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dc.contributor.advisorMcClenaghan, Seanen
dc.contributor.authorSTRATFORD, JAMES PHILLIPen
dc.date.accessioned2020-10-21T13:03:59Z
dc.date.available2020-10-21T13:03:59Z
dc.date.issued2020en
dc.date.submitted2020en
dc.identifier.citationSTRATFORD, JAMES PHILLIP, The petrography and geochemistry of pyrite-hosted orogenic gold deposits in the Grampian Terrane of north-west Ireland and Scotland, Trinity College Dublin.School of Natural Sciences, 2020en
dc.identifier.otherYen
dc.identifier.urihttp://hdl.handle.net/2262/93872
dc.descriptionAPPROVEDen
dc.description.abstractThe Neoproterozoic-Cambrian Dalradian Supergroup of north-west Ireland and central Scotland accommodates vein-hosted gold deposits associated with uplift and deformation during the Ordovician Grampian arc-continent collision event (475-460 Ma) of the Palaeozoic Caledonian Orogenic Cycle (475-405 Ma). The Grampian Terrane hosting these strata was subjected to regional greenschist to amphibolite facies metamorphic conditions which enabled protracted Au and trace element mobility, and the generation of auriferous vein networks. This thesis has sought to discover the extent of this mobility across the orogen and the preservation of Au signatures, feasible sources of Au in north-west Ireland, and the relationship between Au emplacement, deformation and metamorphism associated with orogenesis. Gold occurrences are examined from the deposit to regional-scale. Reflected light microscopy, Scanning Electron Microscopy (SEM), Energy- Dispersive X-Ray Spectroscopy (EDS/EDX) and Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA ICP-MS) analyses are conducted on vein and wall-rock samples from four vein-hosted Au deposits and occurrences (Curraghinalt and Cavanacaw, Sperrins Inlier; Cloonacool, Ox Mountains Central Inlier; Cononish, SW Scotland) along with samples from potential source stratigraphy within the Appin Group (Blair Atholl Subgroup, north Donegal) and Argyll Group (Easdale Subgroup, Slieve League Peninsula of west Donegal). LA ICP-MS analyses of pyrite (spot analyses, n=530; raster element mapping) and pyrrhotite (spot analyses, n=50) have revealed that Au and trace elements were mobile throughout the evolution of the Grampian orogen, from the earliest stages of deformation- fabric development to relatively late timing associated with orogenic collapse, and that the Blair Atholl Subgroup (Appin Group) and Easdale Subgroup (Argyll Group) present viable sources of Au and associated metals. Mobility was facilitated by dehydration reactions at the greenschist-amphibolite facies transition, during collision of the incumbent arc with the Laurentian margin. At the largest deposit on the island of Ireland, Curraghinalt, Au is not genetically associated with the growth of pyrite and is derived from an external source, likely related to dehydration of the Laurentian margin and fluid mixing. Episodic rupture caused by decompression and seismic pumping is likely to have facilitated the injection of fluids into pathways (structural weaknesses), with phase separation mechanisms (including fluctuations in fO2 and pH) and fluid-rock interactions aiding the localised precipitation of sulphide and Au. Implications for exploration vectoring are included in this thesis.en
dc.publisherTrinity College Dublin. School of Natural Sciences. Discipline of Geologyen
dc.rightsYen
dc.titleThe petrography and geochemistry of pyrite-hosted orogenic gold deposits in the Grampian Terrane of north-west Ireland and Scotlanden
dc.typeThesisen
dc.contributor.sponsorScience Foundation Ireland (SFI)en
dc.contributor.sponsorEuropean Union (EU)en
dc.type.supercollectionthesis_dissertationsen
dc.type.supercollectionrefereed_publicationsen
dc.type.qualificationlevelDoctoralen
dc.identifier.peoplefinderurlhttps://tcdlocalportal.tcd.ie/pls/EnterApex/f?p=800:71:0::::P71_USERNAME:STRATFOJen
dc.identifier.rssinternalid220880en
dc.rights.ecaccessrightsembargoedAccess
dc.date.ecembargoEndDate2025-10-21
dc.rights.EmbargoedAccessYen


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