Palaeoenvironmental records from the West Antarctic Peninsula drift sediments over the last 75 ka.

Vautravers, Maryline J. and Hodell, David A. and Channell, James E.T. and Hillenbrand, Claus-Dieter and Hall, Mike A. and Smith, James and Larter, Robert D. (2012) Palaeoenvironmental records from the West Antarctic Peninsula drift sediments over the last 75 ka. In: Antarctic Palaeoenvironments and Earth-Surface Processes. Geological Society Special Publication, 381 . Geological Society of London.

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We present results of a multi-proxy study on marine sediment core JR179-PC466 recovered from the crest of a sediment drift off the West Antarctic Peninsula at approximately 2300 m water depth. The 10.45 m-long core consists dominantly of glaciomarine terrigenous sedi- ments, with only traces of calcium carbonate (,1 wt%). Despite the very low abundance of calcar- eous foraminifera, planktonic shell numbers are sufficient for stable isotope analyses in two-thirds of the samples studied. The core chronology is based on oxygen isotope stratigraphy and corre- lation of its relative palaeomagnetic intensity (RPI) with a stacked reference curve. According to the age model, core PC466 spans the last 75 ka, with average sedimentation rates of between about 4 and 25 cm ka 21 . Planktonic foraminifera abundances fluctuate between 0 and 30 individ- uals per gram throughout the core, with minima observed during Marine Isotope Stage (MIS) 2 (14–29 ka before present, BP) and MIS4 (57–71 ka BP). Planktonic foraminifera are present in the Holocene but more abundant in sediments deposited during MIS3 (29–57 ka BP), owing to less dilution by terrigenous detritus and/or better carbonate preservation. During MIS3, forami- nifera maxima correlate with Antarctic warming events as recorded in the d 18 O signal of the EPICA Dronning Maud Land (EDML) ice core. They indicate higher planktonic foraminifera production and better carbonate preservation west of the Antarctic Peninsula during that time. The abundance of ice-rafted detritus (IRD) in core PC466 increased during the last deglaciation between about 19 and 11 ka BP, when numerous icebergs drifted across the core site, thereby releasing IRD. During this time, sea-level rise destabilized the Antarctic Peninsula (APIS) and West Antarctic (WAIS) ice sheets that had advanced onto the shelf during the sea-level low- stand of the Last Glacial Maximum (LGM; c. 19–23 ka BP). Overall, our results demonstrate that it is possible to establish an age model and reconstruct palaeoceanographical and climatic changes at high temporal resolution from sedimentary sequences recovered at 2300 m water depth from a West Antarctic drift.

Item Type: Book Section
Uncontrolled Keywords: 2012AREP; IA64; BAS;
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Volume: 381
Identification Number: doi: doi 10.1144/SP381.12
Depositing User: Sarah Humbert
Date Deposited: 27 Oct 2012 10:02
Last Modified: 23 Jul 2013 10:04

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