雅鲁藏布江缝合带开合演化模式的探讨

Discussion on the Model of Evolution of Open-Close Structure of the Yaluzangbu Suture Zone

通过对雅鲁藏布江缝合带的蛇绿岩、构造混杂岩的地质调查及其岩石化学、地球化学特征的分析,进一步证实了雅鲁藏布江缝合带萨嘎分岔的存在,探讨了雅鲁藏布江缝合带的演化模式。将雅鲁藏布江缝合带分为南、北两带,南带起始于二叠纪末期印度板块向北漂移过程中的伸展作用,到三叠纪末—早侏罗世,雅鲁藏布江缝合带南带伸展作用加剧,并伴有洋壳的裂陷和蛇绿岩的侵位,在较短暂的双向俯冲、碰撞后焊接了仲巴陆块。晚侏罗世到早白垩世之后,雅鲁藏布江缝合带北带再次扩张、俯冲,直到始新世晚期整个缝合带开始剧烈碰撞、造山、隆起,形成了雄伟的青藏高原。

Sage diverge of Yaluzangbu suture zone has been verified further in this article through the field investigation of ophiolite and m61ange and the analysis of their lithochemistry and geochemistry. The model of evolution of Yaluzangbu suture zone has been discussed. Yaluzangbu suture zone can be divided into two different epoch zones （the north zone and the south zone）. This kind of model originated from the extension function in the course of Indian Plate drifting northward in Late Permian Period. Spread function of the south zone of the Yaluzangbu suture zone aggravated, followed ocean crust splitting and ophiolite emplacing from Late Triassic to Early Jurassic. After subducting and collisioning momentarily in both sides, Zhongba land had been welded. After Late Jurassic and Early Cretaceous, the north zone of the Yaluzangbu suture zone had been expanding, subducting again, till Late Eocene Epoch the whole Yaluzangbu suture zone had been collisioning and mountainbuilding and raising, the great Qinghai-Tibet Plateau had been formed.