青藏高原东南缘点苍山-哀牢山杂岩带中片麻岩的变质演化及深熔作用特征  

Metamorphic evolution and anatexis of gneissic rocks in the Diancangshan-Ailaoshan metamorphic complex belt,southeastern Tibet Plateau

作　　者：王舫[1] 刘福来[1] 刘平华[1] 

机构地区：[1]大陆构造与动力学国家重点实验室,中国地质科学院地质研究所,北京100037

出　　处：《岩石学报》2011年第11期3280-3294,共15页Acta Petrologica Sinica

基　　金：中国地质调查局地质调查工作项目(1212011121276);创新研究群体科学基金项目(40921001)联合资助

摘　　要：片麻岩是点苍山-哀牢山变质杂岩带最常见的岩石类型,主要由夕线石榴黑云二长片麻岩、石榴黑云斜长片麻岩以及含十字石蓝晶夕线石榴片麻岩所组成,其原岩的化学成分与华北克拉通典型孔兹岩系十分相似。岩相学、成因矿物学和变质反应性质研究以及温压条件估算结果表明,研究区片麻岩类岩石变质峰期的温压条件为T=700～770℃,P=0.5～0.8GPa,已达到或接近麻粒岩相变质,晚期退变质阶段的温压条件为T=600～650℃,P=0.35～0.45GPa。片麻岩变质演化的P-T轨迹具有顺时针型式。在麻粒岩相变质阶段,片麻岩类岩石普遍发生深熔作用,主要表现为含水矿物黑云母的脱水熔融和长英质矿物的部分熔融。该项研究对于进一步揭示青藏高原东南缘点苍山-哀牢山造山带的变质演化深熔作用机理及动力学过程具有重要的科学意义。The gneissic rocks,which consist mainly of sillimanite-garnet-biotite gneiss,garnet biotite gneiss and staurolite-and kyanite-bearing sillimanite garnet gneiss,are widely distributed in the Diancangshan-Ailaoshan metamorphic complex belt.Combined the petrography,genetic mineralogy with metamorphic reaction,the P-T conditions for each metamorphic stage has been obtained using geo-thermometer and-barometers.The mineral assemblage for the peak metamorphic stage records P-T condition of 700～770℃ and 0.5～0.8GPa.In contrast,the mineral assemblage for the late retrograde stage records P-T condition of 600～650℃ and 0.35～0.45GPa,indicating the gneissic rocks in the Diancangshan-Ailaoshan complex belt experienced a granulite-facies metamorphism overprinted with a late retrogression.These results have an important significance for in-depth studying the metamorphic evolution,anatexis and dynamic process of the Diancangshan-Ailaoshan complex belt.

关 键 词：麻粒岩相变质 深熔作用 片麻岩 点苍山-哀牢山变质杂岩带 青藏高原 

分 类 号：P588.345[天文地球—岩石学]