苏鲁超高压变质带桃行榴辉岩及高压脉体中流体包裹体研究  

Fluid inclusions in the ultra-high pressure metamorphic rocks and high pressure metamorphic veins at Taohang in the Sulu terrane.

作　　者：范宏瑞[1] 刘爽[1] 胡芳芳[1] 杨奎锋[1] 金成伟[1] 

机构地区：[1]中国科学院地质与地球物理研究所矿产资源研究重点实验室,北京100029

出　　处：《岩石学报》2008年第9期2003-2010,共8页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40673032和40721062)资助

摘　　要：桃行榴辉岩是苏鲁超高压变质带中段主要榴辉岩体密集分布区之一。流体包裹体研究表明,榴辉岩矿物及高压脉体石英中捕获有五种类型的流体包裹体:在超高压—高压榴辉岩相条件下捕获的 N_2±CH_4包裹体;在榴辉岩发生麻粒岩相叠加变质作用期间被捕获的 B 型纯 CO_2液相包裹体;在高压榴辉岩重结晶阶段被捕获的 C 型 CO_2-H_2O 包裹体和 D 型高盐度水溶液包裹体;超高压岩石折返过程中的最晚阶段(角闪岩相退变质甚至更晚)捕获的 E 型低盐度水溶液包裹体。利用榴辉岩矿物及高压脉体石英中捕获的流体包裹体类型及期次可以重建超高压变质作用板片折返过程中的流体性状与演化,而石榴石中捕获的纯 CO_2包裹体为本区榴辉岩相岩石遭受了麻粒岩相叠加提供了佐证。Taohang eclogites in the southeastern Shandong Province are located in the middle part of the Sulu ultra-high-pressure metamorphic terrane, eastern China. Eclogites occur as blocks in granitic gneisses. Fluid inclusions in eclogites and eclogite-facies quartz veins at Taohang have preserved remnants of peak metamorphic and exhumation fluids. Detailed fluid inclusion studies reveal trapping of five type fluid inclusions in high and ultrahigh pressure eclogite minerals and vein quartz. These are A-type N2 ± CH4 inclusion trapped at high and ultra-high pressure eclogite-facies metamorphic condition, B-type pure-CO2 liquid phase inclusion with higher density trapped during granulite-facies overprinting metamorphism of eclogites, C-type CO2-H2O inclusion and D-type hypersaline inclusion trapped in high pressure eclogite-facies re-crystallization stage, and E-type low salinity H2O inclusion trapped in the latest stage of ultrahigh pressure exhumation （amphibolite-facies retrogression ）. The possibility of deciphering the relative chronology of the fluid pulses can provide fluid evolution history during exhumation of ultra-high-pressure metamorphic rocks. Identification of crowded-distributing pure-CO2 liquid inclusions with higher density trapped in garnet of eclogites provides an evidence for granulite-facies overprinting metamorphism at Taohang.

关 键 词：流体包裹体 榴辉岩 石英脉 折返 桃行 苏鲁 

分 类 号：P588.348[天文地球—岩石学]