ARCHITECTURE AND TECTONIC EVOLUTION OF COMPOSITE BASIN-MOUNTAIN SYSTEM IN SICHUAN BASIN AND ITS ADJACENT AREAS

Basin-mountain system is one of the frontier research fields in the study of continental geodynamics. Four orogenic belts occur around and are coupled with Sichuan basin. Therefore, analysis of the architecture and tectonic evolution of the basin-mountain system in Sichuan Basin and its adjacent areas would be very important to gain a deeper understanding of the tectonic framework of and petroleum reservoir distribution in Sichuan basin. Based on the results of interpretation of seismic profiles, evolution of deposition and analysis of clastic rock characteristics, ESR, K-Ar and Rb-Sr isotopic dating and fission track thermochronology analysis, new progresses were made in understanding the architecture, tectonic deformation and evolution of the basin-mountain system in Sichuan Basin and its adjacent areas in this paper. The tectonic deformation of the basin-mountain system shows characteristics of proceeding in zones, segments or layers. The authors put forward in this paper the new concept basin-mountain system, which is controlled asynchronously by the multi-stage thrusting action of multiple orogenic belts. The composite basin-mountain system around Sichuan Basin was comprised of some basin-mountain subsystems, i.e., the northeast Sichuan Basin-Daba Mountains basin-mountain subsystem, the west Sichuan Basin-Longmen Mountains basin-mountain subsystem and the east Sichuan Basin-Xuefeng Mountains basin-mountain subsystem, and so on. It was found that these basin-mountain subsystems interacted and interfered with one another, and were superimposed and united with one another in forming the basin-mountain system around Sichuan Basin.