苏丹Fula凹陷Fula-Moga变换构造特征分析  

Characteristics analysis of the FulaMoga transfer zone of the Fula sag, Sudan

作　　者：王彦奇 张光亚[1] 魏国齐[1] 陈竹新[1] 任荣[1] 黄彤飞 喻志骅 刘计国[1] 万宜迪 Wang Yanqi;Zhang Guangya;Wei Guoqi;Chen Zhuxin;Ren Rong;Huang Tongfei;Yu Zhihua;Liu Jiguo;Wan Yidi(PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083;School of Earth and Space Sciences,Peking University,Beijing 100871)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]北京大学地球与空间科学学院,北京100871

出　　处：《地质科学》2023年第1期273-288,共16页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：中国石油天然气股份有限公司科技项目(编号:2021DJ0301)资助。

摘　　要：Muglad盆地是中非剪切带南侧的一个中—新生代陆内裂谷盆地,位于该盆地东北部的Fula凹陷内的中央断裂带是最重要的含油气区带之一。受地震资料品质及勘探研究程度限制,前人对于该地区的构造特征及形成演化有着不同的认识。本文基于Fula凹陷地震及钻、测井资料,采用二维及三维断距定量分析技术,对中央断裂带的构造几何特征、断距分布特点及形成演化史进行研究。结果表明:1) Fula凹陷中央断裂带的主干断裂之间的几何关系为背向倾斜,位移变换方式为叠覆式,中部地区以堑垒式结构向东、西两侧过渡,其属于背向叠置型变换构造。2)中央断裂带的主干断裂沿走向分段性明显,每条主干断裂都由数目不等的多条小断层连接而成。其中F1、F3与F2断层分别由2、3与3条小断层首尾相接而成。3)中央断裂带各主干断裂主要从第二期裂陷时开始活动,并在后两期裂陷作用中主干断裂活动强度表现为“由强转弱”的突变特征,同时研究区内伸展作用并不均衡,伸展中心快速向北迁移。The Muglad Basin is a Meso-Cenozoic intracontinental rift basin on the southern side of the Central Africa Shear Zone(CASZ)and the central fault zone in the Fula sag, which is in the northeast of the basin, bears rich hydrocarbon resources. The limitation of the seismic data and the degree of exploration research has led previous scholars to have different understanding of the structural characteristics and evolution of the region. Based on the seismic, drilling and well logging of the Fula sag, the two-and-three-dimensional fault throw quantitative analysis were utilized to study the geometric characteristics, fault throw distribution and formation and evolution history of the central fault zone. Results show that: 1)the relative dip direction of the main faults, F1 and F3,in the central fault zone is divergent. The map position of the fault relative to the other is overlapping.The tectonic style in the middle section is a “graben-horst” combination. Hence the Fula-Moga transfer zone belongs to the divergent-overlapping type. 2)The main faults of the central fault zone are obviously segmented along strike, which are connected by a handful of modest faults. The main faults F1, F3, and F2 are laterally connected by 2, 3, and 3 minor faults, respectively. 3)The main faults comprising the central fault zone have been active mainly since the second rifting, and above faults weakened abruptly in activity intensity during the transition period between the last two riftings. During these two riftings, the extension in the study area was uneven, and the extensional center moved northward rapidly.

关 键 词：几何特征 断层分段生长 断距回剥 Fula-Moga变换构造 Fula凹陷 Muglad盆地 非洲 

分 类 号：P542[天文地球—构造地质学]