西藏改则地区昂拉仁错中—下二叠统昂杰组—下拉组地层古生物

Lithostratigraphy and Biostratigraphy of Angjie Formation-Xiala Formation of Middle-Lower Permian in Anglaren Co of Gaize Area,Tibet

详细描述了西藏自治区改则县拉清乡汤模长二叠系剖面,自下而上划分为拉嘎组、昂杰组和下拉组。讨论了二叠系昂杰组和下拉组的岩性组合特征和沉积环境,其中昂杰组横向延伸不稳定向西相变尖灭。依据化石分布及组合特征,建立了Neoschwagerina-Chusenella conicocylindrica蜓组合带、Pachyphloia ovata-Eotuberitina reitlingerae非蜓有孔虫组合带、Lytvolasma asymetricum-Bradyphyllum caninoidia珊瑚组合带和Akagophyllum coqenense-Amplexocarinia muralis珊瑚组合带。昂杰组为早二叠世,下拉组下部为中二叠世栖霞期,而下拉组上部为中二叠世茅口期,并以暖水型气候环境为主。在昂杰组—下拉组中发现了珊瑚的2个新种和1个新亚种,并进行了描述。新种名称分别为Lophotabularia longiseptata sp.nov.和Iranophyllum longiseptatum sp.nov.,新亚种名称为Cyathocarinia tuberculata multiseptata sub sp.nov.。

Permian section located at Tangmochang of Laqing town, Gaize county, Tibet autonomous region was described in details;the lithologic characteristics and sedimentary environment of Angj ie Formation and Xiala Formation were discussed;according to the characteristics and distribution of fossils,assemblage zones were built;finally,two new species and one new subspecies of rugosa were discovered and described.The results show that the Permian section is divided into Laga Formation,Angj ie Formation and Xiala Formation from bottom to top;Angjie Formation exists only in the eastern area and disappears toward the west because of facies change;there are Neoschwagerina-Chusenella conicocylindrica fusulinid assemblage zone, Pachyphloia ovata-Eotuberitina reitlingerae non-fusulinid foraminiferida assemblage zone,Lytvolasma asymetricum-Bradyphyllum caninoidia rugosa assemblage zone and Akagophyllum coqenense-Amplexocarinia muralis rugosa assemblage zone; Angjie Formation belongs to Early Permian,the lower Xiala Formation belongs to Xixia period of Middle Permian,but the upper Xiala Formation belongs to Maokou period of Middle Permian with warm climate;the new species are Lophotabularia longiseptata sp. nov. and Iranophyllum longiseptatum sp.nov.,and the new subspecies is Cyathocarinia tuberculata multiseptata sub sp.nov.