Late Quaternary Bering Strait opening recorded by Nd isotopes in western Arctic sediments

This is the authors' abstract. We don't add key points for this paper.

Since the closure of the Isthmus of Panama, the shallow (∼53 m) Bering Strait constitutes the only Northern Hemisphere Pacific–Atlantic gateway, connecting the North Pacific and North Atlantic through the Arctic Ocean. There is so far little direct geologic evidence for its opening in relation to sea-level changes prior to the Holocene. Here we present exchangeable neodymium (Nd) isotope composition ( 143 Nd/ 144 Nd expressed in epsilon units, εNd) records from a sediment core HLY0501-5JPC, recovered from the Chukchi–Alaska margin, to reconstruct Pacific Water inflow to the western Arctic Ocean. Middle Holocene to recent sediments (<8 ka) show radiogenic εNd values of −5.9 ± 0.5 (± 1σ; n = 17), reflecting a strong Pacific-derived Nd signal. Earlier intervals exhibit large εNd variability between unradiogenic values (−9.3 ± 1.4; n = 5; down to ∼ −11.5), not unlike those of the modern-like intermediate North Atlantic Water mass in the area, and strong Pacific-Water-influenced signatures (−5.4 ± 0.3; n = 6; up to ∼ −5.0). We interpret this εNd-value range to indicate circulation patterns varying from nil Pacific influx to conditions comparable to those of the late Holocene. This record demonstrates sporadic and variable Pacific Water inflow over time, likely governed by sea-level thresholds and/or changes in regional circulation. It suggests that the Bering Strait opened prior to the middle Holocene, possibly during the last deglaciation (∼13–11 ka) or an older high-sea-level interval. Nd isotope measurements in longer, well-dated sediment records from the Chukchi–Alaska margin could help to document the sensitivity of this shallow ocean gateway to sea-level changes and to highlight its role in regulating potential North Pacific-North Atlantic exchanges in relation to large-amplitude climate changes.