塔里木盆地杜瓦剖面二叠—三叠系界线及其特征

BOUNDARY BETWEEN PERMIAN AND TRIASSIC AND ITS CHARACTERISTICS IN DUWA SECTION OF TARIM BASIN

在塔里木盆地南缘杜瓦剖面上发现了中下三叠统，建立了晚二叠世、早三叠世、中三叠世早期３个孢粉组合，分别为：（１）Ａｌｉｓｐｏｒｉｔｅｓ－Ｌｕｅｃｋｉｓｐｏｒｉｔｅｓｖｉｒｋｋｉａｅ－Ｔａｅｎｉａｅｓｐｏｒｉｔｅｓｗｕｎｔｏｎｇ－ｇｏｕｅｎｓｉｓ－Ｐｒｏｔｏｈａｐｌｏｚｙｐｉｎｕｓ组合，（２）Ｋｒａｅｕｓｅｌｉｓｐｏｒｉｔｅｓ－Ｌｕｎｄｂｌａｄｉｓｐｏｒａ－Ｍｉｎｔｏｓａｃｃｕｓ－Ｔａｅｎｉａｅｓｐｏｒｉｔｅｓ组合，（３）Ｍｉｎｕｔｏｓａｃｃｕｓ－Ｐｒｉｓｔｉｎｕｓｐｏｌｌｅｎｉｔｅｓ－Ｔａｅｎｉａｅｓｐｏｒｉｔｅｓ－Ｌｕｎｄｂｌａｄｉｓｐｏｒａ－Ｒｅｔｕｓｏｔｒｉｌｅｔｅｓ组合。二叠—三叠系界线上下具有孢粉化石突变、化学元素及粘土矿物含量变化较大、岩性一致、沉积连续的特征。

Mid-lower Triassic was found in Duwa section in the south margin of Tarim basin and three sporopollen assemblages were established: ① Alisporites-Luechisporitesvirkkiae-Taeniaesporites wuntonggouensis-Protohaploxypinus assemblage of Late Permian;②Kraeuselisporites-Lundbladispora-Minutosaccus-Taeniaesporites assemblage of Early Triassic; and ③Minutosaccus-Pristinuspollenites-Taeniaesporites-Lundbladispora-Retusotriletes assemblage of early Mid Triassic. Break of sporopollen fossil, highly variable chemical element and content of clay minerals and continuity in lithology and sedimentary facies distinguish the Permian-Triassic boundary.