印支运动以来中国海陆地势演化及阶梯地貌特征

Terrain evolution of China seas and land since the Indo-China movement and characteristics of the stepped landform

地势是地面高低起伏的形势,是地球内营力和外营力共同作用的结果,是地壳内部结构、构造及其发展在地表的反映.空间重力异常与地形、地貌密切相关,反映地壳内部结构和构造的变化.均衡原理认为高山下面地壳厚,平原下面地壳薄,即地势的起伏同莫霍面的起伏呈镜像关系.中国海陆地质地球物理系列图编制了大地构造格架图和大地构造格架演化图等专题图件,对中国海陆各主要块体的时空演化进行研究,研究了中国海陆地势的"跷跷板"演化过程.本文根据中国海陆1∶500万空间重力异常图和莫霍面深度图分析了海陆地貌特征,按照构造地貌的分类原则,将中国海域和陆域作为一个整体进行地貌分类,在中国大陆地势呈三个地貌阶梯的基础上,总结出中国海陆地貌总体特征为西高东低,呈五级阶梯分布.

Terrain is the situation of the ground rising and falling, which is controlled by both the endogenetie and exogenic forces of the earth. The terrain reflects the internal structure, construction, and evolution of the crust. Free-air gravity anomalies are related to topography and geomorphology. It is considered that the crust that under mountains is thicker than that under plains by the equalization principle. There is a mirror image relationship between crust thickness and terrain relief. The map series of geology and geophysics of China seas and land include figures of tectonic framework and evolution of tectonic framework. The temporal evolution of the main blocks is studied in both of the maps, which elaborate the evolution of Chind s terrain as a “Seesaw”. This paper analyzes the geomorphological features by the flee-air gravity anomaly map and Moho depth distribution map. In accordance with the principle of tectonic landform classification, the general characteristics of China seas and land is viewed as a whole which shows five terrain steps from west to east on the basis of three geomorphological ladders of Chinese land.