燕山中、新元古代沉积盆地构造演化

燕山中、新元古代沉积盆地是一个经历了十亿年演化的长寿盆地。在漫长的地质历史时期中,受华北地台北缘构造环境变化的制约,该盆地经历了三个阶段的演变。裂陷槽阶段(1800Ma～1600Ma)形成一个北东向半地堑式的楔形槽地,团山子-大红峪期火山活动是裂陷作用顶峰的标志。之后,华北地台北侧古大洋板块发生第一次消减作用,裂陷槽迅速消亡,成为一支废弃的裂谷。裂陷槽消亡后盆地向克拉通盆地过渡的阶段(1600Ma～1200Ma),其构造特点是一方面盆地日趋稳定,另一方面还残留了某些裂陷特征。克拉通盆地阶段(1200Ma～800Ma),沉积了典型的地台盖层沉积,沉积物厚度小,厚度变化小,相变也小,盆地表现出整体同升同降的特点,形成数个区域性的间断面。此时,华北地台北侧的古亚洲洋已经封闭消失,沉积盆地古地理格局发生了根本性的变化,转而向东与大洋沟通。

Tectonic Evolution of the Meso-Neoproterozoic Sedimentary Basin in Yanshan Range

The Meso-Neoproterozoic sedimentary basin in Yanshan Range is a long live one about 1 000 Ma.Controlled by tectonic environment in the northern edge of the North China Platform,the basin underwent 3 evolutional stages during its development.The first is aulacogen stage(1 800 ~ 1 600 Ma) in which an oblique graben-shaped-sphenoid trough was formed in northeastern direction.The volcanic action in the Tuanshanzi and Dahongyu Formations is the mark of the highest peak of the chasmic activity.And then,the aulacogen was consumed rapidly because of the first consumption of the palaeo-ocean plate on the north of the North China Platform,and became a discarded rift.The second one is transitional stage(1 600 ~ 1 200 Ma),in which the basin changed into a craton basin since the aulacogen was consumed.The tectonic in this stage was characterized by that the basin became stable gradually on one hand,and some marks of the chasmic activity were remained on other hand.The third one is craton stage,in which the typical sedimentary cover of platform were formed with stable small thickness and little facies change.In addition,the basin showed rise and subsidence simultaneously,and formed some regional sedimentary break.And then,the Ancient Asia Ocean to the north of the North China Platform was closed,and the palaeo-geographic pattern was essentially changed and the palaeo-basin turned to link up the eastern ocean.