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首页> 外文期刊>Earth, planets and space: EPS >Environmental magnetic record and paleosecular variation data for the last 40 kyrs from the Lake Biwa sediments, Central Japan
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Environmental magnetic record and paleosecular variation data for the last 40 kyrs from the Lake Biwa sediments, Central Japan

机译：来自日本中部琵琶湖沉积物的最后40个基日的环境磁记录和古目变化数据

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摘要

We have conducted paleomagnetic and environmental magnetic analysis of a sediment piston core recovered from Lake Biwa, central Japan. Tephrochronology and AMS radiocarbon dating showed that this core covers the time period since about 40 kyr BP. The variation of paleomagnetic direction shows a good agreement with the PSV record for the last 10 kyrs from the deeper water site (BIWA SV-3; Ali et al ., 1999), although the amplitudes are subdued probably due to the relatively lower accumulation rate at the shallower site. Inclination lows of the pre-Holocene interval are correlated to PSV records reported from the marine sediments off Shikoku and in the Japan Sea. In addition, the variation of magnetic mineral concentration reflects environmental changes during the last glacial period. It is suggested that the flux of fine-grained magnetite, probably associated with greater precipitation, was increased during interstadial periods. The variation of anhysteretic remanent magnetization is likely correlated to the Dansgaard-Oeschger (D-O) cycles recorded in Greenland ice cores. An apparent swing of the PSV curve is recognized at about 27 ka, but evidence for the Mono Lake excursion at 32 ka around the D-O events 6 and 7 is unclear. Combination of the detailed paleomagnetic record and the sub-Milankovitch climate cycles thus provides better resolution for understanding geomagnetic secular variation and polarity excursions in space and time.
机译：我们对从日本中部琵琶湖回收的沉积物活塞芯进行了古磁和环境磁分析。年代学和AMS放射性碳测年表明，该岩心涵盖了自大约40 yr BP开始的时间。古磁方向的变化与较深水位的最后10个基元的PSV记录显示出良好的一致性（BIWA SV-3; Ali等人，1999），尽管振幅可能由于相对较低的积累速率而减弱了在较浅的地方。全新世前间隔的低倾角与四国海域和日本海中海洋沉积物报告的PSV记录相关。另外，磁性矿物浓度的变化反映了上一个冰川期的环境变化。建议在相间期增加细粒磁铁矿的通量，这可能与更大的降水有关。滞回剩磁的变化可能与格陵兰冰芯中记录的Dansgaard-Oeschger（D-O）循环有关。 PSV曲线的明显摆动在大约27 ka时被确认，但是尚不清楚D-O事件6和7周围32 ka处的Mono Lake漂移的证据。详细的古磁记录和亚米兰科维奇气候周期的组合因此为理解地磁长期变化和时空极性偏移提供了更好的分辨率。

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