金沙江、澜沧江、怒江地区地体-裂谷构造与演化

THE TERRENES- RIFTS STRUCTURES AND THEIR EVOLUTION IN THE JINSHAJIANG-LANCANGJIANG AND NUJIANG AREA

三江地区的地质结构以亲陆地体与亲洋地体及其间的亲弧地体相间排列为特征。亲陆地体有哀牢山型、扬子型、冈瓦纳型、保山型、昌都型等。亲陆地体裂离主要发生于早奥陶世、早石炭世、晚二叠世－早三叠世，裂谷作用和海底扩张作用导致亲洋地体形成。晚海西期、早印支期和晚印支期洋壳俯冲，导致洋内弧、陆缘弧等亲弧地体及岛弧裂谷系形成。地体联合发生于寒武纪末、石炭纪末、二叠纪末和中三叠世末，最终形成结构复杂的三江联合地体，并于晚三叠世自南而北逐渐增生于扬子地台西缘。增生后的中新生代大陆构造发展时期，以沿边裂陷、沿边走滑构造岩浆带和沿边走滑叠缩陆内造山带发育为特征。

The geologic texture in the Jinshajiang- Lancangjiang and Nujiang area is characterized by continental one alternating with oceano·-phile one and arc-phile terrene. The continent-phile can be divided into five types: the Alnaoshan, the Yangtze, the Gondwna,the Baoshan and the Changdo. Splitting of the continento-phile mainly occurred in early Ordovician, early Carboniferous and late Permia-early Triassic by rifting and sea-floor spreading formed Oceanic-phile terrwenes. Such arc-phile terrenes as oceanic arc and epicontinental arc and arc-rift system were made by B-subduction in late Hercynia, early and late Indocynian. Amalgmation of terrenes occurred at the end of Cambrian, the end of Carboniferous, and of Permian and middle Triassic, the Jinshajiang-Lancangjiang and Nujiang area united terrenes then formed and was accreted onto the western margin of the Yangtze platform. In Meso-Cenozoic Era of continental tectonic development,it is characterized by taphrogeny, strike-slip tectonic-magmatic belts and slip-telescoped intracontinental orogenic belts along the boundary faults of terrenes. The formation of intracontinental orogenic belts was closely related to under-crust subduction of continental mantle lithosphere and terrene structure on the surface.