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Titre du document / Document title

Metallogenic overview of the Nain Province, northern Labrador

Auteur(s) / Author(s)

WILTON D. H. C. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Department of Earth Sciences, Centre for Earth Resources Research, Memorial University of Newfoundland, St. John's, Newfoundland, CANADA

Résumé / Abstract

The Nain Province (NP) of northern Labrador is a >600 km long by ≤100 km wide Archean craton that has undergone relatively little mineral exploration until economically significant concentrations of orthomagmatic nickel sulphide were discovered by Diamond Fields Resources (DFR) at Voisey's Bay. Due to the great time span between crust formation and final intrusive activity (ca. 3.9 Ga to 1.27 Ga), there were, however, numerous metallogenic events within the NP. The NP was intruded by the ca. 1.3 Ga to 1.2 Ga Nain Plutonic Suite (NPS) composite anorthosite-granite complex. The NPS divides the NP into the southern Hopedale Block (90 km by 150 km) and the northern Saglek Block (375 km long by ≤50 km wide). These two blocks appear to represent two distinct Archean cratonic nuclei, each with its own distinct metallogenic history. The NPS is a coalesced assemblage of composite intrusions which include anorthosite, troctolite, norite, gabbro and granite. The Hopedale Block contains the Hunt River and Florence Lake greenstone belts, and the Weekes Amphibolite which represents remnants of the older Hunt River greenstone belt. Geologically, these belts have some potential to host komatiitic Kambalda-style nickel, volcanogenic massive sulphide (VMS) and mesothermal lode gold mineralization. The unconformity between Paleoproterozoic cover sequences and the trondhjemite-tonalite-granodiorite (TTG) suite which engulfed the greenstones was the locus for lead-zinc-bearing quartz-carbonate veins. Minor fracture-hosted uraninite showings are also present in the TTG. The Saglek Block is a high-grade gneiss terrane with deformed Archean supracrustal sequences but no greenstone belts. Within the gneiss are variably-sized enclaves that range in composition from anorthositic to ultramafic; some of these latter xenoliths contain abundant fuchsite. There are also three small anorthositic to ultramafic meta-igneous complexes present in the gneiss near Okak Bay. Some Archean metasedimentary and mafic gneiss supracrustal sequences contain iron-oxide and sulphide members. The sulphide-bearing Tasiuyak paragneiss defines the cratonic suture between the NP and Churchill (Rae) Province. Along the cratonic suture between the NP and Churchill Province from Ramah Bay north are remnants of the Archean (or Paleoproterozoic) Hutton Anorthosite Suite. Ultramafic layers within the suite contain chromite and elevated Ni values. Three ca. 2.0 Ga supracrustal sequences were deposited in small fault-bounded basins within the NP. The Snyder Group contains pyrrhotitiferous massive sulphide horizons. The Mugford Group contains SEDEX-like massive sulphide blocks in a debris flow and ultramafic sills with unusual PGE concentrations; alaskitic granite cutting basement gneiss to the group contains stockwork-like pyritiferous quartz veins. The Ramah Group contains numerous MVT-style zinc-lead sulphide occurrences. The Reid Brook Intrusion of the NPS contains enormous and high-grade nickel-copper-cobalt massive sulphide bodies at the Voisey's Bay deposit. Exploration in the northern portions of the NPS in 1995 has indicated the presence of other potentially economic nickel sulphide horizons.

Revue / Journal Title

CIM bulletin    ISSN  0317-0926   CODEN CIBUBA 

Source / Source

1996, vol. 89, no997, pp. 43-52 (1 p.3/4)

Langue / Language

Anglais

Editeur / Publisher

Canadian Institute of Mining, Metallurgy and Petroleum, Montréal, PQ, CANADA  (1974) (Revue)

Mots-clés anglais / English Keywords

metallogeny

;

Nain Massif

;

Labrador

;

mineral exploration

;

cratons

;

Archean

;

sulfides

;

nickel ores

;

granitoids

;

granites

;

anorthosite

;

troctolite

;

norite

;

greenstone belts

;

komatiite

;

massive deposits

;

gold ores

;

mineralization

;

trondhjemite

;

tonalite

;

granodiorites

;

lead-zinc deposits

;

uraninite

;

gneisses

;

Terranes

;

ultramafics

;

stockwork deposits

;

pyrite

;

copper ores

;

Eastern Canada

;

North America

;

Precambrian

;

plutonic rocks

;

igneous rocks

;

gabbros

;

metamorphic rocks

;

Mots-clés français / French Keywords

Métallogénie

;

Massif Nain

;

Labrador

;

Prospection minière

;

Craton

;

Archéen

;

Sulfure

;

Nickel substance

;

Granitoïde

;

Granite

;

Anorthosite

;

Troctolite

;

Norite

;

Ceinture roche verte

;

Komatiite

;

Amas minéralisé

;

Or substance

;

Minéralisation

;

Trondhjemite

;

Tonalite

;

Granodiorite

;

Gîte plomb zinc

;

Uraninite

;

Gneiss

;

Province du Nain

;

Baie Voisey

;

Bloc Saglek

;

Bloc Hopedale

;

Terrane

;

Ultrabasite

;

Stockwerk

;

Pyrite

;

Cuivre substance

;

Canada Est

;

Amérique du Nord

;

Antécambrien

;

Roche plutonique

;

Roche ignée

;

Gabbro

;

Roche métamorphique

;

Mots-clés espagnols / Spanish Keywords

Metalogenia

;

Macizo Nain

;

Labrador

;

Prospección minera

;

Cratón

;

Arqueano

;

Sulfuro

;

Niquel sustancia

;

Granito

;

Anortosita

;

Norita

;

Cinturón ofiolítico

;

Masa mineralizada

;

Oro sustancia

;

Mineralización

;

Granodioritis

;

Yacimiento plomo cinc

;

Uraninita

;

Gneis

;

Terrane

;

Ultrabasita

;

Stockwerk

;

Pirita

;

Cobre sustancia

;

Canadá Este

;

America del norte

;

Antecámbrico

;

Roca granuda

;

Roca ignea

;

Gabro

;

Roca metamórfica

;

Localisation / Location

INIST-CNRS, Cote INIST : 3949, 35400005320396.0010

Nº notice refdoc (ud4) : 3008102



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