Mineral magnetic and geochemical records of late Glacial climatic change from two northwest European carbonate lakes |
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| Authors: | SR Nolan J Bloemendal JF Boyle RT Jones F Oldfield M Whitney |
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| Institution: | (1) Environmental Magnetism Laboratory, Department of Geography, University of Liverpool, Roxby Building, PO Box 147, Liverpool, L69 3BX, U.K.;(2) Department of Geography, Edge Hill University College, St. Helens Road, Ormskirk, Lancashire, L39 1QB, U.K |
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| Abstract: | We present the results of mineral magnetic measurements and geochemical analyses of late Glacial sediments from two marl-precipitating lakes in the Northwest of England. Mineral magnetic assemblages dominated by detrital and/or authigenic ferrimagnetic minerals, and enhanced delivery of metal elements, characterise a lower (Oldest Dryas) and an upper (Younger Dryas) phase of catchment instability, with detrital clay and silt sedimentation. Magnetic mineral assemblages with lower concentrations of finer ferrimagnetic grains characterise the authigenic carbonate sediments (marls). The marls indicate both enhanced lake productivity and catchment stability in response to prevailing warm conditions during the Bølling - Allerød Interstadial. The Bølling - Allerød marl phase contains two short-term, low amplitude shifts characterised by changes in the concentration and the size of ferrimagnetic grains. These shifts may represent the Older Dryas and the Amphi-Atlantic Oscillation, short-lived Northern hemisphere climatic deteriorations. Overall, the results suggest that marl lakes are sensitive indicators of Lateglacial climatic change, and that these changes are readily identifiable through the use of mineral magnetic measurements. |
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| Keywords: | environmental magnetism lacustrine marl late Glacial climate change |
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