长江流域中央造山系盆-山体系的构造样式分析及其动力学机制探讨

盆地和造山带是在空间展布和形成机制上具有密切联系的构造体系。盆 -山体系的构造样式分析 ,不仅可以重塑造山带及其邻区盆地的盆山耦合过程和景观演化 ,而且是探索造山作用对地貌、气候、资源、能源、环境和灾害等方面控制作用的基础。按照地球动力学环境 ,可以归纳为三种主要类型 ,即伸展、挤压、走滑盆 -山体系 ,结合其所处的大地构造体制和板块运动阶段 ,可以得出盆 -山体系构造样式的综合分类方案。长江流域的地质 -生态环境与自然灾害受到中新生代以来地壳运动和秦岭 -大别等造山作用的严格制约与影响。根据盆地原型和盆缘造山带之间的配置关系和成因联系 ,研究区长江流域中央造山系的典型盆 -山体系构造样式主要有桐柏 -大别造山带与中扬子北缘的江汉洞庭断陷盆地 ,秦巴边缘冲断造山带与上扬子北缘的四川前陆盆地。本文按同造山期、晚造山期和后造山期演化阶段 ,依此分析两个典型盆 -山体系的构造样式演化特征及其动力学机制探讨

ANALYSIS OF STRUCTURAL STYLES OF THE BASIN-RANGE SYSTEMS IN THE CENTRAL-CHINA OROGENIC CHAIN OF YANGTZE VALLEY AND THE DYNAMIC MECHANISM

Basin and orogenic belt belong to the same tectonic system which have close connections in spatial evolution and dynamic mechanism. Structural styles analysis of basinrange system, not only may rebuild basin-range coupling process and landscape evolution of orogenic belt and its adjacent basin,but also become the foundation in exploring how orogenesis control relief, climate, resources, energy and environment. In the light of dynamicmechanism, three main basin-range system types may be reduced to, namely, compress, stretch, strike-slip complex type. In combination with their geotectonic settings, a comprehensive classification scheme may be deduced for structural styles of basin-range system. Natural disasters and eco-environment in the Yangtze Valley have been restricted and impressed by crustal movement and Qinling-Dabie orogenesis since the Mesozoic and Cenozoic. In terms of collocating relation and contacting basin prototype and orogenic belt around the basin for cause of formation, typical structural styles of basin-range system in the central orogenic chain within the Yangtze Valley comprises coupling Tongbo-Dabie orogenic belt and Jianghan-Tongting fault basin at the northern margin of the central Yangtze landmass, and coupling Qinling-Dabie mountain margin thrust orogenic belt and Sichuan foreland basin at the northern margin of the upper-Yangtze landmass. The paper analyzes evolutionary features of two typical structural styles of basin-range system during late-orogenic and postorogenic stages, and probes into their dynamic mechanism. It is emphasized that, in different stages of basin-range system of different properties and basin-mountain transformation process, different structural styles may be formed; and different associations of structural styles can form different types of natural disasters and eco-environment systems.