High-resolution records of deglaciation and palaeomagnetism in the Late-Quaternary sediments of Windermere, UK

• Main Author: Avery, Rachael
• Format: Thesis
• Language: English
• Published: University of Southampton 2017
• Subjects: Greenland; Ice Sheet
• Online Access: https://eprints.soton.ac.uk/421112/; https://eprints.soton.ac.uk/421112/1/Avery_Rachael_PhD_Thesis_May_2018.pdf

Windermere, in the Lake District, UK, is a glacial ribbon lake that has accumulated sediment since its exposure after the retreat of the British and Irish Ice Sheet (BIIS). A coring campaign by the British Geological Survey in partnership with the University of Southampton has recovered a suite of sediment cores from Windermere, which document lacustrine sedimentation from ~15 ka to the present day. The varved nature of some of the sediments has offered the opportunity to investigate the nature and timing of events in the northern UK over the Lateglacial (~14.7 – 11.7 ka BP). In particular, the placement of Windermere between continental Europe and Greenland provided the impetus to investigate the laminations further, with the possibility that climatic leads and lags across the region may be identified should the chronology prove robust enough. Also, the seismic work already carried out in Windermere implied that the initial retreat of ice from the lake during the last deglaciation was fairly rapid, and the recovery of the cores was intended in part to test this claim using suspected varves recovered. A third possibility, once the cores had been recovered and other investigations were underway (prior to this study), was that the palaeomagnetic nature of the sediment may be ascertained and the UK palaeomagnetic master curve of Turner & Thompson (1981; obtained in part from Windermere sediments) may be updated and extended using newer measurement and dating techniques. A suite of techniques were used to analyse the cores, including (but not limited to) scanning electron microscope imagery of resin-embedded thin sections, Itrax XRF core scanning, palaeomagnetic measurements, and grain size analysis. The upper part of the varve sequence is more organic-rich and was radiocarbon-dated to provide a Holocene (~11.7 ka – present) age-depth model. Palaeomagnetic measurements from the Holocene were placed on this age-depth model and stacked to form a new Holocene geomagnetic palaeosecular variation curve for the UK, ...