In-phase anomalies in Beryllium-10 production and palaeomagnetic field behaviour during the Iceland Basin geomagnetic excursion
In-phase anomalies in Beryllium-10 production and palaeomagnetic field behaviour during the Iceland Basin geomagnetic excursion
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DOI：
10.1016/j.epsl.2007.10.051
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发表时间：
2008-01-30
影响因子：
5.3
通讯作者：
Kubik, Peter W.
中科院分区：
文献类型：
--
作者：
Knudsen, Mads Faurschou;Henderson, Gideon M.;Kubik, Peter W.
与地磁偏移有关的宇宙生成放射性核素产生速率的增加已被用作海洋和陆地档案中过去气候记录之间的全球关联点。我们研究了Be-10产量变化的相对时间和相应的古地磁信号，在最大的更新世漂移之一，冰岛盆地（IB）事件（约190 kyr），记录在两个具有高沉积速率的海洋沉积物岩心（ODP地点1063和983）中。通过使用Th-230（xs）归一化Be-10沉积速率和自生Be-10/Be-9来估计偏移期间Be-10产率的变化。得到的Be-10产量与从相同的离散样品中获得的地磁场行为的高分辨率记录进行了比较。在这些高沉积速率岩心中，我们没有发现明显的古地磁信号锁定深度的证据。其他岩心中明显的锁定深度有时可能是样品分辨率较低的结果。我们的研究结果还表明，IB漂移期间Be-10产量增加的时期持续时间更长，并且很可能比相应的古地磁异常开始得更早，这与先前的观测结果一致，即极性转变发生在极性转变之前地磁场强度减弱的时期之后。本研究缺乏古地磁锁定深度的证据，表明Be-10信号与与偏移和倒转相关的古地磁异常之间没有系统的抵消，这对不同档案气候记录的全球相关性具有重要意义。(C) 2007 Elsevier B.V.版权所有
Increases in the production rate of cosmogenic radionuclides associated with geomagnetic excursions have been used as global tie-points for correlation between records of past climate from marine and terrestrial archives. We have investigated the relative timing of variations in Be-10 production rate and the corresponding palaeomagnetic signal during one of the largest Pleistocene excursions, the Iceland Basin (IB) event (ca. 190 kyr), as recorded in two marine sediment cores (ODP Sites 1063 and 983) with high sedimentation rates. Variations in Be-10 production rate during the excursion were estimated by use of Th-230(xs) normalized Be-10 deposition rates and authigenic Be-10/Be-9. Resulting Be-10 production rates are compared with high-resolution records of geomagnetic field behaviour acquired from the same discrete samples. We find no evidence for a significant lock-in depth of the palaeomagnetic signal in these high sedimentation-rate cores. Apparent lock-in depths in other cores may sometimes be the result of lower sample resolution. Our results also indicate that the period of increased Be-10 production during the IB excursion lasted longer and, most likely, started earlier than the corresponding palaeomagnetic anomaly, in accordance with previous observations that polarity transitions occur after periods of reduced geomagnetic field intensity prior to the transition. The lack of evidence in this study for a significant palaeomagnetic lock-in depth suggests that there is no systematic offset between the Be-10 signal and palaeomagnetic anomalies associated with excursions and reversals, with significance for the global correlation of climate records from different archives. (C) 2007 Elsevier B.V. All rights reserved.