The newly discovered ca. 1.35 Ga metamafic rocks in the Oulongbuluke Block, NW China, and its record for transition from the Columbia to Rodinia supercontinent

Abstract The Oulongbuluke Block is an integral part of the Columbia and Rodinia supercontinents, but lack rock records from transitional period between supercontinents during mid–late Mesoproterozoic has impeded our understanding tectonic relationship Block, which lies supercontinents. In this contribution, we present a systematic petrographic, geochemical, zircon U-Pb-Hf investigation newly discovered metamafic rocks in Block. results show that have protolith age ca. 1.35 Ga arcrelated metamorphic 1.11–1.09 Ga. samples are geochemically characterized by relatively high FeOT/MgO FeOT low SiO2, MgO, K2O + Na2O, shows tholeiitic affinity. These exhibit slight light rare earth element (LREE) depletion flat heavy (HREE) content with no obvious Eu anomalies slightly negative Nb, Sr, Zr anomalies. conditions similar to those enriched midoceanic-ridge basalt (E-MORB) normal mid-oceanic-ridge (N-MORB). studied also positive ?Hf(t) values (2.96–7.04). Hence, protoliths may been produced variable degrees melting spinel-phase lherzolite mantle mid-oceanic ridge setting was probably induced plume. presence indicates experienced final breakup supercontinent at Ga, arc-related metamorphism coincided convergence supercontinent. changed arc Mesoproterozoic, likely response transition