黄河口凹陷明化镇组下段网状浅水三角洲沉积

为了认识湖盆萎缩期网状浅水三角洲的沉积特征和沉积模式，利用测井、录井、取芯、粒度、地震等资料，对黄河口凹陷明化镇组下段低位域地层进行了分析。研究认为，黄河口凹陷明化镇组下段低位域网状浅水三角洲河道砂体主要是垂向加积作用的产物，河道平面上呈网状、交织状，具有宽深比小、稳定性强等特点，砂体发育程度中等；其形成于低坡降背景，三角洲平原和前缘相带均有网状河道发育，河道呈花状，沉积微相类型多样，天然堤、河漫滩、席状砂等溢岸沉积物大量发育，形成以溢岸沉积物为主的“河道花”模式。网状浅水三角洲河道两侧均发育天然堤，增加了其侧向稳定性，决口改道是形成新河道的主要机理。

Anastomosed Shallow-water Delta of the Lower Member of Minghuazhen Formation in Huanghekou Sag

In order to understand the sedimentary model of anastomosed shallow-water delta during the shrinking period of a lake basin,the study analysed the lower Member of Minghuazhen Formation of the Huanghekou Sag integrating well logging,mud logging,core,grain size analysis and seismic data.The results indicate that the sand body of the anastomosed shallow-water delta in the lower Member of Minghuazhen Formation of the Huanghekou Sag is mainly a product of vertical accretion.The river channel is net-like and interlaced,with a small width-to-depth ratio and a strong stability,and sand bodies are moderately developed.It′s formed in the low slope where network channels develop both in the delta plain and the delta front facies.The channels are flower-like,and the sedimentary microfacies.The natural levees,floodplains and sheet sands account for most sediments.The formation process is the model of“channels flower-like”dominated by overbank sediments.From the formation mechanism,natural levees are developed on both sides of the anastomosed shallow-water delta,which increase lateral stability,and the diversion is the main mechanism for the forming of new channels.