Abstract: The Huangyanggou diorite porphyrite pluton intruded in the limestone of the Late Jurassic Hongqilafu Formation, which is located in Tianshuihai-Kalakunlun Terrane. In order to determine its formation age and reveal the petrogenesis and tectonic background, LA-ICP-MS zircon U-Pb geochronology and whole-rock geochemical analysis of Huangyanggou diorite porphyry were carried out.The zircon U-Pb age of the pluton is 159.9 Ma, which is formed in a post-collisional extensional environment. The magma source is characterized by mantle source, with the assimilation and mixing of crustal materials, which indicated the formation conditions were low pressure, strong oxidation environment and experienced intermediate differentiation. The pluton is characterized by low silicon (w(SiO₂)=56.11%-57.36%), high calcium (w(CaO)=4.29%-6.59%), and alkali-rich (w(Na₂O+K₂O)=6.00%-7.96%), and belongs to quasi-aluminous (A/NCK=0.79-0.95) rocks. It is also enriched in large ionic lithophile elements (K, Rb, Ba, Th, U) and depleted high field strength (Nb, Ta, Zr, Hf) elements, with a weak Eu negative anomaly (δEu mean 0.97). Through the comparative study of the regional magmatic activities, the Huangyanggou pluton has a strong affinity with the Pa’a I-type granite in the Geji area of the Bangonghu-Nujiang suture zone, and is consistent with the formation ages of the magmatic rocks exposed in this suture zone. It indicates that the Huangyanggou diorite porphyrite in the south of the Tianshuihai terrane is a magmatic response to the southward subduction of the Meso-Neo-Tethys Ocean in the northern Bangonghu-Nujiang suture zone.

Key words: West Kunlun, Huangyanggou, diorite porphyrite, Tethys Ocean, zircon U-Pb dating