Abstract: The characteristics of the Paleogene sedimentary phase in each system tract in the main sequence of Baiyun Sag were analyzed on the basis of drilling and seismic data,and the seismic phase,seismic velocity,lithology,sedimentary characteristics of paleotography and geography setting of the local area.The research results show that Wenchang sequence and Enping sequence are different in evolution stages.Wenchang sequence was deposited in the faulting period.The shore-shallow lake sedimentary facies developed in the low system tract(LST),and the semi-deep lake sedimentary facies developed in lacustrine-expanding system tract(EST).There were three source systems in the north,southwest and southeast parts,and the fan delta-shallow coastal lake-semi-deep lake sedimentary systems developed in the high system tract(HST).Enping sequence was deposited in the period of transformation from faulting to depression.The channel-filling sediment developed in the high parts of structure in LST,and the shallow coastal lake sediment developed in middle sag of LST.The semi-deep lake sedimentary facies developed in EST.There were two source systems in the north and south parts of HST and also developed(fan) delta-shallow coastal lake-semi-deep lake sedimentary systems.

Key words: Pearl River Mouth Basin, deep-water area, Baiyun Sag, seismic phase, seismic velocity, sedimentary system, sedimentary facies

摘要： 以珠江口盆地白云凹陷钻井和地震资料为基础,根据地震相、地震速度岩性指数、沉积古地形特征和区域地质背景等资料综合分析了白云凹陷古近系主要层序各体系域的沉积相发育特征。研究结果表明,白云凹陷古近系文昌层序与恩平层序是属于两个不同演化阶段的层序。文昌层序是断陷期沉积,低位体系域发育滨浅湖相沉积,湖扩体系域发育中深湖相沉积,高位体系域沉积期有北部、西南部和东南部3个物源体系,发育(扇)三角洲-滨浅湖-中深湖沉积体系。恩平层序属于断陷向坳陷转换期的沉积,低位体系域在构造高部位发育河道充填沉积,在凹陷内发育滨浅湖相沉积;湖扩体系域发育中深湖相沉积;高位体系域沉积期有北部和南部2个物源体系,发育(扇)三角洲-滨浅湖-中深湖沉积体系。

关键词: 珠江口盆地, 深水区, 白云凹陷, 地震相, 地震速度, 沉积体系, 沉积相