論文

査読有り
2015年4月24日

Age of Matuyama-Brunhes boundary constrained by U-Pb zircon dating of a widespread tephra

Geology
  • Yusuke Suganuma
  • ,
  • Makoto Okada
  • ,
  • Kenji Horie
  • ,
  • Hiroshi Kaiden
  • ,
  • Mami Takehara
  • ,
  • Ryoko Senda
  • ,
  • Jun-Ichi Kimura
  • ,
  • Kenji Kawamura
  • ,
  • Yuki Haneda
  • ,
  • Osamu Kazaoka
  • ,
  • Martin J. Head

43
6
開始ページ
491
終了ページ
494
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1130/G36625.1
出版者・発行元
Geological Society of America

The youngest geomagnetic polarity reversal, the Matuyama-Brunhes boundary (MBB), provides an important datum plane for sediments, ice cores, and lavas. Its frequently cited age of 780 ka is based on orbital tuning of marine sedimentary records, and is supported by 40Ar/39Ar dating of Hawaiian lavas using recent age calibrations. Challenging this age, however, are reports of younger astrochronological ages based on oxygen isotope stratigraphy of high-sedimentation-rate marine records, and cosmogenic nuclides in marine sediments and an Antarctic ice core. Here, we present a U-Pb zircon age of 772.7 ± 7.2 ka from a marinedeposited tephra just below the MBB in a forearc basin in Japan. U-Pb dating has a distinct advantage over 40Ar/39Ar dating in that it is relatively free from assumptions regarding standardization and decay constants. This U-Pb zircon age, coupled with a newly obtained oxygen isotope chronology, yields an MBB age of 770.2 ± 7.3 ka. Our MBB age is consistent with those based on the latest orbitally tuned marine sediment records and on an Antarctic ice core. We provide the first direct comparison between orbital tuning, U-Pb dating, and magnetostratigraphy for the MBB, fulfilling a key requirement in calibrating the geological time scale.

リンク情報
DOI
https://doi.org/10.1130/G36625.1
URL
http://pubs.geoscienceworld.org/geology/article-pdf/43/6/491/3547642/491.pdf

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