Characteristics of detrital zircon U-Pb geochronology and Hf isotopics from Liwu Group within the Changqiang dome on the southeastern margin of Songpan-Ganzi terrane and its tectonic implications

The Changqiang dome, located in the Muli area at the south end of the triangled Sonpan-Ganzi terrane, Tibetan Plateau, sandwiched by the Qiangtang terrane to the west and the Yangtze block to the east. The Changqiang dome composes of low-grade metasedimentary core, the Liwu Group. In order to precisely constrain the protolith age of the Liwu Group and delineate its provenance characteristics, two low-grade metamorphic sedimentary samples collected from the Liwu Group were studied by zircon LA-ICP-MS U-Pb dating and in situ Lu-Hf isotope analyses. Zircon grains from two samples show high Th/U ratios, and distinct oscillatory zoning texture, as well as positive Ce anomalies, negative Eu anomalies, and HREE enrichments, indicating an igneous origin. Totally, 155 zircon U-Pb ages were yielded for two samples, including four major age populations, e. g. 476 similar to 675Ma, 715 similar to 812Ma, 820 similar to 1000Ma and 2. 4 similar to 2. 6Ga. Lu-Hf isotopes were analyzed on 137 corresponding zircon grains, yielding a wide range of Hf isotopic composition, with epsilon(Hf) (t) values of -22 similar to +14. The detrital zircon age group of 476 similar to 560Ma is probably related to the Pan-african events occurred along the northern margin of the Gondwana. Based on previous studies, we propose the 715 similar to 1000Ma zircons were derived from the Neoproterozoic magmatisms within the Yangtze terrane and Jiangnan orogeny. In addition, Paleoproterozoic ages indicate the possibility of the growth of the continental crust event.