Volcanoes and climate: the triggering of preboreal Jökulhlaups in Iceland

Type Article
Date 2020-04
Language English
Author(s) Van Vliet-Lanoë Brigitte1, Knudsen Oskar2, Guðmundsson Agust3, Guillou Hervé4, Chazot Gilles1, Langlade Jessica5, Liorzou Celine1, Nonnotte Philippe1
Affiliation(s) 1 : Géosciences Ocean, UMR 6538 Brest University, CNRS, ue@b, IUEM, Pl.N.Copernic, 29280, Plouzané, France
2 : Klettur Consulting Engineers, Bildshofda 12, 102, Reykjavik, Iceland
3 : Jarðfræðistofan ehf, 200, Hafnarfjorður, Iceland
4 : CNRS-CEA, UMR 8212 LSCE, Domaines CNRS, Bât. 12, Av. de la terrasse, 91198, Gif/Yvette, France
5 : Microsonde de l’Ouest, Ifremer-Centre de BretagneTechnopole Brest Iroise, BP 70, 29280, Plouzané, France
Source International Journal Of Earth Sciences (1437-3254) (Springer Science and Business Media LLC), 2020-04 , Vol. 109 , N. 3 , P. 847-876
DOI 10.1007/s00531-020-01833-9
Keyword(s) Holocene, Deglaciation, Iceland, Geomorphology, Glacial, Flood, Sedimentology, Tephra, Glacio-isostatic rebound, Permafrost, Saksunarvatn event, Askja S
Abstract

The Early Holocene (12–8.2 cal ka) deglaciation and pulsed warming was associated in Iceland with two major generations of jökulhlaups around the Vatna ice-cap (Vatnajökull), at ca 11.4–11.2 cal ka and ca 10.4–9.9 cal ka, and major tephra emissions from the Grímsvötn and Bárðarbunga subglacial volcanoes. The earliest flood events were recorded inland during the Middle Younger Dryas and their deposits were overlain by the Early Preboreal Vedde Ash (11.8 cal ka). The first Holocene flood events (ca 11.4–11.2 cal ka) are issued from a glacial advance. The second, and major, set of floods was partly driven by the Erdalen cold events and advances (10.1–9.7 10Be ka) initially issued from the Bárðarbunga (10.4, 10.1–9.9 ka) and Grímsvötn volcanoes (Saksunarvatn tephra complex, ca. 10.2–9.9 cal ka). These floods were also fed by the residual glacio-isostatic depressions below the Vatnajökull that enabled the storage of meltwaters in large subglacial lakes or aquifers until ca. 9.3 cal ka. This storage was enhanced by ice-damming and permafrost, especially during the twinned Erdalen events. Due to the glacio-isostatic rebound, the general slope was nearly flat, and the valley was partly filled with sediments until ca 10.8 cal ka. Temporary lacustrine deposits in this valley resulted from the very broad splay of waters as for the ca 11.2 cal ka and ca 10.1–9.9 cal ka flood, due to regional permafrost. These floods had a potential duration of several months as they were mostly fed by climate-driven meltwater. The maximal volume evacuated by these events did not greatly exceed 1 × 106 m3 s−1 from the flood-affected transverse profile of the valleys that remain partly filled with sediments.

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Van Vliet-Lanoë Brigitte, Knudsen Oskar, Guðmundsson Agust, Guillou Hervé, Chazot Gilles, Langlade Jessica, Liorzou Celine, Nonnotte Philippe (2020). Volcanoes and climate: the triggering of preboreal Jökulhlaups in Iceland. International Journal Of Earth Sciences, 109(3), 847-876. Publisher's official version : https://doi.org/10.1007/s00531-020-01833-9 , Open Access version : https://archimer.ifremer.fr/doc/00613/72489/