尼日尔三角洲深水区层序地层及地震相研究

中新世至上新世，研究区发育深海平原和陆坡坡脚沉积。缺少反映海平面变化的上超特征和削截现象，很难利用地震反射终止类型（上超、顶超、削截）进行层序界面识别。文中利用深水区沉积旋回的地震相特征差异进行层序界面识别，并建立了研究区层序演化模式:低位体系域发育重力流沉积（块状搬运复合体、浊积扇）———海侵高位体系域深海泥质发育。以层序为格架进行地震相和沉积相在时间和空间分布特征分析。研究区识别出两类叠加地 震相样式:杂乱反射块状搬运复合体———丘形水道—堤岸复合体（浊积扇）———平行反射深海泥质沉积；丘形水道—堤岸复合体（浊积扇）———平行反射深海泥质沉积。

Study on Sequence Stratigraphy and Seismic Facies in Deep-water Niger Delta

The strata of Miocene and Pliocene in the study area deposit in the deepsea plain and toe of slope.Characters of the onlap and truncation which represent eustasy cannot be recognized in seismic data.It is difficult to recognize the sequence boundary with seismic termination such as onlap,toplap and truncation.In this paper,the sequence boundary can be identified by characters in seismic facies of sedimentary cycle.Model of sequence evolution,LST developing gravity flow deposition(mass-transport complex and turbidite fan),T-HST developing deep sea mud,has been built up.Characters of seismic facies and sedimentary facies are analyzed in sequences.Two seismic facies stacking pattern have been recognized in the study area: chaotic mass-transport complexes overlain by hummocky channel-levee complexes(turbidite fan) and capped by parallel to subparallel hemipelagic drape complexes;hummocky channel-levee complexes(turbidite fan) and capped by parallel to subparallel hemipelagic drape complexes.