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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
B02103,
15 PP., 2006
doi:10.1029/2004JB003584
Millennial- to submillennial-scale features of the Matuyama-Brunhes geomagnetic polarity transition from Osaka Bay, southwestern Japan
Research Center for Inland Seas and Graduate School of Science and Technology, Kobe University, Kobe, Japan
Research Center for Inland Seas and Graduate School of Science and Technology, Kobe University, Kobe, Japan
Department of Earth and Planetary Sciences, Kobe University, Kobe, Japan
Department of Earth and Planetary Sciences, Kobe University, Kobe, Japan
Graduate school of Human and Environmental Studies, Kyoto University, Kyoto, Japan
Faculty of Human Studies, Taisei Gakuin University, Sakai, Japan
Institute of Natural and Environmental Sciences, University of Hyogo, Sanda, Japan
A high-resolution magnetic record of the Matuyama-Brunhes (MB) reversal transition was obtained from homogeneous marine clay in a 1700-m core from Osaka Bay. The transition stretches over a core length of 6.4 m and yields four short reversal episodes. Two predate the main MB boundary (MBB), and two postdate it. We made diatom analyses of sediments to estimate relative sea level changes and constructed an age model by correlation with the astronomically calibrated marine oxygen isotope curve. The age model shows the short reversal episodes, with durations of <1 kyr, occurred at 4–5 kyr intervals within stage 19, and the MBB occurred about 5 kyr after the sea level highstand corresponding to isotopic event 19.3. It also shows the paleointensity minimum of 15–20% of the postreversal mean occurred at about 6 kyr before the MBB and another minimum at about 1 kyr after. Four virtual reverse-to-normal polarity boundaries found in this study suggest different ages for the MBB could be observed in lava flow studies. Some millennial- to submillennial-scale transition features found in this study are compatible with the previous numerical simulations of geomagnetic field reversal.
Received 17 December 2004; accepted 29 November 2005; published 28 February 2006.
Citation: (2006), Millennial- to submillennial-scale features of the Matuyama-Brunhes geomagnetic polarity transition from Osaka Bay, southwestern Japan, J. Geophys. Res., 111, B02103, doi:10.1029/2004JB003584.
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