| 用微体古生物定量水深法对东营凹陷沙四上亚段沉积早期湖泊水深再造 |
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| 引用本文： | 苏新,丁旋,姜在兴,胡斌,孟美岑,陈萌莎.用微体古生物定量水深法对东营凹陷沙四上亚段沉积早期湖泊水深再造[J].地学前缘,2012,19(1):188-199. |
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| 作者姓名： | 苏新 丁旋 姜在兴 胡斌 孟美岑 陈萌莎 |
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| 作者单位： | 1. 中国地质大学（北京）,北京,100083
2. 中国地质大学（北京）,北京100083／北京大学,北京100083 |
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| 基金项目： | 教育部长江学者与创新团队发展计划项目 |
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| 摘 要： | 东营凹陷广布的始新统沙河街组四段上亚段滩坝砂岩具有十分巨大的勘探价值和潜力。对沙河街组沙四上亚段滩坝砂体的精细勘探,要求对古水深展开水深量化再造的研究。文中在对东营凹陷47口含沙四上亚层段低位域层段多门类微体古生物分析和高分辨层序地层学地层划分基础上,确定量化估计水深的古生物替代标志,获得如下主要研究成果:(1)获得较高分辨率(2m等深线表示)的东营凹陷沙四上亚段低位体系域沉积期间古水深量化等值图;(2)东营凹陷是一个以滨浅湖(水深0～15m)为主的湖泊;(3)湖盆具"北深陡南浅缓"的特点,湖边高地或隆起向湖方向深入的岬角一带与陡坡冲积环境相邻;(4)湖盆凹陷内"东西分异"的次级地貌格局,从东向西,出现较深水区、中央深水区和西南浅水带,其长轴均为北东-南西走向。上述结果可与前人研究比较或验证,表明文中所获的多门类微体化石叠合水深量化标志和结果可信。
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| 关 键 词： | 古水深 微体化石 滩坝 低位体系域 沙四上亚段 始新统 东营凹陷 |
Using of multi-microfossil proxies for reconstructing quantitative paleo-water depth during the deposit period of LST of Es4s in Dongying Depression |
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| Su Xin,Ding Xuan,Jiang Zaixing,Hu Bin,Meng Meicen,Chen Mengsha.Using of multi-microfossil proxies for reconstructing quantitative paleo-water depth during the deposit period of LST of Es4s in Dongying Depression[J].Earth Science Frontiers,2012,19(1):188-199. |
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| Authors: | Su Xin Ding Xuan Jiang Zaixing Hu Bin Meng Meicen Chen Mengsha |
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| Institution: | 1,2 1.China University of Geosciences(Beijing),Beijing100083,China 2.Peking University,Beijing100083,China |
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| Abstract: | Large-scale lacustrine beach-bar oil pools have been discovered recently in Dongying Depression,Shandong Province.The beach-bar sequences in the upper fourth member(with an age of about 45 Ma to 42 Ma)of the Eocene Shahejie Formation(Ess4)became the important exploration targets in this area.However,distributions and deposit environments of beach-bars were poorly studied.Lake water depth is an important control factor for deposition and distribution of beach-bars.A micropaleontological study was carried out with the objective to obtain quantitative paleo-water depths during the deposit periods of the Ess4in Dongying Depression.Early Middle Eocene microfossils(ostracodes,microphytoplankton and benthic algae)from 47 wells were analyzed.A method of determining quantitative water depths by using of multi-microfossil proxies was developed.As a result,the early Middle Eocene paleo-bathymetric map illustrated with 2 misobath for Dongying Depression was reconstructed.The results showed that Dongying Depression was generally a shallow to deep lake during that period,with water depth ranging from 0malong its coast to more than 30min the central area(Well Haoke 1).Three features were seen from the variation of water depths.(1)Northern area is characterized by deeper waters,steeper and narrower lake slopes,whereas flatter and wider beach terraces covered by shallower waters occur in the southern region.(2)Steep and narrow lake slopes are clearly related to the headlands of highlands on lake coasts.(3)Three water zones with NE-SW extending direction were recognized:a small shallow lake zone(about 6m)from Well Lai 9to Well Wang 18in the northern-east corner of Dongying Depression,the largest and deepest zone in the central,and a very shallow terrace bar(< 3.5m)occurred in the south-west area.These features were well correlative to abundant sedimentary data and evidences from previous studies.For example,delta deposits founded in the northern deep waters and beach-bar occurred in the southern areas.All correlations suggested that the multi-microfossil proxies for quantitative water depths are reliable.The paleo-bathymetric map with relative high resolution provided possibility to understand and depict small-scale deposit areas for shallow water beach-bars and deep water deltas.This study also suggested that microfossil study could still serve as a useful tool for updated oil exploration,however,good microfossil records with high time resolution combined with high resolution seismic and sequence analysis are needed. |
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| Keywords: | paleo-water depth microfossils beach-bars the lowstand systems tract Ess4 Eocene Dongying Depression |
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