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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >~(10)Be evidence for delayed acquisition of remanent magnetization in marine sediments: Implication for a new age for the Matuyama-Brunhes boundary
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~(10)Be evidence for delayed acquisition of remanent magnetization in marine sediments: Implication for a new age for the Matuyama-Brunhes boundary

机译：〜（10）证明海洋沉积物中剩余磁化的延迟获取：对Matuyama-Brunhes边界新时代的暗示

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摘要

Fluxes of the meteoric cosmogenic radionuclide ~(10)Be vary with changes in the incoming cosmic rays modulated by geomagnetic field intensity variations. The variability in the ~(10)Be flux can be used to synchronize ice cores, as well as marine sediments, by comparison with the relative paleointensity variations of the geomagnetic field. However, lock-in of the paleomagnetic signal at some depth below the sediment-water interface in marine sediments through acquisition of a post-depositional remanent magnetization (PDRM) adds uncertainty to synchronization. Despite the long history of such studies, the magnitude of the PDRM lock-in depth remains controversial. In this article, we present clear evidence for a downward offset of the paleointensity minimum relative to the ~(10)Be flux anomaly at the Matuyama-Brunhes (M-B) geomagnetic polarity boundary, which we interpret to result from a ~15cm PDRM lock in depth. This lock-in depth indicates that up to several tens of thousands years of age offset probably occurs when a paleomagnetic record is used for dating marine sediments, and the age of the M-B boundary should be revised to ca. 10kyr younger, which is consistent with a younger ice core derived age of 770±6ka (2δ). This cosmogenic age tuning strategy will contribute to refining paleomagnetic-based age models for marine sediments and identifying of lead-lag relationships for global abrupt environmental changes.
机译：流星宇宙放射性核素〜（10）的通量随受地磁场强度变化调制的入射宇宙射线的变化而变化。与地磁场的相对古强度变化相比，〜（10）Be通量的变化可用于使冰芯以及海洋沉积物同步。但是，通过获取沉积后剩余磁化强度（PDRM）来锁定海洋沉积物中沉积物-水界面以下某个深度的古磁信号会增加同步的不确定性。尽管此类研究历史悠久，但PDRM锁定深度的大小仍存在争议。在本文中，我们提供了清晰的证据，表明相对于Matuyama-Brunhes（MB）地磁极性边界处的〜（10）Be通量异常，古强度最小值有向下偏移，我们认为这是由于〜15cm PDRM锁定深度。这种锁定深度表明，当使用古磁记录对海洋沉积物进行测年时，可能会发生长达数万年的年龄偏移，并且应将M-B边界的年龄修改为约。年轻10kyr，这与年轻的冰芯派生年龄770±6ka（2δ）相一致。这种宇宙成因的年龄调整策略将有助于完善海洋沉积物的基于古磁的年龄模型，并为全球突然的环境变化识别铅-铅关系。

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