| 山东济阳坳陷始新统-渐新统天文地层界线年龄分析 |
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| 作者单位： | 中石化胜利油田有限公司地质科学研究院,中国地震局地质研究所,中国科学院国家天文台 |
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| 摘 要： | 山东济阳坳陷沙河街组上部天文地层研究是以牛38井沙三段中亚段顶界年龄34.892Ma作为标定,分析和计算出沙二段下亚段底年龄为33.799Ma、沙段二段上亚段底为33.338Ma、沙一段底为32.940Ma和东营组底为31.829Ma。从天文地层界线年龄分析,沙三段-沙二段界线的年龄大致可对比为"国际地层表(2004)"始新统-渐新统界线年龄33.90Ma,而沙二段下亚段-上亚段界线年龄比国际始新统-渐新统界线的滞后大约600ka。在"中国区域地层表"始新统-渐新统界线年龄(32Ma)和"国际地层表"的始新统-渐新统界线年龄(33.9Ma)之差的1.9Myr,大致相当于本区计算的沙一、二段的持续时间。SP数据的小波分析表明,在沙二段-沙三上亚段界线附近,即约33.8Ma之后,约405ka周期开始变得不明显、不规则,幅度亦下降,剧烈突变发生时间在33.4Ma左右。上述界线对应偏心率周期的理论值突变的时间。因此推论始新世-渐新世转折期是偏心率多个理论周期重迭而导致的一个特殊的时期,也是本区沙二段下亚段这段地层形成不整合面的时间,大约在33.8—33.4Ma期间。
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| 关 键 词： | 天文地层 小波分析 沙河街组 始新世—渐新世 古近纪 济阳坳陷 山东 |
ASTROSTRATIGRAPHIC AGE ANALYSIS OF THE EOCENE-OLIGOCENE BOUNDARY IN THE JIYANG SAG,SHANDONG |
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| Authors: | YAO Yi-min XU Dao-yi HAN Yan-ben YIN Zhi-qiang and ZHANG Hai-feng Geological Scientific Research Institute of Shengli Oilfield Company SINOPEC Dongying Institute of Geology China Earthquake Administration Beijing National Astronomical Observatories Chinese Academy of Sciences Beijing |
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| Institution: | YAO Yi-min 1),XU Dao-yi 2),HAN Yan-ben 3),YIN Zhi-qiang 3) and ZHANG Hai-feng 1) 1) Geological Scientific Research Institute of Shengli Oilfield Company,SINOPEC,Dongying,257015,2) Institute of Geology,China Earthquake Administration,Beijing,100029,3) National Astronomical Observatories,Chinese Academy of Sciences,Beijing,100012 |
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| Abstract: | The result of astrostratigraphic study of the upper part of the Shahejie Formation in the Jiyang Depression is defined as 34.892Ma in age at the upper boundary of the Middle Submember of Member 3 of the Shahejie Formation (shortened to Sha3) in Well Niu-38. Based on the analysis and calculation, the base of the Lower Submember of Sha2 is 33.799Ma in age, the base of the Upper Submember of Sha2 is 33.338Ma, the base of Sha1 is 32.946Ma and the base of the Dongying Formation is 31.829Ma. Age analysis of the astrostratigraphic study shows that the Sha3/Sha2 boundary age may be roughly correlated with Eocene/Oligocene (Shortened to E/O) boundary age 33.90Ma in the "International Stratigraphic Chart" (2004), and the Lower/Upper Submember boundary age of Sha2 lagged depositionally about 600ka behind the E/O boundary age in that Chart. There is an age difference of 1.9Ma between the E/O boundary age of 32Ma in the "Regional Stratigraphic Chart of China" and the E/O boundary age of 33.9Ma in the "International Stratigraphic Chart", roughly corresponding to the age of Sha1 and Sha2 calculated in this paper. The wavelet analysis of SP data shows that near the Sha2/Upper Submember of Sha3 boundary, i.e. after about 33.8Ma, 405ka periodicity began to become unclear, irregular, with amplitude also falling and a sharp abruptness happening at about 33.4Ma. The boundary mentioned above corresponded to the time of abruptness of the eccentricity period theoretical value. Thus, it is deduced that the E/O time (33.7? ?3.5 Ma) is a special time interval resulted from the intercombination of multiple theoretical periods of the eccentricity and is also the time-period during which unconformity surface was formed in the Lower Submember of Sha2, during about 33.8—33.4Ma. |
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| Keywords: | astrostratigraphiy wavelet analysis Shahejie Formation Eocene-Oligocene boundary Jiyang Deprssion Shandong Province |
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