Geochronology and Petrogenesis of Ahetala Granodiorite in South Tianshan Orogenic Belt, Xinjiang: New Constraints on the Tectonic Evolution of the South Tianshan Ocean

The Ahetala granodiorite is located in the western section of South Tianshan Orogenic Belt (STOB), which great significance regarding dispute on closing date Ocean (STO) and tectonic evolution STOB. To determine setting petrogenesis, study petrography, electron probe microanalysis (EPMA), LA-ICP-MS zircon U–Pb geochronology, major trace elements analyses are carried out for granodiorite. Based dating, was emplaced at 282.1 ± 1.3 Ma (MSWD = 1.11). Geochemically, characterized by metaluminous (A/CNK 0.86–0.87), rich alkali (K2O + Na2O 6.80–7.13), belongs to high-K calc-alkaline I-type granite. They enriched LREE depleted HREE (LREE/HREE 9.02–13.89) exhibit insignificant Eu anomalies (δEu 0.94–0.97). large ion lithophile (e.g., K, Sr, Ba) high field-strength Ta, Ti, Nb, P). Nb/Ta values (10.97–18.10), Zr/Hf (39.41–40.19), Mg# (54.87–56.02) MgO content biotites (13.42–14.16), M value (M Mg/(Mg Fe2+)) amphiboles (0.68–0.75), suggest that originates from crustal contamination mantle-derived magmas. Combined with regional geological background, previous research, nature granodiorite, we a transitional stage volcanic arc (syn-collision) post-collision closed Early Permian.