Millennial‐ to submillennial‐scale features of the Matuyama‐Brunhes geomagnetic polarity transition from Osaka Bay, southwestern Japan
Millennial‐ to submillennial‐scale features of the Matuyama‐Brunhes geomagnetic polarity transition from Osaka Bay, southwestern Japan
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DOI：
10.1029/2004jb003584
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发表时间：
2006-02
影响因子：
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通讯作者：
M. Hyodo;Dipzli K. Biswas;Takako Noda;N. Tomioka;T. Mishima;C. Itota;Hiroshi P. Sato
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文献类型：
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作者：
M. Hyodo;Dipzli K. Biswas;Takako Noda;N. Tomioka;T. Mishima;C. Itota;Hiroshi P. Sato
[1]从大坂湾1700米岩芯的均质海相粘土中获得了Matuyama-Brunhes（MB）反转跃迁的高分辨率磁记录。过渡延伸超过6.4米的核心长度，并产生四个短期反转插曲。两个早于主MB边界（MBB），和两个postdates. We硅藻沉积物分析，估计相对海平面的变化，并建立了一个年龄模型的相关性与天文校准的海洋氧同位素曲线。年龄模型显示，在第19阶段，短反转事件发生在4-5 kyr的时间间隔内，持续时间<1 kyr，而MBB发生在对应于同位素事件19.3的海平面高点之后约5 kyr。它还表明，在MBB之前约6 kyr，古强度最小值为后地震平均值的15-20%，另一个最小值发生在MBB之后约1 kyr。在这项研究中发现的四个虚拟的反向到正常极性的边界表明不同的年龄的MBB可以观察到熔岩流的研究。在这项研究中发现的一些千年到亚千年尺度的过渡功能是兼容的地磁场反转的数值模拟。
[1] 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.