| 河南东濮凹陷古近系沙三中亚段重力流沉积与伴生遗迹化石组合 |
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| 引用本文： | 张洪安,王长征,蒋飞虎,靳亚勤,胡斌.河南东濮凹陷古近系沙三中亚段重力流沉积与伴生遗迹化石组合[J].古地理学报,2020,22(6):1157-1170. |
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| 作者姓名： | 张洪安 王长征 蒋飞虎 靳亚勤 胡斌 |
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| 作者单位： | 1. 中国石化中原油田分公司,河南濮阳 457001;2. 河南理工大学资源环境学院,河南焦作 454003;3. 中原经济区煤层(页岩)气河南省协同创新中心,河南焦作 454003 |
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| 基金项目： | 国家科技重大专项(编号: 2016ZX05006-004)和河南省自然科学基金项目(编号: 13181012)共同资助; |
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| 摘 要： | 基于对东濮凹陷97口钻井岩心的详细观察和分析,在古近系沙河街组沙三中亚段湖相沉积中识别出滑动、滑塌、碎屑流和浊流共4种类型的重力流沉积。各种类型沉积的主要判识特征如下: (1)滑动沉积以保留部分原始沉积构造、层内准同生小型断裂构造及较大角度的地层倾角(陡倾构造)发育、伴生Skolithos-Palaeophycus遗迹组合或Planolites-Taenidium遗迹组合为主要特征; (2)滑塌沉积以砂岩层顶、底面均与暗色泥岩呈突变接触以及岩层内部发育各种同生软沉积物变形构造(如包卷层理、火焰状构造、泄水构造、液化脉和各种撕裂屑等)为主要鉴别特征;(3)碎屑流沉积以砂岩呈块状构造、顶部发育漂浮砾石、底部泥岩撕裂屑发育并可见“泥包砾”现象、砂岩顶、底面均与暗色泥岩突变接触为特征;滑塌沉积和碎屑流沉积序列的上部常常伴生Mermoides-Parapaleodictyon遗迹组合; (4)浊流沉积以发育完整或不完整的鲍马序列为主要特征,浊积砂体下部见正粒序层理,底面见有冲刷痕、不规则槽模、重荷模等沉积构造,中上部发育深湖沉积中常见的Semirotundichnus-Puyangichnus遗迹组合。综合分析上述各种重力流沉积特征和伴生遗迹化石组合所体现的水深变化规律,认为遗迹化石组合随着湖水深度的增加呈分带性,与重力流沉积随水深增加而出现的滑动—滑塌—碎屑流—浊流沉积序列具有明显的一致性,且伴随重力流沉积而产生的生物扰动作用是增强的。因此,生物扰动构造(遗迹化石)的研究不仅对湖相沉积中储集层物性的分析具有重要意义,而且针对重力流沉积类型的判识还能提供重要的生物遗迹学信息。
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| 关 键 词： | 东濮凹陷 沙河街组 重力流沉积 遗迹化石组合 生物扰动构造 |
| 收稿时间： | 2020-02-23 |
Gravity flow deposits associating with ichnoassemblages within the middle Member 3 of Paleogene Shahejie Formation in Dongpu sag,Henan Province |
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| Zhang Hong-An,Wang Chang-Zheng,Jiang Fei-Hu,Jin Ya-Qin,Hu Bin.Gravity flow deposits associating with ichnoassemblages within the middle Member 3 of Paleogene Shahejie Formation in Dongpu sag,Henan Province[J].Journal of Palaeogeography,2020,22(6):1157-1170. |
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| Authors: | Zhang Hong-An Wang Chang-Zheng Jiang Fei-Hu Jin Ya-Qin Hu Bin |
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| Institution: | 1. SINOPEC Zhongyuan Oilfield Company,Henan Puyang 457001,China;2. Institute of Resources and Environment,Henan Polytechnic University,Henan JiaoZuo 454003,China;3. Henan Collaborative Innovation Center of Coal(Shale)Seam Gas in Central Plains Economic Zone,Henan JiaoZuo 454003,China |
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| Abstract: | Based on the observation and analyses of 97 exploratory well cores in Dongpu sag,four types of gravity flow(including sliding,slumping,debris flow and turbidity current)deposits in lacustrine facies have been recognized within the middle Member 3 of the Paleogene Shahejie Formation. Their main identification marks are outlined as follows: (1)the sliding deposits are characterized by the partial preservation of primary sedimentary structures,the development of small penecontemporaneous fracture or fault in sandstone beds,and steep dip of strata,with Skolithos-Palaeophycus ichnoassemblage and/or Planolites-Taenidium ichnoassemblage,which commonly occurred in the shore and shallow lake environments. (2)General characteristics of slumping deposits mainly are the abrupt contact between sandstone beds(top and bottom)and dark mudstone beds,and development of all kinds of penecontemporaneous soft-sediment deformation structures such as convolution bedding,flame structure,water-escape structure,liquefied vein and tearing debris. (3)The sandy debris flow deposits are mainly marked by the massive sandstone,abrupt contact between sandstone beds(top and bottom)and dark mudstone beds,as well as developing floating gravels near the top of sandstone beds and tearing mudstone debris in the bottom of sandstone beds,sometimes with occurring the mud-coated intraclasts. Meanwhile,slumping and sandy debris flow deposits commonly associated with the Mermoides-Parapaleodictyon ichnoassemblage produced in semi-deep water lake environment. (4)The turbidity deposit is mainly indicated by the complete or incomplete Bouma sequences,normal-graded bedding,and all kinds of sole marks such as scour marks,irregular flute casts and load casts,and the Semirotundichnus-Puyangichnus ichnoassemblage frequently occurred in the middle to upper parts of the turbidite beds that formed in deep-water lake environment. After comprehensive analyses of above four types of gravity flow deposits and water-depth variation reflected by different ichnoassemblages,it can be considered that ichnoassemblage changes appear a zonation with the depth of the lake,which is consistent with variations in gravity flow deposits from sliding-slumping-debris flows to turbidity currents,and the bioturbation generated with gravity flow deposits is enhanced. Therefore,the research of bioturbation structures(ichnofossils)is not only of great significance to study the physical property of sandstone reservoir in lacustrine deposits,but also to provide important ichnological information for discerning various types of gravity flow deposits. |
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| Keywords: | Dongpu sag Shahejie Formation gravity flow deposit ichnoassemblage bioturbation structure |
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