班公湖-双湖-怒江-昌宁-孟连新元古代-中生代沉积盆地演化

Evolution of Neoproterozoic-Mesozoic Sedimentary Basins in BangonghuShuanghu-Nujiang-Changning-Menglian Suture Zone

在详细理清区内地层格架的基础上,整理和归纳了研究区内各沉积盆地岩石建造组合和时代依据,最后在板块构造学说和大陆动力学观点的理论指导下,划分盆地类型,寻找盆地演化的时空规律,了解原-古特提斯大洋从发生、发展到消亡的过程.通过归纳总结,将前新生代原-古特提斯大洋在该区的演化划分为与盆地演化对应的4个阶段.对研究区内的3个主要结合带的盆地演化进行了系统总结,其中龙木错-双湖洋盆与昌宁-孟连洋盆都存在奥陶纪的具MORB性质的蛇绿混杂岩,并且二者均在二叠纪末、早三叠世初发生弧-陆碰撞作用,说明二者可能共同代表了一个统一的古特提斯洋在研究区的残余.以班公湖-怒江洋盆为代表的残余古特提斯洋在早石炭世开始扩张并持续演化到早白垩世,它们代表了古特提斯洋盆的最终消亡.

In the light of the stratigraphic framework,the authors collected and summarized evidences of the rock formations and their ages in the sedimentary basins of the Bangonghu-Shuanghu-Nujiang-Changning-Menglian suture zone.With the guid-ance of the plate tectonic theory and continental dynamics,the basin types are also classified in the study area to explore the temporal and spatial evolution of the basins and to better the understanding of the opening,extension and closing of the Paleo-Tethys oceans.Four evolutional stages of the Pre-Cenozoic Paleo-Tethys oceans corresponding to the basinal evolution in the study area are distinguished.It is found that Ordovician ophiolitic m＆#233;lange of MORB characteristics occurred in both the Long-mu-Shuanghu and the Changning-Menglian oceanic basin,two of which prove to have experienced arc-continent collision during the end Permian-Early Triassic transition,suggesting a united remnant oceanic basin of the Paleo-Tethys.The remnant Paleo-Tethys represented by the Bangonghu-Nujiang oceanic basin,on the other hand,opened in the Early Carboniferous and evolved to a closure in the Early Cretaceous,marking the final disappearance of the Paleo-Tethys.