Multiple 10Be records revealing the history of cosmic-ray variations across the Iceland Basin excursion
Multiple 10Be records revealing the history of cosmic-ray variations across the Iceland Basin excursion
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DOI：
10.1016/j.epsl.2016.01.034
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发表时间：
2016-04
影响因子：
5.3
通讯作者：
K. Horiuchi;Kanae Kamata;S. Maejima;S. Sasaki;Nobuyoshi Sasaki;T. Yamazaki;S. Fujita;H. Motoyama;H. Matsuzaki
中科院分区：
文献类型：
--
作者：
K. Horiuchi;Kanae Kamata;S. Maejima;S. Sasaki;Nobuyoshi Sasaki;T. Yamazaki;S. Fujita;H. Motoyama;H. Matsuzaki
宇宙成因10 Be是宇宙射线通量的代理，其自然记录提供了有关过去的地磁场和太阳活动的强度变化的重要信息。10 Be记录也作为一个强有力的工具，全球同步之间的各种paleocarchives和阐明沉积过程中的自然reversible磁化收购。然而，高分辨率（几十年到几百年）的10 Be记录是稀缺的，特别是那些超过几万年的。在这里，我们提出了多个高分辨率10 Be记录的冰岛盆地地磁漂移间隔（约。170-200 kyr ago）获得的沉积物芯（自生10 Be/9 Be比）和冰芯（大气10 Be通量）。比较沉积10 Be记录与相对古强度从相同的核心，我们发现的差异，即使在相邻的核心之间的磁锁定深度。沉积物和冰芯的10 Be代用记录表现出共同的特征：不对称的大尺度变化，在最大值附近有一个17 kyr的准高原，具有特征性的中期低压，以及在此期间宇宙射线通量的多千年波动。最小同步和叠加的10 Be记录表明，最大宇宙射线通量发生在188.5-190.0 kyr前，是现在通量的两倍。叠加曲线的小波分析揭示了主导的4-kyr和次级8-kyr周期性，这两者都可以解释为内在的地磁周期。高分辨率冰芯记录的子波频谱显示出1.7 kyr的周期性，并在10 Be的最大值周围有些混合的数百年周期，这可能代表了这一时期的太阳周期。来自多个古档案馆的高分辨率10 Be记录既提供了宇宙射线通量的强大代理记录，也是基于宇宙射线变化进行详细全球同步的宝贵工具。
Cosmogenic10Be is a proxy of cosmic-ray flux, and its natural records provide vital information about the past intensity variability of the geomagnetic field and solar activity.10Be records also serve as powerful tools for global synchronization among a variety of paleoarchives and for elucidating sedimentary processes on natural remanent magnetization acquisition. However, high-resolution (multi-decadal to multi-centennial) records of10Be are scarce, especially those older than several tens of thousands of years. Here we present multiple high-resolution10Be records of the Iceland Basin geomagnetic excursion interval (ca. 170–200 kyr ago) obtained from sediment cores (authigenic10Be/9Be ratio) and an ice core (atmospheric10Be flux). Comparing sedimentary10Be records with relative paleointensity from the same cores, we found differences in the magnetic lock-in depth, even between adjacent cores. The10Be-proxy records from the sediment and ice cores exhibit common characteristics: an asymmetric large-scale variation, a ∼7-kyr quasi-plateau around the maximum with a characteristic mid-term depression, and multi-millennial fluctuations in cosmic-ray flux during this interval. Minimal-synchronized and stacked10Be records show that maximum cosmic-ray flux occurred 188.5–190.0 kyr ago and was double the present flux. A wavelet analysis of the stacked curve reveals dominant 4-kyr and secondary 8-kyr periodicities, both of which can be interpreted as intrinsic geomagnetic cycles. The wavelet spectrum of the high-resolution ice-core record shows a periodicity of 1.7 kyr and somewhat intermingled multi-centennial cycles around the maxima of10Be, which likely represent solar cycles in this period. High-resolution10Be records from multiple paleoarchives provide both a robust proxy record of cosmic-ray flux and a valuable tool for detailed global synchronization based on cosmic-ray variations.