Tectono-Stratigraphy and Sedimentary Infill Characteristics of Xujiahe Formation in Western Sichuan Foreland Basin

Abstract

The Xujiahe Formation tectono-stratigraphy is characterized by binary system tracts (tectonic active ones and tectonic stable ones) in western Sichuan depression, coincided with its episodic-orogenesis evolution phases as a peripheral foreland basin. Tectonic activity is suggested not just to control sequence stratigraphy development, but also to assign the sediment-infilling patterns within sequence successions. Based on Vail’s sequence stratigraphy theory, integration of data from boreholes with seismic reflection allowed the analysis of tectono-stratigraphy types and their main controlling factors, as well the illustration of sedimentary characteristics in or between orogeny episodes. The results show that: (1) the Xujiahe Formation’s sub-members (T3x2-T3x5) alternatively shift between the binary system tracts: T3x2 and T3x4 belong to tectonic active system tracts, while T3x3 and T3x5 tectonic stable ones; (2) tectonic activity controls tectono-stratigraphy development; (3) coarse grained deposition dominate in the tectonic active system tracts, as alluvial fan – braided river delta – lacustrine facies prevail in T3x2 and T3x4, while fine grained sediments distribute widely in the tectonic stable system tracts, for meandering river delta – lacustrine and swamp facies predominate in T3x3 and T3x5. Key words: tectono-stratigraphy; binary system tracts; sedimentary infill; Xujiahe Formation; western Sichuan foreland basin

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018