Geomagnetic episodes of the last 1.2 Myr recorded in Chinese loess
Geomagnetic episodes of the last 1.2 Myr recorded in Chinese loess
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DOI：
10.1029/2001gl014024
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发表时间：
2002-04
影响因子：
5.2
通讯作者：
Y. Pan;R. Zhu;Q. S. Liu;B. Guo;L. Yue;H. Wu
中科院分区：
文献类型：
--
作者：
Y. Pan;R. Zhu;Q. S. Liu;B. Guo;L. Yue;H. Wu
在渭南黄土剖面中发现了松山-布鲁内斯(M/B)边界、Jaramillo正常亚时(J/M)的终止以及三次年轻的地磁漂移[朱等，1994,1998,1999]。最近，我们在同一剖面上进行了进一步的古地磁定向研究，恢复了Jaramillo Normal Subchron(M/J)和四次地磁漂移的开始，其中两次在布伦斯，两次在松山晚期。在该剖面中发现的7次漂移都是以黄土为单位的，而在古土壤中没有发现预期的漂移，这表明短暂的地磁信号可能只在黄土单位中被记录下来，并可能在古土壤单位中被强烈的成壤作用完全平滑或抹去。在新天文时间尺度(HLD00)的约束下，估算了地磁漂移和反转边界的年龄。我们初步将这些漂移与以前的结果进行了关联，表明大锁定模型可能不适用于整个黄土剖面，尽管在主要边界上观察到了一些明显的正年龄差异。
The Matuyama‐Brunhes (M/B) boundary, termination of Jaramillo normal subchron (J/M) as well as three young geomagnetic excursions has been revealed in the Weinan loess section [ Zhu et al., 1994 , 1998 , 1999 ]. Recently, we carried out further paleomagnetic directional studies on the same section and recovered the onset of the Jaramillo normal subchron (M/J) and four geomagnetic excursions, two in the Brunhes and two in the late Matuyama. The fact that all seven excursions found in this section are in loess units and expected excursions in paleosols are not found suggests that short‐lived geomagnetic signals could be only recorded in loess units, and may have been fully smoothed or wiped out in paleosol units by strong pedogenesis. Constrained by a new astronomical timescale (HLD00), ages of the geomagnetic excursions and reversal boundaries have been estimated. We tentatively correlated these excursions with previous results, indicating that a large lock‐in model may not be correct for the whole loess profile, although some apparently big positive age discrepancies were observed for the main boundaries.