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对新发现的出露在雅鲁藏布江缝合带南侧的一套古新世地层及其中的放射虫动物群进行了研究.新建折巴群代表雅鲁藏布江缝合带南侧的一套古新世深水硅质岩及复理石沉积,包括下部富含硅质岩的桑单林组和上部以砂页岩为主的者雅组.根据放射虫动物群的层位分布及横向对比,划分出放射虫化石带RP1～RP6(65～55 Ma).折巴群可能代表了欧亚大陆逆冲加载到印度被动大陆边缘产生的前陆盆地沉积.根据前陆盆地演化,初步判断雅鲁藏布江中段的碰撞时间为白垩纪/第三纪之交(约65 Ma).雅鲁藏布江前陆盆地沉积覆盖在印度被动大陆边缘沉积之上,为油气提供了较佳生、储、盖条件.
A newly discovered sequence of Paleocene stratigraphy and its radiolarian fauna exposed to the south of the Yarlung Zangbo suture zone was newly discovered. A new set of Paleocene deep-water siliceous rocks that represent the south of the Yarlung Zangbo suture zone And dolomitic sediments, including the lower part of the siliceous rocks in the Sanglin Group and the upper part of the sand shale-based Ya group. According to the larvae fauna and stratigraphic distribution and horizontal division, the division of radiolarian fossil belts RP1 ~ RP6 (65 ~ 55 Ma). The Holocene may represent the foreland basin sediments that Eurasia thrust into the Indian passive continental margin.According to the evolution of the foreland basin, the collision time of the middle Brahmaputra river was determined as Cretaceous / Tertiary (about 65 Ma). The Brahmaputra foreland basin was deposited above the passive continental margin of India, providing better conditions for hydrocarbon generation and accumulation.