北京北部上侏罗统辫状河体系沉积特征  

Sedimentary Characteristic of Braided River of Upper Jurassic Outcrops in North of Beijing

作　　者：郭佳[1] 邓宏文[1] 季春辉[1] 秦雁群[1] 

机构地区：[1]中国地质大学能源学院,北京100083

出　　处：《现代地质》2011年第4期642-649,共8页Geoscience

基　　金：国家"十一五"重大专项项目(2009ZX05009-002)

摘　　要：根据野外露头的沉积构造和沉积层序特征,对北京北部延庆硅化木国家地质公园上侏罗统后城组进行沉积相研究,认为该地区以辫状河沉积为主,构成辫状河体系的4种沉积微相类型包括河道、心滩、河间湖泊和溢岸沉积,其中的溢岸沉积相当于曲流河中发育的决口河道与决口扇沉积。运用基准面旋回变化原理,识别出了2个中期旋回和构成中期旋回的多个短期旋回。总结了基准面旋回特征,阐明了地层叠加样式随A/S(可容纳空间/沉积物供给)比值的变化规律,认为低A/S比值时,河道砂体的连通性较好,而高A/S比值时,河道较孤立,连通性较差;且溢岸沉积的地层厚度随着A/S比值的增加不断增大,溢岸沉积的厚度可以作为判断可容纳空间大小的一个依据。The sedimentary facies of the Upper Jurassic Houcheng Formation silicified wood outcrops in north of Yanqing area are interpreted jointly with sedimentary structure and characters of sedimentary sequence.This area mainly developed braided river deposits.The main sedimentary microfacies include channel,channel bar,pond and overflow deposits.Two stratigraphic cycles of increasing and decreasing accommodation/sediment supply（A/S） regimes are identified.The two mid-term cycles are divided into several short-term cycles.This paper summarized the characteristics of base-level cycle,and clarified how the stratigraphic stacking pattern changed with different A/S ratios.The connectivity of channel sand is good under low A/S ratio and vice versa.The thickness of overflow deposits can be seen as the judgment basis of accommodation as it increases with rising A/S ratio.

关 键 词：辫状河 露头 沉积特征 基准面旋回 地层叠加样式 A/S比值 溢岸沉积 

分 类 号：TE121[石油与天然气工程—油气勘探]