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 Megagrapton-Arthrophycus 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.