摘要
长期以来,昆嵛山混合杂岩体的形成时代一直是个争论不休的问题,其一主要观点认为它形成于中元古代以前。本文根据野外地质特征及黑云母K-Ar法,Rb-Sr全岩-矿物内部等时线法及Rb-Sr全岩等时线法,确认岩体是由两期混合岩化形成的,分别发生于610.8Ma和134.3Ma。显微构造、岩石学、岩石化学及地球化学等特征表明岩体的原岩与徐克勤的同熔型一致,但成岩方式却类似干改造型。指出岩石非单一类型所能概括。
The Kunyushan migmatite complex is exposed in the eastern part of Jiao- dong, which is composed mainly of granodiorite and mozonitic granite. Its country rocks are represented by metamorphic rocks of the early Proterozoic Jiaodong Group. This complex, occurring as a huge N-NE-trending batholith, is controlled by the deep Moping-Jimo fault belt. The Kunyushan migmatite complex with an isotopic age o_1 134.3 Ma was formed by migmatization in the process of Mesozoic faulting and regional metamorphism. But before the Mesozoic migmatization, it had experienced another migmatization which has a Rb-Sr isochron age of 610.8Ma.The origial rocks of the migmatite complex were the mixture of sedimentary rocks and intermediate volcanic rocks from the lower crust. It is proved by the initial ^(37)Sr/^(36)Sr ratio (0.7071), too.
出处
《地质论评》
CAS
CSCD
北大核心
1989年第4期285-296,共12页
Geological Review
