中国西部盆山系统的耦合关系及其动力学模式——以龙门山造山带—川西前陆盆地系统为例

Coupling Relationships of Sedimentary Basin-Orogenic Belt Systems and Their Dynamic Models in West China——A Case Study of the Longmenshan Orogenic Belt-West Sichuan Foreland Basin System

造山带与沉积盆地是形成于统一的地球动力学系统之中的一对孪生体,由此构造了盆山系统。盆山系统是陆块相互作用、岩石圈层圈相互耦合的复杂系统,主要表现为物质的循环系统和能量的交换系统。盘山系统形成演化过程中造山带和沉积盆地之间一切相互作用的总和即为盆山间的耦合关系。盆山系统是中国西部中新生代构造的基本格局,并有单侧盆地型盆山系统和双侧盆地型盆山系统两种基本类型。小陆块拼合、多旋回构造运动和陆内构造活动强烈等是中国西部盆山系统形成演化的地质背景。中国西部盆山系统盆山间耦合关系在垂向上表现为造山带隆升与沉积盆地沉降呈镜像关系,在横向上表现为物质流和能量流循环均有两个传递方向,并且盆山系统岩石圈各层圈间有着强烈的相互作用。中国西部盆山系统盆山间耦合关系的动力学模式为C(陆内)-型俯冲,对于单侧盆地型盆山系统其耦合关系的动力学模式为L(龙门山)-型俯冲,而双侧盆地型盆山系统其耦合关系的动力学模式为T(天山)-型俯冲。

Orogenic belts and sedimentary basins are twins developed in a geodynamic system, which formed a sedimentary basin-orogenic belt system. A sedimentary basin-orogenic belt system is a complex system formed by the interactions of continental blocks and the coupling of different spheres in the lithosphere, both of which are substance cycling systems and energy exchanging systems. The coupling relationships between sedimentary basins and orogenic belts refer to all of their interactions in their formation and evolution. Sedimentary basin-orogenic belt systems are characteristic of the basic Mesozoic-Cenozoic structural pattern in West China. There are two fundamental types of sedimentary basin-orogenic belt systems in West China, i. e. simple-flank-basin sedimentary basin-orogenic belt system and double-flank-basin sedimentary basin-orogenic belt system. Microcontinental amalgamation, multi-cycle tectonic movements and intensive intracontinental tectonic activities are the main geologic setting of the formation and evolution of sedimentary basin-orogenic belt systems in West China. The coupling relationships of sedimentary basin-orogenic belt systems include: (1) enantiomorphous relationship between the uplifting of orogenic belts and the vertical subsiding of sedimentary basins, (2) bi-direction transfer of substance flow and energy flow in the horizontal direction, and (3) intensive interactions between different spheres of the lithosphere. The coupling relationship dynamic model of the sedimentary basin -orogenic belt systems in West China is a C (intracontinental)-subduction, which is an L (Longmenshan)-subduction for the simple-flank-basin sedimentary bain-orogenic belt systems and T(Tianshan)-subduction for the double-flanks-basin sedimentary basin-orogenic belt systems.