关键词: 遗迹化石, 层序地层学, 塔里木盆地, 塔中地区, 志留系

Abstract: Based on core and well-logging data，combined with re-gional geological setting, the local succession of Silurian Central Tarim Basin is divided into three type 1 third-order deposition-al sequences, namely, sequence 1，sequence 2 and sequence 3.Because of the lack of lowstand systems tract, these sequences consist solely of transgressive systems tract and highstand sys-
terns tract. The transgressive deposit of sequence 1 can be sub-divided, from base to top, into two main facies;(1)thin-bed-ded sandstone alternating with thin-bedded mudstone ;(2)planar stratified sandstone. Facies 1，which is dominated by lid-al bedding thin sandstone alternating with thin-bedded mud-
stone, reflects mixed flat sedimentary environment. Because of mediate hydrodynamics and favorable eco-environment, trace fossils, including fodinichnia and domichnia, develops in mass. From base to top, the abundance and diversity of these trace fossils decrease gradually as with the bioturbation index. Facies 2，which is represented by planar-stratified or parallel-stratified
sandstone, reflect sand flat sedimentary environment with hydro-dynamic condition. Due to high hydrodynamics and unsuitable condition for organism, the abundance and diversity are relative-ly low, leading to existence of scatted dwelling burrows. The highstand systems tract of sequence 1，which is mainly products of mud flat, exhibits a succession of fining-and shallowing up-
wards parasequences. The mud flat , which is characterized chiefly by domichnia and fodinichnia, has different ichnogenus, abundance and diversity compared to facies 2. In the highstand deposit, the abundance, diversity and bioturbation index also show a gradual decrease from base to top. In conclusion , not on-ly the composition, abundance and diversity of trace fossils differ among systems tract of the same sequence, but also the charac-
leis of trace fossils show some regularity within the same systems tract.

Key words: trace fossils, sequence stratigraphy, Tarim Basin, Silurian