Zircon LA-ICP-MS U-Pb dating of Bairiqili gabbro pluton in East Kunlun orogenic belt and its geological significance

Located in the middle of East Kunlun, the Bairiqili gabbro pluton consists of olivine gabbro, anorthosite and amphibolite gabbro. LA-ICP-MS zircon U-Pb dating suggests that the main facies hornblende gabbro intruded at 248.9 ± 4.2 Ma, being part of the Early Triassic magmatism during Paleo-Tethys ocean subduction. Based on previous researches, the authors hold that the Mesozoic magma mixing in the East Kunlun orogenic belt started at least in Early Triassic, and that the Bairiqili pluton provides a window for the study of magma mixing at the subduction stage in East Kunlun. Meanwhile, a large number of inherited zircon ages indicate that East Kunlun basement underwent multi-stage and polycyclic tectono-magma event in Precambrian, and the newly-discovered old age of 2109 ~ 2310 Ma may suggest that there existed another magmatic event in Early Proterozoic, whose geological significance deserves further researches.