Abstract The Tibet Plateau is a key region to understand the evolution of the Tethys Oceans. The finding of Permian–Triassic eclogites and Carboniferous–Triassic ophiolites indicated the existence of a Paleo–Tethys Ocean in the Lhasa terrane, although the mechanism of subduction and exhumation mechanism of the high–pressure rocks remains equivocal. Here we focus on deformation, metamorphism, and geochronology of key rocks in the Sumdo area with a view to constrain the tectonic evolution of the Tethys Ocean and the geodynamic mechanism of eclogite exhumation. Structural analysis indicates two main stages of deformation (D1 and D2) in the study area. The D1 deformation (264–235 Ma) is dominated by penetrative Sn+1 foliation and solid rheological folds, resulted from the first type eclogites (~260 Ma), with exhumation at ~240 Ma along the subduction channel. The D2 deformation (213–180 Ma) is characterized by the tight and isoclinal overturned folds and thrust faults, related with the collisional exhumation (~200 Ma) of the second type eclogite (~230 Ma). Spreading of the Bangong–Nujiang and Indus–Yarlung Zangbo Tethys Oceans triggered the closure of Sumdo Tethys Ocean, as well as their initial subduction.

中文翻译：

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青藏高原拉萨地体榴辉岩的俯冲-碰撞与折返

摘要 青藏高原是了解特提斯洋演化的关键区域。二叠纪-三叠纪榴辉岩和石炭纪-三叠纪蛇绿岩的发现表明拉萨地体中存在古特提斯洋，尽管高压​​岩石的俯冲和折返机制尚不明确。在这里，我们重点关注松岛地区关键岩石的变形、变质和年代学，以期约束特提斯洋的构造演化和榴辉岩剥露的地球动力学机制。结构分析表明研究区有两个主要的变形阶段（D1 和 D2）。D1 变形（264-235 Ma）主要是由第一类榴辉岩（~260 Ma）产生的穿透性 Sn+1 叶理和固体流变褶皱，沿着俯冲通道在 ~240 Ma 处折返。D2 变形 (213-180 Ma) 的特征是紧密和等斜的翻转褶皱和逆冲断层, 与第二类榴辉岩 (~230 Ma) 的碰撞剥落 (~200 Ma) 相关。班公-怒江和印度河-雅鲁藏布江特提斯洋的扩张引发了苏都特提斯洋的闭合和最初的俯冲。