Organic and inorganic proxy development for advective heat flux in a basal-melt-dominated glacial system: Petermann Fjord, North Greenland

Abstract. Mass loss from the Greenland Ice Sheet directly impacts sea level rise and the freshwater balance of the ocean. Petermann Glacier, North Greenland, provides a unique setting to explore atmosphere-ocean-ice interactions in a basal melt–dominated system using proxy records. We analyse organic (sea ice-associated highly branched isoprenoids (HBIs) and open water phytoplankton sterols) and inorganic (¹⁰Be, ²³⁰Th) proxies from five sediment cores spanning the inner to outer Petermann Fjord to investigate oceanic advection and glacial dynamics, during times when the ice shelf occupied extended (after 0.6 ka BP) and reduced (pre-0.6 ka BP) positions. Results show higher fluxes of ¹⁰Be, HBIs, and sterols during the reduced ice shelf phase. However, ¹⁰Be, HBIs, and sterols are also present in sediments deposited when the ice shelf was extended, suggesting lateral advection and glacial meltwater contribute to their deposition. Whilst ¹⁰Be has previously been applied as a proxy for ice shelves and perennial sea ice, in Petermann Fjord our results indicate that lateral advection, enhanced by buoyant subglacial melt, is the dominant source of ¹⁰Be, with glacial melt providing secondary input. Our study highlights the potential to use a multi-proxy approach to reconstruct circulation regimes and advective heat flux patterns in basal-melt-dominated environments.