Radiocarbon wiggle-match dating of proglacial lake sediments – Implications for the 8.2 ka event |
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Authors: | Anne Hormes Maarten Blaauw Svein Olaf Dahl Atle Nesje Goran Possnert |
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Institution: | aÅngstromlaboratory, Uppsala University, 75120 Uppsala, Sweden;bSchool of Geography, Archaeology and Palaeoecology, Queen's University, Belfast, Northern Ireland, UK;cDepartment of Geography, University of Bergen, Breiviksveien 40, 5045 Bergen, Norway;dDepartment of Earth Science, University of Bergen, Allégaten 41, 5007 Bergen, Norway |
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Abstract: | The problem of insufficient age-control limits the utilisation of the 8.2 ka BP event for modelling freshwater forcing in climate change studies. High-resolution radiocarbon dates, magnetic susceptibility and lithostratigraphic evidence from a lake sediment core from Nedre Hervavatnet located at Sygnefjell in western Norway provide a record of the early Holocene. We use the method of radiocarbon wiggle-match dating of the lake sediments using the non-linear relationship between the 14C calibration curve and the consecutive accumulation order of the sample series in order to build a high-resolution age-model. The timing and duration of Holocene environmental changes is estimated using 38 AMS radiocarbon dates on terrestrial macrofossils, insects and chironomids covering the time period from 9750 to 1180 cal BP. Chironomids, Salix and Betula leaves produce the most consistent results. Sedimentological and physical properties of the core suggest that three meltwater events with high sedimentation rates are superimposed on a long-term trend with glacier retreat between 9750 and 8000 cal BP. The lake sediment sequence of Nedre Hervavatnet demonstrates the following: only a reliable high-resolution geochronology based on carefully selected terrestrial macrofossils allows the reconstruction of a more refined and complex environmental change history before and during the 8.2 ka event. |
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Keywords: | Radiocarbon wiggle-match dating Norway Holocene Glacier variations 8 2  ka event 9 2  ka event Nedre Hervavatnet Fannarå kbreen Jotunheimen |
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