Climate, Fjord Morphology, and Oceanographic controls on Glacier Retreat and Sedimentation in Bellsund, Southwestern Svalbard

Abstract

We investigate subbottom acoustic data combined with sedimentology and stratigraphy from a 470 cm­long sediment core from Bellsund, southwestern Svalbard, to reconstruct glacier dynamics and environmental change since the last deglaciation. Our results indicate that a marine­based glacier occupied Bellsund around 15 ka BP, subsequently retreated, with a temporary stillstand near the inner basin around 14 ka BP. By the onset of the Younger Dryas (YD), the glacier fronts had reached the mouths of the tributary fjords. Notably, glacier retreat in Bellsund progressed more slowly than in the adjacent Isfjorden, most likely due to topographic constrictions at the mouths of its tributary fjords (e.g., Eholmen and Akseløya), which acted as pinning points. No evidence is found for glacier re­advance during the YD. Following the YD, rapid glacier retreat into the tributary fjords contributed to meltwater discharge and terrestrial input, which in turn was associated with glacier­distal, glacimarine sedimentation with reduced ice rafting until 10.7 ka BP. During the early to middle Holocene (9.5？3.3 ka BP), Bellsund experienced a condensed sedimentary environment, likely reflecting the combined influence of intensified bottom current activity driven by Atlantic Water inflow, relative sea­level fall due to glacio­isostatic uplift, and local bathymetric highs. Since 3.3 ka BP, glacial influence in Bellsund has been dominated by input from the adjacent southern tributary fjord (Recherchefjorden). Our findings highlight the interplay of climate forcing, fjord morphology, and oceanographic processes in shaping glacier behavior and environmental change in glaciated Arctic fjord systems.