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TitleU-Pb geochronology and lithogeochemistry of the host rocks to the Reid gold deposit, Exploits Subzone-Mount Cormack Subzone boundary area, central Newfoundland
AuthorSandeman, 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 (Open Access)
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20140471
PublisherNewfoundland and Labrador Department of Natural Resources
Mediaon-line; digital
File formatpdf
ProvinceNewfoundland and Labrador
AreaGander River
Lat/Long WENS -56.0000 -55.5000 48.5000 48.2500
Subjectsgeochronology; metallic minerals; mineral deposits; lithogeochemistry; granitic rocks; uranium lead dates; radiometric dates; trondhjemites; mineralization; zircon dates; alteration; porphyry deposits; drillholes; cores; geochemical analyses; Coy Pond Complex; Reid gold deposit; Exploits Subzone; Mount Cormack Subzone; Ordovician; Cambrian
Illustrationsgeological sketch maps
ProgramTargeted Geoscience Initiative (TGI-4), Intrusion/Porphyry Ore Systems
AbstractThe 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.