以层序地层学及沉积学理论为指导,综合运用测井、 录井以及地震资料,将尼日尔Termit盆地上白垩统Madama组划分为一个三级层序(MS),并进一步识别出低位体系域、海侵体系域以及高位体系域.在等时层序地层格架内,识别出前积反射地震相、河道充填反射地震相、平行-亚平行反射地震相以及杂乱反射地震相等四种类型,并识别出辫状河三角洲的沉积相类型.认为层序MS的低位体系域主要发育辫状河三角洲前缘亚相,高位体系域则主要发育辫状河三角洲平原亚相.Madama组整体表现为一个海退的沉积演化过程.

On the basis of logging data and seismic data, the Madama Formation of Upper Cretaceous in Termit Basin in Niger was interpretated as a third-order sequence, which includes a lowstand system tract(LST), a transpressive system tract(TST) and a highstand system tract(HST). In this study, four major seismic facies (progradational seismic facies, channel filling seismic facies, parallel to subparallel reflection seismic facies and clutter reflection seismic facies) and one sedimentary facies(braided river delta) have been identified. The LST mainly developed the braided river delta front, the HST mainly developed the braided river delta plain, and the sedimentary evolution of Madama Formation is a regressive process as a whole.