Abstract: East Kunlun orogenic belt is a composite orogenic belt in the middle part of Qinghai Province. There exist a large number of gabbro, diabase and diabase dykes in NW direction in northern Qimantag area. Due to the invasion of the mafic dyke into the geological body in Proterozoic-Silurian period, the average TiO2 content of the mafic dyke is 1.63%, suggesting typical high titanium rocks. The geochemical composition of the rocks is consistent with the intraplate basalt, characterized by the enrichment of large ion lithophile elements and relatively low high field elements. U-Pb isotopes of zircon from the diabase were determined by LA-ICP-MS and 206Pb/238U dating of 22 zircon samples, which yielded an isotopic age of 380.3Ma±1.5Ma(MSWD=1.4), evidently suggesting that Eastern Kunlun-Qimantag region had entered the stage of intracontinental extension in Late Devonian.