The affinity of the Hexi Corridor and Australia—Evidence from U-Pb geochronology and Hf isotopes of detrital zircons from Middle Cambrian strata in Niushoushan

U-Pb geochronology and Lu-Hf isotopic studies of detrital zircons from middle Cambrian sediments of Niushoushan area, eastern Hexi Corridor, show three major groups of U-Pb age: 0.6-0.8Ga (peak at 669Ma), 1.0-1.3Ga (peak at 1173Ma), and 1.6-1.8Ga (peak at 1710Ma), which are significantly different from the detrital zircons U-Pb age spectrum of the upper strata in the Hexi Corridor belt. The characteristics of the detrital zircon U-Pb age spectra and Hf isotopes indicate that the detrital zircons 1.0-1.3Ga and 1.7-1.75Ga in age might have originated from southwest Australia, which is consistent with the evidence of paleontological and paleomagnetic studies in the Hexi Corridor. The Jinning-age (0.8-1.0Ga) detrital zircons that appear in the middle Ordovician strata in Hexi Corridor may indicate the changes of the source area of detrital materials, which resulted from the expansion of the North Qilian Ocean. The detrital zircons 0.4-0.5Ga in age extracted from post Ordovician strata were probably produced by the uplift of Qilian orogenic belt as well as the erosion and weathering processes in the Hexi Corridor.