Taphonomic signature of benthic foraminifera linked to methane release in the Barents Sea

This study investigates methane seepage dynamics over the past several centuries in the southwestern Barents Sea through an integrated analysis of foraminiferal taphonomy, stable carbon isotopes, and the lipid biomarkers glycerol dialkyl glycerol tetraethers (GDGT) based molecular biomarkers. We examined the preservation state of nine calcareous benthic foraminiferal species from sediment core HH1141, grouping test alterations into five taphonomic categories. These preservation patterns correlate with geochemical indicators of methane emissions, such as depleted δ13C values of carbonate tests and organic matter and elevated Methane Index (MI), allowing the identification of three stratigraphic units reflecting distinct seepage regimes. Along with this gradient, electron microscopy and microprobe analyses reveal widespread diagenetic overgrowths and mineral replacements linked to anaerobic oxidation of methane. Furthermore, species-specific responses highlight that Elphidium clavatum, Stainforthia feylingi, Stainforthia loeblichi and Cassidulina reniforme are more susceptible to alteration, while Melonis barleeanus shows remarkable resistance. The observed temporal variability in methane seepage is interpreted as the result of multifactorial environmental drivers, including changes in subsurface dynamics and bottom-water conditions. This multidisciplinary approach demonstrates the utility of foraminiferal taphonomy as a sensitive proxy for methane-rich environments and cold seep evolution, especially in polar regions undergoing rapid climatic and oceanographic change.