A record of Holocene glacial and oceanographic variability in Neny Fjord, Antarctic Peninsula

Abstract

Analyses of a 12 m marine sediment core from Neny Fjord, Marguerite Bay, Antarctic Peninsula (68.2571°S, 66.9617°W), yield a high-resolution record of Holocene climate variability. The sediments preserve signals of past glacial and marine environments and offer a unique insight into atmospheric and oceanic forcings on the western Antarctic Peninsula climate. Dating of basal material reveals that deglaciation of the fjord occurred prior to 9040 cal. yr BP and provides a minimum constraint on the timing of deglaciation close to the southern Antarctic Peninsula ice-divide. Continuous deposition of ice-distal sediments and seasonally open-water diatoms indicates that the site has not been over-ridden by glacier ice during the Holocene. A facies of sand-rich material offers the only evidence of a localized glacier advance, during the mid Holocene. Statistical analysis of diatom assemblage data reveals several climatic episodes of varying magnitude and duration. These include an early-Holocene warm period (~9000 and ~7000 cal. yr BP), potentially associated with influx of Circumpolar Deep Water onto the continental shelf and coinciding with widespread glacial retreat and Holocene collapse of the George VI Ice Shelf. The mid-Holocene (~7000 to ~2800 cal. yr BP) sediments are characterized by diatom assemblages indicative of less pervasive sea-ice cover and prolonged growing seasons with evidence of increased meltwater discharge from ~4000 cal. yr BP. The youngest sediments (~2800 cal. yr BP to present) contain a record that is consistent with the widely documented ‘neoglacial’ period followed by an abrupt reversal and climate amelioration from sometime after ~200 cal. yr BP.