Holocene sea-ice dynamics in Petermann Fjord in relation to ice tongue stability and Nares Strait ice arch formation

Abstract. The Petermann 2015 expedition to Fjord and adjacent Hall Basin recovered a transect of cores, extending from Nares Strait underneath the 48 km long ice tongue glacier, offering unique opportunity study ice–ocean–sea interactions at interface these realms. First results suggest that no existed in for large parts Holocene, raising question role ocean marine cryosphere collapse re-establishment tongue. Here we use multi-proxy approach (sea-ice-related biomarkers, total organic carbon its isotopic composition, benthic planktonic foraminiferal abundances) explore Holocene sea dynamics OD1507-03TC-41GC-03PC outer Fjord. Our are line with tight coupling terrestrial this region and, connection other regional reconstructions, give insights into evolution arches associated landfast Strait. late stages Thermal Maximum (6900–5500 cal yr BP) were marked by reduced seasonal concentrations lack arch formation. This was followed transitional period towards Neoglacial cooling 5500–3500 BP, where southern might have formed, but an early breakup formation likely caused prolonged open water season enhanced pelagic productivity Between 3500 1400 records stable northern only, short 2500–2100 BP formed intermittently response atmospheric spikes. A arch, or even double arching, is also inferred after BP. Thus, both inception small ? 2200 rapid expansion 600 preceded transition regime Strait, suggesting stabilizing effect on Glacier.