Porphyry deposits of the Canadian Cordillera

摘要: Porphyry deposits are intrusion-related, large tonnage low grade mineral with metal assemblages that may include all or some of copper, molybdenum, gold and silver. The genesis these is related to the emplacement intermediate felsic, hypabyssal, generally porphyritic intrusions commonly formed at convergent plate margins. Porphyry Canadian Cordillera occur in association two distinctive intrusive suites: calc-alkalic alkalic. In Cordillera, during separate time periods: Late Triassic Middle Jurassic (early Mesozoic), Cretaceous Eocene (Mesozoic-Cenozoic). Deposits early Mesozoic period least three different arc terranes (Wrangellia, Stikinia Quesnellia) a single deposit occurring oceanic assemblage Cache Creek terrane. These were located outboard from continental North America formation most their contained porphyry deposits. Some this have been emplaced terrane collisions. Metal suite Mo-Cu (Brenda), Cu-Mo (Highland Val-ley, Gibraltar), Cu-Mc-Au-Ag (Island Copper, Schaft Creek) Cu-Au (Kemess, Kerr). alkalic characterized by (Copper Mountain, Afton-Ajax, Mt. Milligan, Mount Polley, Galore Creek). Although silver recovered copper mining operations, data seldom included published reserve figures. Those available range 1-2 grams per tonne (g.t -1 ). Alkalic restricted display petrology, alteration mineralization suggest similar tectonic setting for both Quesnellia Early time. The younger deposits, late Mesozoicto Cenozoic age, an intra-continental setting, after host accreted western margin America. interpreted n settings, individual hosted variety older country rocks. also snow spectrum associations: (Huckleberry, Berg), (-Mo) (Bell, Granisle, Fish Lake, Casino), Mo (Endako, Boss Kit-sault, Quartz Hill), Mo-W (Logtung), Au-W (Dublin Gulch) Au (Ft. Knox). There maybe continuum between Mo, Mo-W, Au-Mo-W distribution timing post-accretion likely reflect major crustal structures subduction geometry. Cordilleran metallic show full morphological depth relationships found worldwide. addition, contains numerous which rare worldwide: unusual, possibly syntectonic Gibraltar deposit; end-member gold-rich granite-hosted such as Ft. Knox (Alaska). Resume Les gisements de porphyres metallogeniques sont grands basses teneurs, qui associes des phenomenes intrusifs et dont l'assemblage metallique peut contenir du cuivre, molybdene, l'or l'argent. La genese ces est reliee la mise en place plutons hypabyssaux, generalement porphyriques composition intermediaire felsique generes zone contact plaques convergentes. Les cordilleres canadiennes deux suites intrusives distinctes : une calco-alcaline alcaline. Ces se formes au cours periodes separees premiere, Triassique superieur Jurassique moyen (Mesozoique inferieur) et, l'autre, Cretace l'Eocene (Mesozoique/Cenozoique). Des Mesozoique inferieur existent dans moins trois milieux differents Quesnellia), alors que le milieu oceanique ne renferme qu'un seul gisement ce type. Lors plupart metallogeniqes inferieur, trouvaient dehors plaque continentale l'Amerique Nord. Il possible certains cette premiere periode soient constitues lors collisions terranes. Parmi les metalliques calco-alcaline, on retrouve ceux Brenda (Mo-cu), Highland Valley (Cu-Mo), Island Copper (Cu-Mo-Au-Ag) Kemess Kerr (Cu-Au). Les alcaline, tels Polley Creek, caracterises par un Cu-Au. Bien l'argent soit extrait cupriferes calco-alcalines alcalines, il qu'il fait mention donnees publiees sur calculs reserve, teneurs font l'ordre 1a 2 grammes tonne. alcaline exclusivement d'âge mesozoique leur parente petrologique, d'alterations mineralisations permet penser ont tous subi effets d'environnements tectoniques semblables inferieur. Les plus jeunes, cenozoique, intracontinental, apres d'origine leurs aient ete soudes bordure ouest d'arcs continentaux, pense-t-on, mais aujourd'hui sein roches encaissantes variees anciennes. On tout eventail d'associations jeunes Huckleberry Berg Bell, Casino (Cu-Au- Mo'), Endako, Kitsaut, Hill (Mo), Logtung (Mo-W), Dublin Gulch (Au-W) (Au). pourrait existe compsitionnelle continue entre Au-Mo- W d'Au. La chronologie post-acretionnairess probablement reflet l'influence grandes crustales parametres geometriques subduction. Les presentent caracteristiques morphologiques relations profondeur autres type monde. Cependant, renferment nombreux d'une plutot ailleurs C'est cas peu courant, possiblement syntectonique, fin granitique riche enor, tel Alaska.