Biostratigraphical, geochemical and palaeomagnetic studies have demonstrated that the Lhasa Terrane occupied a low-latitude southern hemisphere region during Late Permian to Early Triassic time. However, the palaeogeographical relationship of the South Qiangtang and the Lhasa terranes remains a topic of debate. The principal dispute focusses are on whether the Bangong-Nujiang Suture Zone (BNSZ) separating the terranes was an ocean during the Late Permian to Early Triassic. Resolution of this problem requires the recognition and investigation of Permian - Triassic boundary (PTB) deposits and fossils of the Lhasa Terrane, especially proximal to the E-W trending Longgar-Gongbujiangda Fault, a region that has heretofore been considered devoid of these deposits. Our investigation of the Longgar area reveals that carbonate deposits correlated with the Middle Permian Xiala Formation are similar to PTB rocks described from elsewhere. We recovered conodont faunas spanning the Wuchiapingian and Changhsingian stages of the Permian and the Early Triassic Olenekian stage. Our results demonstrate that the studied carbonate succession ranges from the Upper Permian to the Upper Triassic (perhaps to the Lower Jurassic). The documented conodont succession demonstrates that PTB strata accumulated in the Longgar area. Thus, Late Permian and Early Triassic conodonts described from the Lhasa Terrane suggest a connection with the South Qiangtang Terrane. The BNSZ during this period of time was part of a carbonate platform that connected the Lhasa Terrane and the South Qiangtang Terrane.

中文翻译：

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拉萨地块南部龙噶地区新发现的五家坪阶至奥列涅克阶牙形石及其古生物地理意义

生物地层、地球化学和古地磁研究表明，拉萨地体在晚二叠世至早三叠世时期占据了南半球低纬度地区。然而，南羌塘与拉萨地体的古地理关系仍是一个争论的话题。主要争议集中在分隔地体的班公-怒江缝合带（BNSZ）是否是晚二叠世至早三叠世期间的海洋。解决这个问题需要对拉萨地体的二叠纪-三叠纪边界（PTB）沉积物和化石进行识别和调查，特别是靠近东西向的龙嘎-工布江达断层，该区域迄今为止被认为没有这些沉积物。我们对 Longgar 地区的调查表明，与中二叠统夏拉组相关的碳酸盐沉积物与其他地方描述的 PTB 岩石相似。我们发现了跨越二叠纪五家坪阶和长兴阶以及早三叠世奥列内克阶的牙形石动物群。我们的结果表明，所研究的碳酸盐岩层序范围从上二叠统到上三叠统（可能到下侏罗统）。记录在案的牙形石演替表明 PTB 地层在 Longgar 地区积累。因此，从拉萨地体描述的晚二叠世和早三叠世牙形石表明与南羌塘地体有关。这一时期的BNSZ是连接拉萨地体和南羌塘地体的碳酸盐台地的一部分。