摘要
鄂尔多斯盆地长7段为半深湖-深湖沉积环境,沉积稳定连续,且记录了米氏周期.本文针对深度与沉积时间如何转换及地层时间轴如何建立等问题,首先采用傅里叶变换和小波变换对模拟的地球轨道周期信号进行分析,识别出米氏周期,并论证两种方法用于识别米氏旋回的可行性;进而基于鄂尔多斯盆地长7段实际测井数据,建立了频谱分析与小波深频分析米氏旋回、沉积时间及速率的方法步骤与公式,研究出小波尺度与地球轨道周期的关系,形成转换模型公式,并通过B159井的测井曲线识别出该井长7段的米氏旋回,计算出该井长7段的平均沉积速率分别为5.05 cm·ka^(-1)、5.07 cm·ka^(-1).最后分析了鄂尔多斯盆地长7段地层旋回主要受404 ka的长偏心率周期控制,通过重构长、短偏心率周期小波系数曲线,建立了B159井长7段的浮动天文年代标尺,形成了天文年代标尺计算方法与步骤.结果证实长7段共记录了6个长偏心率旋回和20个短偏心率旋回,得出长7段124 m的地层沉积时限约为2.4 Ma.浮动天文年代标尺的建立有助于对各种地质事件的持续时间做出精确估计,为深时地球研究助力.
The Chang 7 member in the Ordos Basin belongs to semi-deep to deep lacustrine depositional environment.The deposition process is stable and continuous,which recordes the Milankovitch cycles.This paper aims at converting the depth to the deposition time and establishing the stratigraphic time axis.First,we adopt the Fourier and wavelet transform to simulate and analyze the Earth orbital period signal,respectively,to identify Milankovitch cycles.The feasibility of the two methods is also demonstrated.Second,we establish the workflow and formulas of analyzing Milankovitch cycles,the depositional time and rate using spectrum analysis and wavelet deep-frequency analysis based on the logging data of the Chang 7 member.We obtain the transformation relationship between the wavelet scale and the Earth orbital period.Subsequently,we acquire Milankovitch cycles of the Chang 7 member using the logging data of Well B159.The average depositional rate of the Chang 7 member is subsequently calculated to be 5.05 cm·ka^(-1)and 5.07 cm·ka^(-1),respectively.Finally,we conclude that the stratigraphic cycle of the Chang 7 Member is mainly controlled by the long eccentricity period of 404-ka.The floating astronomical age scale of the Chang 7 member is established by reconstructing the wavelet coefficient curve of the long and short eccentricity period.The results confirm that there are 6 long eccentricity cycles and 20 short eccentricity cycles in the Chang 7 member,The depositional time limit of the Chang 7 Member is about 2.4 Ma within a depth interval of 124 m.The establishment of the floating astronomical time scale is conductive to accurately estimating the duration time of various geological events,which would benefit the deep-time Earth research.
作者
徐敬领
霍家庆
宋连腾
昝灵
XU JingLing;HUO JiaQing;SONG LianTeng;ZAN Ling(School of Geophysics and Information Technology,China University of Geosciences(Beijing),Beijing 100083,China;Petrochina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;Research Institute of Exploration&Development,SINOPEC East China Oil&Gas Company,Nanjing 210019,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第7期2766-2778,共13页
Chinese Journal of Geophysics
基金
国家自然科学基金项目“湖相页岩薄互层脆性矿物含量与含气量的关系研究”(41302107)
教育部中国地质大学(北京)基本科研项目(2652018270)联合资助。
关键词
米氏周期
频谱分析
小波深频分析
沉积速率
天文年代标尺
Milankovitch cycles
Spectrum analysis
Wavelet deep-frequency analysis
Depositional rate
Astronomical time scale
