LATE TRIASSIC TRACE FOSSILS AND ICHNOFACIES IN THE BAXI-QOIJE AREA, ZOIGE, SICHUAN

Very abundant and diverse trace fossils have been first discovered in Late Triassic strata in the Baxi Qoijê area, Zoigê, Sichuan. The author describes 22 ichnogenera and 34 ichnospecies. Based on the relative abundance of the ichnogenera in different horizons, 4 ichoassemblages may be distinguished: （1） Helminthopsis Phycosiphon ichnoassemblage, （2） Dendrotichnium Neonereites ichnoassembalge, （3） Paleodictyon ichnoassemblage,and （4） Taenidium Cosmorhaphe ichnoassembalge. The above ichnoassemblages are analogous to Zoophycos and Nereites ichnofaices of Seilacher. In terms of trace fossils, it is suggested that the Late Triassic depositional environment in the area experienced the evolution from the middle lower slope through lower slope to abyssal basin margins.