吐哈盆地北缘二叠系与三叠系界线

The Peimian-Triassic Boundary on the Northern Margin of the Turpan Hami Basin of Xinjiang, NW China

对吐哈盆地北缘锅底坑组中部和上部孢粉组合研究后发现 ,中部组合见有晚二叠世的重要分子 L uecki-sporites及二叠纪的重要分子 H amiapollenites,以具肋双囊粉含量明显较高为特征 ;上部组合出现了具有一定含量的早三叠世的典型分子 L undbladispora,三叠纪的常见分子 Chasmatosporites,以及以 Taeniaesporites的含量较高为特征。两个组合既具有明显的不同 ,但共有分子又在 2 0种以上 ,占各自组合孢粉种总数的一半以上 ,这说明二者又具有连续过渡的性质。因此 ,桃东沟剖面二叠系 -三叠系生物地层界线应划在锅底坑组上部 ,位于锅底坑组与韭菜园组岩石地层界线以下约 40 .49m处 (即第 12层与第 11层之间 )

The present paper presents the result of the study on the biostratigraphical boundary between the Triassic and Permian sediments on the Northern margin of the Turpan hami Basin of Xinjiang, NW China. The spores and pollen under this study were from the middle and upper parts of the Guodikeng Formation. Some important Permian pollen members of Lueckisporites, Hamiapollenites were from the middle part of the Guodikeng Formation. The upper part of the fomation contains Early Triassic Lundbladispora and Triassic pollen grains Taeniaesporites, Chasmatosporites . Therefore, the biostratigraphical boundary between Triassic and Permian is 40.43m lower than the lithological boundary between the Early Triassic Jiucaiyan Formation and the Late Permian Guodikeng Formation at the Taodonggou section. Our study also reveals a transitional feature of the palynofloras because a number of common elements, i.e., Baculatisporites comaumensis, Osmundacidites wellmanii, Kraeuselisporites spinosus, K. apiculatus, Cordaitina rugulifer, Protohaploxypinus somoilovichi, Striatoabieites bricki, Taeniaesporites albertae, Alisporites australis, A. parvus, Piceites enodis, Abietineaepollenites pectinellus , etc., have been found above and below the biostratigraphical boundary.