Postglacial relative sea-level changes in northwest Iceland: evidence from isolation basins, coastal lowland sediments and raised shorelines

• Main Authors: Brader, MD, Lloyd, JM, Barlow, NLM, Norðdahl, H, Bentley, MJ, Newton, AJ
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2017
• Subjects: Reykjanes; Bak; Vestfirðir; Breiðafjörður; Laugardalur; Heggstaðanes; Hlöðuvík; Hrútafjörður; Rekavík; Ice Sheet; Iceland; North Atlantic
• Online Access: https://eprints.whiterose.ac.uk/117732/; https://eprints.whiterose.ac.uk/117732/1/1-s2.0-S0277379116306400-main.pdf

Relative sea-level (RSL) data can provide valuable constraints on land uplift associated with former ice loading and can therefore be used to differentiate between contrasting ice unloading scenarios. Within this study, isolation basin, coastal lowland and geomorphological evidence is employed to reconstruct RSL changes in northwest (NW) Iceland, which may have experienced contrasting uplift patterns. Under local (NW) uplift, highest RSL would be expected in central Vestfirðir, whereas highest RSL would be closest to the main ice-loading centre under regional (central Iceland) uplift. In total, four new RSL records are presented based on 16 sea-level index points (SLIPs) and 4 limiting ages from sites principally focussed along a transect of locations away from central Iceland. The new RSL records highlight the spatial variability of Holocene RSL changes and provide constraints on deglacial timing. There is a clear increase in marine limit elevation with proximity to the proposed principal ice loading centre in central Iceland. Highest recorded marine limit shorelines are found in the Hrútafjörður-Heggstaðanes area (southeast), the lowest in Hlöðuvík and Rekavík bak Látrum (north), and at an intermediate elevation in Reykjanes-Laugardalur (central Vestfirðir). Evidence from Breiðavik-Látrar records early rapid deglaciation in Breiðafjörður or a complex interplay of multiple uplift centres. RSL fell rapidly following deglaciation in a number of locations as a result of the quick response of the Icelandic lithosphere to unloading. The new RSL data along this particular transect show a pattern of uplift that is consistent with extensive regional glaciation emanating from central Iceland, which could have important implications for proposed ice sheet configuration and patterns of deglaciation, glacio-isostatic adjustment modelling and the potential volume of meltwater input into the North Atlantic.