摘要
软碰撞是指陆块间，主要是微陆块间的弱碰撞。软碰撞后，陆块间尚未焊合，处于"联而不合"的状态。在新的构造阶段，这些陆块间又可再一次挤压和地壳缩短，发生大陆壳的消减造山作用，使一个大陆的大陆壳叠覆在另一个大陆的大陆壳之上，这就是陆一陆叠覆造山作用。东亚诸陆块在古生代软碰撞后，曾长期处于"联而不合"的状态，只有再经过华为西、印支、燕山多旋回的陆-陆叠覆和走滑-挤压造山作用之后，它们才在动力学上最终焊合为一体，即经历了多旋回的缝合作用才合为一体。
Microcontinents that constitute the present East Asan continent were P8rt Of the in-terchange tectonic domain between Gondwana and Siberia (Laurasia) in the geological past. In Paleozoic Era these small masses were mostly located to the south of the palaeo-Asian ocean, be-longing to the structurally complicated northern margin of Gondwana; in Mesozoic Era they were mainly situated to the north of the Tethys, belonging to the structurally complicatedsouthern margin of the palaeo-Asian continent (eastern Laurasia) . In the course of the closureof the palaeo-Asian ocean the orogeny that happened there was not a violent collision orogenybetween the Gondwana and the Siberia continents proper but a slight or, say, soft collision be-tween the microcontinents on their complicated margins. Generally speaking, when microconti-nents or small masses collide with each other, the orogeny is usually slight because of lesser ki-netic energy. The tectonomagmmatic activity is mainly restricted to the overthruting continentalcrust, and the underthrusting one is only affected slightly. Afer colision, the oceanic basin dis-appear, but sea water does not definitely withdraw and mountains do not necessarily come into being, leading to such collision that calls forth no response of mountain building. Thus, the mi-crocontinents, though being connected, are not to be jointed into a single continent in dynamicrespect, that is to say, they are in a state of 'connection rather than integrtion'. These non-u-nited microcontinents may be subjected to another orogeny in a new tectonic cycle and new geo-dynamic conditions. The continental block lying in a low position will be again underthrust be-neath the high mass, resulting in the subduction orogeny of continental crust, i. e., the superpo-sition of the margin of one continent upon that of another, which is called continental superposi-tion orogeny. The continental masses can be geodynamically welded as a whole only after long-term and polycyclic continent-continent superposition or, say, polycyclic suturing. The weldingprocess between the Sino-Korean block and the Yangtze block, which was accomlished not on-ly by the Caledonian collisional orogeny, but also by the Variscan, Indosinian and Yanshanianpolycyclic superposition orogeny as well as the strike-slip-compressional orogeny, is an exampleof soft collision and polycyclic suturing.
出处
《地学前缘》
EI
CAS
CSCD
1999年第3期85-93,共9页
Earth Science Frontiers
基金
原地质矿产部重点科技项目!9501123
