Deforming bed conditions associated with a major ice stream of the last British ice sheet

Citation
Co. Cofaigh et Dja. Evans, Deforming bed conditions associated with a major ice stream of the last British ice sheet, GEOLOGY, 29(9), 2001, pp. 795-798
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
GEOLOGY
ISSN journal
0091-7613 → ACNP
Volume
29
Issue
9
Year of publication
2001
Pages
795 - 798
Database
ISI
SICI code
0091-7613(200109)29:9<795:DBCAWA>2.0.ZU;2-Y
Abstract
The Irish Sea ice stream was the largest ice stream to drain the last Briti sh ice sheet, and around the margins of the Celtic Sea it deposited a shell y diamict facies that has been variously interpreted as subglacial till or distal glacial marine mud. We present new observations on the sedimentology of the shelly diamict and overlying sediments from the south coast of Irel and, and demonstrate that the shelly diamict facies is a subglacial deforma tion till deposited during onshore movement of a grounded Irish Sea ice str eam. Stratigraphic and chronological data indicate that this occurred durin g the last glaciation, and this is regionally consistent with marine geolog ical evidence from the Celtic Sea. We propose that the deforming bed tills along the south coast of Ireland are the onshore record of a rapid advance of an unstable Irish Sea ice stream into the Celtic Sea. This advance was f acilitated, at least in part, by a saturated substrate of readily deformabl e, fine-grained, marine sediment. This implies an unstable and dynamic Iris h Sea ice stream during oxygen isotope stage 2, and therefore extension of the last British ice sheet into the Celtic Sea far south of its traditional ly interpreted limits.