中文摘要：

根据新资料结合前人的研究成果对西藏南部仁布以东上三叠统复理石两套地层郎杰学群和涅如组的岩层特征、化石面貌、碎屑组成、沉积特性、地球化学等方面进行了总结及分析。对比研究结果显示,除亚相、岩层厚度分布、砂岩与板岩比例、重矿物ZTR指数变化趋势有一定的差异外,郎杰学群和涅如组的其他十余项特性（颜色、岩性、碎屑组分、重矿物组成、ZTR指数、沉积构造、微量元素、稀土元素、Hf同位素、碎屑锆石同位素年谱、变质变形）相似度极高。分析认为,少数特性差异是地层体地质记录的正常现象,不应成为郎杰学群和涅如组各自独立的主要依据;另一方面,大量相似度极高的各项特性指示它们具有相同或极其相似的沉积盆地和物源构造背景,既不属于喜马拉雅地体也不属于增生楔,而可能同源于拉萨地体或者其他未知地体,属于与造山带有关的沉积盆地建造。进而建议,将涅如组归并为郎杰学群的一个组,仁布-张达-隆子断裂可能是雅鲁藏布江缝合带俯冲消减的东部主断裂或者早期俯冲的南部边界断裂。

英文摘要：

Features of the Upper Triassic flysch Langjiexue Group and Nieru Formation in southern Tibet were summarized and analyzed by combination of the former and present works, within which stratigraphic property, fossil association, detritus component, sedimentation, geochemistry and metamorphism as well as deformation were contrasted. Study results show that most of the features are pretty similar between Langjiexue Group and Nieru Formation except for a few indexes such as subfacies, thickness, ratio of sandstone / slate, ZTR tendency. The discrepancy of the four indexes is not suggested as real reasons to separate the two lithostratigraphic units because changes of subfacies, thickness, and ratio of lithology are normal within and among formations. The high similarities of features indicate that they could have been deposited in a same sedimentary basin and tectonic setting, probably in the basin related to orogenism. In other words, they could be formed in neither the passive margin （Himalayan terrane） nor accretionary wedge （Yarlung Zangbo suture）. It is proposed that the Nieru Formation is a unit of the Langjiexue Group but not independent. Furthermore, the Renbu-Zhangda-Longzi fault is suggested as either the main fault of the Late Cretaceous oceanic subduction within the Yarlung Zangbo suture zone or a southern boundary fault of the Late Jurassic-Early Cretaceous subduction of the paleo-ophiolite crust.