Climate variability and glacial processes in eastern Iceland during the past 700 years based on varved lake sediments |
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| Authors: | JOHAN STRIBERGER SVANTE BJÖRCK ÓLAFUR INGÓLFSSON KURT H KJÆR IAN SNOWBALL CINTIA B UVO |
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| Institution: | 1. Department of Earth and Ecosystem Sciences, Division of Geology – Quaternary Sciences, Lund University, S?lvegatan 12, SE‐223 62, Lund, Sweden;2. University of Iceland, Department of Earth Sciences, IS‐101, Reykjavík, Iceland;3. Centre for GeoGenetics, Natural History Museum, University of Copenhagen, ?ster Voldgade 5‐7, DK‐1350 Copenhagen K, Denmark;4. Department of Water Resources Engineering, Lund University, Box 118, SE‐221 00, Lund, Sweden |
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| Abstract: | Striberger, J., Björck, S., Ingólfsson, Ó., Kjær, K. H., Snowball, I. & Uvo, C. B. 2010: Climate variability and glacial processes in eastern Iceland during the past 700 years based on varved lake sediments. Boreas, 10.1111/j.1502‐3885.2010.00153.x. ISSN 0300‐9483. Properties of varved sediments from Lake Lögurinn in eastern Iceland and their link to climate and glacial processes of Eyjabakkajökull, an outlet glacier of the Vatnajökull icecap, were examined. A varve chronology, which covers the period AD 1262–2005, was constructed from visual observations, high‐resolution images, X‐ray density and geochemical properties determined from X‐radiography and X‐ray fluorescence scanning. Independent dating provided by 137Cs analysis and eight historical tephras verify the varve chronology. The thickness of dark‐coloured seasonal laminae, formed mainly of coarser suspended matter from the non‐glacial river Grímsá, is positively correlated (r=0.70) with winter precipitation, and our 743‐year‐long varve series indicates that precipitation was higher and more varied during the later part of the Little Ice Age. Light‐coloured laminae thickness, controlled mainly by the amount of finer suspended matter from the glacial river Jökulsáí Fljótsdal, increased significantly during the AD 1972 surge of Eyjabakkajökull. As a consequence of the surge, the ice‐dammed Lake Háöldulón formed and recurrently drained and delivered significant amounts of rock flour to Lake Lögurinn. Based on these observations, and the recurring cyclic pattern of periods of thicker light‐coloured laminae in the sediment record, we suggest that Eyjabakkajökull has surged repeatedly during the past 743 years, but with an increased frequency during the later part of the Little Ice Age. |
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