Late-Holocene climatic change recorded in sediment cores from Ellis Fjord, eastern Antarctica

Abstract

An analysis of diatom assemblages, Total Organic Carbon (TOC), carbon-nitrogen ratio, δ13C, biogenic silica and carboniate in two marine sediment cores from Ellis Fjord, eastern Anitarctica, reveals episodes of climatic change at 3600, 2500. 2000 and 1000 yr BP. Using the diatom data, principal component analysis, the fast-ice index (FI), benthic index (BI) and snow index (SI) (which are derived from the diatom data). a period of reduced temporal sea-ice cover is identified prior to 2500 BP. There was a large increase in sea-ice extent between 2500 and 2000 BP followed by a smaller decline. Tenmporal sea-ice extent after 2000 BP was still significantly greater than prior to 2500 BP. Both cores xvere taken from anoxic basins within the fjJord. It was found that the better preservationi allowed the recognition of taxa such as Clraetocelos vegetative cells, which are inot usually preserved. This enabled the distinction between ice-edge blooms, dominated by Fragilariopsis curta, and open-water blooms dominated by Chaeitoceros. Even though Watts Basin receives a significant summer meltwater input each year, it has not been possible to recognize this signal in the sedimiient core.

The sedimentary legacy of a palaeo-ice stream on the shelf of the southern Bellingshausen Sea: Clues to West Antarctic glacial history during the Late Quaternary

“…This interpretation is in agreement with the relatively high C org /N tot ratios of this unit, which may result from nitrogen limitation in response to ice cover (e.g. McMinn et al, 2001;Yoon et al, 2010). In cores GC358, GC359, GC360, GC362, GC370, GC371, GC372 and PS2533-2 the increasing influence of seasonal open-water conditions towards the top of the gravelly sandy mud is reflected by an increase of C org and/or CaCO 3 concentrations, the onset of bioturbation and/or the increase of silt and clay contents ( Fig.…”

“…C org /N tot ratios up to 30 have been reported from Holocene Antarctic shelf sediments and were attributed to enhanced supply of terrestrial organic material or (lipid-rich) organic matter from marine benthic algae in combination with limited nitrogen availability under sea-ice cover (e.g. Yoon et al, 2000Yoon et al, , 2010McMinn et al, 2001;Presti et al, 2003). Inorganic nitrogen is likely to contribute to the low C org /N tot ratios in the gravelly diamictons at sites GC362, GC365 and GC366, because these sediments are characterised by the highest illite contents in the study area (Fig.…”

Late Miocene paleoenvironment of the Lambert Graben embayment, East Antarctica, evident from: Mollusc paleontology, sedimentology and geochemistry

“…The Battye Glacier Formation TOC% is low (b 0.655%), similar to that in Holocene sediments from Lallemand Fjord in the Antarctic Peninsula (b 0.4%) (Taylor et al, 2001). The nitrogen levels in the Battye Glacier Formation (b 0.119%) are within or below the lower range of values reported from Recent Antarctic sediments (DeMaster et al, 1996;McMinn et al, 2001). The TOC : N ratios express the degree of nutrient limitation at the time of algal growth (Redfield et al, 1963;McMinn, 2000).…”

“…The TOC : N ratios express the degree of nutrient limitation at the time of algal growth (Redfield et al, 1963;McMinn, 2000). In modern marine conditions the ratio of TOC:N is commonly 6.6, but increases to 7.7-20 when algae become N-limited (Redfield et al, 1963;McMinn et al, 2001). High TOC : N ratios N 7.7 and N20 are evident in several Battye Glacier Formation samples; however, there is much reworked Amery Group coal within the formation (Online Appendix 4), which could have caused the TOC:N ratio to be relatively high N 20 (Rullkö tter, 2000), preventing an assessment of algal N-limitation.…”

Late Quaternary deglaciation and climate history of the Larsemann Hills (East Antarctica)

“…2000 cal. yr BP in Kirisjes Pond, concomitant with a rapid cooling in Antarctic ice-cores (Masson et al, 2000) and sediment cores in the open marine environment (Taylor and McMinn, 2002) and marine embayments (McMinn, 2000;McMinn et al, 2001) in Prydz Bay, possibly linked with Neoglacial cooling. In addition, short dry periods in Kirisjes Pond are recognised between ca.…”