纪晓琳^1,,
王万银^1,,,
杜向东²,
鲁宝亮¹,
黄兴文²,
冯旭亮^1,3,
郭允²
1. 长安大学重磁方法技术研究所, 长安大学地质工程与测绘学院, 长安大学西部矿产资源与地质工程教育部重点实验室, 西安 710054
2. 中海油研究总院, 北京 100027
3. 西安石油大学地球科学与工程学院, 西安 710065


详细信息

作者简介: 纪晓琳, 女, 1986年生, 工程师, 博士, 主要从事重、磁位场理论及应用研究和教学工作.E-mail:jixl@chd.edu.cn

通讯作者: 王万银, 男, 1962年生, 博士, 教授, 博士生导师, 主要从事重、磁位场理论及应用研究和教学工作.E-mail:wwy7902@chd.edu.cn

中图分类号: P631

收稿日期:2017-09-04
修回日期:2019-02-02
上线日期:2019-04-05

Tectonic division by gravity and magnetic anomaly data of salt-bearing basins, south-central section of West Africa

JI XiaoLin^1,,
WANG WanYin^1,,,
DU XiangDong²,
LU BaoLiang¹,
HUANG XingWen²,
FENG XuLiang^1,3,
GUO Yun²
1. Institue of Gravity and Magnetic Tecnology, School of Geology Engineering and Geomatics, Chang'an University, Key Laboratory of Western China's Mineral Resources and Geological Engineering, Ministry of Education, Chang'an University, Xi'an 710054, China
2. Exploration Department of CNOOC China Limited, Beijing 100027, China
3. School of Earth Sciences and Engineering, Xi'an Shiyou University, Xi'an 710065, China


More Information

Corresponding author: WANG WanYin,E-mail:wwy7902@chd.edu.cn

MSC: P631

--> Received Date: 04 September 2017
Revised Date: 02 February 2019
Available Online: 05 April 2019


摘要
摘要:西非中南段含盐盆地位于大西洋东岸浅海区，在构造演化的过渡阶段形成了巨厚的Aptian期蒸发盐岩，将该区分为盐上层、盐层和盐下层三个构造层序.而盐岩的遮蔽效应使得盐下层地震反射品质差、盐下层序研究程度低，致使裂谷主控断裂、裂谷规模及展布形态不清楚.本文利用重、磁资料覆盖面广、横向分辨能力强、受盐岩影响小的优势，结合地震及地质资料，研究了西非中南段含盐盆地盐下构造格局.通过研究表明，西非中南段含盐盆地整体呈现"东西分带，南北分块"的构造特征；重新厘定了里奥穆尼、加蓬、下刚果和宽扎4个含盐盆地边界；识别了2个盐下裂谷带及其内部28个盐下凹陷，盐下凹陷呈现垒堑相间的结构特征；推断了盐下一级断裂16条，二级断裂23条，呈现"东西拉张，北东走滑"的力学特征.该项研究成果为该区盐下地震层序再解释、盐下油气战略选区及下一步勘探部署提供了地球物理依据.
关键词: 西非中南段/
含盐盆地/
盐下裂谷/
盐下断裂/
最小曲率/
位场分离

Abstract:The salt-bearing basins in south-central section of West Africa are located on the east coast of the Atlantic Ocean. The thick salt rock formed during the Aptian period that happened at the transition stage of structural evolution, which is divided into three tectonic sequences:upper salt layer, salt layer and lower salt layer. It is a big challenge to research the major faults that control the boundaries of rifts and morphological dimensions of rifts based on the poor-quality seismic reflection data that is influenced by the shading effect of salt rock. In this paper, we study the subsalt structure of salt-bearing basins in this region using gravity and magnetic anomaly data which have several advantages such as wide area coverage, strong horizontal resolution and less effect from salt rock. In addition, combining the seismic reflection and geologic data, we further study the tectoniv pattern of subsalt in this area. Results suggest that the salt-bearing basins in south-central section of West Africa are characterized by "zones in east-west and blocks in south-north". The boundaries of Rio Muni Basin, Gabon Basin, Lower Congo Basin and Kwanza Basin are redefined. Two subsalt rifts and 28 subsalt sags are identiflied, where are present alternating uplifts and depressions. We also infer 16 first-order and 23 second-order subsalt faults, which exhibit "extension in east-west and strike-slip in north-east". The results of this study provide geophysical supports to the seismic sequence reanalysis, choosing exploration areas of subsalt oil and gas and the exploration deployment in the next step.
Key words:South-central section of West Africa/
Salt-bearing basins/
Subsalt rifts/
Subsalt fault/
The minimum curvature technique/
Potential field data separation



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