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Synthesis of magnetostratigraphy of the Cretaceous System in the northwest Pacific: Results from the Nemuro Group and the lower Yezo Group

西北太平洋白垩系磁性地层综合：根室群和下虾夷群的结果

基本信息

批准号：
14540439
负责人：
KODAMA Kazuto
金额：
$ 1.98万
依托单位：
Kochi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540439/
关键词：
Cretaceous System magnetostratigraphy Nemuro Group Yezo Group Hokkaido Sakhalin 羽幌古丹別

项目摘要

This study provides a new magnetostratigraphic data from the lower Yezo Group and the Nemuro Group in Hokkaido, Japan. Compilation of this data set and those from elsewhere as Kyushu, Shikoku and Sakhalin of Russian Far East leads to a comprehensive, intra-regional correlation of the Upper Cretaceous strata in the Northwest Pacific, which can be calibrated to the geomagnetic polarity time scale in the late Cretaceous. The combined magnetostratigraphic and biostratigraphic correlation has assigned these zones to the Late Cretaceous geomagnetic polarity chrons including C31r through C33r and the Cretaceous long normal interval. Corresponding geomagnetic reversals have been documented from the Upper Cretaceous successions of the Western Interior of North America, in combination with high-resolution ammonite biostratigraphy and radiometric age dates. Biostratigraphy of the Great Valley Sequence in California is also well-defined, but there is only one reversed interval that can be correlated with polarity chron C33r. The most complete record of polarity reversals in South Sakhalin would provide an integrated reference scheme which can be of significant use not only to correlate dissimilar faunal assemblages of disparate regions in the North Pacific, but also to contribute to a global definition of Upper Cretaceous stage boundaries.

本研究为日本北海道下野三群和Nemuro群提供了新的磁地层资料。将该数据集与来自俄罗斯远东地区九州、四国和库页岛等地的数据集进行汇编，可以对西北太平洋上白垩统地层进行全面的区域内对比，并可校准为晚白垩统地磁极性时间尺度。结合磁地层和生物地层对比，将这些带划分为晚白垩世C31r ~ C33r地磁极性年代史和白垩世长正常层序。结合高分辨率鹦鹉螺生物地层学和放射性年龄测定，研究了北美西部内陆上白垩统的相应地磁倒转。加州大峡谷层序的生物地层学也很明确，但只有一个逆层段可以与极性时间C33r相对应。南库页岛最完整的极性逆转记录将提供一个综合参考方案，该方案不仅对北太平洋不同地区的不同动物组合具有重要意义，而且还有助于对上白垩纪阶段边界的全球定义。