Sites U1621–U1623. Proceedings of the International Ocean Discovery Program Volume 403 publications

The Bellsund drift coring sites are located on a plastered sediment drift that developed along the lower continental slope (1700–1800 m water depth) of the western margin of Svalbard under the influence of the northward-flowing West Spitsbergen Current (WSC) (Rebesco et al., 2013) (Fig- ure F1). The Bellsund drift has built up over millions of years since the opening of the Fram Strait (17–10 Ma) (Jakobsson et al., 2007; Engen et al., 2008; Ehlers and Jokat, 2013), which determined the onset of the contour current circulation system in the area (Eiken and Hinz, 1993; Gebhardt et al., 2014), with development of sediment drifts covering large areas of the European North Atlan- tic margin, including the Norwegian Sea, Barents Sea, the western margin of Svalbard, and along the eastern side of the Fram Strait (Laberg et al., 2005). Sediment drifts are depocenters developing under persistent bottom currents (Stow et al., 2002; Rebesco, 2014b) that substantially rework the sediments delivered to the marine environment through terrestrial and marine processes. The bottom currents transport sediments, oxygen, and nutrients along the margin, making the envi- ronment ideal for biological productivity with sediments rich in carbonate biogenic fraction if postmortem diagenetic conditions allow for their preservation. The Bellsund drift recorded the continental input associated with the expansion and retreat of the paleo-Svalbard–Barents Sea Ice Sheet (SBSIS) during the past glacial and interglacial cycles (glacial debris flows and sediment- laden meltwater plumes) and the variability of the warm WSC through its effect on the marine biological productivity in the water column (Lucchi et al., 2018; Caricchi et al., 2019; Torricella et al., 2022, 2025; Gamboa Sojo et al., 2024). Its location between the Storfjorden Trough Mouth Fan (TMF) to the south and the Bellsund TMF to the north provided some protection from direct glacigenic input from the paleo-SBSIS during the past glaciations while still capturing a record of the ice sheet dynamics.