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Abstract

Abrupt, millennial-scale climate events characterize the most recent deglaciation. However, their nature remains poorly understood. Previous work has shown enhanced glacial melt signals from the European/Scandinavian Ice Sheet and a rapid recession of the Laurentide Ice Sheet (LIS) in Eastern Maine during Heinrich Stadial 1 (HS-1). These observations challenge the idea that stadials were year-round cold excursions in the Northern Hemisphere. We aim to determine if European HS-1 melt signals are coeval with LIS meltwater in the Gulf of Maine (GOM) marine sediment record, which was ice-proximal during much of the last deglaciation. Here we present geochemical records (δ¹⁸O, Mg/Ca, calculated δ¹⁸O_seawater) developed using benthic foraminifera from a new GOM sediment core, EN-669-GGC-40, spanning ∼17.5–11.5 cal ky BP. We find that the documented portion of HS-1 in the GOM can be divided into two phases: the earlier (HS-1b, ∼17.5–15.9 cal ky BP) being characterized by large-amplitude variations of δ¹⁸O_sw, which we interpret as a series of intervals of enhanced meltwater runoff from the LIS. The later period (HS-1a, ∼15.9–14.7 cal ky BP) is characterized by a rapid and sustained isotopic depletion of δ¹⁸O_sw from 15.7 to 15.3 cal ky BP which we interpret as a persistent melting episode, consistent with rapid collapse of glacial ice in Eastern Maine. Our results support the hypothesis that HS-1 was characterized by warm(ing) summers and hypercold winters in the North Atlantic region (Denton et al., 2005, https://doi.org/10.1016/j.quascirev.2004.12.002, Denton et al., 2022, https://doi.org/10.1016/j.quascirev.2022.107750).

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