Documenting accurately amplitude and rhythms of geomagnetic variations is a prerequisite to understand the mechanisms triggering geomagnetic excursions and reversals. We present new authigenic 10Be/9Be ratio (Be ratio) results covering the 60-20 ka time interval from equatorial core MD05-2920. The most significant Be ratio peak is located 18 cm above the main relative paleointensity (RPI) minimum recorded in this sequence. These are interpreted as two independent recordings of the geomagnetic dipole moment (GDM) decrease linked to the Laschamp excursion dated at ca 41 ka. The stratigraphic offset is assignable to post-depositional magnetization lock-in processes resulting in time delay of 1.6 ka. The Be ratio and RPI records show comparable asymmetric behavior before and after the dipole low. The Be ratio record is combined with three other series to construct a global record of 10Be paleoproduction variations. This compilation demonstrates the strong coherence of low and mid latitudes data sets and its comparison with 10Be-flux records from polar regions fully supports the hypothesis of a global atmospheric 10Be production doubling during the Laschamp. The Be ratio stack is converted in terms of GDM using both a theoretical model and a reconstruction of GDM values using absolute paleointensities measured on lava flows. Both methods provide similar results. The dipole moment record derived from this approach (BeDM 20-60) shows the following characteristics: high field values (> 11 × 1022 Am2) prior to a sharp two-steps dipole decrease until reaching minimum values (1.8 ± 0.7 × 1022 Am2) between 41.6 and 40.9 ka at the time of the Laschamp excursion. The GDM partly recovers up to values of ∼ 6.3 × 1022 Am2 , and oscillates in this range, without showing any sharp decreases that could be associated with excursions reported within the 38-20 ka time interval (e.g. the Mono Lake excursion).

中文翻译：

---

宇宙成因 10Be 生产记录揭示了拉尚偏移 (20–60 ka) 期间地磁偶极矩 (GDM) 的动态

准确记录地磁变化的幅度和节奏是了解触发地磁偏移和反转机制的先决条件。我们提出了新的自生 10Be/9Be 比率（Be 比率）结果，涵盖了赤道核心 MD05-2920 的 60-20 ka 时间间隔。最显着的 Be 比峰位于该序列中记录的主要相对古强度 (RPI) 最小值上方 18 厘米处。这些被解释为与约 41 ka 的拉尚偏移相关的地磁偶极矩 (GDM) 减少的两个独立记录。地层偏移可分配给沉积后磁化锁定过程，导致 1.6 ka 的时间延迟。Be 比率和 RPI 记录在偶极低点之前和之后显示出类似的不对称行为。Be 比率记录与其他三个系列相结合，构建了 10Be 古生产变化的全球记录。该汇编证明了低纬度和中纬度数据集的强一致性，并将其与极地地区的 10Be 通量记录进行比较，完全支持拉尚期间全球大气 10Be 产量翻番的假设。Be 比率堆栈使用理论模型和使用在熔岩流上测量的绝对古强度重建 GDM 值在 GDM 方面进行转换。两种方法都提供类似的结果。从这种方法 (BeDM 20-60) 得出的偶极矩记录显示以下特征：高场值 (> 11 × 1022 Am2) 在急剧的两步偶极下降之前达到最小值 (1.8 ± 0.7 × 1022 Am2)在 41.6 和 40 之间。在 Laschamp 游览时 9 ka。GDM 部分恢复到 ∼ 6.3 × 1022 Am2 的值，并在此范围内振荡，没有显示任何可能与 38-20 ka 时间间隔内报告的偏移（例如 Mono Lake 偏移）相关的急剧下降。