Late Caledonian dyke-swarms of northern Britain: Spatial and temporal intimacy between lamprophyric and granitic magmatism around the Ross of Mull pluton, Inner Hebrides

Rock, N. M. S.; Hunter, Robert H.

doi:10.1007/bf01821065

Cited by 35 publications

(12 citation statements)

References 26 publications

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“…Rock & Hunter 1987;Fowler & Henney 1996;Fowler et al 2008;Ghani & Atherton 2008). The significance of high-K small melt fractions from the lithospheric mantle was first recognized by McKenzie (1989), who stated that such melts generally crystallize at depth and may form a metasomatic layer within the lithosphere.…”

Section: Source Of Magmatismmentioning

confidence: 98%

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

Cooper

Crowley

Hollis

et al. 2013

JGS

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An intrusion of trachy-andesite, representative of a newly discovered suite of high-K-Ba-Sr, calcalkaline 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 (T DM Hf) 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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Section: Source Of Magmatismmentioning

confidence: 98%

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

Cooper

Crowley

Hollis

et al. 2013

JGS

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“…BGS K-Ardata). In the Ross of Mull (the nearest area to Colonsay documented recently), type (1) dykes at c. 405 Ma postdate the c. 415 Ma granite, whereas type (3) sheets arc metamorphosed by this pluton (Rock & Hunter, 1987).…”

Section: Correspondence and Notesmentioning

confidence: 94%

‘Lamprophyre’ minor intrusions of Colonsay – a comment

Rock

1988

Geol. Mag.

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“…Hildebrand and Whalen 2014a, b). Within the Caledonian orogen in Britain, the association in time and space of appinitic, lamprophyric and voluminous granitic magmas is one in which the mantle components are chemically and isotopically similar and the magmas of all three rock groups are genetically related (Rock and Hunter 1987;Fowler and Henney 1996). The felsic components include large batholiths that were probably derived by fractionation of shoshonitic magma (Fowler 1988).…”

Section: Regional Implicationsmentioning

confidence: 99%

Age, Geochemistry and Origin of the Ardara Appinite Plutons, Northwest Donegal, Ireland

Murphy

Nance

Gabler

et al. 2019

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In northwest Donegal, Ireland, a large number of coeval appinitic (hornblende-plagioclase-rich) plutons and lamprophyre dykes occur around the Ardara pluton, a granitic satellite body and one of the oldest phases of the ca. 428–400 Ma composite Donegal Batholith. The appinite units form a bimodal (mafic–felsic) suite in which hornblende is the dominant mafic mineral and typically occurs as large prismatic phenocrysts within a finer grained matrix. Lamprophyre dykes are mafic in composition with a geochemistry that is very similar to that of the mafic appinite bodies. Both mafic rocks are subalkalic, with calc-alkalic and tholeiitic tendencies, and show trace element abundances indicating that the mantle source was contaminated by subduction zone fluids. 40Ar/39Ar analysis of hornblende separated from two samples of appinite yield mid-Silurian (434.2 ± 2.1 Ma and 433.7 ± 5.5 Ma) cooling ages that are interpreted to closely date the time of intrusion. Hence, according to the available age data, the appinite bodies slightly predate, or were coeval with, the earliest phases of the Donegal Batholith. Sm–Nd isotopic analyses yield a range of initial εNd values (+3.1 to –4.8 at t = 435 Ma) that, together with trace element data, indicate that the appinitic magmas were likely derived from melting of metasomatized sub-continental lithospheric mantle and/or underplated mafic crust, with only limited crustal contamination during magma ascent. The appinitic intrusions are interpreted to have been emplaced along deep-seated crustal fractures that allowed for mafic and felsic magma to mingle. The magmas are thought to be the products of collisional asthenospheric upwelling associated with the closure of Iapetus and the ensuing Caledonian orogeny, either as a result of an orogen-wide delamination event or as a consequence of more localized slab break-off.RÉSUMÉDans le nord-ouest du Donegal, en Irlande, un grand nombre de plutons appinitiques (riches en hornblendes ou en plagioclases) et de dykes de lamprophyres contemporains se retrouvent autour du pluton d’Ardara, un corps satellite granitique et l’une des phases les plus anciennes du batholite composite de Donegal, âgé d’environ 428–400 Ma. Les unités de l’appinite forment une suite bimodale (mafique–felsique) dans laquelle la hornblende est le minéral mafique dominant et se présente généralement sous forme de grands phénocristaux prismatiques au sein d’une matrice à grains plus fins. Les dykes de lamprophyres ont une composition mafique dont la géochimie est très similaire à celle des corps d’appinite mafique. Les deux roches mafiques sont subalcaliques, avec des tendances calcoalcalines et tholéiitiques, et elles montrent des teneurs en éléments traces indiquant que la source du manteau a été contaminée par des fluides de zone de subduction. L'analyse 40Ar/39Ar des hornblendes provenant de deux échantillons d'appinite donne des âges de refroidissement du Silurien moyen (434,2 ± 2,1 Ma et 433,7 ± 5,5 Ma) qui sont interprétés comme étant proches de la date de l’intrusion. Par conséquent, selon les données d’âge disponibles, les corps d’appinite sont légèrement antérieurs ou contemporains des toutes premières phases du batholite de Donegal. Les analyses isotopiques Sm–Nd aboutissent à une gamme de valeurs εNd initiales (+3,1 à -4,8 à t = 435 Ma) qui, associées aux données des éléments traces, indiquent que les magmas appinitiques sont probablement dérivés de la fusion d'un manteau lithosphérique souscontinental métasomatisé et / ou d’une croûte mafique sousplaquée, avec une contamination crustale limitée lors de l'ascension du magma. Les intrusions appinitiques sont interprétées comme s'étant mises en place le long de fractures profondes de la croûte qui ont permis au magma mafique et au magma felsique de se mélanger. On pense que les magmas sont les produits de la remontée (upwelling) asthénosphérique collisionnelle associée à la fermeture de l’océan Iapetus et à l'orogenèse calédonienne qui s'ensuit, soit à la suite d'un délaminage à l'échelle de l'orogène, soit à la suite d'une rupture plus localisée de la plaque.

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Late Caledonian dyke-swarms of northern Britain: Spatial and temporal intimacy between lamprophyric and granitic magmatism around the Ross of Mull pluton, Inner Hebrides

Cited by 35 publications

References 26 publications

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

‘Lamprophyre’ minor intrusions of Colonsay – a comment

Age, Geochemistry and Origin of the Ardara Appinite Plutons, Northwest Donegal, Ireland

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