Middle–Late Triassic southward-younging granitoids: Tectonic transition from subduction to collision in the Eastern Tianshan–Beishan Orogen, NW China

Abstract To constrain the closure mechanism and time of Paleo-Asian Ocean, we report new geochronological geochemical data for Triassic granites along a NW–SE corridor from Eastern Tianshan to Beishan, NW China. Seven have U-Pb ages that young southwards 245 Ma 234 in Kanguer accretionary complex, 237 eastern Central block, 229 223 Liuyuan complex. Granites complex formed by fractional crystallization are peraluminous, high-K, calc-alkaline, crust-derived. They very low MgO (Mg# = 6–9), Cr, Ni contents, their high ?Nd(t) (+3.40) ?Hf(t) (+4.49 +11.91) isotopes indicate Dananhu arc crust was juvenile. The Huaniushan pluton displays signatures both A1- A2-type (Y/Nb 0.32–3.39). All other block aluminous A2-types with K2O + Na2O, Al, rare earth elements (REE), Zr Nb Y, Ga, Fe/Mg, Y/Nb remarkable depletions Eu, Ba, Nb, Ta, Sr, P, Ti. broad range 9–59), Isr (0.70741–0.70945) values, negative ?Nd (t) (?2.98 ?1.14), moderate (?1.22 +7.78), which suggests mixture mantle crustal components. These 245–223 granitoids show marked Nb-Ta point subduction origin. Notable enrichments Nd-Hf Late likely an indication collision. Integration previous enables us conclude delamination oceanic slab upwelling induced partial melting thickened during tectonic transition multiple supra-subduction margin collisional setting Triassic.