长岭断陷构造特征及白垩纪以来的构造演化

Structural characteristics and post-Cretaceous tectonic evolution of the Changling Rift

长岭断陷发育3条古老的深大断裂,对白垩纪以来的沉积构造发展演化起明显的控制作用。通过井下火山岩锆石U-Pb年龄的测定,说明长岭断陷中基性火山岩属营城早期的产物,而其上部的酸性火山岩主要为营城晚期的产物。两期火山岩夹持的地层当属营城中期沉积。提出了断陷期存在火石岭和营城两期断陷湖盆,盆地的展布及控制因素存在差异。火石岭期断陷的长轴方向均为北东向展布,受西部的新安镇-红岗断裂和东部的长春-大安断裂控制,已发现油气资源丰度相对较大;营城期断陷的长轴方向均为近南北向展布,受早期断裂及其顷轴方向同期断层双重控制,已发现油气资源丰度相对较小。受先存深大断裂的边界作用及盖层介质条件的调协作用的共同影响,该区复杂的构造具有空间上的协调性、差异性及时间上的统一性、有序性。

Three deep major faults are well developed in Changling rift and they significantly control the post-Cretaceous sedimentary and tectonic evolution.Zircon U-PB dating of the volcanic rock samples from wells reveals that the interme-diate-mafic volcanic rocks in Changling rift were formed in the early Yingcheng period,and the overlying acidic volcanic rocks were formed in the late Yingcheng period.The strata between these two sets of volcanic rocks should be deposited during the middle Yingcheng period.During rifting,two rifted lacustrine basins occurred in the Huoshiling and Yingcheng periods respectively and their distributions and controlling factors are different.During the Huoshiling period,the NE-trending major axis direction of the Changling rift was controlled by Xin＇anzhen-honggang fault in the west and Changchun-da＇an faults in the east,,and the discovered resource abundance is high.In contrast,during the Yingcheng period,the NS-trending major axis of the Changling rift was jointly controlled by the early faults and the concordant faults in dipping axis direction,and the discovered resource abundance is low.Under the joint control of the pre-existing deep major faults and cap rocks,the complex structures in the study area are characterized by harmonization and diversity in space,and unity and order in time.