Geochemistry and zircon U-Pb ages of the volcanic rocks in southern Galinge, Qinghai Province

Volcanic rocks are well developed in southern Galinge which lies in mid-eastern Qimantag Mountain of the western part of the East Kunlun Mountains. The investigation shows that the volcanic activity from explosive phase to overflow phase is more pronounced and there are four rhythms at most. According to the zircon U-Pb age (222.2±2.1Ma) obtained by the LA-ICPMS for the tuff in the study area, the volcanic rocks should be assigned to Late Triassic (T₃e) rather than to volcanic rocks of top Silurian-Early Devonian Qigaisu Formation (S₄D₁q¹) assigned by previous researchers. Geochemical studies of the rocks show that the volcanic rocks are of sub-alkaline-calc-alkaline series rich in potassium and characterized by cognate magma evolution, and have the geochemical features of arc rocks and collisional volcanic rocks. They are the products of intracontinental orogenesis, and hence the geological information of magmatic evolution of the East Kunlun Qimantag orogenic belt in the Late Triassic period is well documented.