Mesozoic multi-direction collision tectonic evolution of the Ordos Basin, China:Insights from the detrital zircon and apatite(U-Th)/He analyses

The Ordos Basin(OB) in the western part of the North China Craton(NCC), was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics. Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC. In this work, the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB, and have provided new evidence for the regional tectonic evolution. The(U-Th)/He chronological data states the weighted ages of 240-235 Ma, 141 Ma with the peak distribution of 244 Ma,219 Ma, 173 Ma, 147-132 Ma. The thermal evolution, geochronological data, and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2) the Late Triassic-Early Jurassic;(3) the Late Jurassic-Early Cretaceous;(4) the Late Cretaceous-Early Paleogene. It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB. Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.