Geochemical and mineralogical characteristics of fjord sediments in Arctic Svalbard: insights into Holocene glacial activity and weathering variability

Abstract

The Svalbard archipelago at the border of the Arctic Ocean experiences substantial glacier retreat due to global warming, resulting in a retreat of glacier termini from the marine to terrestrial settings. However, the impact of these transitions on marine environments remains poorly understood. To improve our understanding of how Arctic Svalbard responds to fluctuations in climate and glaciers, we reconstructed past glacimarine environments in Hornsund, southern Svalbard, over the last 4,900 years. By tracking sediment provenance using detrital neodymium isotopes and quartz-to-carbonate ratios, we revealed a progression from nearly open-marine conditions with minimal glacial activity during the middle Holocene to gradual seaward glacial expansion into the Neoglacial period (4,000 years B.P. to 790 C.E.). Glaciers likely retreated landward during the Medieval Warm Period (MWP; 790 to 1,470 C.E.), punctuated by significant readvances at least twice. The Little Ice Age (LIA) witnessed multiple glacial advances into the marine environment, followed by an overall glacial retreat in modern times. Geochemical analysis of authigenic sediment components indicates pronounced enrichments of middle rare earth elements, particularly during rapid glacial advances such as the MWP and LIA, which we interpret as enhanced glacial erosion and accelerated sulfide oxidation. Paleo-analogues from the middle Holocene, characterized by minimal marine-terminating glaciers and reduced sulfide weathering, suggest potential future declines in sulfur-related bioessential nutrient fluxes into Arctic coastal environments and subsequently to marine ecosystems.