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TitreGeological and structural controls on hydrothermal alteration and W-Mo mineralization in the Sisson deposit, New Brunswick
AuteurLang, J R; Duncan, R; Lentz, D; Zhang, W; Bustard, A; McFarlane, C R M; Thorne, K G
SourceL'Association géologique du Canada-L'Association minéralogique du Canada, Réunion annuelle conjointe, Recueil des résumés vol. 37, 2014 p. 151-152
LiensOnline - En ligne (PDF 8.75 MB)
RéunionGAC-MAC Joint annual meeting; Fredericton, NB; CA; mai 2014
Documentpublication en série
Mediaen ligne; numérique
Référence reliéeCette publication est reliée Lang, J R; Duncan, R; Lentz, D R; Zhang, W; Bustard, A; McFarlane, C R M; Thorne, K G; (2015). Geological and structural controls on hydrothermal alteration and W-Mo mineralization in the Sisson deposit, New Brunswick, TGI 4 - Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation, Commission géologique du Canada, Dossier public 7843
SNRC21J/06; 21J/07
Lat/Long OENS-67.5000 -66.5000 46.5000 46.2500
Sujetsaltération hydrothermale; roches intrusives; roches ignées; molybdène; tungstène; minéralisation; diorites quartz iques; zones de cisaillement; roches hôtes; scheelite; molybdenite; wolframite; pétrologie ignée et métamorphique; minéraux métalliques; Ordovicien; Cambrien
ProgrammeÉtude des gîtes porphyriques, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
The Sisson deposit is a Late Devonian, structurally-controlled, intrusion-related W-Mo deposit located in west-central New Brunswick. Resources are estimated at 383 Mt grading 0.067% WO3 and 0.021% Mo (measured/indicated) and 178 Mt grading 0.051% WO3 and 0.021% Mo (inferred). Host rocks to Sisson include quartz diorite and gabbro phases (432 Ma; U-Pb on titanite) of the Howard Peak intrusion on the west, which are in fault contact across the vertical, north-trending Sisson shear zone with north-northwest-striking, steeply east-dipping metavolcanic and metasedimentary rocks of the Cambrian to Ordovician Tetagouche and Miramichi Groups on the east. Re-Os dates of ~378 Ma on molybdenite overlap U-Pb dates on zircon from narrow granite dykes within the deposit, which are likely related to the Late Devonian Nashwaak Granite batholith located immediately northwest of the deposit. The deposit is cut by narrow, undeformed, barren granite porphyry dykes dated at ~364 Ma (U-Pb on zircon).
The Sisson deposit obliquely straddles the Sisson shear zone. Hydrothermal activity comprises: (1) early, weakly to unmineralized amphibole veinlets with albite alteration envelopes and small, erratically-distributed zones of biotite±pyrite alteration; (2) quartzscheelite veinlets with biotite envelopes; (3) quartz-molybdenite±scheelite veinlets with sericite envelopes; (4) mostly late but possibly long-lived, larger and more continuous, polymetallic quartz-shear veins with broad sericite envelopes and associated sulphide-rich veinlets, which also introduced minor Cu, Bi, Sb, As, Pb and Zn to the deposit; and (5) rare endoskarn with scheelite mineralization of uncertain timing in narrow granite dykes intersected only at depths of >400 metres. Alteration is mostly restricted to the envelopes which enclose veinlets. Scheelite mineralization occurs primarily in quartz veinlets and their alteration envelopes, molybdenite is restricted to quartz veinlets, and minor ferberitic wolframite, mostly replaced by scheelite, occurs in some quartz-scheelite veinlets and in most quartz-shear veins.
Veins throughout the deposit form a sheeted array with consistent northwest strike and steep to moderate southwest dips. The nature and geometry of the vein sets are most compatible with formation during crustal extension, which was synchronous with sinistral, synhydrothermal displacement across the north-trending Sisson shear zone. The structural plumbing system focused ascent of W-mineralizing fluids from intrusions at depth, the presence of which is indicated by syn-hydrothermal granite dykes within the deposit. Precipitation of W and Mo mineralization resulted from chemical interactions between hydrothermal fluids and wall rock at a low fluid to rock ratio, and from changes in sulphur and oxygen fugacity.