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TitreU-Pb geochronology and lithogeochemistry of the host rocks to the Reid gold deposit, Exploits Subzone-Mount Cormack Subzone boundary area, central Newfoundland
AuteurSandeman, H; McNicoll, V; Evans, D T W
SourceNewfoundland and Labrador, Department of Natural Resources, Geological Survey, Report, Current Research 12-1, 2012 p. 85-102
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140471
ÉditeurNewfoundland and Labrador Department of Natural Resources
Documentpublication en série
Mediaen ligne; numérique
Lat/Long OENS -56.0000 -55.5000 48.5000 48.2500
Sujetsgisements minéraux; lithogéochimie; roches granitiques; datations au uranium-plomb; datations radiométriques; trondhjémites; minéralisation; datations au zircon; altération; gisements porphyriques; trous de forage; carottes; analyses géochimiques; Sous-zone d'Exploits ; géochronologie; minéraux métalliques; Ordovicien; Cambrien
Illustrationsgeological sketch maps
ProgrammeÉtude des gîtes porphyriques, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
The Reid gold deposit of the Brady option exploration licences in NTS map area 2D/05 of central Newfoundland was discovered
in 2002, through prospecting and sampling of arsenopyrite-bearing quartz-plagioclase porphyry float, in an area of
extensive till cover, immediately north of the Northwest Gander River. Reid deposit mineralization is hosted in ophiolitic
basalt, diabase dykes and trondhjemite of the Coy Pond Complex that likely occur in a series of thrust-bound slices, marking
the boundary between the eastern Exploits Subzone (Dunnage Zone) and the ellipsoidal Mount Cormack Subzone, a tectonic
window into the underlying Gander Zone. Trench and drillcore data indicate that the Reid deposit mineralization occurs as
randomly oriented sericite-chlorite-Fe-carbonate-pyrite-arsenopyrite alteration, hosted mainly in silicified and quartzveined,
quartz-plagioclase porphyritic granitoid (Reid porphyry) and to a lesser extent, in basalt, diabase and microgabbro
of the Coy Pond Complex. The porphyry both crosscuts, and is intruded by fine-grained diabase and basalt. Lithogeochemical
data for the porphyry, diabase and lava indicate that these are all tholeiitic, trace-element depleted, supra-subduction zone
rocks. The Reid (deposit) porphyry is a trondhjemite and likely represents the final product of fractional crystallization of
strongly depleted tholeiitic mafic rocks of the ophiolite complex.
The U-Pb zircon geochronology indicates the Reid (deposit) trondhjemite crystallized in the Cambrian at 510 ± 4 Ma
and the Coy Pond Complex is, therefore, the oldest known ophiolite fragment in the Appalachian-Caledonide orogen.