基底构造在沉积盆地的形成与演化过程中扮演着重要的角色.本文利用地球物理资料和地表地质调查数据,对二连盆地早白垩世断陷分布规律与基底构造特征及其关系进行了研究,并分析了基底构造对富油凹陷的控制作用.结果表明,二连盆地早白垩世68个断陷总体上自北东向南西呈弥散式分布,这些断陷可分为南部断陷群与北部断陷群,断陷群夹持在隆起之间,总体上构成了正负相间的盆岭构造格局.基底构造控制着二连盆地早白垩世断陷分布,表现为:断陷群沿着深断裂分布;坳陷对应着基底先存复向斜,隆起对应着基底先存复背斜;刚性的锡林浩特地块分割了断陷群.深断裂作为构造薄弱区在伸展变形过程中优先重新活动,并控制着断陷的发育与分布;盖层演化和基底构造之间具有良好的继承性;基底流变性发生突变的区带对断陷的发育与分布也具有控制作用.盆地基底断裂带上叠的凹陷、基底断裂带交汇处上叠的凹陷和刚性基底上新生的凹陷在伸展变形过程中构造继承性好、沉降量大、优质烃源岩发育,是富油凹陷发育的有利区域.
Basement-involved structures plays an important role in formation and evolution of sedimentary basins.Based on geophysical data and geological survey,this paper focuses on the distribution of Early Cretaceous faulted sags,the characteristics of basement-involved structures in the Erlian Basin and their relationship,and the control action of basement-involved structures on hydrocarbon-enriched sags.The results show that Early Cretaceous 68 faulted sags in the Erlian Basin present a dispersive distribution from NE to SW.These sags can be grouped into the south sag group and the north sag group.Two sag groups are separated by uplifts,and both sag groups and uplifts displays a basin-range-like tectonic framework together.The distribution of Early Cretaceous faulted sags in the Erlian Basin was strongly influenced by basement-involved structures,which can be proved by that the Early Cretaceous faulted sags developed along pre-existing deep faults,and that the depressions was superposed over the Hecynian synclinorium,while the uplifts had a genetic relationship with the Hecynian anticlinorium,and that the rigid the Xilinhot massif separated the two sag groups.The preexisting deep faults strongly weakened the lithosphere and localized strain,and having a priority in activity under extensional setting,which control the development and distribution of Early Cretaceous faulted sags.The tectonic evolution of sedimentary covers has a good inheritance from the basement-involved structures.The zone where a rheological property varied also has an influence on the distribution of Early Cretaceous faulted sags.The Early Cretaceous faulted sags superposed on pre-existing deep faults,the intersection of pre-existing deep faults and rigid massif have an enough subsidences and form abundant high-quality source rocks during the basin evolution period,and these sags are the potential hydrocarbon-enriched sags.