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A U-Pb age for the Late Caledonian Sperrin Mountains minor intrusions suite in the north of Ireland: timing of slab break-off in the Grampian terrane and the significance of deep-seated, crustal lineaments

A U-Pb age for the Late Caledonian Sperrin Mountains minor intrusions suite in the north of Ireland: timing of slab break-off in the Grampian terrane and the significance of deep-seated, crustal lineaments
A U-Pb age for the Late Caledonian Sperrin Mountains minor intrusions suite in the north of Ireland: timing of slab break-off in the Grampian terrane and the significance of deep-seated, crustal lineaments
An intrusion of trachy-andesite, representative of a newly discovered suite of high-K–Ba–Sr, calc-alkaline minor intrusions (termed herein the Sperrin Mountains suite), hosted within the Grampian terrane in the north of Ireland, has been dated by U–Pb zircon at 426.69 ± 0.85 Ma (mid-Silurian; Wenlock–Ludlow boundary). Geochemistry reveals a close association with the Fanad, Ardara and Thorr plutons of the Donegal Batholith and the Argyll and Northern Highlands Suite of Scotland. The deep-seated Omagh Lineament appears to have limited eastward propagation of the Sperrin Mountains suite from beneath the main centre of granitic magmatism in Donegal. A Hf depleted mantle model age (TDMHf) of c. 800 Ma for trachy-andesite zircons indicates partial melting from a source previously separated from the mantle. Whole-rock geochemistry of the suite is consistent with a model of partial melting, triggered by slab break-off, following thrusting of Ganderia–Avalonia under the Southern Uplands–Down–Longford accretionary prism (i.e. Laurentian margin). The new age constrains the timing of this event in the north of Ireland and is consistent with the petrogenesis of Late Caledonian high-K granites, appinites and minor intrusions across the Caledonides of northern Britain and Ireland.
0016-7649
603-614
Cooper, M.R.
64aa3faa-3106-4a54-8cb6-7920c5c09f22
Crowley, Q.G.
9886c7c5-bd3a-4640-bac7-9a7c2de50865
Hollis, S.P.
61c30119-6a19-4985-940b-99fcca8da59e
Noble, S.R.
9f757555-802d-4b9d-9248-b4a30dcf03f4
Henney, P.J.
64fccc1a-5212-4cf4-8394-15fcc26aa254
Cooper, M.R.
64aa3faa-3106-4a54-8cb6-7920c5c09f22
Crowley, Q.G.
9886c7c5-bd3a-4640-bac7-9a7c2de50865
Hollis, S.P.
61c30119-6a19-4985-940b-99fcca8da59e
Noble, S.R.
9f757555-802d-4b9d-9248-b4a30dcf03f4
Henney, P.J.
64fccc1a-5212-4cf4-8394-15fcc26aa254

Cooper, M.R., Crowley, Q.G., Hollis, S.P., Noble, S.R. and Henney, P.J. (2013) A U-Pb age for the Late Caledonian Sperrin Mountains minor intrusions suite in the north of Ireland: timing of slab break-off in the Grampian terrane and the significance of deep-seated, crustal lineaments. Journal of the Geological Society, 170 (4), 603-614. (doi:10.1144/jgs2012-098).

Record type: Article

Abstract

An intrusion of trachy-andesite, representative of a newly discovered suite of high-K–Ba–Sr, calc-alkaline minor intrusions (termed herein the Sperrin Mountains suite), hosted within the Grampian terrane in the north of Ireland, has been dated by U–Pb zircon at 426.69 ± 0.85 Ma (mid-Silurian; Wenlock–Ludlow boundary). Geochemistry reveals a close association with the Fanad, Ardara and Thorr plutons of the Donegal Batholith and the Argyll and Northern Highlands Suite of Scotland. The deep-seated Omagh Lineament appears to have limited eastward propagation of the Sperrin Mountains suite from beneath the main centre of granitic magmatism in Donegal. A Hf depleted mantle model age (TDMHf) of c. 800 Ma for trachy-andesite zircons indicates partial melting from a source previously separated from the mantle. Whole-rock geochemistry of the suite is consistent with a model of partial melting, triggered by slab break-off, following thrusting of Ganderia–Avalonia under the Southern Uplands–Down–Longford accretionary prism (i.e. Laurentian margin). The new age constrains the timing of this event in the north of Ireland and is consistent with the petrogenesis of Late Caledonian high-K granites, appinites and minor intrusions across the Caledonides of northern Britain and Ireland.

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More information

Published date: July 2013
Additional Information: Supplementary material: Geochemical data are available at www.geolsoc.org.uk/SUP18600.
Organisations: Geology & Geophysics

Identifiers

Local EPrints ID: 355027
URI: http://eprints.soton.ac.uk/id/eprint/355027
ISSN: 0016-7649
PURE UUID: da0c3f5a-5f65-47c8-a50c-5369f184410b

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Date deposited: 25 Jul 2013 09:14
Last modified: 14 Mar 2024 14:27

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Contributors

Author: M.R. Cooper
Author: Q.G. Crowley
Author: S.P. Hollis
Author: S.R. Noble
Author: P.J. Henney

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