Jurassic Trench basin of the Bangong-Nujiang Ocean in the Central Tibet: Record of clastic material mixing from Lhasa and Qiangtang terranes

• Published in: Palaeogeography, palaeoclimatology, palaeoecology Vol. 670; p. 112958
• Main Authors: Lai, Wen, Deng, Tao, Qiu, Shifan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.07.2025
• Subjects: basins; Central Tibet; China; detritus; evolution; Jurassic; Jurassic period; palaeogeography; Palaeotopography; paleoclimatology; paleoecology; provenance; Provenance analysis; sediments; subduction; tectonics; zircon; China; Jurassic; Provenance analysis; Central Tibet; Palaeotopography
• ISSN: 0031-0182
• DOI: 10.1016/j.palaeo.2025.112958

The early growth, subduction, and demise history of the oceans in the Tibetan Plateau remains a subject of significant controversy, particularly the evolution history of the Bangong-Nujiang Meso-Tethyan Ocean. Sedimentary records serve as faithful carriers of orogenic belt evolution. Here, we present a newly-discovered Jurassic deep-marine gravity-fan succession that is over 250 m thick. We employ multi-proxy, single-grain provenance analysis and forward modeling of sediment mixture on this sequence to reconstruct the Mesozoic Meso-Tethyan Ocean tectonic evolution in the Lunpola region. We find the detritus was deposited in a trench and was sourced from the accretionary wedge, island arc, and continent block. Through quantitative mixed modeling calculations of detrital zircon U-Pb ages, we found that the two detrital zircon samples from the Jienu Group obtained in this study indicated a source contribution of 73–79 % from the Qiangtang terrane, 10–17 % from the Lhasa terrane, and 10–11 % from the Tethyan Himalayan tectonic belt. This result directly proves that the Bangong-Nujiang Ocean was the ancient ocean between the Lhasa terrane and the Qiangtang terrane, rather than between the Himalayan terrane and the Qiangtang terrane during Jurassic. •A Jurassic trench sequence has been discovered in BNSZ, central Tibet.•The trench basin recorded detritus from multiple sources, including the accretionary wedge, arc, Lhasa and Qiangtang terranes.•Quantitative provenance mixing modeling reveals that the southern side of the BNO in Jurassic is the Lhasa terrane.