Petrogeochemistry and zircon U-Pb chronology of the Yangzong rhyolite porphyry along Ailao Mountain tectonic belt

This paper presents bulk petrogeochemistry and zircon U-Pb dating results for the Yangzong rhyolite porphyry in Luchun County, Yunnan Province. LA-ICP-MS zircon U-Pb dating results show that the Yangzong rhyolite porphyry was formed in the Late Permian (263.1±2.3Ma). The Yangzong rhyolite porphyry is characterized by SiO₂ content of 71.08%~80.26%, alkali (Na₂O+ K₂O) 4.67%~8.67%, and Na₂O＜K₂O. It is enriched in LREE and Rb, Th, U, Ni, Cs, Zr, Hf, As, K and depleted in Sr, Ta, Ba, Cr, Zn, W with negative Eu anomalies (δEu=0.05~0.57). According to the diagrams, the Yangzong rhyolit porphyry was formed in the tectonic environment of island arc-continent or continental-arc collision, indicating that the branch of Paleo-Tethys Ocean or arc basin in Ailao Mountain tectonic belt might have been closed in the Late Permian (263.1±2.3Ma).