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TitreStructural and tectonic controls on Devonian intrusion related mineralisation on the Connaigre Peninsula, Newfoundland
TéléchargerTéléchargement (publication entière)
AuteurRuberti, G; Rogers, N; Kellett, D A; van Staal, C R; Hanchar, J
SourceTGI 4 - Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation; par Rogers, N (éd.); Commission géologique du Canada, Dossier public 7843, 2015 p. 559-560, (Accès ouvert)
LiensCanadian Database of Geochemical Surveys, downloadable files
LiensBanque de données de levés géochimiques du Canada, fichiers téléchargeables
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
Référence reliéeCette publication est contenue dans Rogers, N; (2015). TGI 4 - Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation, Commission géologique du Canada, Dossier public 7843
Lat/Long OENS -56.5000 -55.0000 48.0000 47.5000
Sujetsgisements porphyriques; cuivre porphyrique; prospection minière; minéralisation; altération; éléments d'indice; tungstène; molybdène; étain; bismuth; gisements minéraux; interpretations structurelles; roches intrusives; roches granitiques; zones tectonostratigraphiques; datations au uranium-plomb; géologie économique; tectonique; géologie structurale; Paléozoïque; Dévonien; Silurien
Illustrationslocation maps; plots; photographs
ProgrammeInitiative géoscientifique ciblée (IGC-4), Étude des gîtes porphyriques
Diffusé2015 06 11
Résumé(disponible en anglais seulement)
The Canadian Appalachians represent an archetypal ancient, accretionary orogen the study of which has played a substantial role in developing modern geological concepts. From the initial simplistic models of a mountain belt deriving from the closure of the Iapetus Ocean, our understanding has evolved, recognising a richer, more complex geological history. Current models define multiple collisions between arcs and microcontinents due to the closures of interposed oceans and seaways. Delineating specific tectonic events provides context to the various periods and styles of mineralisation produced, which in turn can define new exploration models for the next generation of deposits.
One of the least understood deposit types in the Canadian Appalachians are the Devonian granitoid intrusion-related Sn-W-Mo mineralisation. The Connaigre Peninsula was selected to study such deposits as it contains a variety of supracrustal units plus (apparently) barren and mineralised intrusives within a relatively constrained and accessible area. The distributions of the main lithotectonic packages indicate three distinct tectonic blocks that were amalgamated by the Middle Devonian, and subsequently intruded by Upper Devonian granitoids concurrent with clastic sedimentation.
The ca. 376 Ma Old Woman Stock contains several known Mo occurrences. Molybdenite is disseminated and associated with vugs containing dog-tooth quartz, and intense alteration zones (up to 5 cm wide) are localised along north - south to north-west - south-east trending joints. The distribution of deposits demonstrates a potential linkage between regional structures and the localisation of mineralisation. At the large scale, the Connaigre Peninsula in the Upper Devonian is interpreted to be in extension associated with far removed non-orthogonal accretion of other peri-Gondwanan elements to composite Laurentia. It is notable however that the mineralisation does not occur at a major fault, but rather at the intersection of a prominent north- east to south-west lineament and well-developed north - south to north-west - south-east jointing. The implication is that the high-angle intersection of breaks that are contemporaneous with intrusion but have relatively little motion provide ideal pathways for mineralising fluids. In contrast to the Old Woman Stock, the adjacent, approximately coeval to slightly younger Belleoram Granite is apparently barren. It remains unclear why the Belleoram Granite contains no known Sn-W-Mo mineralisation. Possible explanations include: i) its hybrid nature makes it compositionally unsuitable; ii) it formed at too shallow a crustal depth; or iii) it was too dry and did not develop fluid pathways.