长江源各拉丹冬地区晚二叠世乌丽群类生物组合

长江源各拉丹冬地区二叠系乌丽群中的晚二叠世类化石 ,可分为两个组合 ,产于乌丽群下部那益雄组的Palaeofusulina parafusiformis- N anlingella simplex组合 ,产于乌丽群上部拉卜查日组的 Gallowayinella meitienen-sis- Palaeofusulina sinensis组合 ,这两个类化石组合属种分异度低 ,丰度高。该生物群属于特提斯动物群 ,在羌塘盆地及华南地区具有广泛的区域对比性。各拉丹冬及其邻近地区的二叠纪类生物群均为暖温型 ,属华夏特提斯区的分子

LATE PERMIAN FUSULINID ASSEMBLAGES FROM GELADANDONG IN THE SOURCE REGION OF YANGTZE RIVER,QINGHAI

The Late Permian fusulinid fauna from the Wuli group in Geladandong area of the source region of Yangtze River, southern Qinghai Province, which found during the geological mapping, may be divided in ascending order into the following two assemblages:1)Palaeofusulina parafusiformis-Nanlingella simplex Assemblage: This assemblage characterized by the presence of a great amount of Palaeofusulina parafusiformis Lin, Palaeofusulina minima Sheng et Chang and Nanlingella simplex (Sheng et Chang) from the Nayixiong Formation, the lower part of Wuli Group. A few species of Palaeofusulina in the assemblage characterized by having a small shell, relatively broad and low septal folds sparsely and simply arranged, representing the primitive forms of this genus in the early evolutionary stage. Therefore this assemblage may be considered to indicate the beginning of Changhsingian, and may be correlated with the Palaeofusulina minima-Nankinella guizhouensis Subzone from the Changhsing Formation in the western Guizhou and Palaeofusulina minima-Nanlingella simplex Subzone in southern China. 2)Gallowayinella meitienensis-Palaeofusulina sinensis Assemblage: It is easy to recognize them at the outcrop area because of the presence of abundant Gallowayinella meitienensis (Chen) from the Labuchari Formation, the upper part of Wuli Group. Palaeofusulina in the assemblage was rish and varied, such as P. sinensis Sheng, P. nana Likharev, P. fusiformis Sheng, P. subcylindrica Sheng et Nie, P. sp.. Its characteristic forms are those with larger shell, relatively complex septal folds, which represent the primitive forms of this genus in the high evolutionary stage. Therefore this assemblage may indicate the upper part of Changhsingian and is correlated with P. sinensis Subzone from the Changhsing Formation in western Guizhou and southern China. The Late Permian fusulinids from Geladandong area biogeographically belong to the Tethys Realm. As they and the Middle Permian fusulinids in adjacent Tuotuohe both represent a warm climate fauna, they are considered to be the elements of Cathaysia Tethys Province.