Latest Olduvai short‐lived reversal episodes recorded in Chinese loess
Latest Olduvai short‐lived reversal episodes recorded in Chinese loess
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DOI：
10.1029/2007jb005264
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发表时间：
2008-05
影响因子：
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通讯作者：
Tianshui Yang;M. Hyodo;Zhenyu Yang;L. Ding;Huidi Li;Jianli Fu;Shubing Wang;Hongwei Wang;T. Mishima
中科院分区：
文献类型：
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作者：
Tianshui Yang;M. Hyodo;Zhenyu Yang;L. Ding;Huidi Li;Jianli Fu;Shubing Wang;Hongwei Wang;T. Mishima
[1] 在中国南部黄土高原宝鸡市附近相距约300 m的两个平行黄土剖面上获得了重复的高分辨率磁记录。这揭示了奥杜瓦正常极性亚时带最上部至少有八次短暂的极性反转事件。岩石磁学实验和低场磁化率的各向异性证实，短期反转的多次发生并不是由于岩石磁学和/或沉积原因造成的。假设奥杜瓦伊亚时间内的积累速率恒定，则两个部分的短发作区估计分别跨越约 24-30 ka 和 24-31 ka。每个短集的持续时间约为 0.3 ka 至 2.1 ka。目前的结果与之前的全球观测结果一起表明，多次短暂反转的发生是最新的奥杜瓦伊亚时间所特有的。当时地球发电机可能处于异常状态。
[1] A duplicate high-resolution magnetic record was obtained from two parallel loess sections separated by about 300 m near Baoji city, southern Chinese Loess Plateau. This reveals at least eight short-lived reversed polarity episodes in the uppermost part of the Olduvai normal polarity subchronozone. Rock magnetic experiments and anisotropy of low-field magnetic susceptibility confirm that the multiple occurrence of short-lived reversals is not due to rock-magnetic and/or sedimentary causes. Assuming a constant accumulation rate within the Olduvai subchron, the short episode zone was estimated to span about 24–30 ka and 24–31 ka for the two sections, respectively. The duration of each short episode ranges from about 0.3 ka to 2.1 ka. The present results together with previous worldwide observations show that the occurrence of numerous short reversals is peculiar to the latest Olduvai subchron. The geodynamo may have been in an anomalous state at that time.