东营凹陷南坡沙四上亚段滩坝砂体的 沉积特征及模式

Sedimentary characteristics and models of beach-bar sandbodies in the upper part of the fourth member of Paleogene in the south slope of Dongying depression

关键词:  滩坝  沉积特征  沉积模式  东营凹陷

Key words:  beach-bar  sedimentary characteristics  sedimentary model  Dongying depression

摘要:

东营凹陷南坡古近系沙河街组沙四上亚段沉积时期广泛发育滨浅湖滩坝砂体沉积。在钻井岩心描述及其相 关测试分析的基础上,结合录井、测井等资料的综合分析和古地形研究，系统探讨滨浅湖滩坝砂体的沉积特征和沉 积模式。结果表明:滨浅湖滩坝砂体以细砂岩、粉砂岩为主,其中石英含量中等,长石和岩屑含量较高，粒度概率曲 线以发育跳跃和悬浮组分的两段式为主，沉积构造以浪成交错层理、浪成波痕、生物扰动等为特征，且沉积相序主要 为反序、复合相序;根据滩坝砂体的沉积特征和空间分布,可划分出坝亚相和滩亚相，其中坝亚相又可划分出坝主 体、坝侧缘微相，滩亚相又可划分出滩脊、滩席微相。

Abstract:

During the period of the upper part of the fourth member of Shahejie formation ( Es4 ) of Paleogene, the south slope of Dongying depression developed abundant beach-bar sandbodies. Based on the description and its associated test and analysis of the cores combined with the analysis of logging data and paleotopography, the sedimentary characteristics and models of beach-bar sandbodies in shore-shallow lacustrine were systematically summarized. The lithology of beach-bar sandbodies is mainly fine sandstone and siltstone. The quartz content in beach-bar sandstones is middle level，and the feldspar content and the lithic content are relatively high. The grain size probability curves are mainly two-segment of contents bouncing population and suspension population. Sedimentary structures are characterized by wave-cross bedding t wave-generated ripple and bio-turbation, and the sedimentary facies sequences are characterized by reverse grading and composite grading. According to the sedimentary and distribution characteristics, beach-bar sandbodies can be divided into bar subfacies and beach subfacies. And the former includes main body of bar microfacies and margin of bar microfacies, while the latter includes beach ridge microfacies and beach mat microfacies.