海底麻坑表征及成因研究——以尼日尔三角洲为例

Characteristics and genesis of submarine pockmarks--A case from the Niger Delta

基于西非几内亚湾尼日尔三角洲盆地研究区约1300 km2的高分辨率三维地震资料,研究麻坑的剖面特征、平面展布形态、麻坑与水道的关系、麻坑的成因。通过对目的层位的精细解释及多种地震属性提取的方法,在研究区西北部发现了75个麻坑,在海底水道上方发现了56个麻坑,以及在研究区其他区域分布的62个麻坑。研究区主要有条带状麻坑、复合麻坑和孤立麻坑三种麻坑样式。麻坑的成因和分布模式受埋藏水道段侵蚀和切割的影响,麻坑下方地层中相应的浊积水道产生流体,流体向上运移导致地层不连续,进而对麻坑的形成和分布产生影响。根据麻坑下方地层特征和充填模式,将麻坑的成因分为古水道成因和断裂成因。

Based on the high-resolution three-dimensional seismic data of about 1300 km2 acquired from the Niger Delta Basin of the Gulf of Guinea in West Africa,studied in this paper are the temporal and spatial distribution patterns of pockmarks,the relationship between pockmarks and sea bottom channels,and the genesis of various types of pockmarks.Through the fine interpretation of the target horizon and the extraction of various seismic attributes,there have found 75 pockmarks in the northwest of the study area,56 pockmarks found above channels,and 62 pockmarks distributed in other parts of the study area.There are three types of pockmarks,such as pockmarks in belts,complex pockmarks and isolated pockmarks.The causes and distribution patterns of pockmarks are affected by the erosion and cutting of buried channel sections.The corresponding turbidity channels in the stratum below the pockmarks produce fluids.The upward migration of fluids causes the stratum to be discontinuous,which in turn affects the stratum and distribution of pockmarks.According to the stratigraphic characteristics and filling mode,the genesis of pockmarks is classified into ancient channel genesis and fault genesis.