中文摘要：

利用岩心观察、薄片鉴定、粒度分析、古生物鉴定、测井解释及地震分析等资料和手段,在断陷湖盆中识别出一种特殊的沉积模式：洪水-漫湖-下切谷沉积。在层序地层格架内,对惠民凹陷临南地区古近系沙三下亚段进行研究。研究结果表明：沙三下亚段可划分为2个层序。层序一时期,湖盆初始发育,水体不稳定,划分为低位、湖侵和高位3个体系域,发育了洪水-漫湖沉积。低位体系域主要发育洪水水道和砂泥混合坪沉积;湖侵体系域,洪水水道消失,主要以泥坪沉积为主;高位体系域主要以砂坪和砂泥混合坪沉积为主。层序二时期,湖盆逐渐趋于稳定,研究层位沙三下亚段只发育了低位体系域,全区以三角洲前缘沉积为主,细分为水下分流河道、分流间湾、河口砂坝和远砂坝微相,同时,在低位体系域湖平面下降过程中,层序一时期消失的洪水水道复活,在三角洲前缘沉积基础上发育下切谷沉积,分为下切谷水道、水道天然堤和水道间漫溢微相。在纵向上构成洪水-漫湖-下切谷沉积模式。有利砂体主要发育于层序一的砂坪和洪水水道微相,以及层序二的下切谷水道、三角洲前缘水下分流河道、河口砂坝和远砂坝微相。其中砂坪砂体和三角洲前缘砂体连片性较好,洪水水道和下切谷水道砂体为孤立条带状发育。

英文摘要：

A special depositional model, flood-overlake-incised valley, was identified in faulted lake basin by core observation, thin section identification, grain size analysis, fossil identification, log and seismic interpretation. The sedimentary characteristics were studied in the sequence stratigraphic framework from an example of the lower part of the third member of Palaogene Shahejie Formation, Linnan area, Huimin depression. The results show that the stratum of the lower part of the third member of Paleogene Shahejie Formation can be divided into two sequences. During sequence one, the lake basin is in the initial development stage and the water body is unstable. Flood-overlake deposition is developed. Sequence Ⅰ can be further divided into three systems tracts. In the lowstand systems tracts, the flood channel and mixing flat are developed. In the transgressive systems tracts, the flood channel disappears and themain sedimentary microfacies is mud flat. In the highstand systems tracts, sand flat and mixing flat are developed. During sequence Ⅱ, the lake basin becomes more stable and the sedimentary environment becomes normal lake gradually. The studied interval only has the lowstand systems tracts. The sedimentary facies mainly change into the delta front contained microfacies of the underwater distributary channel, the channel mouth bar, the distal bar and the interdistributary estuary. When the lake level drops in the lowstand systems tracts, the earlier disappeared flood channel reactivates as an incised valley which contains microfacies of the incised valley channel, the channel levee and the channel overflowing. The favorable sand mainly deposits in microfacies of the sand flat and the flood channel in sequence Ⅰ and the underwater distributary channel, the channel mouth bar and the distal bar in delta front and incised valley channel in sequence Ⅱ. On the contrary with the isolated channel sand strips, the sand body deposited in sand flat and delta front displays good continuous distribution.