Ice-marginal volcanic sequence in Iceland found on a nondescript gradual hillslope: An unexpected record of ice thickness late in deglaciation

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dc.citation.articleNumber108195en_US
dc.citation.journalTitleJournal of Volcanology and Geothermal Researchen_US
dc.citation.volumeNumber455en_US
dc.contributor.authorPutnam, Audrey R.en_US
dc.contributor.authorSiebach, Kirsten L.en_US
dc.contributor.authorBedford, Candice C.en_US
dc.contributor.authorSimpson, Sarah L.en_US
dc.contributor.authorThorpe, Michael T.en_US
dc.contributor.authorTamborski, Joseph J.en_US
dc.contributor.authorRampe, Elizabeth B.en_US
dc.date.accessioned2024-10-29T14:11:22Zen_US
dc.date.available2024-10-29T14:11:22Zen_US
dc.date.issued2024en_US
dc.description.abstractVolcanism increases when glaciers melt because isostatic rebound during deglaciation decreases the pressure on the mantle, which enhances decompression melting. Anthropogenic climate change is now causing ice sheets and valley glaciers to melt around the world and this deglaciation could stimulate volcanic activity and associated hazards in Iceland, Antarctica, Alaska, and Patagonia. However, current model predictions for volcanic activity associated with anthropogenic deglaciation in Iceland are poorly constrained, in part due to uncertainties in past volcanic output over time compared to ice sheet arrangements. Further work specifically characterizing glaciovolcanic and ice-marginal volcanoes in Iceland is needed to reconstruct volcanic output during time periods with changing ice cover. Here, we describe a previously unrecognized ice-marginal volcanic sequence on a broad, gradual hillslope southeast of Langjökull and the Jarlhettur volcanic chain in Iceland's Western Volcanic Zone. Although previously mapped as interglacial lavas, canyons in this area revealed two southwest-dipping sequences of pillow-bearing tuff-breccias between pāhoehoe lava flows above modern lake Sandvatn. These pillow-bearing tuff-breccias and the quenched meter-scale cavities in coherent lava and cube-jointed facies show lavas came into contact with ice and pockets of trapped meltwater. However, clasts within the tuff-breccias include a mixture of pillow lavas and pāhoehoe fragments, requiring that the subaqueous tuff-breccia facies were derived from subaerial flows. In addition, we observed interfingering of subaerial and transitional subaqueous-subaerial pāhoehoe lava flows with the pillow-bearing tuff-breccias. We propose that during a deglaciation, subaerial lavas sourced upslope from near Skálpanes flowed downslope to the south and came into contact with thin ice north of the modern lake Sandvatn. We constrain the local ice at this time to be ∼30–50 m thick. Importantly, this finding demonstrates that ice-marginal deposits that can provide paleo-environmental constraints may be hidden in terrains without morphologically distinct glaciovolcanic edifices.en_US
dc.identifier.citationPutnam, A. R., Siebach, K. L., Bedford, C. C., Simpson, S. L., Thorpe, M. T., Tamborski, J. J., & Rampe, E. B. (2024). Ice-marginal volcanic sequence in Iceland found on a nondescript gradual hillslope: An unexpected record of ice thickness late in deglaciation. Journal of Volcanology and Geothermal Research, 455, 108195. https://doi.org/10.1016/j.jvolgeores.2024.108195en_US
dc.identifier.digital1-s2-0-S0377027324001872-mainen_US
dc.identifier.doihttps://doi.org/10.1016/j.jvolgeores.2024.108195en_US
dc.identifier.urihttps://hdl.handle.net/1911/117953en_US
dc.language.isoengen_US
dc.publisherElsevieren_US
dc.rightsExcept where otherwise noted, this work is licensed under a Creative Commons Attribution-NonCommercial (CC BY-NC) license.  Permission to reuse, publish, or reproduce the work beyond the terms of the license or beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.rights.urihttps://creativecommons.org/licenses/by-nc/4.0/en_US
dc.titleIce-marginal volcanic sequence in Iceland found on a nondescript gradual hillslope: An unexpected record of ice thickness late in deglaciationen_US
dc.typeJournal articleen_US
dc.type.dcmiTexten_US
dc.type.publicationpublisher versionen_US
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