Sangam: A Confluence of Knowledge Streams

Internal dynamics condition centennial-scale oscillations in marinebased ice-stream retreat

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dc.creator Smedley, RK
dc.creator Chiverrell, RC
dc.creator Ballantyne, CK
dc.creator Burke, MJ
dc.creator Clark, CD
dc.creator Duller, GAT
dc.creator Fabel, D
dc.creator McCarroll, D
dc.creator Scourse, JD
dc.creator Small, D
dc.creator Thomas, GSP
dc.date 2018-02-01T08:09:49Z
dc.date 2017-09-01
dc.date 2018-02-01T08:09:49Z
dc.identifier Vol. 45, Iss. 9, pp. 787 - 790
dc.identifier 10.1130/G38991.1
dc.identifier http://hdl.handle.net/10871/31262
dc.identifier 0091-7613
dc.identifier Geology
dc.description This is the final version of the article. Available from Geological Society of America via the DOI in this record.
dc.description Rates of ice-stream retreat over decades can be determined from repeated satellite surveys and over millennia by paleoenvironmental reconstructions. Centennial time scales are an important temporal gap in geological observations of value in process understanding and evaluation of numerical models. We address this temporal gap by developing a 3 ka and 123 km retreat time series for the Irish Sea ice stream (ISIS), a major outlet draining the last British-Irish ice sheet. The Llŷn Peninsula (northwest Wales, UK) contains numerous ice-marginal indicators from which we reconstructed a robust chronological framework of margin oscillations. The landscape documents the retreat of a former marine-terminating ice stream through a topographic constriction, across a reverse bed slope, and across variations in calving margin width. New dating constraints for this sequence were integrated in a Bayesian sequence model to develop a high-resolution ice-retreat chronology. Our results show that retreat of the ISIS during the period 24-20 ka displayed centennial-scale oscillatory behavior of the margin despite relatively stable climatic, oceanic, and relative sea-level forcing mechanisms. Faster retreat rates coincided with greater axial trough depths as the ice passed over a reverse bed slope and the calving margin widened (from 65 to 139 km). The geological observations presented here over a 123-km-long ice-retreat sequence are consistent with theory that marine-based ice can be inherently unstable when passing over a reverse bed slope, but also that wider calving margins lead to much faster ice retreat.
dc.description This paper was supported by a Natural Environment Research Council consortium grant (BRITICE-CHRONO NE/J008672/1). H. Wynne etched grains for optically stimulated luminescence dating. We thank D. Benn, P. Dunlop, and an anonymous reviewer for their comments.
dc.language en
dc.publisher Geological Society of America
dc.relation 1GSA Data Repository item 2017258, site descriptions and field and analytical methods, is available online at http://www.geosociety.org/datarepository/2017/, or on request from editing@geosociety.org.
dc.rights © 2017 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license.
dc.subject United Kingdom
dc.subject Great Britain
dc.subject sediments
dc.subject geochronology
dc.subject optically stimulated luminescence
dc.subject glacial geology
dc.subject Cenozoic
dc.subject Pleistocene
dc.subject upper Pleistocene
dc.subject Europe
dc.subject Wales
dc.subject Western Europe
dc.subject Quaternary
dc.title Internal dynamics condition centennial-scale oscillations in marinebased ice-stream retreat
dc.type Article


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