报告人：李顺，副研究员 ，中山大学

邀请人：张召儒

时间：2019年12月24日（星期二）9：30~10：30

地点：徐汇校区海洋学院楼120会议室

摘要：

Reconstructing the Wilson cycle of the Bangong-Nujiang Tethyan Ocean (BNTO) plays an indispensable role in understanding the linkage between Gondwana dispersion and Tibetan Plateau accretion. The existence of the BNTO is inferred from presence of dismembered ophiolite bodies along the Bangong-Nujiang suture zone that separates Lhasa from Qiangtang. Based on a detailed synthesis of ophiolite, metamorphism, magmatism, lithostratigraphy and tectonism from the Lhasa-Qiangtang collision zone, we try to reconstruct the birth and demise of the BNTO. Our results suggest that the BNTO initially opened in the Late Permian (~260 Ma), as indicated by the earliest record of oceanic crust/MOR-type ophiolite. Regionally, strong evidence supports a northward subduction of the BNTO beneath Qiangtang, likely initiating in the Early Jurassic (~195 Ma). Meanwhile, the recognition of an incomplete arc-trench system on the northern Lhasa margin supports a southward subduction beneath Lhasa as well, with unclear timing of subduction initiation. The onset and migration of peripheral foreland basin system on the northern Lhasa margin indicate that that final closure of the BNTO did not occur until the latest Jurassic-Early Cretaceous (~150–130 Ma). Therefore, the Wilson cycle of the BNTO is hereby reconstructed, providing significant insights into the amalgamation of the Tibetan Plateau.