Late Holocene Paleomagnetic Secular Variation in the Chukchi Sea, Arctic Ocean

Abstract

The geomagnetic field behavior in polar regions remains poorly understood and documented. Although a number of Late Holocene paleomagnetic secular variation (PSV) records exist from marginal settings of the Amerasian Basin in the Arctic Ocean, their age control often relies on a handful of radiocarbon dates to constrain ages over the past 4,200 years. Here we present well‐dated Late Holocene PSV records from two sediment cores recovered from the Chukchi Sea, Arctic Ocean. The records are dated using 26 14C measurements, with local marine reservoir corrections calibrated using tephra layers from the 3.6 cal ka BP Aniakchak eruption in Northern Alaska. These 14C‐based chronologies are extended into the post‐bomb era using caesium‐137 dating, and mercury isochrons. Paleomagnetic measurements and rock magnetic analyses reveal stable characteristic remanent magnetization directions, and a magnetic mineralogy dominated by low‐coercivity minerals. The PSV records conform well to global spherical harmonic field model outputs. Centennial to millennial scale directional features are synchronous between the cores and other Western Arctic records from the area. Due to the robust chronology, these new high‐resolution PSV records provide a valuable contribution to the characterization of geomagnetic field behavior in the Arctic over the past few thousand years, and can aid in developing age models for suitable sediments found in this region.

A 1300-year microfaunal record from the Beaufort Sea shelf indicates exceptional climate-related environmental changes over the last two centuries

“…The model was constructed using the OxCal program (version 4.4;Bronk Ramsey, 2008, 2009 and we applied the Marine20 curve (Heaton et al, 2020). We used a ΔR of 330 ± 41 years based on a 3600-year-old tephra layer in a sediment core of the Chukchi Sea (Pearce et al, 2017;West et al, 2022). It is similar to the ΔR of 308 ± 111 years based on 14 C ages of seven mollusks collected in the nearshore areas of Alaska prior to bomb testing (Table S4; cf.…”

Continuous synchronization of the Greenland ice-core and U-Th timescales using probabilistic inversion

“…The numerical approach builds upon previous work using a hidden Markov model for automated synchronization of paleoclimate records (Cutmore et al, 2021;Muschitiello et al, 2020Muschitiello et al, , 2019Sessford et al, 2019;West et al, 2021West et al, , 2019. The model employed here uses constraints imposed by the MCE, i.e.…”

Challenging Radiocarbon Chronostratigraphies in Central Arctic Ocean Sediment

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Radiocarbon ages of planktic foraminifers and other biogenic carbonates from recent marine sequences of the Arctic Ocean remained so far, the least challenged dating tool (e.g., West et al, 2022). The principal debated issue about the 14 C approach has been the assessment of the apparent age of the marine dissolved inorganic carbon at present and through time, thus the ΔR value to use for converting radiocarbon ages into calibrated ages (e.g., Hanslik et al, 2010;Pearce et al, 2017).

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