A thin-skinned thrust model for ice-marginal glacitectonic detachment and emplacement of Carboniferous bedrock rafts at Kilcummin Head, NW Ireland

Vaughan, David P.; Phillips, Emrys; Lee, Jonathan R.; Hart, Jane K.. 2024 A thin-skinned thrust model for ice-marginal glacitectonic detachment and emplacement of Carboniferous bedrock rafts at Kilcummin Head, NW Ireland. Proceedings of the Geologists' Association, 135 (3). 260-281. https://doi.org/10.1016/j.pgeola.2024.04.001

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Official URL: http://dx.doi.org/10.1016/j.pgeola.2024.04.001

Abstract/Summary

This paper presents the results of a detailed macro- and microscale structural study of the glacitectonised sequence at Kilcummin Head on the western side of Killala Bay, County Mayo, northwest Ireland. The sequence comprises two laterally extensive, thrust-stacked rafts of Carboniferous limestone and mudstone emplaced upon the in situ bedrock of the Ballina Limestone Formation. Restored cross-sections reveal that the glacitectonised sequence has undergone extensive deformation and shortening of 61 %. This accompanied the formation of a prominent thrust-moraine associated with a northward ice advance across Killala Bay during the Midlandian (Devensian). A five-stage model is proposed to describe the deformation. Stage 1 comprises detachment of the rafts, and the majority of the sequence shortening. North-directed transport of the rafts occurred on a major décollement surface located at the base of the rafted sequence, marked by a mudstone-rich glacitectonite. Stage 2 accommodated further shortening via a series of imbricate thrusts leading to the stacking of the bedrock rafts (Stages 3 and 4). Stage 5 saw final stacking of rafts within a prominent thrust-block moraine, followed by the deposition of a sequence of coarse-grained, ice-marginal glacigenic deposits.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1016/j.pgeola.2024.04.001
ISSN:	00167878
Date made live:	08 Aug 2024 13:04 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/537828

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1016/j.pgeola.2024.04.001

ISSN:

00167878

Date made live:

08 Aug 2024 13:04 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/537828