珠江口盆地白云北坡珠江组下部陆架边缘沉积演化

Sedimentary Evolution of the Lower Zhujiang Group Continental Shelf Edge in the North Slope of Baiyun Sag,Pearl River Mouth Basin

根据层序地层学理论,运用地震相、地震沉积学等分析手段,结合钻井、测井等资料,对珠江口盆地白云北坡珠江组下部的沉积演化进行了研究,研究发现：珠江组下部发育陆架边缘三角洲海相沉积体系,地震剖面中陆架边缘三角洲前缘分布在Y2井区及以南区域,平面上呈菱形,其两侧发育改造的滨海砂坝,南部发育斜坡浊积扇,这三者形成了海退体系中的主要岩性圈闭;X1、Y1井区及以北发育海进体系中的滨海砂坝圈闭.海平面升降、物源供给和构造古地貌对沉积演化和圈闭形成过程中起明显的控制作用.21.0～19.0 Ma期间,海平面下降和河流回春作用是形成陆架边缘三角洲的主要原因,构造古地貌及其控制的古水深控制了相带展布与边界.

According to the theory of sequence stratigraphy, using analysis methods such as seismic facies, seismic sedimentology and combining the drilling and logging datas, a study was conducted to the sedimentary evolution of the north slope of the Baiyun Pearl River Mouth Basin. Results show that the lower part of Zhujiang Group mainly develops the shelf edge deltaic and marine deposit, the shelf edge delta developed in the Y2 wells area and the southern in the seismic profiles. The plane shape of the delta front is like diamond. Both wings sides of the delta front develop coastal sand dam and the south develop slope turbidite fan. All the three sedimentary bodies form the main trap type of the regressive systems.Sea level change, sediment supply and ancient landform control the sediment evolution and the trap formation. During 21-19 Ma, sea level decline and the Pierl River rejuvenation caused the formation of shelf edge delta and the ancient landform affected the sediment facies distribution and boundary.