Petrogeochemistry and zircon geochronology of the Wolonggang granite porphyry in the western segment of the East Kunlun: Implications for tectonic setting of the Hoh Xil-Songpan-Ganzi Block and regional antimony mineralization timing

The 12 petrogeochemistry and 2 zircons LA-ICP-MS U-Pb age tests were carried out on the basis of field investigation for the granite porphyry samples of the Wolongang pluton in the western part of the East Kunlun in order to understand the tectonic evolution of the northwestern margin of the Hoh Xil-Songpan-Ganzi block and the relationship between the intrusive rocks and the regional shallow metamorphic hydrothermal deposits. The results show that the content of SiO₂ in granite porphyry is 64.96%~71.24%, they were high potassium, sodium rich and poor calcium. Their AR values were 1.97~2.95 and A/CNK were 0.98~1.16, which were high potassium calcareous alkaline series. The rocks are relatively enriched with Cs, Rb, Ba, U and Nd and are depleted of Zr, Hf, Sr, Ti and Y. The total amount of REE is 151×10^-6~239×10^-6, LREE/HREE is 8.10~14.53 and δEu is 0.54~0.70, which has obvious negative europium anomaly. The results of zircon ²⁰⁶Pb/²³⁸U dating were 205.6±1.6Ma (MSWD=0.34, n=17) and 204.7 ±2.6Ma (MSWD=2.0, n=16), indicating that the Wolonggang pluton formation was at the end of the Late Triassic. According to the comprehensive analysis, it is concluded that the northwestern margin of the Hoh Xil-Songpan-Ganzi block should be in the extensional post-collision tectonic setting at the end of the Late Triassic, and the formation time of the regional shallow metamorphic hydrothermal deposits is later than the end of late Triassic.