中国东北松辽盆地晚白垩世青山口组浮动天文年代标尺的建立  

Establishment of floating astronomical time scale for the terrestrial Late Cretaceous Qingshankou Formation in the Songliao basin of Northeast China

作　　者：吴怀春[1] 张世红[1] 黄清华[2] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室 [2]大庆油田有限责任公司勘探开发研究院,黑龙江大庆163712

出　　处：《地学前缘》2008年第4期159-169,共11页Earth Science Frontiers

基　　金：国家重点基础研究发展计划“973”项目(2006CB701406);教育部新世纪优秀人才支持计划(NCET-04-0727);中国地质大学地质过程与矿产资源国家重点实验室开放基金项目(GPMR200651)

摘　　要：松辽盆地上白垩统青山口组主要由深湖相黑色泥岩、页岩组成，是大庆油田最重要的烃源岩之一，但长期以来对其年代学框架存在很大争议。对松辽盆地“松科1井”南井（茂206井）自然伽马测井和密度测井数据进行小波分析和连续滑动窗口频谱分析，表明茂206井青山口组记录了稳定的Milankovitch旋回。由长、短偏心率、地轴斜率和岁差周期造成的地层旋回厚度分别为39、13．5～9、5～3．8和2．5～1．7m。茂206井青山口组沉积速率变化不大，平均沉积速率为9．63cm／ka，沉积时限为5．16Ma。通过对长、短偏心率周期进行高斯带通滤波，建立了茂206井青山口组的“浮动”天文年代标尺。青山口组共记录了12．7个长偏心率周期和47．7个短偏心率周期。确定出青山口组1段下部油页岩层段对应的古湖泊缺氧事件（LAE1）持续时间约为250ka，与白垩纪Cenomanian-Turonian时期第二次大洋缺氧事件（OAE2）的持续时间接近。青山口组天文年代标尺的确立为约束青山口组沉积期各种地质事件的持续时间提供了年代学依据。The Upper Cretaceous Qingshankou Formation （K2qn） in the Songliao basin （SLB） of Northeast China,which consists of lacustrine mudstone and shale, is one of the most important rock sources in the Daqing oil field. However, the geochronology framework of the K2qn has been debated for a long time. In this study, detailed evolutionary wavelet analysis and sliding windows of spectral analysis were conducted on the natural gamma-ray logging and density logging data of the Kzqn from the south well of the SLCORE-1 （Mao206）, and the results reveal that the Mao206 section preserves stable Milankovitch cycles. The major cycles of ~39 m, 13. 5-9 m,5-3. 8 m, and 2. 5-1.7 m are considered to be caused, respectively, by long and short eccentricity, obliquity, and precession. The accumulation rate of the K2qn varied slightly, and the mean accumulation rate was estimated as 9. 63 cm/ka. The accumulation time of the K2qn of the Mao206 can then be estimated as 5.16 Ma. A ＂floating＂ astronomical time scale was established by filtering the long and short eccentricity cycles of ～39 m and 13.5-9 m, respectively. The K2qn was found to have 12. 7 long and 47. 7 short eccentricity cycles. The duration of the lacustrine anoxic event 1 （LAE1） in the K2qn is estimated as 250 ka, which is close to the duration of ocean anoxic event 2 （OAE2） at the Cenomanian-Turonian boundary. The establishment of floating astronomical time scale of the K2 qn provides geo-chronological constraints on the duration of different kinds of geological events.

关 键 词：松辽盆地 青山口组 旋回地层学 天文年代标尺 

分 类 号：P533[天文地球—古生物学与地层学]