LA-ICP-MS zircon U-Pb dating of granodiorite from Delisi-tan of the Buqingshan area, southern margin of East Kunlun Mountains, and its geological implications

The Buqingshan tectonic mélange, which is an important tectonic boundary on the southern margin of East Kunlun Mountains, is located in the northeast of the Tibetan Plateau. In this area, tectonic movement is active and Early Paleozoic-Late Pa-leozoic intermediate-acidic intrusive rocks are well developed. With high-precision geochronologic analysis, LA-ICP-MS zircon U-Pb dating was conducted for zircons from Delisitan granodiorite and, as a result, the ²⁰⁶Pb/²³⁸U weighted average age of 414.3±1.8Ma was obtained, which implies that the Delisitan granodiorite was formed in Late Silurian-Early Devonian period. Summary of previous researches shows that the granodiorite was the product of partial melting of the subducting oceanic crust, and this means that the Proto-Tethys oceanic crust of Buqingshan area was subducted northward from Cambrian until Late Silurian-Early Devonian. These results provide a new constraint for the study of tectonic evolution in the East Kunlun area.