四川盆地复合盆山体系的结构构造和演化

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

盆山体系研究是当前大陆动力学探索的热门。四川盆地周缘为造山带所围绕,盆地与造山带存在着耦合关系。系统地分析四川盆地和周缘造山带组成的盆山体系的结构和演化特征对深入认识四川盆地的构造和油气分布规律具有重要的意义。通过构造剖面的解释、沉积充填特征和陆源碎屑物源的分析以及同位素年代学的分析,研究了四川盆地盆山体系的结构、构造变形特征和演化历史。四川盆地与周缘造山带均以冲断褶皱带相耦合,构造变形在平面上和纵向上具有明显的分带性和层次性的特点。提出了"复合盆山体系和亚盆山体系"的概念,并认为四川盆地及周缘造山带组成了一个复合盆山体系,并由多个次一级的亚盆山体系所组成,各亚盆山体系是互相影响、互相叠加、互相干扰联合的。这在一定程度上丰富了盆山体系的认识。

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 ＂ composite 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-Long- men 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.