腾冲地块西缘那邦基性麻粒岩中石榴石 Sm - Nd 等时线年龄及其意义  

The garnet Sm Nd isochron age and significance of the metamorphic basalt from the western Tengchong area, southwest Yunnan, China

作　　者：季建清[1] 钟大赉[2] 

机构地区：[1]北京大学地质学系,北京100871 [2]中国科学院地质研究所,北京100029

出　　处：《岩石学报》1999年第3期359-363,共5页Acta Petrologica Sinica

基　　金：国家自然科学基金 "九五"重点项目;国家自然科学基金青年基金

摘　　要：石榴石 Ｓｍ  Ｎｄ 等时线法是近年来常用于较新年龄的测年方法。腾冲地块西缘新近发现的基性麻粒岩中石榴石和全岩的 Ｓｍ  Ｎｄ 等时线年龄为 １７～２５ Ｍａ， 是该麻粒岩经受后期变形变质作用的年龄， 与区内右旋走滑断裂活动时限相一致，为确证腾冲地区的右旋走滑断裂是印支地块逸出的西部边界提供了 Ｓｍ  Ｎｄ 等时线方法的年龄约束。并推断石榴石 Ｓｍ  Ｎｄ 体系的封闭温度较低， 应低于那邦变质基性岩晚期变质作用的６４０℃～７２０℃。The Sm Nd dating in garnets becomes an important new method for dating the Mesozoic and Cenozoic samples recently The Sm Nd isochron ages in garnets and whole rock of the basaltic granulite from the western edge of Tengchong block are about 17～25Ma, indicating the age of the later metamorphic event owing to the deformational movement of the Cenozoic dextral strike slip faults It gives an important dating constraint for determining the western boundary of the extrusion Indo China block according to Tapponnier's slip line field theory It also can be concluded that the closure temperature for the Sm Nd system in garnet is lower than 640℃～720℃ that is the temperature of the later metamorphism

关 键 词：石榴石 封闭温度 麻粒岩 钐-钕等时年龄 

分 类 号：P588.346[天文地球—岩石学] P578.947[天文地球—地质学]