东营凹陷盐家地区砂砾岩体沉积期次精细划分与对比

东营凹陷盐家地区沙河街组四段上亚段（简称沙四上亚段）重力流舌状体式叠覆沉积的砂砾岩体不具备“层状”地层特征，应用常规方法进行沉积旋回划分和对比很难保证时间上的等时性。针对该问题，引入天文地层学中气候旋回受天文周期驱动的理论，研究砂砾岩体的形成条件及控制因素，对砂砾岩体进行时间域的等时性控制，然后在相同的时间域内进行旋回界面的识别与旋回对比。通过对研究区砂砾岩沉积进行米兰科维奇旋回特征分析，确定研究区地层旋回主要受偏心率周期控制，并计算得出第一优势旋回厚度为151.7 m和第二优势旋回厚度为61.4 m。以米兰科维奇旋回分析结果为主，同时结合层序地层学基准面旋回理论，根据岩心和成像测井相层序分析，确定地层划分方案，将研究区沙四上亚段划分为4个四级层序和11个五级层序。以优势旋回频率信息对测井曲线进行滤波处理，同时根据基准面旋回特征，以滤波后的曲线为依据进行地层旋回的横向对比，建立了地层旋回对比格架，实现砂砾岩体沉积期次的精细划分与对比。

Fine division and correlation of conglomerate sedimentary cycles in Yanjia area of Dongying depression

The conglomerate in gravity-flow linguloid overlapped deposits of the upper sub-member of Member Sha-4 in Yanjia area of Dongying depression has no “stratified” layers, thus it is difficult to guarantee the isochroneity of the conglomerate through conventional depositional cycle division and correlation. In order to solve this problem, we studied formation conditions and controlling factors of the conglomerate by introducing a theory of astronomic stratigraphy that climatic cycles are driven by astronomic cycles. When the time domain of the conglomerate was isochronously defined, the identification of cyclic boundaries and the correlation of cycles could be achieved within an identical time domain. Through the Milankovitch cycle characteristic analysis on conglomerate deposits in the study area, the eccentricity cycle was determined to predominate stratigraphic cycles of strata in the study area, and the thickness of the first and second dominant cycles was calculated to be 151.7 m and 61.4 m, respectively. On the basis of the result from the Milankovitch cycle analysis and in combination with a base level cycle theory of sequence stratigraphy, a formation division scheme was determined according to sequence analysis of core and FMI data, and deposits of the upper sub-member of Member Sha-4 in the study area were divided into 4 circles of the fourth-grade sequence and 11 circles of the fifth-grade sequence. The Minlankovitch curve was obtained by filter analysis on the frequency information of dominant cycles, and on the basis of characteristics of base level cycles, a lateral correlation of formation cycles was made through filtered curves. A correlation framework of formation sequences and cycles was then established, and it makes the high-resolution division and correlation of depositional episodes of the conglomerate come true.