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Resolving the paradox of conflicting glacial chronologies: Reconstructing the pattern of deglaciation of the Magellan cordilleran ice dome (53–54°S) during the last glacial – interglacial transition

McCulloch, Robert D.; Bentley, Michael J.; Fabel, Derek; Fernández-Navarro, Hans; García, Juan-Luis; Hein, Andrew S.; Huynh, Carla; Jamieson, Stewart S.R.; Lira, María-Paz; Lüthgens, Christopher; Nield, Grace A.; San Román, Manuel; Tisdall, Eileen W.

Resolving the paradox of conflicting glacial chronologies: Reconstructing the pattern of deglaciation of the Magellan cordilleran ice dome (53–54°S) during the last glacial – interglacial transition Thumbnail


Authors

Robert D. McCulloch

Derek Fabel

Hans Fernández-Navarro

Juan-Luis García

Andrew S. Hein

Carla Huynh

Christopher Lüthgens

Manuel San Román

Eileen W. Tisdall



Abstract

Raised shorelines and associated lacustrine sediments in the central Estrecho de Magallanes (Strait of Magellan) have been interpreted as products of cordilleran glaciers impounding a large proglacial lake and preventing drainage to the South Pacific and Southern Ocean during the Late glacial between c. 15.0 and 12.0 cal ka BP. However, a growing body of glacial geological evidence points towards an earlier retreat of the Magellan cordilleran ice dome, insufficient to dam lakes at that time. We critically re-evaluate the extant evidence for the c. 15.0–12.0 cal ka BP lake, here named ‘Lago Kawésqar’, and provide further sedimentological and chronological evidence for its existence. We also provide new cosmogenic surface nuclide dating of erratic and bedrock samples collected from extensive field campaigns that confirm the rapid and widespread retreat of the Magellan ice fields to the inner fjords of the Fuegian archipelago by c. 16.0 ka. To resolve the apparent paradox between these two lines of evidence we propose that glacial isostatic adjustment led to a topographic barrier to lake drainage rather than an ice dam. We use Glacial Isostatic Adjustment modelling to demonstrate that rapid isostatic recovery following the early deglaciation after c. 17.0 cal ka BP likely led to elevation of the present shallow south-western coastal margin of the Fuegian archipelago. Final drainage of Lago Kawésqar was probably caused by neotectonic subsidence of the same margin along the boundary of the South American – Scotia tectonic plates at c. 12.0 cal ka BP.

Citation

McCulloch, R. D., Bentley, M. J., Fabel, D., Fernández-Navarro, H., García, J.-L., Hein, A. S., Huynh, C., Jamieson, S. S., Lira, M.-P., Lüthgens, C., Nield, G. A., San Román, M., & Tisdall, E. W. (online). Resolving the paradox of conflicting glacial chronologies: Reconstructing the pattern of deglaciation of the Magellan cordilleran ice dome (53–54°S) during the last glacial – interglacial transition. Quaternary Science Reviews, Article 108866. https://doi.org/10.1016/j.quascirev.2024.108866

Journal Article Type Article
Acceptance Date Jul 28, 2024
Online Publication Date Sep 6, 2024
Deposit Date Sep 10, 2024
Publicly Available Date Sep 10, 2024
Journal Quaternary Science Reviews
Print ISSN 0277-3791
Electronic ISSN 1873-457X
Publisher Elsevier
Peer Reviewed Peer Reviewed
Article Number 108866
DOI https://doi.org/10.1016/j.quascirev.2024.108866
Public URL https://durham-repository.worktribe.com/output/2853028

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