RT info:eu-repo/semantics/article
T1 Abrupt last glacial dust fall over southeast England associated with dynamics of the British-Irish ice sheet
A1 Stevens, Thomas
A1 Sechi, Daniele
A1 Bradák, Balázs
A1 Orbe, Ragna
A1 Baykal, Yunus
A1 Cossu, Giulia
A1 Tziavaras, Charilaos
A1 Andreucci, Stefano
A1 Pascucci, Vincenzo
K1 Loess
K1 Pegwell bay
K1 Luminescence
K1 Multi-proxy
K1 Brickearth
K1 Palaeoenvironment
K1 Física
K1 Physics
K1 Ciencias medioambientales
K1 Environmental sciences
K1 Geología
K1 Geology
AB Loess deposits in southern Britain contain a record of dust, climate and landscape dynamics over the lastglacial, yet their age and accumulation rate remain poorly known. Furthermore, the environmentalcontrols on the loess-soil stratigraphy shown in the thickest deposits in southeast England are stilldebated. Here we apply the first high sampling resolution quartz optically stimulated luminescencestudy of dust accumulation and loess formation in Britain at the Pegwell Bay site in east Kent. We couplethis to mineral magnetic, particle size and geochemical analyses to understand climate, environment andpost depositional modification of the loess. The luminescence ages and Bayesian age modelling resultssuggest two phases of greatly enhanced dust accumulation at the site. Loess began to accumulate aroundc. 25e23.5 ka, coinciding with Heinrich event 2, and after subsequent lower accumulation rates, a secondenhanced phase of deposition occurred at around 20e19 ka.We propose a model where the dynamics ofthe British-Irish and Fennoscandian Ice Sheets, associated glacial lake drainage, and linked reorganisationsof atmospheric circulation, all controlled loess accumulation in southern Britain. Accumulation inthe first phase was triggered by increased sediment supply from initial retreat of the North Sea ice lobe,and drainage of Dogger Lake. Loess accumulation during this phase was enhanced by easterly winds fromAtlantic depressions tracking to the south of Britain, caused by the maximum extent of the Irish Sea IceStream at c. 25e24 ka. The subsequent retreat of the western part of the British Irish Ice Sheet thenallowed storm tracking further north, which reduced effectiveness of dust transporting winds acrosssouthern Britain, while sediment supply and availability was reduced in North Sea source areas. A secondretreat of the maximum extent of the North Sea Lobe of ice after c. 21e20 ka would have led to anotherabrupt input of sediment-rich ice dammed lake and meltwater from eastern England and the North Seainto the exposed southern North Sea area. This would have again dramatically increased sedimentavailability for transport and deposition as loess in SE England, resulting in the second dust accumulationphase. We also propose that the abrupt stratigraphic change from calcareous to non-calcareous loess upsection at Pegwell Bay was driven, not by these changes in dust input, but rather deepening of thepermafrost active layer after c. 21 ka. This deepening was associated with warmer and wetter conditionsdriven by Atlantic storms tracking further north following the regression of the Irish Sea Ice Stream andoverall ice sheet retreat. As such, last glacial dust dynamics and loess accumulation in Britain is highlyinfluenced by the interaction of the British Irish Ice Sheet the Fennoscandian Ice sheet, Atlantic stormtracks, and the topography and drainage of the exposed North Sea.
PB Elsevier
SN 0277-3791
YR 2020
FD 2020-12
LK http://hdl.handle.net/10259/6103
UL http://hdl.handle.net/10259/6103
LA eng
NO Swedish ResearchCouncil (VR grant 2017e03888) and the Quaternary Research Association(QRA) Quaternary Research Fund. BB acknowledges thefinancial support of project BU235P18 (Junta de Castilla y Leon,Spain) and the European Regional Development Fund (ERD).
DS Repositorio Institucional de la Universidad de Burgos
RD 23-nov-2024