白云-荔湾凹陷珠江组大型深水水道体系沉积特征及成因机制
Sedimentary Characteristics and Genesis of the Deepwater Channel System in Zhujiang Formation of BaiyunLiwan Sag

深水水道体系是近年来在白云-荔湾凹陷东缘珠江组上段深海泥岩背景中新发现的大型深水沉积体系，但是其沉积特征、沉积过程与主控因素尚不清楚.综合利用大量二维、三维地震数据以及钻井、测井资料，揭示了白云-荔湾凹陷东缘珠江组大型深水水道体系的沉积要素构成、外部几何形态、内部充填结构及其沉积演化.在此基础上，进一步探讨了物源供给、陆架坡折带、古地貌对深水水道体系的控制作用，明确了其主控因素，提出了“源貌共控”的成因机制.研究表明珠江组大型深水水道体系由水道、天然堤和朵叶3种沉积要素构成，并以水道为主体.从北至南可依次细分为白云凹陷段、南部隆起段和荔湾凹陷段，其中白云凹陷段以侵蚀型水道为主，南部隆起段以侵蚀-加积型水道为主，荔湾凹陷段以加积型水道为主，在空间上构成了重力流流体能量逐级递减的“三级水道”充填演化特征.3个分段水道内部均可识别出两期水道事件，且充填样式各具特征.珠江组深水水道体系的发育与展布受北部珠江三角洲体系、陆架坡折带和限制性地貌3大因素共同控制.
The deepwater channel system is a largescale deepwater sedimentary system which was newly found in abyssal mudstone of the upper Zhujiang Formation, eastern margin of BaiyunLiwan sag in recent years. However, its sedimentary characteristics, sedimentary processes and main controlling factors are unclear yet.Based on substantial 2D, 3D seismic and well logging data, the depositional elements, geometry, internal architecture and sedimentary evolution of the deepwater channel system in Miocene Zhujiang Formation of BaiyunLiwan sag were studied. In addition, the source supply, shelf break belt, palaeogeomorphology and their controlling effects on distribution, internal architecture and evolution of the deepwater channel system were discussed. Finally, the genetic mechanism of it was built.The results show that the deepwater channel system consists of channel, levee, and lobe, and channel is the primary depositional element. The deepwater channel can be subdivided into Baiyun sag segment, southern uplift segment and Liwan sag segment from north to south,which is mainly erosional channel, erosionalaggradational channel and aggradational channel, respectively. And it presents an evolutionary characteristic of “thirdorder channel” from north to south because the energy of gravity flow weakened by descending order. Two periods of channel evolution in vertical succession can be identified in each segment by identifying secondary erosional surfaces in the interior of channel. And there are distinctive internal filling properties in different channel evolution and different segments because of different fillings and transformation processes. The formation and development of deepwater channel system resulted from the interaction between the northern Pearl River Delta, shelf break belt and restricted paleotopography in eastern BaiyunLiwan sag.