燕山运动和中国大陆晚中生代的活化

燕山运动可分为2类:一是印支期拼合大陆外侧的新特提斯洋消减及嗣后的碰撞引起的内硅镁质的造山运动,形成滇藏、东南沿海、苏鲁和蒙古-鄂霍次克造山带;二是拼合大陆内部因古缝合线或古深断裂活化发生的内硅铝质的(陆内的)造山运动,前者如川黔湘-鄂南、湘赣闽和阴山-燕山褶皱-冲断系,后者如川南-滇东和中扬子褶皱-冲断系及江南冲断-推覆带.文章剖析了中国大陆晚中生代活化的时空特征,指出陆内造山带及冲断带的发育受制于东亚燕山期山系的形成,简述了研究构造-岩浆活化对内生矿产和油气资源评价的指导意义.

THE YANSHANIAN OROGENY AND LATE MESOZOIC ACTIVATION IN CHINA CONTINENT

The Asian continent was composite, with most microcontinents being of Gondwanaland origin, resulting from progressive Gondwana dispersion and reamalgamation. The Indosinian orogeny created the China SE Asia Subcontinent, which was surrounded by the Neotethyan oceans. In Middle Jurassic Early Cretaceous, the Neotethyan oceans subducted and somewhere collision occurred, which reactivated the fossil sutures or deep fractures, and resulted in the intracontinental orogeny. Geodynamically, the Yanshanian orogenies can be classified into ensimatic one (along the marginal areas of the amalgamated continent) and ensialic one (in the interior of the amalgamated continent). The main features of ensimatic orogens and ensialic ones, including rejuvenation of fossil sutures and deep fractures, were briefly described, and the spatial time occurring of the Yanshanian orogenies analysized. The East China was a part of the East Asia Yanshanides, which created in Late Jurassic Early Cretaceous, and collapsed in the latest Early Cretaceous and Late Cretaceous. Correspondingly, the granitism there could be separated into two episodes: the early one related to the orogenic process, and the later one to collapse of the Yanshanides. The dynamic source for the intracontinental orogeny in China continet was derived by the Neotethyan subduction and collision in the East Asia, for example, both the piggyback and overstep thrusting in Sonth China propagated towards the interior, namely, towards the NW. The Yanshanian tectonics inspired the evaluation of metallic ore deposits and oil gas resources.