Triassic magmatism and tectonic setting of Eastern Tianshan, NW China: constraints from the geochemistry and zircon U–Pb–Hf isotopes of granitoids in the Yamansu area

Introduction: To provide constraints on the Triassic tectonic setting of Eastern Tianshan, an integrated study was conducted geochronological and geochemical data for granodiorites, monzogranites, two-mica granites from Yamansu area northern margin Central NW China. Geochronlogy Method Results: Zircon U–Pb dating indicated crystallization ages ca. 250–241 Ma. Geochemistry The granodiorites (ca. 250 Ma) were medium-K calc-alkaline I-type granitoids, with crust-derived elements ratios (e.g., Ti/Zr, Ti/Y, Nb/Ta), low Sr/Y ratios, moderate negative Eu anomalies (Eu/Eu* = 0.56–0.57), suggesting their derivation partial melting crustal materials plagioclase as a major residual phase at <12 kbar. monzogranites 247 showed adakitic characteristics, high SiO 2 MgO, Cr, Ni contents Nb/Ta indicating origin thickened mafic lower crusts relatively pressure (12–15 kbar). 244 Ma 241 high-K features highly fractionated granites. They generated by medium-to-high-K to intermediate rocks pressures <5 kbar, accompanied mainly feldspar fractional crystallization. All granitoids had zircon ε Hf (t) values +7.8 +2.1, corresponding T DM2 1132–773 Ma, juvenile possible sources. Discussion: Geochronological investigations studied together published data, suggest that important period granitic magmatism in Tianshan. Considering all available geological we formed intracontinental environment possibly controlled far-field effects Paleo-Tethys system, contemporaneous compression extension deep shallower lithosphere depths, respectively, during Triassic.