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

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

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)491-494
Number of pages4
JournalGeology
Volume43
Issue number6
DOIs
Publication statusPublished - Apr 24 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Geology

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