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A review of molybdenite, and fluorite mineralization in Caledonian granite basement, western Ireland, incorporating new field and fluid inclusion studies, and Re-Os and U-Pb geochronology.

Feely, Martin and Costanzo, Alessandra and Gaynor, Sean P. and Selby, David and McNulty, Emma (2020) 'A review of molybdenite, and fluorite mineralization in Caledonian granite basement, western Ireland, incorporating new field and fluid inclusion studies, and Re-Os and U-Pb geochronology.', Lithos., 354-355 . p. 105267.

Abstract

The recent discovery of late-magmatic quartz vein hosted molybdenite, and exceptional gem quality vein fluorite, in the Caledonian Galway Granite Complex (GGC), has prompted a review of these contrasting styles of mineralisation in the late-Caledonian granite basement, Connemara, western Ireland. Existing published U-Pb and Re-Os chronometry and fluid inclusion microthermometry are combined with new: a) geological field observations, b) U-Pb zircon and Re-Os molybdenite geochronometry and c) fluid inclusion microthermometry to generate a new pressure-temperature-time model (P-T-t) of mineralization for the GGC. Re-Os chronometry molybdenite indicates that granite related molybdenite mineralisation extended from 423 to 380Ma overlapping with the GGC emplacement history determined by U-Pb zircon chronometry. The P-T-t model reflects initial granite emplacement and Mo-mineralisation at ∼423Ma followed by lower P and T granite emplacement and related quartz vein hosted Mo-mineralisation at ∼410Ma (Carna pluton), ∼400Ma (Kilkieran pluton) and at ∼380Ma (Costelloe Murvey granite). The gem quality fluorite veins in the GGC represent late-Triassic hydrothermal mineralisation. These veins form part of a regional N Atlantic-European Triassic-Jurassic hydrothermal mineralisation province. Vein emplacement was triggered by the rifting of the N Atlantic facilitating crustal thinning and subsidence of continental crust and initiating hydrothermal activity at the margins of Mesozoic basins.

Item Type:Article
Full text:Publisher-imposed embargo until 09 November 2020.
(AM) Accepted Manuscript
Available under License - Creative Commons Attribution Non-commercial No Derivatives.
File format - PDF
(28584Kb)
Status:Peer-reviewed
Publisher Web site:https://doi.org/10.1016/j.lithos.2019.105267
Publisher statement:© 2019 This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Date accepted:28 October 2019
Date deposited:15 November 2019
Date of first online publication:09 November 2019
Date first made open access:09 November 2020

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