东营凹陷南部古近系沙四下亚段米兰科维奇旋回驱动的湖盆环境演化与沉积响应  

Environmental evolution and sedimentary response of lake basins driven by Milankovitch cycles in the lower sub-member of Member 4 of Paleogene Shahejie Formation,Southern Dongying Sag

作　　者：李荣堃 操应长[1] 林敉若 王艳忠[1] 焦红岩 LI Rongkun;CAO Yingchang;LIN Miruo;WANG Yanzhong;JIAO Hongyan(School of Geosciences in China University of Petroleum(East China),Qingdao 266580,China;Xianhe Oil Production Plant,Shengli Oilfield Company,SINOPEC,Dongying 257237,China)

机构地区：[1]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [2]中石化胜利油田分公司现河采油厂,山东东营257237

出　　处：《中国石油大学学报(自然科学版)》2025年第2期28-41,共14页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家自然科学基金项目(42488101,42072161)。

摘　　要：针对米兰科维奇旋回驱动的滨浅湖环境演化及细粒物质沉积过程尚不明确的关键问题,以东营凹陷南部沙四下亚段滨浅湖细粒沉积岩为研究对象,综合运用岩石学分析、孢粉和元素地球化学分析、频谱和小波分析等手段,识别出稳定的米兰科维奇旋回信号,揭示长、短偏心率及斜率周期共同驱动的滨浅湖环境演化及其对细粒物质沉积作用的控制。结果表明,在长、短偏心率负相位叠加引起的相对干旱期,季节性较弱且湖平面整体较低,浅水三角洲大面积发育,斜率升高引起的短暂湖平面上升将促使浅水三角洲向湖盆南缘周期性退积,导致水下分流河道微相的薄层粉细砂岩与滩席微相的厚层泥岩交替沉积;当浅水三角洲不发育时,滨浅湖环境中粉砂级沉积物供给不足,主要发育泥坪微相的厚层泥岩;而斜率升高引起的短暂湿润气候将触发洪水事件,导致粉砂级细粒物质随洪水进入湖盆,并在湖浪改造下堆积形成砂坪微相的薄层粉砂岩。在长、短偏心率正相位叠加引起的相对潮湿期,季节性较强且湖平面整体较高,季风作用下的沿岸流易于改造浅水三角洲砂体,导致滨浅湖环境主要发育滩坝沉积,斜率周期驱动的高频湖平面波动将进一步引起滩脊微相的薄层粉砂岩与滩席微相的厚层泥岩频繁更替。在长偏心率正(负)相位与短偏心率负(正)相位叠加引起的气候过渡期,湖泊水位整体高于相对干旱期但低于相对潮湿期,季节性一般,斜率周期驱动的高频湖平面波动主要引起河口坝微相的薄层粉砂岩与滩席微相的厚层泥岩交替沉积。The evolution of sedimentary environments driven by astronomical cycle in shallow lakes,along with the depositional processes of fine-grained sediments,remains unclear.In this study,comprehensive analyses of petrology,palynology and geochemistry,as well as spectral and wavelet analyses,have been conducted on shallow-lacustrine sediments from the lower fourth Member of Shahejie Formation in the southern Dongying Sag.The influences of eccentricity and obliquity on the evolution of sedimentary environment and the deposition of fine-grained sediments were elucidated.During arid periods driven by the negative-phase superposition of long and short eccentricity,lake levels fell,and seasonality was weak,leading to the widespread development of shallow-water deltas.On this basis,a temporary lake-level rise caused by increased obliquity further induced the periodic retrogradation of the shallow-water delta toward the southern edge of the basin.These processes ultimately resulted in the alternating deposition of thin-bedded silty fine sandstones(from underwater distributary channels)and thick-bedded mudstones(from beach mats).When shallow water deltas were poorly developed,the supply of silt-grained sediments was insufficient,leading to deposition of thick-bedded mudstones(from mud flats)in the shallow-lacustrine environment.Subsequently,transient humid climates driven by increased obliquity triggerred flood events that transported silt-grained sediments into the shallow-lake environment.Lake waves further reworked these sediments,forming siltstones(from sand flats).During humid periods driven by the positive-phase superposition of long and short eccentricity,lake levels rose,and seasonality was strong.Coastal currents,influenced by monsoons,reshaped the shallow-water delta,leading to formation of beach bars in the shallow-lake environment.Additionally,high-frequent lake-level fluctuations driven by obliquity resulted in the alternating deposition of thin-bedded siltstones(from beach bars)and thickly-bedded mudstones(from b

关 键 词：米兰科维奇旋回 东营凹陷 滨浅湖 细粒沉积岩 沉积环境 

分 类 号：TE122[石油与天然气工程—油气勘探]