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TitrePetrology, chronology and sequence of vein systems: Systematic magmatic and hydrothermal history of a major intracontinental shear zone, Canadian Appalachians
AuteurPe-Piper, G; Piper, D J W; McFarlane, C R M; Sangster, C; Zhang, Y; Boucher, B
SourceLithos vol. 304-307, 2018 p. 298-310, https://doi.org/10.1016/j.lithos.2018.02.016
Année2018
Séries alt.Ressources naturelles Canada, Contribution externe 20180087
ÉditeurElsevier
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1016/j.lithos.2018.02.016
Mediapapier; en ligne; numérique
Formatspdf; html
ProvinceTerre-Neuve-et-Labrador; Nouveau-Brunswick; Nouvelle-Écosse; Île-du-Prince-Édouard; Québec
SNRC1; 2; 3; 10; 11; 12; 13; 20; 21; 22; 30; 31
Lat/Long OENS -84.0000 -51.0000 55.0000 33.0000
Sujetsgéologie du substratum rocheux; caractéristiques structurales; zones de cisaillement; failles; fractures; lithologie; roches ignées; roches volcaniques; roches intrusives; granites; gabbros; antécédents tectoniques; marges plaques; magmatisme; orogénies; intrusions; filons; plutons; volcanisme; système hydrothermal; minéralisation; mise en place; paragenèse; formation de failles; formation de fissures; subduction; métasomatose; manteau terrestre; analyses au microscope électronique à balayage; datation radiométrique; datation au uranium-plomb; analyse par spectromètre de masse; gisements minéraux; potentiel minier; bassins; Province Appalachienne; Zone de cisaillement de Cobequid ; Orogenèse Alleghanienne; Laurentie; Bassin de Magdalen ; Terrane d'Avalon ; Terrane de Meguma ; Zone de cisaillement de Central Piedmont ; Groupe de Fountain Lake ; Groupe de Mabou ; Groupe de Windsor ; Bassin de Cumberland ; Pluton de Wyvern ; Faille de Rockland Brook ; Faille de Cobequid ; Bassin de Kennetcook ; Pluton de Pleasant Hills ; Pluton de West Moose River ; Faille de Kirkhill ; Pluton de Cape Chignecto ; tectonique; pétrologie ignée et métamorphique; géochronologie; géologie économique; Phanérozoïque; Mésozoïque; Paléozoïque; Permien; Carbonifère; Dévonien; Silurien; Ordovicien; Cambrien; Précambrien; Protérozoïque
Illustrationsgeoscientific sketch maps; block diagrams; geochronological charts; photographs; photomicrographs; cartoons; Concordia diagrams; plots; schematic cross-sections
ProgrammeInitiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
Intra-continental shear zones developed during continental collision may experience prolonged magmatism and mineralization. The Cobequid Shear Zone formed part of a NE-SW-trending, orogen-parallel shear system in the late Devonian-early Carboniferous, where syn-tectonic granite-gabbro plutons and volcanic rocks 4 km thick were progressively deformed. In late Carboniferous to Permian, Alleghanian collision of Africa with Laurentia formed the E-W trending Minas Fault Zone, reactivating parts of the Cobequid Shear Zone. The 50 Ma history of hydrothermal mineralization following pluton emplacement is difficult to resolve from field relationships of veins, but SEM study of thin sections provides clear detail on the sequence of mineralization. The general paragenesis is: albite±quartz±chlorite±monazite->biotite->calcite, allanite, pyrite-> Fe-carbonates, Fe-oxides, minor sulfides, calcite and synchysite. Chronology was determined from literature reports and new U-Pb LA-ICPMS dating of monazite and allanite in veins.
Vein mineralization was closely linked to magmatic events. Vein emplacement occurred preferentially during fault movement recognised from basin-margin inversion, as a result of fractures opening in the damage zone of master faults. The sequence of mineralization, from ca. 355 Ma riebeckite and albite veins to ca. 327 (-305?) Ma siderite-magnetite and sulfide mineralization, resembles Precambrian iron-oxide-copper-gold (IOCG) systems in the literature. The abundant magmatic Na, halogens and CO2 in veins and some magmatic bodies, characteristic of IOCG systems, were derived from the deeply subducted Rheic Ocean slab with little terrigenous sediment. Regional extension of the Magdalen Basin caused asthenospheric upwelling and melting of the previously metasomatized sub-continental lithospheric mantle. Crustal scale strike-slip faulting facilitated the rise of magmas, resulting in high heat flow driving an active hydrothermal system.
Résumé(Résumé en langage clair et simple, non publié)
Cette étude permet de dater et d'interpréter génétiquement des veines minéralisées le long d'une zone de faille majeure en Nouvelle-Écosse.
GEOSCAN ID308313