尼日尔三角洲里奥-德雷盆地泥底辟变形与形成演化特征

Deformation and evolution of mud diapirs in Rio Del Rey Basin, Niger Delta

余一欣 王涛 陈占坤 苏玉山 张纪新 吴世祥

Yixin Yu Tao Wang Zhankun Chen Yushan Su Jixin Zhang Shixiang Wu

尼日尔三角洲东北部的里奥-德雷盆地发育多条阿卡塔组泥底辟构造带，对油气成藏产生了重要影响。根据泥岩隆升幅度及其与周围地层的接触关系，可将泥底辟划分为复杂形态刺穿型和简单形态隐伏型两类。平面上，泥底辟主要呈近SN向的条带状和圆点状展布，并影响上覆地层的发育，形成3类正断层。泥底辟主要经历了中渐新世之前的初始沉积-微弱活动期、晚渐新世-中新世的强烈隆升活动期以及上新世至今的微弱活动-整体埋藏期等3个形成演化阶段。泥底辟的发育除受到重力滑动作用及上覆地层的差异负载作用影响外，还受到盆地东南部大西洋转换断层及泥下基底断裂的影响。对里奥-德雷盆地泥底辟构造发育特征的研究，有助于分析泥底辟对圈闭、储层发育以及油气运移的影响。

Several mud diapir belts developed in the Akata Formation mudstone are closely linked to the accumulation of hydrocarbon in the Rio Del Rey Basin, northeast Niger delta. According to their heights and contact relationships to peripheral strata, the mud diapirs can be divided into complicated pierced and simple buried styles, with S-N trending elongations or scattering dots in a plane view. Influenced by mud diapirs, three kinds of normal faults have developed in the overburden. The evolution of mud diapirs experienced three stages: the deposition and weak activity stage before the middle Oligocene, intense rising stage during the late Oligocene and Miocene, and weak activity and buried stage after the Miocene. In addition to the influence exerted by gravitational sliding and differential loading induced from the overburden, the formation of mud diapirs are also subjected to some Atlantic transform faults in the southeast part of the Rio Del Rey Basin and basement faulting activities. The study is helpful to the analysis of the impact of these diapirs upon the development of traps and reservoirs as well as hydrocarbon migration in the basin.

10.11743/ogg20210617