| 东营凹陷孔一段“红-灰”岩层旋回沉积记录:以王家岗地区王46井为例 |
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| 引用本文： | 年涛,姜在兴,刘惠民,黄壹铭,邓有根,孟嘉轶,李扬.东营凹陷孔一段“红-灰”岩层旋回沉积记录:以王家岗地区王46井为例[J].地质科技通报,2022,41(3):32-43. |
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| 作者姓名： | 年涛 姜在兴 刘惠民 黄壹铭 邓有根 孟嘉轶 李扬 |
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| 基金项目： | 国家科技重大专项2016ZX05056国家自然科学基金项目42072140油气资源与探测国家重点实验室开放课题基金PRP/open-2102陕西省教育厅科研计划项目20JK0850 |
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| 摘 要： | 渤海湾盆地东营凹陷始新统孔店组一段(孔一段)发育了垂向叠置的“红-灰”组合岩层，并呈现出一定的旋回沉积特征。为了深入了解该地层的沉积过程及其对古气候变化的响应，研究以东营凹陷王家岗地区重点探井王46井为例，基于年代地层格架的约束，利用岩心、录井和自然伽马测井曲线对孔一段进行了旋回沉积记录的研究，揭示了地层的旋回沉积过程。红层响应于洪水漫湖产生的漫湖泥和漫湖砂滩，而灰绿色韵律层属于间歇性湿润期的浅湖砂滩沉积，二者在垂向上突变接触。伽马曲线的连续小波分析和频谱分析表明该地层的沉积过程受控于米兰科维奇天文旋回的偏心率和岁差周期，造成的旋回地层厚度分别为39.4 m和6.9 m。通过对125 ka的偏心率周期进行带通滤波，建立了孔一段的“浮动”天文年代标尺。孔一段共记录了33个偏心率周期，判定的沉积时限约为4.13 Ma，地层的视平均沉积速率在0.236~0.408 m/ka之间变化。偏心率和岁差旋回对地层沉积的控制表现为偏心率为极大值时，间歇性湖泊沉积频繁发生，反之则以洪水漫湖沉积为主，同时岁差的极小值对应了间歇性湖泊沉积，反之则主要发生了洪水漫湖沉积。
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| 关 键 词： | 东营凹陷 始新统 旋回沉积 轨道参数 红层 |
| 收稿时间： | 2021-06-28 |
Cyclic sedimentary record of "red-greyish green" beds in the first Member of Eocene Kongdian Formation(Ek1), Dongying Sag: An example from the Well Wang 46 in Wangjiagang area |
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| Abstract: | Vertically superimposed "red-greyish green" assemblages are developed in the first member of the Eocene Kongdian Formation (Kong1 member) in the Dongying sag of the Bohai Bay Basin, showing certain cyclic sedimentary characteristics.Inorder to better understand its depositional process and response to paleoclimate variation, the study took the Wang 46 well, which is located in the Wangjiagang area, as an example.Calibrated by the stratigraphic ages, cyclostratigraphy analysis has been conducted in the formation using cores, logging cuttings and gammaray(GR) curve to reveal its cyclic depositional process.The red beds correspond to flooded lacustrinemud and sandy beach deposited during flood events, while the greyish greenrhythm beds belong to the shallow lacustrine sand beach sediments in the intermittent wet period, and the two types of deposits are superposed with abrupt contacts.The continuous wavelet and spectral analysis of the GR curve indicate that the depositional process of the Ek1 member is controlled by the Milankovitch eccentricity and precession cycles, resulting in the thicknesses of the cyclically deposited formations are 39.4 m and 6.9 m, respectively.The "floating" astronomical time scale of the Ek1 member has been established by the band filtering of the 125 ka eccentricity cycle, and the Ek1 member is found to have 33 eccentricity cycles.The apparent average deposition rate changes between 0.236 m/ka and 0.408 m/ka.The eccentricity and precession cycles have controlled the depositional process: the maximum eccentricities mainly correspond to frequent occurrences of temporary lacustrine, on the contrary, it mainly developed flooded lacustrine.And, the temporary and perennial flooded lacustrine occurred during the periodsof minimum and maximum precessions, respectively. |
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