Geochemical, geochronological features and tectonic significance of volcanic rocks of Zhucun Formation in Baxoi area, eastern Tibet, China

There are volcanic rocks which are made up of intermediate-acid volcanic－clastic rocks and lavas in the northwest Baxoi County， eastern Tibet. So far, the genesis of these rocks are poorly studied, including their formation age and tectonic significance. They were refered as Zhucun formation. The authors have obtained zircon U－Pb dating age of 128±2Ma of the amphibole dacite of Zhucun formation so the age of the Zhucun formation is defined as Early Cretaceous. The geochemical characteristics of the Zhucun formation reflect that the volcanic rocks formed in the volcanic arc setting of the Nujiang oceanic subduction to Gangdis－Nyainqentanglha plate which is part of the Boshula mountains volcanic arc. Compared to Boshulaling Early Crateceous granodiorite, they have the same magma resources but show different facies. The authors also think that the closing of the Bangong Co－Nujiang suture belt in eastern Tibet was finished during early cretaceous.