Ediacaran−Early Devonian prolonged scissors-like closure of the Proto-Tethys Ocean between the South China Block and Gondwana

The Tethyan evolution of Tibet and Southeast Asia has been studied extensively, but the closure of the Proto-Tethys Ocean between the South China Block and Gondwana remains poorly constrained. To address this, we analyzed multiple datasets documenting the tectono-sedimentary evolution of the South China Block, with a specific focus on the lower Devonian succession in the Ninglang−Yanyuan region of the southwestern South China Block. Sedimentary facies analysis reveals foreland basin formation in the late Early Devonian, with paleocurrent data indicating sediment transport from the plate boundary. Detrital zircon analysis of the fluvial-deltaic succession yielded one major age population at ca. 870−700 Ma and two smaller age groups at ca. 670−500 Ma and ca. 1000−900 Ma. By integrating zircon U-Pb ages, trace elements, Hf isotopes, and paleocurrent data, we identified provenance linked to the Indian margin of Gondwana and the uplifted basement of the southwestern South China Block, supporting a late Early Devonian collision between the southwestern South China Block and Gondwana. Additionally, we compiled and reinterpreted 24,000 detrital zircon U-Pb ages and Hf isotope data from the Tibet−Southeast Asia Tethyan realm. By synthesizing this dataset with the Ediacaran−Middle Devonian sedimentary-paleogeographic evolution of the South China Block, we observe that both South China Block uplift and Gondwanan Indian detrital input initiated along the eastern margin of the South China Block and progressed southwestward. Coupled with the evolution of marine paleobiogeographic affinities between the South China Block and East Gondwana, we propose that the Proto-Tethys Ocean separating the South China Block and Gondwana underwent a prolonged, scissors-like closure during the Ediacaran−Early Devonian, likely driven by the documented clockwise rotation of Gondwana.