A 62-ka geomagnetic palaeointensity record from the Taymyr Peninsula, Russian Arctic
A 62-ka geomagnetic palaeointensity record from the Taymyr Peninsula, Russian Arctic
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DOI：
10.5194/gchron-2021-12
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发表时间：
2021-06
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通讯作者：
S. Scheidt;M. Lenz;R. Egli;D. Brill;M. Klug;K. Fabian;M. M. Lenz-M.;R. Gromig;J. Rethemeyer;B. Wagner;Grigory Federov;M. Melles
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作者：
S. Scheidt;M. Lenz;R. Egli;D. Brill;M. Klug;K. Fabian;M. M. Lenz-M.;R. Gromig;J. Rethemeyer;B. Wagner;Grigory Federov;M. Melles
抽象的。这项工作代表了第一个古地磁研究的沉积记录莱文森-莱辛湖，这是最深的湖泊在北方中西伯利亚。对从湖泊中部采集的46米长的Co 1401岩芯上部38米的730个离散样品进行了古地磁分析。进行了交变磁场退磁实验，以获得特征剩磁。利用磁化率、无滞后剩磁和等温剩磁对部分天然剩磁进行归一化，确定相对古强度。Co 1401的年代学来自加速质谱仪放射性碳年龄，光释光测年，以及642个离散样品的相对古强度与GLOPIS-75参考曲线的相关性。本研究主要集中在>10 ka的部分，但包括了岩芯上部的初步结果。该记录包括地磁漂移Laschamps和莫诺湖，并解决了足够的地磁特征，建立一个年表，连续覆盖~62 ka。结果表明，在45 ~ 95 cm ka−1之间，沉积作用持续，沉积速率很高。与沉积速率较低的参考记录的数据集相比，磁记录的可变性较低，这表明磁记录的锁定深度较高。尽管由于Co 1401的取芯没有芯段重叠，因此只能谨慎使用特征剩磁磁化的水平分量，但Co 1401的磁记录是北极切线柱体的相对古强度和古长期变化的唯一高分辨率记录，可追溯到~62 ka。
Abstract. This work represents the first palaeomagnetic study carried out on the sedimentary record of lake Levinson-Lessing, which is the deepest lake in northern Central Siberia. Palaeomagnetic analyses were carried out on 730 discrete samples from the upper 38 m of the 46 m-long core Co1401, which was recovered from the central part of the lake. Alternating field demagnetisation experiments were carried out to obtain the characteristic remanent magnetisation. The relative palaeointensity is determined using the magnetic susceptibility, the anhysteretic remanent magnetization and the isothermal remanent magnetization for normalization of the partial natural remanent magnetization. The chronology of Co1401 derives from accelerated mass spectrometer radiocarbon ages, optically stimulated luminescence dating, and correlation of the relative palaeointensity of 642 discrete samples with the GLOPIS-75 reference curve. This study focuses on the part >10 ka but although includes preliminary results for the upper part of the core. The record includes the geomagnetic excursions Laschamps and Mono Lake, and resolves sufficient geomagnetic features to establish a chronology that continuously covers ~62 ka. The results reveal continuous sedimentation and high sedimentation rate between 45 and 95 cm ka−1. High lock-in depths are suggested from the low variability of the magnetic record compared to data sets of reference records with lower sedimentation rate. Although the horizontal component of the characteristic remanent magnetization can only be used with caution because Co1401 was cored without core segment overlap, the magnetic record of Co1401 is the only high-resolution record of relative palaeointensity and palaeosecular variations from the Arctic tangent cylinder going back to ~62 ka.