珠江口盆地番禺4洼古近系文昌组三元地震构形解释技术

在源-汇系统格架下，以地震构形分析为基础，对珠江口盆地番禺4洼古近系文昌组沉积相、古地貌和地震构形属性切片进行了研究，划分了沉积单元，定性—半定量指出了各沉积单元边界，并优选了2个勘探潜力区带。研究结果表明： ①珠江口盆地番禺4洼古近系文昌组源-汇系统分为3类，西北部发育缓坡发散型源-汇系统，纵向上呈扇三角洲—湖泊—辫状河三角洲动态演化特征，地震上由中—强反射过渡到中—弱振幅平行反射，再演变为高频中振幅前积反射；西南部发育长轴汇聚型源-汇系统，辫状河三角洲稳定发育，以楔状展布为主；陡坡平行型源-汇系统在控洼断层上盘发育多期叠置的扇三角洲沉积，整体上呈楔形，反映了物源充沛背景下的扇三角洲平原—前缘的沉积特征。②研究区文昌组沉积期的古地貌整体上具有“东断西超”的格局，文五段—文四段沉积期，研究区为强烈断陷期，局部构造运动使西北和东南抬升，中部形成了构造脊和2个次洼；文三段—文二段沉积期，进入断坳期，沉积中心整体向东迁移，湖盆萎缩，西部遭受剥蚀。③研究区缓坡发散型源-汇区发育7个沉积单元，主要为扇三角洲前缘叠置连片的水下分流河道和薄层席状砂；长轴汇聚型源-汇区发育4个沉积单元，以辫状河三角洲前缘水下分流河道和分布广泛的前缘席状砂为主；陡坡平行源-汇区发育水下扇、扇三角洲前缘和浊积扇等4个沉积单元。④西南部的长轴汇聚型源-汇系统和西北部缓坡发散型源-汇系统为研究区的勘探潜力区。

Ternary seismic configuration interpretation technology of Paleogene Wenchang Formation in Panyu 4 depression,Pearl River Mouth Basin

Under the framework of source-to-sink system, the sedimentary facies, palaeogeomorphology and seismic configuration attribute slices of Paleogene Wenchang Formation in Panyu 4 depression of the Pearl River Mouth Basin were studied based on seismic configuration analysis, the sedimentary units were divided, the boundaries of each sedimentary unit were defined qualitatively and semi quantitatively, and two exploration potential zones were selected. The results show that:(1) Three types of source-to-sink systems of Paleogene Wenchang Formation were found in Panyu 4 depression of the Pearl River Mouth Basin. A gentle slope divergent source-to-sink system is developed in the northwest, which is characterized by the dynamic evolution of fan delta, lake and braided river delta in the vertical direction, and the seismic configuration changes from medium-strong reflection sheet filling to medium-weak amplitude parallel reflection, and then to high-frequency medium amplitude progradation reflection. A long axis convergent source-to-sink system is developed in the southwest, and the braided river delta is developed stably, which is mainly wedge-shaped in configuration. A steep slope parallel source-to-sink system is developed in the hanging wall of fault controlling depression with stable multi-stage overlapped fan delta, which is generally characterized by a wedge-shaped configuration, reflecting the sedimentary characteristics of fan delta plain-front under the background of abundant sources.(2) The sedimentary palaeogeomorphology of Wenchang Formation in the study area is generally faulted in the east and superposed in the west. During the deposition of the fifth and fourth members of Wenchang Formation, it was in a strong fault depression period. Local tectonic movement raised the northwest and southeast, and a structural ridge and two sub depressions formed in the central part. During the deposition of the third and second member of Wenshan Formation, it entered fault depression period, the sedimentation center moved eastward as a whole, the lake basin shrank, and the western strata were denuded.(3) Seven sedimentary units are developed in the gentle slope divergent source-to-sink area of the study area, which are mainly superimposed underwater distributary channels and thin sheet sand in fan delta front. Four sedimentary units are developed in the long axis convergent source-to-sink area, which are dominated by underwater distributary channels and widely distributed front sheet sand in braided river delta front. In the steep slope parallel source-to-sink area, there are four sedimentary units, including underwater fan, fan delta front, turbidite fan.(4) The long axis convergent source-to-sink system in the southwest and the gentle slope divergent source-to-sink system in the northwest are the exploration potential areas in the study area.