A 62-ka geomagnetic palaeointensity record from the Taymyr Peninsula, Russian Arctic

Abstract

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.

Climate and environmental history at Lake Levinson‐Lessing, Taymyr Peninsula, during the last 62 kyr

“…Bayesian age–depth model of core Co1401, based on palaeomagnetic tie points (redrawn after Scheidt et al . 2021b) and supported by radiocarbon and OSL dating, palaeomagnetic excursions and pollen tie points from core PG1228 (Andreev et al . 2003).…”

“…The chronology of SZ 3 is based on five palaeomagnetic tie points and supported by two chronostratigraphic markers correlated to the geomagnetic events at Mono Lake and Laschamp, as well as by two 14 C ages (Fig. 4; Scheidt et al 2021b). The good correlation with the radiocarbon ages suggests that the amount of reworked OM was lower than in SZ 2.…”

“…4; Scheidt et al . 2021b). The OSL date at 33.97 m shows a larger offset compared with the OSL dates above; however, under consideration of its error the total offset is only about 1 ka.…”

“…The age-depth modelling of SZ 4 is based on four palaeomagnetic tie points, supported by one 14 C age (Fig. 4; Scheidt et al 2021b). The OSL date at 33.97 m shows a larger offset compared with the OSL dates above; however, under consideration of its error the total offset is only about 1 ka.…”

“…Supporting age control is derived from two geomagnetic events at 21.05 and 24.63 m depth, which correspond to the Mono Lake and Laschamp palaeomagnetic excursions (Scheidt et al . 2021b). Palaeomagnetic tie points are supplemented by radiocarbon ( 14 C) dating on 10 samples of macro‐organic remains (Table 1) at the Cologne AMS facility (Dewald et al .…”