A multi-proxy approach to assessing isolation basin stratigraphy from the Lofoten Islands, Norway |
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| Authors: | Nicholas L Balascio Zhaohui Zhang Raymond S Bradley Svein Olaf Dahl Jostein Bakke |
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| Institution: | a Climate System Research Center, Department of Geosciences, University of Massachusetts, Amherst, MA, 01003, USAb Laboratoire Chrono-Environnement, Université de Franche-Comté, 25030 Besançon, Francec Bjerknes Centre for Climate Research, N-5007 Bergen, Norwayd Department of Geography, University of Bergen, N-5007 Bergen, Norway |
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| Abstract: | This study takes a comprehensive approach to characterizing the isolation sequence of Heimerdalsvatnet, a coastal lake in the Lofoten Islands, northern Norway. We use established methods and explore new techniques to assess changes in marine influence. Bathymetric and sub-bottom profiles were acquired to examine basin-wide sedimentation and a 5.8 m sediment core spanning the last 7800 cal yr BP was analyzed. We measured magnetic susceptibility, bulk organic matter properties, molecular biomarkers, diatom assemblages, and elemental profiles acquired by scanning X-ray fluorescence. These characteristics of the sediment reflect detailed changes in salinity and water column conditions as the lake was progressively isolated. Three distinct litho/chemo-stratigraphic units represent a restricted marine phase (7800-6500 cal yr BP), a transitional phase characterized by intermittent marine influence (6500-4900 cal yr BP), and complete isolation and freshwater sedimentation (4900 cal yr BP to present). Although there are uncertainties in the estimate of the threshold elevation of the lake, the timing of these phases generally corresponds with previous interpretations of the local relative sea-level history. This record captures sea-level regression following the Tapes transgression and supports the interpretation of a subsequent sea-level stillstand, dated in Heimerdalsvatnet from 6500 to 4900 cal yr BP. |
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| Keywords: | Relative sea level Isolation basin Holocene Lofoten Islands Norway |
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