力学重点实验室;河南省有色金属地质勘查总院;中国地质科学院矿产资源研究所;
【基金】：国家自然科学基金项目(编号41425010,41503023,41273034) 中国地质科学院地质研究所基本科研业务费项目(编号J1516) 中国地质调查局地质调查项目(编号12120115027101)联合资助成果
【分类号】：P542

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