东昆仑造山带蛇绿岩矿物学特征及其岩石成因讨论

MINERALOGICAL CHARACTERISTICS AND PETROGENESIS OF OPHIOLITES IN EAST KUNLUN OROGENIC BELT, QINGHAI PROVINCE

首次对东昆仑复合造山带不同时代蛇绿岩主要造岩矿物橄榄石、辉石、斜长石进行了系统的矿物化学研究 ,查明了不同蛇绿岩带在矿物成分上的差异 ,对清水泉蛇绿岩带和布青山蛇绿岩带单斜辉石、斜方辉石、斜长石进行了矿物稀土、微量元素的研究 ,阐明了矿物稀土、微量元素与全岩稀土、微量元素的关系 ,证明了在以辉石和橄榄石为主的橄辉岩中 ,单斜辉石的稀土元素基本上代表了全岩的稀土元素。根据地幔岩石中矿物成分特征 ,对不同蛇绿岩带地幔类型进行了讨论 ,并根据实测的辉石、斜长石分配系数 。

This is the first systematic investigation of olivine, orthopyroxene, clinopyroxene, and plagioclase in the Qingshuiguan and Buqingshan ophiolites of the East Kunlun orogenic belt, Qinghai Province. The major rock\|forming minerals in the two ophiolites are unique in major and minor element compositions. On the basis of ICP\|MS analyses, we established the relationships of rare\|earth elements and other trace elements between these minerals and their host rocks. In particular, we confirmed the clinopyroxene as a good proxy for the whole\|rock, rare\|earth element composition of olivine pyroxenites. Also, rare\|earth element geochemical modeling has been performed for the Qingshuiquan ophiolite in order to constrain the composition and the degree of partial melting of the mantle source region.