|Titre||SEDEX Deposits in the Cordillera: Current concepts on their geology, genesis, and exploration|
|Auteur||Paradis, S; Goodfellow, W|
|Source||Commission géologique du Canada, Dossier public 7144, 2012, 11 pages, https://doi.org/10.4095/291878 (Accès ouvert)|
|Éditeur||Ressources naturelles Canada|
|Réunion||Prospectors and Developers Association of Canada (PDAC), International Convention, Trade Show and Investors Exchange; Toronto; CA; mars 6th, 2012|
|Media||en ligne; numérique|
|SNRC||82F; 82G; 82J; 82K; 82M; 82N; 94D; 94E; 94L; 104H; 104I; 105A; 105B; 105C; 105E; 105F; 105G; 105J; 105K; 105L; 105M; 105N|
|Lat/Long OENS||-121.0000 -114.0000 53.0000 49.0000|
|Lat/Long OENS||-130.0000 -125.0000 59.0000 56.0000|
|Lat/Long OENS||-138.0000 -128.0000 64.0000 60.0000|
|Sujets||gîtes sédimentaires; gisements minéraux; zinc; plomb; minéralisation; cadre tectonique; bassins sédimentaires; analyse du bassin; développement du bassin; morphologie; altération; Dépôt de Sullivan ;
Dépôt de North Star ; Dépôt de Kootenay King ; Bassin de Selwyn ; Dépôt de Faro ; Dépôt de Grum ; Dépôt de Vangorda ; Dépôt de Swim ; Dépôt de Driftpile ; Dépôt de Tom ; Dépôt de Jason ; géologie économique; Paléozoïque; Cambrien; Silurien;
|Illustrations||location maps; block diagrams; photographs; stratigraphic columns; cross-sections|
Bibliothèque de Ressources naturelles Canada - Ottawa (Sciences de la Terre)
|Programme||Cordillière du sud IGC-3, Initiative géoscientifique ciblée (IGC-3), 2005-2010|
|Programme||Étude des gîtes de SEDEX, Initiative géoscientifique ciblée (IGC-4)|
|Diffusé||2012 09 20|
|Résumé||(Sommaire disponible en anglais seulement)|
SEDEX (SEDimentary EXhalative) deposits are important resources of Zn and Pb. In addition to Zn and Pb, other potentially economic commodities are: Ag,
Au, Cu, Cd, Sb, Sn, and barite. Major metallogenic districts in the Canadian Cordillera that host SEDEX deposits are:
Mesoproterozoic Sullivan district in southeastern British Columbia, which hosts the world-class Sullivan deposit and other
smaller deposits such as North Star and Kootenay King.
Late Cambrian Anvil district in the Selwyn Basin of central Yukon, which hosts the Faro, Grum, Vangorda, DY, and Swim deposits.
Early Silurian Howard's Pass district in the Selwyn Basin
of the northeastern Yukon, which hosts the world-class Howard's Pass deposits (XY, Brodel, HC, Don, Anniv, OP, Pelly North).
Late Devonian Gataga district of the Kechika Trough (southern extension of Selwyn Basin) in northeastern British
Columbia, which hosts the Cirque, Driftpile, and Akie deposits.
Late Devonian MacMillan's Pass district in the Selwyn Basin of northeastern Yukon, which hosts the Tom and Jason deposits.
The Sullivan deposit and two deposits of the Anvil
district (i.e., Faro and Grum) are past-producers. Other deposits have seen or are undergoing intensive exploration and development work (e.g., Howard's Pass, MacMillan's Pass, Drifpile, Akie, and Cirque).
SEDEX deposits are defined as being
predominantly composed of Zn and Pb hosted in sphalerite and galena that were deposited at or near the seafloor from basinal metalliferous fluids discharged into rift-controlled anoxic sedimentary basins. They consist of vent-distal and vent-proximal
facies. The former is composed of interbedded sphalerite, galena, iron sulphides and clastic sediments, and the latter of variably veined, infilled and replaced bedded sulphides.
Cordilleran SEDEX deposits occur in intracratonic and epicratonic
rifts within reduced marine basins. The architecture of sedimentary basins is characterized by rapid syn-rift subsidence and clastic sedimentation that is overlain by fine-grained clastic and carbonate sediments that accumulated during a post-rift
sedimentation phase. Marine turbidites with interlayered mafic sills of the syn-rift phase host the Sullivan deposit, whereas organic-rich carbonaceous shales/mudstones of the post-rift phase host deposits of the Selwyn Basin. The deposits most
likely formed at or just below the sea floor from warm to hot (~100° up to 300°C), saline (10 to 20% NaCl equiv.) basinal brines that ascended along basin-controlling synsedimentary faults. Deposition and sequestration of metals occurred by
precipitation of sulphide minerals as a result of mixing of metal-transporting brine with locally derived H2S produced by bacterial (and perhaps thermochemical) reduction of local seawater sulphate.
Important exploration vectors include the
Deep-seated synsedimentary faults expressed as abrupt changes in facies and isopachs, intraformational breccias, slumps, debris flows, and fault scarp talus.
Recognition of local fault-controlled paleoenvironments that represent
restricted and stratified basins with anoxic H2S-rich bottom waters.
Organic-rich sediments with >1% Corg.
Anomalous concentrations of redox-sensitive trace elements (e.g., V, Tl, Cd, U, V/Mo, and Re/Mo).
alteration (muscovite, carbonates, and silicates).
Laterally and vertically extensive distal sediments that are mineralogically and chemically zoned around seafloor vents.