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Sequence stratigraphy and biofacies of the Cretaceous and Tertiary (K/T) boundary and its nearby horizons in Hokkaido, northern Japan

日本北部北海道白垩纪和第三纪（K/T）边界及其附近地层的层序地层和生物相

基本信息

批准号：
10640446
负责人：
ANDO Hisao
金额：
$ 1.98万
依托单位：
IBARAKI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2001
项目状态：
已结题

项目摘要

During four years of this project, 1998 to 2001, the Upper Cretaceous Hokobuchi Group and its representatives of the Yezo Supergroup in Hokkaido, have been surveyed from viewpoints of sedimentary facies, megafossil biostratigraphy, biofacies, pollen stratigraphy and others. Besides, the Nemuro Group in east Hokkaido and the Nakaminato Group in Ibaraki Prefecture both correlative with the Hakobuchi Group, are also surveyed briefly for comparison. These results are included in a separated volume of the project report as a list of papers printed and aural presentations in conferences, and their some reprints.In the Nakatonbetsu area, northern Hokkaido, our field survey for a few years, revealed the most high-resolution biostratigraphic framwork of the Campanian to Maastrichtian around Japan, by using ammonoid and inoceramid successions in surface outcrop sections (Ando et al., 2001). Though the upper part of the Hakobuchi Group there include the upper Paleocene according to micro fossil b … More iostratigraphy, we found the unconformity eroding the K/T boundary and its nearby horizons. The uppermost Maastrichtian and lower Paleocene seem to have been eroded away. This means the Yezo forearc basin had continued until late Paleocene after a major event during late Maastrichtian and early Paleocene.The Hokobuchi Group in the Nakagawa area to the west of Nakatonbetsu, shows the western marginal sedimentary facies of the basin, It is composed of the five shallow-marine upward-coarsening facies successions (PS: parasequences) which are several tens to a few hundreds meters in thickness. In the Wakkanai area to the north of Nakagawa, we also discriminated five PSs, On the basis of macrpfossil biostratigraphy established in Nakatonbetsu, the group consists mainly of the Campanian without the Maastichtian in Nakagawa, but of the Campanian and the upper Maastichtian in Wakkanai.These stratigraphic data will provide the important information for reconstruction of dynamic geohistory of the Yezo basin. Less

在1998 ~ 2001年的4年时间里，对北海道上白垩统北渊群及其代表的叶佐群进行了沉积相、巨化石生物地层、生物相、花粉地层等方面的研究。此外，还对与箱渊群相关的北海道东部的根室群和茨木县的Nakaminato群进行了简要的对比考察。这些结果作为印刷的论文和会议上的音频演示的列表以及它们的一些重印本包括在项目报告的单独卷中。在北方北海道的Nakatonbetsu地区，我们几年的野外调查，通过使用地表露头剖面中的菊石和接种层连续性，揭示了日本周围Campanian到Maastrichtian的最高分辨率生物地层框架（Ando et al.，2001年）。根据微体化石B，尽管箱渊群上部也包括上古新统 ...更多信息在地层学上，发现不整合面侵蚀K/T界线及其附近层位。最上面的马斯特里赫特阶和下古新世似乎已经被侵蚀掉了。中屯别以西中川地区的北渊群为该盆地的西缘沉积相，由5个厚度为几十到几百米的浅海向上变粗相序列（PS：准层序）组成。在中川以北的若奈地区，我们也识别出了五个PS，根据Nakatonbetsu建立的大型化石生物地层学，该群主要由Campanian组成，但不包括中川的Maastichtian，而包括若奈的Campanian和上Maastichtian，这些地层资料将为重建Yezo盆地的动力地史提供重要信息。少