摘要
西藏申扎县崩纳藏布和甲岗雪山两个地区出露的岩浆岩体一直被认为是两个较大的花岗岩基 ,但实际地质调查表明 ,这两个岩体中的每一个都可以分解为多个不同岩性的小岩体 ,K- Ar同位素年龄表明 ,这些岩体主要形成于燕山晚期 (90 .5 5 Ma～ 114 .6 7Ma)和喜山早期 (5 8.75 Ma)。对其中部分岩体开展的微量元素、稀土元素以及 Rb- Sr和Sm- Nd同位素的地球化学初步研究表明 ,两地出露的花岗岩体虽然形成于不同时代 ,但具有相同的以壳幔混合带为主的源区。另一方面 ,痕量元素的含量及同位素的组成特征也同时表明了形成于不同时期的岩体具有含量、配分、趋势变化等方面的差异 ,反映其具体的成因和分异演化过程并不相同。
The granite occurred in Bengnazangbu and Jiagang area of Shenzha County,Tibet has been considered as two big granite masses for a long time.Investigation has shown that each granite mass can be divided into several samll rock bodies.The K-Ar isotope dating showed that these rocks were formed mainly in late Yanshenian(90.55 Ma^114.67 Ma) and early Himalayanian(58.75 Ma) Period. The characteristics of petrology,REE,LILE and Rb-Sr Sm-Nd isotopes these granite rocks formed in different peroid may come from the same mixed sources of crust and mantle,with different genesis and differentiation-evolution process.
出处
《矿物岩石》
CAS
CSCD
北大核心
2003年第2期55-61,共7页
Mineralogy and Petrology
