| Titre | New U-Pb geochronological constraints from mineralized granites in southern Newfoundland |
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| Auteur | Kerr, A; McNicoll, V |
| Source | Newfoundland and Labrador, Department of Natural Resources, Geological Survey, Report, Current Research 12-1, 2012 p. 21-38  Accès ouvert |
| Liens | Online - En ligne
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| Image |  |
| Année | 2012 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20140466 |
| Éditeur | Newfoundland and Labrador Department of Natural Resources |
| Document | publication en série |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | pdf |
| Province | Terre-Neuve-et-Labrador |
| SNRC | 11P/10; 11P/11; 11P/14; 11P/15; 12B/07 |
| Région | Grey River; Granite Lake |
| Lat/Long OENS | -57.5000 -56.5000 48.5000 47.5000 |
| Sujets | gisements minéraux; tungstène; molybdène; roches granitiques; datations au uranium-plomb; datations radiométriques; gisements filoniens; métallogénie; minéralisation; datations au zircon; magmatisme;
géochronologie; minéraux métalliques; Dévonien; Silurien |
| Illustrations | cartes géologiques généralisées |
| Programme | Initiative géoscientifique ciblée (IGC-4) Étude des gîtes porphyriques |
| Diffusé | 2012 01 01 |
| Résumé | (disponible en anglais seulement)
This article reports U-Pb SHRIMP geochronological data from granitic rocks associated with W and Mo-Cu mineralization
in the Grey River and Granite Lake
areas of southern Newfoundland. The Grey River area hosts a vein-style tungsten
deposit, and numerous minor base- and precious-metal bearing veins. A potentially large Mo-Cu deposit (Moly Brook) consisting
of sheeted mineralized quartz veins is
now also defined by recent exploration activity. It has long been speculated that
this diverse metallogeny is genetically linked to a largely hidden younger intrusion. The granodioritic host rocks to the
Mo-Cu-bearing vein system gave an age of
411 ± 4 Ma, but fine-grained alaskitic granites that contain disseminated molybdenite
gave a much younger age of 378 ± 4 Ma. Field evidence suggests a contemporaneous relationship between alaskitic
granites and the mineralized veins, indicating
that veins also formed at ca. 378 Ma. Mineralization at Moly Brook thus postdates
its immediate host rocks by >30 m.y., i.e., it is epigenetic. The age interpreted for alaskitic granites and mineralization
matches that obtained from the
François Granite, a geochemically evolved pluton located about 20 km to the east. The age
also overlaps with ages from two other granitoid plutons associated with granophile mineralization in southern Newfoundland.
At Granite Lake, Mo-bearing
veins are hosted by an equigranular biotite-muscovite granite that also contains disseminated
molybdenite, and locally displays intense advanced argillic alteration. The biotite-muscovite granite is thought to be
contemporaneous with
mineralization. The U-Pb zircon data from the granite suggest an age of 388 ± 4 Ma, and indicate
inherited cores of both Silurian (427-417 Ma) and Paleoproterozoic age. If this also records the timing of mineralization, it represents a slightly
older episode of metallogenesis than that at Grey River. It is possible that there is a regional age variation amongst mineralized granites from northwest to southeast, but many more data are needed to confirm this hypothesis. |
| GEOSCAN ID | 295883 |
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