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东尼日尔Termit盆地是中西非裂谷系中典型的中—新生代裂谷盆地。在充分应用钻井和地震解释资料的基础上,根据构造、沉积充填及主要区域性不整合面的特征,分析了该盆地的演化过程。盆地内主要发育两类断层,第一类断层形成于早白垩世,于古近纪发生继承性活动,第二类断层为形成于古近纪的新生断层。全盆地普遍存在4个主要区域性不整合面,分别位于下白垩统、上白垩统、古近系、新近系—第四系底部。下白垩统和古近系沉积特征受断层活动控制明显,上白垩统和新近系沉积中心位于盆地中部,在其沉积时构造活动较弱。构造和沉积充填特征表明,Termit盆地经历了白垩纪和古近纪—第四纪两期裂谷旋回叠置的演化过程。下白垩统和古近系沉积于同裂谷期,沉积充填受断层活动控制;上白垩统和新近系—第四系沉积于后裂谷期,以热沉降拗陷作用为主。
The Termit Basin in East Niger is a typical Meso-Cenozoic rift basin in the Central and West African Rift System. Based on the full application of drilling and seismic interpretation data, the evolution of the basin is analyzed according to the features of structure, sedimentary filling and major regional unconformities. Two types of faults are mainly developed in the basin. The first type of fault was formed in the Early Cretaceous and inherited activity occurred in the Paleogene. The second type was a new-born fault formed in the Paleogene. There are four major regional unconformities in the whole basin, which are located at the bottom of Lower Cretaceous, Upper Cretaceous, Paleogene, Neogene and Quaternary, respectively. The sedimentary features of the Lower Cretaceous and Paleogene are controlled by faults. The sedimentary centers of the Upper Cretaceous and Neogene are located in the central part of the basin, and tectonic activity is weak during their deposition. Tectonic and sedimentary filling characteristics indicate that the Termit Basin underwent the evolution of the Cretaceous and Paleogene-Quaternary rift cycles. Lower Cretaceous and Paleogene sediments in the same rifting period, sedimentary filling controlled by faulting; Upper Cretaceous and Neogene-Quaternary sediments in the post-rifting period, mainly by thermal subsidence depression.