K-rich lamellar exsolution in clinopyroxene:Constraint on the depth of peridotite source at Zhimafang  

作　　者：ZHAOWenxia HUYuxian XIAFeng WANGXimei LIAOChengzhu JIANGDan 

机构地区：[1]SunYat-SenUniversity,InstrumentationAnalysis&ResearchCenter,Guangzhou510275,China

出　　处：《Chinese Science Bulletin》2004年第7期711-715,共5页

摘　　要：The oriented lamellar K-rich exsolutions within clinopyroxene host were recognized in garnet peridotite mas-sif at Zhimafang in the Sulu ultrahigh pressure metamorphic terrane, eastern China. EMP and TEM analyses revealedthat the composition and the index of electron diffraction for this exsolution are corresponding with phlogopite, and theshape is the lamellae with 1 mm in width and 5 to 30 mm inlength. Moreover, the topotaxy is that the (001) of K-rich exsolution parallels to (100) of the clinopyroxene host. Theelectron diffraction analyzing shows the exsolution is of a 1M polymorphism. The high-resolution lattice fringe image dis-plays the stack features along [001], which only a layer min-eral shows. We conclude that the clinopyroxene with 1M and K-rich exsolution was probably derived from mantle depthsover 240 km, thus resulting from decompressional exsolution in the initial stage of slab exhumation.The oriented lamellar K-rich exsolutions within clinopyroxene host were recognized in garnet peridotite mas-sif at Zhimafang in the Sulu ultrahigh pressure metamorphic terrane, eastern China. EMP and TEM analyses revealedthat the composition and the index of electron diffraction for this exsolution are corresponding with phlogopite, and theshape is the lamellae with 1 mm in width and 5 to 30 mm inlength. Moreover, the topotaxy is that the (001) of K-rich exsolution parallels to (100) of the clinopyroxene host. Theelectron diffraction analyzing shows the exsolution is of a 1M polymorphism. The high-resolution lattice fringe image dis-plays the stack features along [001], which only a layer min-eral shows. We conclude that the clinopyroxene with 1M and K-rich exsolution was probably derived from mantle depthsover 240 km, thus resulting from decompressional exsolution in the initial stage of slab exhumation.

关 键 词：斜辉石 橄榄岩 深度约束 K-富集层 脱溶 地幔对流 大陆地壳物质 电子衍射 深度俯冲 板块挖掘 超高压力 

分 类 号：P54[天文地球—构造地质学] P588.125[天文地球—地质学]