Lithogeochemical Characteristics of Cretaceous Basic Dyke Swarm from Qimantag Region in East Kunlun and Its Geological Significance

The firstly discovered diabase dykes swarm in Qimantag region of East Kunlun has high TiO₂ (1.65%~2.87%) and alkali (2.98%~5.32%) contents, belonging to alkalic basalt series. LA-MC-ICP-MS zircon U-Pb dating of diabase dyke (porphyrite) has obtained an age of 102 Ma, while its Sm-Nd isochron age is (120±8.3)Ma. Therefore, it's confirmed that the early Cretaceous diabase dike is existed in Qimantag region, East Kunlun,and the area had entered the intracontinental extension stage in early Cretaceous.