Seasonally resolved diatom δ18O records from the West Antarctic Peninsula over the last deglaciation

Abstract

A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk O record derived from a high-resolution deglacial seasonally laminated core section off the west Antarctic Peninsula (WAP) is presented here. By extracting and analysing single species samples from individual laminae, season-specific isotope records were separately generated to show changes in glacial discharge to the coastal margin during spring and summer months. As well as documenting significant intra-annual seasonal variability during the deglaciation, with increased discharge occurring in summer relative to spring, further intra-seasonal variations are apparent between individual taxa linked to the environment that individual diatom species live in. Whilst deglacial δ 18 O are typically lower than those for the Holocene, indicating glacial discharge to the core site peaked at this time, inter-annual and inter-seasonal alternations in excess of 3‰ suggest significant variability in the magnitude of these inputs. These deglacial variations in glacial discharge are considerably greater than those seen in the modern day water column and would have altered both the supply of oceanic warmth to the WAP as well as regional marine/atmospheric interactions. In constraining changes in glacial discharge over the last deglaciation, the records provide a future framework for investigating links between annually resolved records of glacial dynamics and ocean/climate variability along the WAP.

Glacial discharge along the west Antarctic Peninsula during the Holocene

“…1a) can be accounted for by glacial discharge during summer and lower contributions in spring 30 , which follows the pattern of modern observations 28 . …”

“…1a). Extremely high post-glacial (13.0-12.0 ka) sedimentation rates in Palmer Deep (2.32 cm yr -1 ) and the preservation of annually laminated sediments 29 allows single taxon δ 18 O diatom samples to be concentrated from individual laminations of near-single-taxa composition and analysed to provide an insight into the seasonality of glacial discharge and melt water input to the margin at that time 30 .…”

Pliocene diatom and sponge spicule oxygen isotope ratios from the Bering Sea: isotopic offsets and future directions

“…The mechanisms governing these offsets in size fractions of > 75 µm are still unresolved, but may be connected with growth effects associated with larger diatoms (Schmidt at al., 2001). Whilst a recent study has identified offsets of up to 4.2 ‰ between different diatom taxa in sediments from the Antarctic coastal margin, this is linked to their habitat within the vertical water column rather than an inter-species effect related to different fractionation in individual taxa (Swann et al, 2013). A similar scenario cannot occur here in the Bering Sea as intra-seasonal water column variations in δ 18 O vary by less than 0.5 ‰ over a depth of 0-1188 m (Schmidt et al, 1999).…”

Ecology and Evolution of Marine Diatoms and Parmales

“…One of the main focuses of recent marine research has been establishing the response of the Antarctic ice sheets during the rapid climatic change that accompanied the last deglaciation (see Swann et al 2013 ). This is important for understanding the susceptibility of these regions to future warming.…”