西藏雅鲁藏布江缝合带蛇绿混杂岩中混杂着大小不一的二叠纪灰岩块体，它的来源一直颇有争议，这些灰岩块体中动物群的古生物地理面貌是判断其来源的重要手段。姜叶玛灰岩体是位于西藏普兰县境内混杂在中生代蛇绿混杂岩中的一个大型二叠纪灰岩块体。其中，中二叠世西兰塔组中含有丰富的非?有孔虫化石，它们主要由Neodiscus，Climacammina，Pachyphloia和Lysites组成，伴生有Dagmarita，Deckerella，Globivalvulina，Neoendothyra，Lasiodiscus，Lasiotrochus，Tetrataxis，Geinitzina，Ichthyofrondina，Nodosaria，Nodosinelloides，Agathammina，Septoagathammina和Shanita，时代相当于中二叠世Capitanian期。古生物地理上，Lysites和Shanita的出现表明这个动物群属于基墨里生物区，它们从古生物地理上以及生物多样性上和印度板块北缘的巴基斯坦盐岭地区以及藏南喜马拉雅区的同时代动物群有显著差别。结合前期?类动物群古生物地理的研究，姜叶玛灰岩块体很可能位于拉萨地块与喜马拉雅之间的新特提斯洋海山上，与两个地块之间都有一定的隔离。这也说明新特提斯打开的时间早于中二叠世。

A slice of Permian limestone blocks, which display block-in-matrix fabric, scattered in the ophiolite melánge within the Yarlung-Tsangpo suture zone. The origin of these limestone blocks has been a focus of debate for decades. The paleobiogeography of the faunas in these limestone blocks is critical in reconstructing the paleogeography. The Gyanyima limestone block is a big limestone block within the ophiolites melánge in Burang County, Tibet. The Xilanta Formation in the Gyanyima limestone block contains diverse foraminifers. They are dominated by Neodiscus, Climacammina, Pachyphloia and Lysites. Other foraminifers include Dagmarita, Deckerella, Globivalvulina, Neoendothyra, Lasiodiscus, Lasiotrochus, Tetrataxis, Geinitzina, Ichthyofrondina, Nodosaria, Nodosinelloides, Agathammina, Septoagathammina and Shanita. The typical Lysites-Shanita assemblage in the fauna suggests a Cimmerian Province that contrast with faunas from the Salt Range of Pakistan and other areas in the Himalaya region in southern Tibet in both paleobiogeography and diversity. Combined with the previous study on the paleobiogeography of fusulines, the Gyanyima limestone block is considered to have originated from a seamount within the Neotethys Ocean. It further suggests that the Neotethys Ocean would have opened to a considerable width to allow for the formation of seamount-type carbonates within this ocean.

第二次青藏高原综合科学考察研究项目（2019QZKK0706）、国家自然科学基金重大研究计划重点项目（91855205）、中国科学院战略性先导科技专项（B类）（XDB26000000）和中国科学院青年创新促进会项目（2016282）联合资助。