The geology and tectonic implications for the Paleogene bimodal volcanic rocks in the middle part of the Gangdise magmatic arc, southern Xizang

The Paleogene volcanic rocks crop out over a wide area of the Zhonglugu region, Coqen, southern Xizang. The rock types are dominated by the basic and acidic volcanic rocks with a small amunt of median volcanic rocks, and may be assigned to the bimodal volcanic rocks. The basic volcanic rocks are relatively enriched in the incompatible elements and REE. The principal sources of detritus lay to the deep seated crustal matter contaminated transitional mantle levels. The acidic volcanic rocks resulted from the remelting of the crustal material in the tectonic setting of incipient rifts during the collapse of island arcs. The recognition of the bimodal volcanic rocks is of important geological implications for the improvement of the knowledge on the formation and development of the Gangdise magmatic arc, southern Xizang.