西昆仑库地早古生代岩浆岩的物源与热源

西昆仑库地早古生代“128”岩体和库地北岩体与早古生代原特提斯洋壳俯冲消减形成的大型韧性剪切带存在时空共生关系,对比分析它们的化学组成特征,认为“128”岩体形成于原特提斯持续俯冲消减阶段,是增生楔杂岩剪切熔融和俯冲洋壳部分熔融岩浆混合、经多期侵位而成;而库地北岩体形成于原特提斯俯冲停止后的热隆位张阶段,是原特提斯俯冲消减阶段形成的增生楔杂岩经一次熔融原地侵位形成。

MATERIAL AND HEAT SOURCES OF THE EARLY PALEOZOIC MAGMATIC ROCKS IN KUDA, WEST KUNLUN

The Caledonian granites in the West Kunlun area are distributed along the north side of Kunlun Mountains. "128" granite and North Kuda granite are located north of Kuda along Xinjiang-Tibet Highway. The source rock and thermodynomics of "128" and North Kuda granites are studied in this paper. Field observation and lab analysis reveal that North Kuda granite and "128"granites have both temporal and spatial relationship with the Caledonian ductile shear zone south of Kuda. Based on whole rocks, REE elements, trace elements and Sm-Nd isotopic data, it is believed that the source rocks of North Kuda granite, "128" granite and ductile shear zone are mainly derived from the accretionary wedge complex formed by the subduction of proto-Tethys. The thermodynamics of " 128 "granite and North Kuda granite is different. "128" granite was formed in a compressional tectonic setting as co-tectonic calc-alkaline granite. Shear heat caused by consistent subduction of Proto-Tethys resulted in a different diagenetic age dated by different isotopic method. North Kuda granite was formed in a tensional tectonic setting characterized by rapid emplacing and cooling, belonging to post-orogeny alkali granite. So the diagenetic age dated by different isotopic method is the same.