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Constraints on the age of the British Tertiary volcanic province from ion microprobe U-Pb (SHRIMP) ages for acid igneous rocks from NE Ireland

J. A. Gamble, R. J. Wysoczanski and I. G. Meighan
Constraints on the age of the British Tertiary volcanic province from ion microprobe U-Pb (SHRIMP) ages for acid igneous rocks from NE Ireland
Journal of the Geological Society of London (March 1999) 156, Part 2: 291-299

Abstract

Using the sensitive high resolution ion microprobe (SHRIMP), U-Pb ages have been determined for zircons separated from rhyolitic obsidian from the Tardree (Sandy Braes) Rhyolite Centre and granites of the Mourne Mountains and Slieve Gullion central igneous complexes of the British Tertiary Volcanic Province. These ages (Tardree, 58.4+ or -0.7 Ma; Mourne, 56.4+ or -1.4 Ma and 55.3+ or -0.8 Ma and Slieve Gullion, 56.5+ or -1.3 Ma) are in close agreement (within error) with results from independent dating methods (Rb-Sr, K-Ar and (super 40) Ar/ (super 39) Ar) and are interpreted as crystallization ages. The euhedral, clear, bipyramidal nature of all separated zircons is indicative of a magmatic origin and, combined with the paucity of zircon grains with any history of inheritance, has implications for granite petrogenesis. When considered with recently published high-precision (super 40) Ar/ (super 39) Ar ages for sanidine separates from the Hebrides, these data help to establish a timeframe for Tertiary magmatism in the NW British sector of the North Atlantic Tertiary Volcanic Province and show that central complex magmatism in NE Ireland was confined to the later stages of activity.


ISSN: 0016-7649
EISSN: 2041-479X
Coden: JGSLAS
Serial Title: Journal of the Geological Society of London
Serial Volume: 156, Part 2
Title: Constraints on the age of the British Tertiary volcanic province from ion microprobe U-Pb (SHRIMP) ages for acid igneous rocks from NE Ireland
Affiliation: Victoria University of Wellington, School of Earth Sciences, Wellington, New Zealand
Pages: 291-299
Published: 199903
Text Language: English
Publisher: Geological Society of London, London, United Kingdom
References: 60
Accession Number: 1999-030543
Categories: Geochronology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, geol. sketch map
N50°00'00" - N59°00'00", W08°00'00" - E01°30'00"
N51°30'00" - N55°19'60", W10°30'00" - W06°30'00"
Secondary Affiliation: Australian National University, AUS, AustraliaQueen's University of Belfast, GBR, United Kingdom
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 199911
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