Precambrian Research | 2021
Neoproterozoic magmatic and metamorphic imprints in the East Kunlun Orogenic Belt, North Tibetan Plateau, NW China: Implications for the assembly and initial breakup of the Rodinia supercontinent
Abstract
Abstract The East Kunlun Orogenic Belt (EKOB), located on the northern margin of the Tibetan Plateau, experienced intense, long-lasting,\xa0and complicated\xa0multi-stage orogeny from the Neoproterozoic to Early Mesozoic. Neoproterozoic magmatic and metamorphic events recorded critical information on Precambrian tectonic evolutionary history. Zircon U-Pb ages of 914\xa0±\xa06.5, 902\xa0±\xa05.3, and 856\xa0±\xa06.8\xa0Ma were determined for granitic gneiss, monzogranite, and charnockite, respectively. Geochemical and petrological studies reveal high SiO2, Al2O3, and K2O content with abundant Al-rich minerals, such as garnet and muscovite, which show typical S-type granite properties. The eHf(t) values ranging from\xa0−\xa06.5 to\xa0+\xa05.6 (TDM2\xa0=\xa01.4–2.2\xa0Ga) indicate a primarily Paleoproterozoic metagreywackes and metapelitic derivation with mantle contribution. Zircon U-Pb results show that amphibolite yielded ages of 846\xa0±\xa05.2\xa0Ma. Geochemistry andeHf(t) values ranging from 10.5 to 15.9 (TDM1\xa0=\xa00.8–0.9\xa0Ga) suggest that the mafic magma originated from depleted mantle metasomatized by subduction fluid. We propose that the Neoproterozoic rocks in this study were generated in syn-orogenesis and incipient continental rift-related extension environment, which\xa0corresponds to the assembly and initial breakup of the Rodinia supercontinent. In the EKOB, The initial breakup-related extension of the supercontinent affected by super plume occurred at ca.\xa0~\xa00.85\xa0Ga. East Kunlun and its adjacent blocks were within a single tectonic domain and recorded important evolutionary history of the Rodinia supercontinent.