Dr. Yigui HAN Department of Earth Sciences, HKU
It remains controversial whether the Tarim and North China cratons linked to Gondwana during Paleozoic time. Early and mid-Paleozoic accretionary and collisional events along the margins of the two cratons enable us to correlate them with the assembly and subsequent dispersal of Gondwana. The northern margins of the cratons are characterized by long-term arc magmatism associated with the subduction of the Paleo-Asian Ocean plate. The subduction initiation occurred at ~500 Ma and was temporally coupled with continental collision events along their southern margins, and also with the final assembly of Gondwana. Zircon U-Pb and Hf isotopic data from the northern margins of the two cratons suggest a transition from advancing to retreating accretionary orogenesis at ~400 Ma, coeval with the dispersion of northern Gondwana and the opening of the Paleo-Tethys Ocean. We propose that the Tarim and North China cratons collided with northern Gondwana at ~500 Ma, corresponding to the assembly of Gondwana and the establishment of oceanic subduction along its peripheral margin. The two cratons dispersed from Gondwana at ~400 Ma, in association with the opening of the Paleo-Tethys Ocean.