准噶尔盆地四棵树剖面孢粉组合及三叠系-侏罗系界线

在实测四棵树剖面的基础上,详细研究了其孢粉组合特征,建立了5个孢粉组合:1)Cameratitriletes和Zonotriletes-Protopinus-Cycadopites组合,2)Cyatheaceae-Pinaceae-Cycadopites组合,3)Cyatheaceae-Pinaceae-Quadraeculina-Cycadopites组合,4)Cyatheaceae-Quadraeculina-Piceaepollenites组合和5)Cyatheaceae-Clas-sopollis-Pinaceae组合,分别产于上三叠统的小泉沟群、下侏罗统的八道湾组和三工河组、中侏罗统的西山窑组和头屯河组。根据孢粉组合特征,结合岩性和沉积及区域资料,将三叠系-侏罗系界线定于38层和39层之间。

SPOROPOLLEN ASSEMBLAGES AND THE TRIASSIC-JURASSIC BOUNDARY AT THE SIKESHU SECTION OF THE JUNGGAR BASIN,XINJIANG

The Sikeshu Section is located on the south-western margin of the Junggar Basin, Xinjiang, and about 40 km southwest of Wusu city. Abundant sporopollen were discovered there. The Late Triassic—Jurassic sporopollen assemblages of the Sikeshu Section measured include: 1) Cameratitriletes and Zonotriletes-Protopinus-Cycadopites assemblage from the Upper Triassic Xiaoquangou Group; 2) Cyatheaceae-Pinaceae-Cycadopites assemblage form Lower Jurassic Badaowan Formation; 3) Cyatheaceae-Pinaceae-Quadraeculina-Cycadopites assemblage from Lower Jurassic Sangonghe Formation; 4) Cyatheaceae-Quadraeculina-Piceaepollenites assemblage from the Middle Jurassic Xishanyao Formation; 5) Cyatheaceae-Classopollis-Pinaceae assemblage from the Middle Jurassic Toutunhe Formation. Based on sporopollen assemblage, lithology, sedimentology and regional correlation, the Triassic-Jurassic boundary should be placed at the contact between Beds 38 and 39.