GEOSCAN, résultats de la recherche

Menu GEOSCAN


TitreMusings on intrusion geometry, chonoliths and mineral deposits
TéléchargerTéléchargements
AuteurSaumur, B -M
SourceCommission géologique du Canada, Présentation scientifique 71, 2017, 41 pages, https://doi.org/10.4095/305828
Année2017
ÉditeurRessources naturelles Canada
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.4095/305828
Mediaen ligne; numérique
Formatspptx
ProvinceNunavut; Terre-Neuve-et-Labrador
SNRC13M; 13N; 13O; 14C; 14D; 14E; 14F; 14L; 24I; 49F/12; 49F/13; 49G; 59E; 59F/01; 59F/07; 59F/08; 59F/09; 59F/10; 59F/14; 59F/15; 59F/16; 59G; 59H; 340B/03; 340B/04; 340B/05; 340B/06; 340B/11; 340B/12; 340B/13; 340B/14; 340C/03; 340C/04; 340C/05; 340C/06; 560A; 560D/01; 560D/02; 560D/03; 560D/04; 560D/05; 560D/06; 560D/07; 560D/08
Lat/Long OENS -96.0000 -84.0000 81.5000 78.0000
Lat/Long OENS -64.5000 -58.0000 59.0000 55.0000
Sujetsgisements minéraux; genèse des minerais; contrôles des minerais; contrôles structuraux; minéralisation; intrusions; chonolites; filons rocheux; filons-couches; laccolithes; mise en place; analyses géométriques; gisements porphyriques; cuivre porphyrique; gîtes sulfureux; nickel; cuivre; volcanisme; magmatisme; magmas; structures flui dales; systèmes d'écoulement; fluage; géologie du substratum rocheux; lithologie; roches mafiques; roches intrusives; caractéristiques structurales; zones de cisaillement; établissement de modèles; Complexe de Wootton Intrusive ; géologie économique; géologie structurale; pétrologie ignée et métamorphique; Phanérozoïque; Tertiaire; Mésozoïque; Crétacé; Paléozoïque; Carbonifère; Précambrien; Protérozoïque
Illustrationsphotographs; schematic representations; graphs; geological sketch maps; 3-D images; geophysical images; stereonet projections; 3-D models; profiles; photomicrographs; diagrams
ProgrammeLIP de l'haut-Arctique de l'ouest de l'Arctique, GEM2 : La géocartographie de l'énergie et des minéraux
Diffusé2017 09 22
Résumé(disponible en anglais seulement)
Several types of intrusion-hosted ore-deposits are formed within geometrically complex bodies, and the so-called "space problem" associated with the emplacement of these bodies within the crust is generally poorly understood. Felsic to intermediate porphyry-Cu systems are often hosted within vertical pipes or stocks that are circular to elongate in plan view. Ni-Cu magmatic sulfide deposits are hosted within structurally complex feeder systems. These often have irregular to tube-shaped geometries unlike typical dykes, sills or laccoliths, which has led to the resuscitation, by exploration and economic geologists alike, of the once-obsolete term "chonolith" to characterise such irregular intrusions. Both porphyry-Cu and magmatic Ni-Cu sulfide systems share other first-order similarities, such as late-stage volatile-rich magmas and emplacement within environments of active deformation, indicating that despite their differences emplacement dynamics may be analogous.
In many cases irregular intrusion geometries can be explained internal and external structural processes. At Voisey's Bay (Labrador, Canada) for instance, magmatic Ni-Cu sulfides are located within dikes and at the base of a geometrically complex magma chamber. The chamber could, a priori, be termed a chonolith; however, detailed 3D structural analysis of the chamber indicates that it consists of an amalgamation of sill-like magma bodies affected by intermittent local activity of faults. Dike-hosted mineralization is located within thickened portions of feeder dikes, which locally resemble some mafic chonoliths in cross-section. The geometry of these dikes is strongly controlled by the interaction of pre-emplacement wall rock structure with intruding magmas, and dike widening by thermo-mechanical erosion of the surrounding wall rocks.
Chonoliths are ideal sites of Ni-Cu-PGE mineralization because they promote high magma fluxes and protracted magma flow-through, thereby favouring the interaction between metal-bearing mafic magmas and sulfide liquids that are progressively enriched in metals. Such processes occur at the relatively local scales of 1-10 km magmatic complexes, and successful exploration must consider small-scale targeting within larger, regional scale igneous provinces. As an example, several magmatic complexes of the High Arctic Large Igneous Province (Nunavut) show first-order architecture that would favour Ni-Cu-PGE potential.
Résumé(Résumé en langage clair et simple, non publié)
Cette presentation scientifique revise les contrôles structuraux sur la mise-en-place d'intrusions magmatiques dans la croute terrestre, ainsi que la géométrie souvent irrégulière (en forme de tube) des intrusions logeant des gîtes de minerais. Des exemples sont discutés: le gisement de Ni-Cu de Voisey's Bay (Labrador) et des complexes magmatiques de la grande province ignée de l'Extrême Arctique.
GEOSCAN ID305828