Evaluating the reliability of radiocarbon chronologies in Arctic Ocean sediments using calcare ous nannofossil bioevents

作者：Mohammad J. Razmjooei, Robert F. Spielhagen, Henning A. Bauch, Flor Vermassen, Martin Jakobsson, Matt O'Regan · 发表于：Palaeogeography Palaeoclimatology Palaeoecology · 年份：2026 · DOI：10.1016/j.palaeo.2026.113847 · 研究领域：Geological Studies and Exploration、Geology and Paleoclimatology Research、Marine and environmental studies

Radiocarbon chronologies for Arctic Ocean sediments are argued to be extremely uncertain due to low sedimentation rates, bioturbation and authigenic calcite growth on microfossils. Mixing of sediments may result in under-or overestimation of the true age of sediments and authigenic calcite growth can yield either anomalously old or, even younger radiocarbon ages. Ascertaining the extent of these processes is necessary to determine the fidelity of late Pleistocene and Holocene Arctic paleoceanographic time-series. A key question is the age of microfossil-bearing sediments overlying a widespread diamict in the central Arctic Ocean, particularly whether it was deposited during Marine Isotope Stage (MIS) 3 between 40 and 50 ka, or during an earlier stadial of the last glacial cycle. Here we use two key calcareous nannofossil bioevents: the abundance peak of Coccolithus pelagicus and the transition from a high abundance of Gephyrocapsa spp. to a dominance of Gephyrocapsa huxleyi to identify Holocene and MIS 3 sediments from the central Arctic Ocean. We show that the timing of these events can be correlated to lower latitude records, providing an important stratigraphic framework to assess Arctic radiocarbon chronologies. Bayesian age-depth models constructed for three carbonate-rich cores yield stratigraphically consistent, monotonic age-depth relationships with acceptable agreement indices and reduced uncertainties relative to unmodelled calibrations. The models reveal variable s...