The East Kunlun Orogenic Belt (EKOB), which is in the northern part of the Greater Tibetan Plateau, contains voluminous Late Triassic intermediate-felsic volcanic rocks. In the east end of the EKOB, we identified highly differentiated peralkaline-like Xiangride rhyolites (~209 Ma) that differ from the widespread andesitic-rhyolitic Elashan volcanics (~232–225 Ma) in terms of their field occurrences and mineral assemblages. The older, more common calc-alkaline felsic Elashan volcanics may have originated from partial melting of the underthrust Paleo-Tethys oceanic crust under amphibolite facies conditions associated with continental collision. The felsic Elashan volcanics and syn-collisional granitoids of the EKOB are different products of the same magmatic event related to continental collision. The Xiangride rhyolites are characterized by elevated abundances of high field strength elements, especially the very high Nb and Ta contents, the very low Ba, Sr, Eu, P, and Ti contents; and the variably high ⁸⁷Sr/⁸⁶Sr ratios (up to 0.96), exhibiting remarkable similarities to the characteristic peralkaline rhyolites. The primitive magmas parental to the Xiangride rhyolites were most likely alkali basaltic magmas that underwent protracted fractional crystallization with continental crust contamination. The rock associations from the early granitoids and calc-alkaline volcanic rocks to the late alkaline basaltic dikes and peralkaline-like rhyolites in the Triassic provide important information about the tectonic evolution of the EKOB from syn-collisional to post-collisional. We infer that the transition from collisional compression to post-collisional extension occurred at about 220 Ma.

东昆仑造山带（EKOB）位于大青藏高原北部，包含大量晚三叠世中长英质火山岩。在 EKOB 的东端，我们确定了高度分化的类过碱向日流纹岩（~209 Ma），它们在野外产状和矿物组合方面与广泛存在的安山-流纹质 Elashan 火山岩（~232-225 Ma）不同。较老的、更常见的钙碱性长英质 Elashan 火山可能起源于与大陆碰撞相关的角闪岩相条件下的下冲古特提斯洋地壳的部分熔融。长英质 Elashan 火山岩和同义词- EKOB 的碰撞花岗岩是与大陆碰撞有关的同一岩浆事件的不同产物。向日流纹岩的特点是高场强元素丰度高，尤其是铌和钽含量非常高，Ba、Sr、Eu、P 和 Ti 含量非常低；和可变高的⁸⁷ Sr/ ⁸⁶Sr 比率（高达 0.96），表现出与特征性过碱性流纹岩的显着相似性。向日得流纹岩的母源原始岩浆很可能是碱性玄武质岩浆，经历了大陆地壳污染的长期分馏。从早期的花岗岩和钙碱性火山岩后期碱性玄武岩堤坝和过碱性般在三叠纪的流纹岩岩石协会提供有关EKOB从构造演化的重要信息SYN -collisional后碰撞。我们推断从碰撞压缩到碰撞后扩展的转变发生在大约 220 Ma。