东特提斯板块会聚边缘与岛弧造山作用

本文重点简述了特提斯构造域内古，中，新三个演化阶段的蛇绿混杂岩与岛弧带的时空展布及其沟－弧－盆体系，所识别出的蛇绿混杂岩，洋中脊拉斑玄武岩，大洋沉积物的岛弧带等地质记录，提供了东特提斯早期大洋岩石圈板块运动的有力证据。同时，与岛弧有关的不同时期不同阶段的各种弧前盆地，弧间盆地和弧后贫地成为造山带板块会聚边缘特征的标志。

PLATE CONVERGENT MARGINS AND ISLAND-ARC OROGENESIS IN EASTERN TETHYS

The spatio-temporal distribution of the ophiolitic melanges and island-arc zones is emphasized in combination with the trench-arc-basin systems in the eastern Tethyan tectonic domain,for which three evolutionary stages of Eo-Tethys,Mid-Tethys and Neo-Tethys have been distinguished.The geological records of the ophiolitic melanges,mid-ocean ridge basalts,oceanic sediments and island-arc zones,which are recognized,have provided essential evidences for plate movement in the early oceanic lithosphere.The plate convergent margins in orogenic zones are characterized by all kinds of fore-arc,inter-arc and back-arc basins which are related with island arcs and formed in varying times and stages.Moreover,the formation and evolution of the distinctive basins are sujected to the effects and controls of different geological settings.It is obvious that most of the basins have experienced three stages of evolution,including rifting and extensional,steady sinking,and compressional and uplifting processes.The first stage is characterized by intense volcanic activities and well-developed fan-deltaic sediments;the second stage by mixed and low-density turbidity current deposits of carbonates and siliciclastics,and the early time of the third stage by the development of submarine fans.It is important that the features of recycling orogenesis in many basins are indicated by the terrigenous clastic sediments of quartzitic mylonite.There is a typical example for arc-arc collision between the Yidun island arc and Shalulishan magmatic arc,or even throughout eastern Tethys.The growth of the Yidun island arc records the transition from immature to mature arc on the basis of the early rift, whereas the Shalulishan magmatic arc was developed on an ancient landmass.The subduction and collision of the two arcs stimulated the uplifting of the Korlondo-Yajin zone.The ovogenesis not only brought westwards about a vast amount of mylonite clasts,but also resulted in the formation of the lag-type granitoids in the Cuojiaoma-Cuomolong zone and of Sn polymetatlic metallogenic zones in the west of Yidun.Besides,the arc-continent collision may be served as an additional model for orogenesis.Finally,the common features are also described for the basins and island arcs on the plate convergent margins in the eastern Tethyan tectonic domain.