Permo-Carboniferous provenance shifts at the northern margin of the North China Craton and their tectonic implications: Detrital zircon U–Pb–Hf records from central Inner Mongolia

Abstract

Permo-Carboniferous provenance shifts at the northern margin of the North China Craton (NCC) were reconstructed. The reconstruction was based on the detrital zircon U–Pb–Hf data from Late Paleozoic sandstones from Ondor Sum and Wude in the Southern Orogenic Belt (SOB) of the Southeast Central Asian Orogenic Belt (SE CAOB). Sandstone samples from the Lower Devonian Naqing Formation, Upper Carboniferous Hailasiamu Formation, and the first and second members of the Upper Carboniferous Amushan Formation in Ondor Sum present a nearly unimodal detrital zircon age grouping (c. 380–520 Ma), and they have similar zircon Hf isotopic compositions with igneous rocks in the SOB, implying that their provenance was from the SOB region. In contrast, samples in the same area from the third to fifth members of the Lower Permian Amushan Formation and the Lower Permian Sanmianjing Formation contain multimodal age groupings, with the ages mainly concentrated at the Late Carboniferous–Early Permian, Neoarchean, and Paleoproterozoic. The coexistence of Neoarchean and Paleoproterozoic grains suggests that the NCC could be a reliable source. In addition, the Hf isotopic composition of the Late Carboniferous–Early Permian zircons overlap with those from the NCC, and therefore, it is concluded that there were Permo-Carboniferous provenance shifts from the SOB to the NCC for the sandstones from the Upper Paleozoic in the Ondor Sum area. Late Carboniferous and Early Devonian sandstone samples from Wude had sediment contributions from both the SOB and the NCC, with detrital zircon grains from the SOB constituting the majority. Whereas, the Early Permian samples from this area contained sediment contributions predominantly from the NCC. We suggest that the Permo-Carboniferous provenance shifts were the result of significant local subsidence of the SOB, and the uplift of the Inner Mongolia Paleo-Uplift after the Early Devonian collision between the Bainaimiao arc belt and the NCC.