四川松潘马拉墩晚三叠世侏倭组的遗迹化石及沉积环境

四川松潘马拉墩晚三叠世侏倭组首次发现大量遗迹化石。本文根据不同遗迹属在不同层位中的相对丰度建立了两个遗迹组合，即Ｍｅｇａｇｒａｐｔｏｎ－Ａｒｔｈｒｏｐｈｙｃｕｓ组合及Ｎｅｏｎｅｒｅｉｔｅｓ－Ｐｈｙｃｏｓｉｐｈｏｎ组合，大致相当于Ｓｅｉｌａｃｈｅｒ（１９６７）［１］的Ｎｅｒｅｉｔｅｓ遗迹相．同时利用遗迹化石及沉积特点进行了沉积环境分析，认为侏倭组的沉积环境为大陆斜坡下部至盆地边缘。

THE LATE TRIASSIC ZHUWO FORMATION IN MALADUN,SONGPAN,SICHUAN: TRACE FOSSILS AND THEIR DEPOSITIONAL ENVIRONMENTS

The abundant and diverse bathyal to abyssal trace fossils were discovered for the first time from the Late Triassic Zhuwo Formation in Maladun,Songpan,Sichuan. According to the relative abundances of the trace fossils in different stratigraphic horizons,two trace fossil assemblages have been established in the present paper. They are the MegagraptonArthrophycus ichnoassemblage and Neonereites-Phycosiphon ichnoassemblage, both of which are roughly analogous to Nereites ichnofacies of Seilacher (1967). Moreover the Zhuwo Formation is also interpreted as having been deposited in the sedimentary environments from lower foreslope to basin margin in terms of trace fossils and sedinmentary characteristics.