Abstract:

To enhance the Mesozoic sequence stratigraphic division and sedimentary fill evolution reconstruction in the Tabei Uplift region of the Tarim Basin， an integral analysis of seismic， logging， core and outcrop data is carried out to redefine the sequence stratigraphic framework， identify the major sedimentary systems and reveal the sedimentary fill evolution features and their correspondence to the emergence and disappearance of the Tabei Uplift. Four second-order sequences （Ⅰ-Ⅳ） and eleven third-order sequences are divided with the recognition of four regional angular unconformities， one regional parallel unconformity and seven local unconformities in the study area. Analyses indicate that during the Late Triassic （Ⅰ-SQ3）， the EW-trending Tabei Uplift provided abundant sediments to its steep narrow north slope and gentle broad south slope where alluvial fan/fan deltas and braided deltas were formed respectively. During the Early Jurassic （Ⅱ-SQ1）， the uplift expanded and provided more sediments to the south slope where larger braided deltas were developed. By the end of deposition of the Lower Cretaceous Kapushaliang Group （Ⅲ-SQ4）， the uplift was mostly disappeared and sediments in the area were mainly sourced from a denuded zone in the southeast and deposited as deltas. By the end of the Lower Cretaceous Bashijiqike times （Ⅳ-SQ3）， the study area turned into a south-dipping slope with sediments mostly sourced from a denuded zone in the east and an orogenic belt in the north and deposited as a shallow-water braided delta. This study may help understand the depositional evolution of the Mesozoic continental lacustrine basin in the region and provide a reference for future exploration.

Key words: sedimentary system, depositional fill evolution, sequence stratigraphy, Mesozoic, Tabei Uplift region, Tarim Basin