西藏南部雅鲁藏布江缝合带的沉积-构造演化

Sedimentary-tectonic Evolution of the Yarlung Zangbo Suture Zone, Southern Tibet

西藏南部雅鲁藏布江缝合带从晚侏罗世至今可能经历了新特提斯洋的两期俯冲作用 ,早期俯冲从晚侏罗世至早白垩世 ,以桑日群和恰布林组为代表 ,雅鲁藏布江古蛇绿岩在此期形成 ;而晚期俯冲从中白垩世至始新世 ,以混杂岩、雅鲁藏布江蛇绿岩和日喀则群为代表 ,拉孜 -浪卡子断裂可能代表了印度大陆与亚洲大陆碰撞的实际地表位置 .由此提出包括新特提斯洋两期俯冲作用在内的五个阶段的雅鲁藏布江缝合带沉积 -构造演化过程 .

The Yarlung Zangbo Suture Zone in southern Tibet might have undergone two subduction processes of the Neo-Tethys from the Late Jurassic to present. The early subduction, represented by the Sangri Group and the Giabulin Formation, started during the Late Jurassic, when the Yarlung Zangbo paleo-ophiolite could form from emplacement of Neo-Tethyan oceanic crust. The late subduction, represented by the melanges, the Yarlung Zangbo ophiolite, and the Xigaze forearc sediments, began during the Early Cretaceous. The Lhaza-Nagarze Thrust might represent the collision suture line between India and Asia. Moreover, five stages of the sedimentary-tectonic evolution including two subductions of the Yarlung Zangbo Suture Zone are suggested here.