Multiple 10Be records revealing the history of cosmic-ray variations across the Iceland Basin excursion (Supplementary tables)

Cosmogenic 10Be 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 of 10Be are scarce, especially those older than several tens of thousands of years. Here we present multiple high-resolution 10Be records of the Iceland Basin geomagnetic excursion interval (ca. 170-200 kyr ago) obtained from sediment cores (authigenic 10Be/9Be ratio) and an ice core (atmospheric 10Be flux). Comparing sedimentary 10Be records with relative paleointensity from the same cores, we found differences in the magnetic lock-in depth, even between adjacent cores. The 10Be-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 stacked 10Be 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 of 10Be, which likely represent solar cycles in this period. High-resolution 10Be 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.宇宙成因¹⁰Be（cosmogenic ¹⁰Be）是宇宙线通量的替代性代用指标，其天然地质记录可为揭示古地磁场强度演化与太阳活动变化提供关键科学信息。¹⁰Be记录同时也是开展多类古环境档案全球同步对比、阐明天然剩磁获取过程中沉积作用机制的有力工具。然而，高分辨率（数十年至数百年尺度）的¹⁰Be记录较为稀缺，尤其是年龄超过数万年的此类记录。本文报道了冰岛海盆地磁漂移事件区间（距今约170~200 kyr）的多套高分辨率¹⁰Be记录，其分别来自沉积物岩芯（基于自生¹⁰Be/⁹Be比值（authigenic 10Be/9Be ratio））与一支冰芯（基于大气¹⁰Be通量（atmospheric 10Be flux））。通过将沉积物¹⁰Be记录与同岩芯的相对古强度（relative paleointensity）数据进行对比，研究发现即便相邻岩芯之间，其磁性锁定深度亦存在差异。沉积物与冰芯的¹⁰Be代用指标记录展现出共同的演化特征：不对称的大规模强度变化、峰值附近持续约7千年的准平台结构并伴随特征性的中期凹陷，以及该时段内宇宙线通量的千年尺度波动。经最小化同步处理与叠加后的¹⁰Be记录显示，宇宙线通量峰值出现于188.5~190.0 kyr前，其强度为现代宇宙线通量的两倍。对叠加曲线的小波分析（wavelet analysis）揭示出以4千年为优势周期、8千年为次要周期的信号，二者均可归因于固有地磁场周期（intrinsic geomagnetic cycles）。高分辨率冰芯¹⁰Be记录的小波谱则显示出1.7千年的周期，且在¹⁰Be峰值附近混杂有若干百年尺度的周期信号，此类信号大概率代表该时期的太阳活动周期。来自多类古环境档案的高分辨率¹⁰Be记录，既可为宇宙线通量提供可靠的代用指标，也可为基于宇宙线变化开展精细全球同步对比提供极具价值的研究工具。