Targeted Geoscience Initiative Initiative géoscientifique ciblée TG ems Ore Sys The Paleozoic carbonate rocks of the southeastern Canadian Cordillera contain a variety of deposit types, including Mississippi Valley-type, magnesite, and REE-F-Ba. These deposits are hosted in weakly deformed, and metamorphosed Paleozoic platform carbonate rocks of the Rocky Mountains. They are found at different stratigraphic levels, however, most of them are hosted in dolostones of the middle Cambrian Cathedral Formation, upper Cambrian Jubilee Formation and Upper Devonian Palliser Formation. Abstract The deposits occur along major structurally controlled facies transitions between the shallow-water carbonate platforms and deeper water basin rocks of the Paleozoic continental margin. The location and geometry of these deposits reflect the juxtaposition of structures (e.g., deep-seated faults at platform to deep-water basin transition) and rock types (i.e., permeable and reactive stratigraphic units) favorable to mineralization. This confluence of favorable conditions resulted from episodic rifting and mineralization along the Paleozoic margin during the middle to Late Cambrian and Late Devonian to Middle Carboniferous. This poster reviews geology, petrography, stable (C, O, S) and radiogenic (Pb, Sr) isotopes, and geochronology of selected carbonate-hosted deposits. Petrography shows dissolution and replacement of the original carbonate by fine-grained “dolomite” followed by different stages of coarser dolomite replacement and cavity fracture fillings (e.g., saccharoidal, sparry and saddle dolomites) accompanied by sulphide deposition, mainly sphalerite, galena and pyrite. Geochemical signatures for each mineralization type show a pattern of dolomitizing and mineralizing fluids interacting with barren host rocks. A more detailed account of the materials presented here can be found in [6]. Geology The carbonate-hosted deposits discussed in this poster are in the southern Rocky Mountain Foreland Belt (RMFB; Figs. 1, 2), which is a thin-skinned thrust- and-fold belt that developed along a basal-detachment fault system initiated by Late Jurassic to Paleogene eastward accretion of allochthonous terranes [7, 8]. The strata within the RMFB consist of late Neoproterozoic to Mid-Jurassic imbricated and folded predominantly sedimentary rocks deposited on or adjacent to the stable craton of the Cordilleran margin of ancestral North America. The strata include: Ÿ Late Jurassic to early Cenozoic marine to non-marine siliclastic rocks eroded from the uplifting Omineca and Foreland belts. Several carbonate-hosted deposits occur along the platform to deep-water basin transition. For example, east of the projected western margin of the Kicking Horse Rim and the Cathedral Escarpment, middle to upper Cambrian, Ordovician, and Upper Devonian shallow-water platform carbonate rocks host Mississippi Valley-type (MVT; e.g. Monarch and Kicking Horse, Boivin−Munroe−Alpine, Shag, Hawk Creek, and Oldman), magnesite (e.g. Mount Brussilof), and rare-earth element (REE)–F-Ba (e.g. Rock Canyon Creek) deposits (Figs. 2, 3; Table 1). West of the Kicking Horse Rim and Cathedral Escarpment, deep- water basin rocks of the Chancellor Group include the Burgess Shale Formation, and lesser accumulations of limestone and lenses of MgO- and Ba-rich chloritic rocks. Ÿ Cambrian to Jurassic platform to deep-water basin transition sequences deposited on and near the ancient continental margin of ancestral North America. The Kicking Horse Rim, which corresponds approximately to the projection of the Cathedral escarpment and other escarpments, is an important Paleozoic fault-controlled, paleogeographic high at the platform to basin facies transition. Ÿ Neoproterozoic to lower Cambrian siliclastic rocks of the Windermere Supergroup deposited during intracontinental rifting. Juneau Juneau Juneau Inuvik Inuvik Inuvik Calgary Calgary Calgary Victoria Victoria Victoria Edmonton Edmonton Edmonton Vancouver Vancouver Vancouver Whitehorse Whitehorse Whitehorse Prince Rupert Prince Rupert Prince Rupert NAb YT YT NAp NAp AA CA ST SM SM SM SM SM SM AX NAb KS QN AA YT YA CG NAp NAb AG WR CG AX NAb AG CG NAc ST WR WR AX NAp QN QN QN OK OK QN NAc CA YT CC CC NAb CA YT SM SM SM SM BR BR CD CD CD PR CR PR CR 108°W 116°W 116°W 124°W 124°W 132°W 132°W 140°W 70°N 66°N 66°N 62°N 62°N 58°N 58°N 56°N 54°N 54°N 50°N 50°N 0 100 200 300 km Coast plutonic complex Alaska Alaska Yukon NWT BC Alberta USA Pacific Ocean Chugach Cache Creek Wrangellia Alexander Yukon-Tanana Yakutat Stikinia Quesnellia Coast complex North America - platform Methow Kootenay Cadwallader Chilliwack Crescent Bridge River Harrison Lake Slide Mountain AX WR CG YA YT ST Okanagan OK QN HA CD CK MT PR CR BR SM CC KS NAb NAp North America - craton & cover NAc Cassiar CA Outboard Insular Intermontane Angayucham, Tozitna Arctic Alaska AA AG N Alaska Ancestral North America TERRANES eastern limit of Cordilleran deformation Kootenay Arc Kootenay Arc Kootenay Arc Rocky Mtns Rocky Mtns Rocky Mtns Carbonate-hosted sulphide Zn-Pb ( ±Ba, ±Ag) deposits Clastic-hosted sulphides (~SEDEX) Carbonate-hosted magnesite Deposit types Figure 1. Terranes of the Canadian Cordillera [1] and location of sediment-hosted deposits in rocks of the Ancestral North America margin. Fig. 2 Fig. 2 Fig. 2 Rocky Mountains Carbonate-hosted Deposits The Paleozoic carbonate rocks of the southeastern Canadian Cordillera contain a variety of deposit types, including MVT, REE-F-Ba, and sparry magnesite. The deposits are at different stratigraphic levels, however, most of them are hosted in dolostones of the middle Cambrian Cathedral, upper Cambrian Jubilee, and Upper Devonian Palliser formations (Fig. 3). Most of them occur along major structurally controlled facies transitions between the shallow-water carbonate platforms and deep-water basin rocks near the shelf-slope break of the Paleozoic continental margin. The location and geometry of these deposits reflect the association of structures (e.g. deep-seated faults at platform to deep- water basin transition) and rock types (i.e. permeable and reactive stratigraphic units) favorable to mineralization. Mississippi Valley-type (MVT) deposits consist of stratabound lenses, layers, pods, breccias, and veins of sulphides preferentially hosted in dolostone of the middle Cambrian Cathedral and Upper Devonian Palliser formations. Examples: Monarch and Kicking Horse, Munroe, Shag, and Boivin (Figs. 4, 5, 6, 7, 8). Orebodies have single or multiple lenses in dolomitized and/or siliceous carbonate rocks. They are at facies transitions between shallow-water carbonate platform and deeper basin rocks and major basement-controlled structures. Sulphides: Pyrite, sphalerite, galena, and minor chalcopyrite. Gangue: Dolomite, fluorite, calcite, quartz, and minor barite. Magnesite deposits are preferentially hosted in middle Cambrian shallow marine carbonate rocks of the Cathedral Formation. Magnesite textures vary widely. Mineralization: Magnesite. Minor to trace minerals: mica, Mg-rich chlorite, talc, palygorskite/attapulgite, boulangerite, chalcocite, huntite, brucite, fersmite, Nb-bearing rutile, goyazite, and euclase. Orebody is steeply dipping and coincides with a crackle breccia in carbonate rocks. Mineralization ( Fig. 10 ): REE-F-Ba in REE-bearing fluorocarbonates [bastnaesite-(Ce), parisite-(Ce), synchysite-(Ce)] and a mixture of REE phosphates including monazite-(Ce). Gangue: Dolomite, pyrite, barite, calcite, quartz, and k-feldspar. Main gangue minerals: Dolomite, calcite, pyrite, quartz, and clay. Example: Mount Brussilof; producing mine (Fig. 9). Orebodies are stratbound layers, lenses, pods and irregular masses of white to grey magnesite hosted in fine-grained dolostone. Rock Canyon Creek REE-F-Ba deposit is hosted by dolostone, dolomitic limestone, and carbonate breccia of the Middle Devonian Cedared and Burnais formations (known to contain silty calcareous gypsum). Paleozoic carbonate-hosted deposits of the southern Rocky Mountains: a review 1* 2 3 2 Paradis, S. , Simandl, G.J. , Drage, N. , D'Souza, R.J. , 4 4 Kontak, D.J. , Waller, Z. 1 Geological Survey of Canada, Sidney, BC 2 British Columbia Geological Survey, Victoria, BC 3 Dalhousie University, NS 4 Laurentian University, ON corresponding author: [email protected] * Recommended citation: Paradis, S., Simandl, G.J., Drage, N., D’Souza, R.J., Kontak, D.J., and Waller, Z., 2020. Paleozoic carbonate-hosted deposits of the southern Rocky Mountains: a review. British Columbia Ministry of Energy, Mines and Petroleum Resources, British Columbia Geological Survey GeoFile 2020-07. Abstract, location, and stratigraphy Geology Geochemistry and Fluid Inclusion Results Ages Acknowledgments: This study benefited from the assistance and collaboration of Fiona Katay (British Columbia Ministry of Energy and Mines, Regional Geologist based in Cranbrook), and field assistant Michaella Yakimoski (student at University of Victoria). We thank David Pighin and Chris Graf for their perspectives on the geology of the Rocky Mountains and providing samples. Baymag Inc. kindly provided access to the Mount Brussilof mine. Special thank you extends to Ian Knuckey, mine manager, and Alex Hogg and Brody Myers, mine geologists. Wylee Fitz-Gerald helped with setting up and editing the final version of this document. References: 1. Colpron, M., and Nelson, J.L., 2011; Yukon Geological Survey, , accessed December 2012; also BC Geological Survey, BC GeoFile 2011-11, . 2. Aitken, J.D., 1971; Bulletin of Canadian Petroleum Geology, v. 19, p. 557– 569. 3. Aitken, J.D., 1989; Bulletin of Canadian Petroleum Geology, v. 37, p. 316–333. 4. Katay, F., 2017; British Columbia Ministry of Energy and Mines, British Columbia Geological Survey, Information Circular 2017-1, p. 73–107. 5. Cui, Y., Miller, D., Nixon, G., and Nelson, J., 2015; British Columbia Ministry of Energy and Mines, British Columbia Geological Survey, Open File 2015-2. 6. Paradis, S., Simandl, G.J., Drage, N., D'Souza, R.J., Kontak, D.J., and Waller, Z., 2020; www.geology.gov.yk.ca/bedrock_terrane.html http://www.empr.gov.bc.ca/Mining/Geoscience/PublicationsCatalogue/GeoFiles/Pages/2011-11.aspx Geological Survey of Canada, Bulletin XXX, p. Y–Z. 7. Price, R.A. 1981; Geological Society of London, Special Publication No. 9, pp. 427–448. 8. McMechan, M.E., 2012; Canadian Journal of Earth Sciences, v. 49, no. 5, p. 693-708. 9. Vandeginste, V., Swennen, R., Gleeson, S.A., Ellam, R.M., Osadetz, K., and Roure, F., 2007; Mineralium Deposita, v. 42, p. 913–935. 10. Yao, Q. and Demicco, R.V., 1997; American Journal of Science, v. 297, p. 892–938. 11. Nesbitt, B.E. and Muehlenbachs, K., 1994; Geology, v. 22, p. 243–246. 12. Veizer, J., Ala, D., Azmy, K., Bruckschen, P., Buhl, D., Bruhn, F., Carden, G.A.F., Diener, A., Ebneth, S., Godderis, Y., Jasper, T., Korte, C., Pawellek, F., Podlaha, O.G., Strauss, H., 1999; Chemical Geology, v. 161, p. 59–88. 13. Choquette, P.W. and James, N.P., 1987; Geoscience Canada, v. 14, p. 3-35. 14. Taylor, H.P., Frechen, J., and Degens, E.T., 1967; Geochimica et Cosmochimica Acta, v. 31, p. 407–430. 15. Simandl, G.J., Petrus, J., Leybourne, M., and Paradis, S., 2018; Resources for Future Generations Resources for Future Generations 2018, Vancouver, British Columbia, June 16-21, 2018, Abstracts. 16. Jeary, V.A., 2002; M.Sc. thesis, University of Calgary, Calgary, Alberta, 250 p. 16. Machel, H.G. and Cavell, P.A., 1999; Bulletin of Canadian Petroleum Geology, v. 47, p. 510–533. 17. Machel and Cavell, 1999; Bulletin of Canadian Petroleum Geology, v. 47, p. 510-533. 18. Farquhar J., Wu, N.P., Canfield, D.E., and Oduro, H., 2010; Economic Geology, v. 105, p. 509–533. 19. Kiyosu, Y. and Krouse, H.R., 1990; Geochemical Journal, v. 24, p. 21–27. 20. Wilkinson, J.J., 2014; Geochemistry of Mineral Deposits: Treatise on Geochemistry (second edition), (ed.) S.D. Scott; Elsevier, v. 13, p. 219–249. 21. Nelson, J.L., Paradis, S., Christensen, J., and Gabites, J., 2002; Economic Geology, v. 97, p. 1013–1036. 22. Kontak, D.J, Paradis, S., Waller, Z., and Fayek, M., 2020; Geological Survey of Canada, Bulletin XXX, p. Y–Z. 23. Horita, J.,2014; Geochimica et Cosmochimica Acta, v. 129, p. 111-124. 24. Leach, D.L., Bradley, D., Lewchuk, M.T., Symons, D.T.A., de Marsily, G., and Brannon, J., 2001; Mineralium Deposita v. 36, p. 711–740. 25. Nelson, J.L., Colpron, M., Piercey, S.J., Dusel-Bacon, C., Murphy, D.C., and Roots, C.F., 2006; Geological Association of Canada, Special Paper 45, p. 323-360. 26. Millonig, L.J., Gerdes, A. and Groat, L.A., 2012; Lithos, v. 152, p. 202–217. 27. Nakai, S.I., Halliday, A N., Kesler, S.E., Jones, H.D., Kyle, J.R., and Lane, T.E., 1993; Geochimica et Cosmochimica Acta, v. 57, p. 417- 427. 28. Symons, D.T.A., Pan, H., Sangster, D.F., and Jowett, E.C., 1993; Canadian Journal of Earth Sciences, v. 30, p. 1028-1036. 29. Smethurst, M.T., Sangster, D.F., Symons, D.T.A., and Lewchuk, M.T., 1999; Bulletin of Canadian Petroleum Geology, v. 47, p. 548-555. 30. Hnatyshin, D. 2018; PhD thesis, University of Alberta, Edmonton, Alberta, 306 p. 31. Hnatyshin, D. van Acken, D., Paradis, S., Creaser, C.R. (in preparation). Submitted to Economic Geology. 32. Paradis, S., Gleeson, S., and Magnall, J., 2014; Prospectors and Developers Association of Canada (PDAC), Zinc session. Abstracts with Programs. 33. Pannalal, S.J., Symons, D.T.A., and Leach, D.L., 2007; Canadian Journal of Earth Sciences, v. 44, p. 1661–1673. 34. Paradis, S., Hnatyshin, D., Simandl, G.J., and Creaser, R.A., 2020; Economic Geology, in press. 35. Symons, D.T.A., Lewchuk, M.T., and Sangster, D.F., 1998; Economic Geology, v. 93, p. 68–83. Deposit Deposit Classification Commodity Formation / Unit Age of Host Rocks Lithology Mineralogy Mount Brussilof Magnesite Magnesite Cathedral Fm Middle Cambrian Magnesite Magnesite. Main gangue minerals: dolomite, calcite, pyrite, quartz, and clay. Minor to trace minerals: mica, Mg-rich chlorite, talc, palygorskite/attapulgite, boulangerite, chalcocite, huntite, brucite, fersmite, Nb-bearing rutile, goyazite, and euclase. Monarch MVT Zn, Pb (±Ag, ±Cd) Cathedral Fm Middle Cambrian Massive to thin-bedded brecciated dolostone Galena, sphalerite and pyrite in gangue of dolomite and calcite. Minor chalcopyrite, barite, quartz and native silver. Kicking Horse MVT Zn, Pb (±Ag, ±Cd) Cathedral Fm Middle Cambrian Massive to thin-bedded brecciated dolostone Galena, sphalerite and pyrite (traces of chalcopyrite) in gangue of dolomite and calcite. Shag MVT Zn, Pb (±Ag) Stephen, Eldon and Waterfowl fms Middle to Upper Cambrian Dolostone Sphalerite, galena, minor pyrite in a gangue of dolomite, quartz, and minor calcite. Munroe MVT Zn Palliser Fm; lower (Morro) mb Upper Devonian Dolostone with fenestral porosity (filled by white sparry dolomite), zebra-like texture, lesser breccia Sphalerite, minor pyrite and galena in a gangue of dolomite; calcite and dolomite fill vugs. Alpine MVT Zn Palliser Fm; lower (Morro) mb Upper Devonian Dolostone Sphalerite, minor pyrite and galena in a gangue of dolomite; calcite and dolomite fill vugs. Boivin MVT Zn Palliser Fm; lower (Morro) mb Upper Devonian Dolostone Sphalerite, minor pyrite and galena in a gangue of dolomite; calcite and dolomite fill vugs. Hawk Creek MVT Zn, Pb (±Ag, ±Au) McKay Group Upper Cambrian- Ordovician Argillaceous limestone, argillite, dolomitic limestone. Sphalerite, pyrite, galena (silver reported) in a gangue of calcite and dolomite. Rock Canyon Creek REE-F-Ba REE-F-Ba Cedared and Burnais fms Middle Devonian Dolostone, dolomitic limestone, carbonate breccia and laminated silty, calcareous gypsum. Dolomite, fluorite, barite, pyrite, quartz, K-feldspar, calcite, REE-fluorocarbonates and REE-phosphates. Oldman MVT Pb, Zn, Ag Upper Palliser Fm Upper Devonian Dolostone, dolomitic limestone, limestone. Galena, pyrite, and sphalerite in a gangue of calcite. Minor: dolomite, ankerite. Table 1. Principal characteristics of carbonate-hosted deposits of southeastern British Columbia invesitaged during this study [16] [16] [9] Middle Cambrian marine carbonates Upper Devonian marine carbonates MASIRBAS 0.7300 0.7250 0.7200 0.7150 0.7100 0.7050 0.7000 -5 -10 -15 -20 d 18 O VPDB 87 86 Sr/ Sr + + Oldman, host dolostone Shag, sparry and saddle dolomite associated to sulphides Hawk Creek, sparry and saddle dolomite associated to sulphides Mount Brussilof; sparry dolomite Mount Brussilof; magnesite Late calcite (veins and vugs) Monarch-Kicking Horse; altered (replacive) dolomite Monarch-Kicking Horse; sparry dolomite Munroe-Boivin, sparry and saddle dolomite associated to sulphides Hawk Creek, dolomitic limestone RCC REE-F-Ba (ferroan) dolomite RCC dolomitic limestone (host rock, not mineralized) RCC altered dolostone (with fluorite) Cathedral Fm limestone (Jeary, 2002) Cathedral Fm dolospar (Jeary, 2002) Cathedral Fm sparry-saddle dolomite at Monarch and Kicking Horse (Vandeginste et al., 2007) RCC calcite (±F) breccia-matrix and veins 18 87 86 Figure 13. δ O versus Sr/ Sr values for various carbonates VPDB associated with deposits of the southern Canadian Rocky Mountains. Middle Cambrian and Devonian marine carbonate values are from [12]. Maximum Sr isotope ratio of basin shale 87 86 (MASIRBAS) is from [17]. Sr/ Sr values of MVT and magnesite hydrothermal dolomites are similar or higher than their host dolostone. However, Rock Canyon Creek dolomites have lower 87 86 Sr/ Sr values than those from MVT and magnesite deposits. CMC DMC Yao and Demicco (1997) Vandeginste et al. (2007) Nesbitt and Muehlenbachs (1994) Meteoric Increased burial and/or hydrothermal fluids + + + + + + + + -8 -14 -12 -6 -4 -2 0 -22 -20 -18 -16 (‰) d 18 O VPDB -8 -6 -4 -2 0 2 4 d (‰) 13 C VPDB + Munroe-Boivin, dolostone (least altered) Munroe-Boivin, saccharoidal dolomite Munroe-Boivin, sparry and saddle dolomite associated to sulphides Shag, altered (replacive) dolomite Shag, dolostone (least altered) Shag, sparry and saddle dolomite associated to sulphides Oldman, host dolostone Mount Brussilof; sparry dolomite Mount Brussilof, magnesite Monarch-Kicking Horse, dolostone (least altered) Monarch-Kicking Horse, altered (replacive) dolomite Monarch-Kicking Horse, sparry dolomite Oldman, calcite associated to sulphides Hawk Creek, dolomitic limestone Hawk Creek, sparry and saddle dolomite associated to sulphides Late calcite (veins and vugs) [9] [10] [11] CMC = Cambrian Marine Carbonate [12] DMC = Devonian Marine Carbonate [12] 13 18 Figure 11. δ C versus δ O of host dolostone and VPDB VPDB hydrothermal dolomites associated with MVT and magnesite deposits. Hydrothermal dolomites associated with 18 mineralization have lower δ O values than their VPDB respective dolostone host rocks. Our data compare well with the hydrothermal dolomites of [9], [10] and [11]. The generalized trends for burial, hydrothermal and meteoric fluids of [13] are illustrated by arrows. y = 1.3709x + 0.9471 R² = 0.8961 Robb Lake MVT Cluster 1 Cluster 2 Cluster 3 B) Deposits of the southern Rocky Mountains Upper crust Orogene Shale curve “Cordilleran carbonate trend” Lead Mountain Pb-Zn deposit 208 206 Pb/ Pb Pb/ Pb 207 206 2.20 2.15 2.10 2.05 2.00 1.85 1.90 1.95 0.90 0.85 0.80 0.75 0.70 Shag Hawk Creek Mt Brussilof magnesite Munroe Oldman Monarch/Kicking Horse Devonian Palliser Fm Mid-Camb Cathedral Fm and equiv. Upper Camb-Ord McKay Group Pb-Zn deposits of the northern Rocky & Mackenzie Mountains and WCSB (including Robb Lake MVT) 207 204 206 204 207 206 208 206 Figure 15. A) Pb/ Pb versus Pb/ Pb; and B) Pb/ Pb versus Pb/ Pb of galena, pyrite, and sphalerite from carbonate-hosted deposits of the southern Rocky Mountains compared to the “Cordilleran carbonate trend”, which includes Zn-Pb occurrences and deposits of the northern Rocky Mountains, Mackenzie Mountains, and Western Canada Sedimentary Basin (WCSB). The data form 3 clusters, each defined by specific deposits. Cluster 1, the least radiogenic group, is from the Monarch, Kicking Horse and Munroe deposits. Cluster 2 consists exclusively of samples from Shag deposits. Cluster 3, the most radiogenic group, consists of Hawk Creek, Mount Brussilof, Oldman, and Munroe deposits, which plot within the “Cordilleran-carbonate trend” defined by carbonate-hosted Zn-Pb deposits and occurrences of the northern Rocky Mountains, Mackenzie platform, and WCSB (cf. [21]). The dashed lines in A) and B) represent the trendline for all the data within the “Cordilleran carbonate trend”. They intersect clusters 1 and 2, and a cluster of unradiogenic lead data from the Lead Mountain deposit, a vein- and fracture-controlled carbonate-hosted sulphide-barite deposits in the western Foreland Belt of the Rocky Mountains. This suggests that Pb signature of clusters 1, 2, and 3 represents mixtures of variably radiogenic end members. Breakup of Rodinia Assembly of Pangea Dispersion of Pangea Pangea stable Pangea unstable Breakup of Pangea Laramide Orogeny Laramide Orogeny (~90-50 Ma) Antler Orogeny (~370-340 Ma) 1 Arc magmatism (NA margin) 600 500 400 300 200 100 PC C O S D C P Tr J K T age (Ma) 600 500 400 300 200 100 PC C O S D C P Tr J K T age (Ma) 3 Pine Point Zn-Pb 6 Salmo Zb-Pb 7 Pend Oreille Zn-Pb 4 Robb Lake Zn-Pb 8 Monarch-Kicking Horse Zn-Pb 5 Prairie Creek Zn-Pb-Ag Carbonate-hosted deposits Host rocks Orogeny/magmatic events Paleomagnetic Radiometric Figure 20. Summary of known radiometric and paleomagnetic ages of Zn-Pb carbonate-hosted 1 2 mineralization and their host rocks. Figure modified from [24]. Data from [25]; Radiometric data 3 from various sources and compiled by [26]. Abbreviation: NA – North America; Radiometric data 4 (Rb-Sr) from [27], paleomagnetic data from [28]; Radiometric data (Rb-Sr) from [21], 5 paleomagnetic data from [29]; Radiometric data (Re-Os) from [30] and [31] (work in progress); 6 7 Radiometric data (Re-Os) from [30], [31] and [32]; Paleomagnetic data from [33], radiometric 8 data from [34]; Paleomagnetic data from [35]. Carbonatites and associated 2 alkaline complexes (NA margin) N 0 100 kilometres Nelson Fernie Castlegar Cranbrook Invermere Kimberley Vernon Revelstoke Field o 49 N o 49 N o 49 N anclinorium anclinorium anclinorium Purcell Purcell Purcell Kootenay Kootenay Kootenay Rocky Mountain Rocky Mountain Rocky Mountain Foreland Foreland Foreland Belt Belt Belt Arc Arc Arc Cathedral Escarpment Rocky Mountain Trench Sediment-hosted deposits Monarch and Monarch and Kicking Horse Kicking Horse Monarch and Kicking Horse Shag Shag Shag Hawk Ck Hawk Ck Hawk Ck Munroe Munroe Munroe Boivin Boivin Boivin Alpine Alpine Alpine Rock Canyon Ck Rock Canyon Ck Rock Canyon Ck Oldman Oldman Oldman Mount Brussilof Mount Brussilof Mount Brussilof U.S.A. U.S.A. U.S.A. Pacific Ocean Pacific Ocean Pacific Ocean Atlantic Ocean Atlantic Ocean Atlantic Ocean Road Rail line Transportation Geology Intrusives Slide Mountain Quesnellia Platformal strata Basinal strata Neogene to Quaternary volcanics Supracrustal Ancestral North America platformal Post accretionary assemblages Terranes Alberta Vein- and fracture-controlled replacement Pb-Zn (±Ag,±Au) Magnesite Stratabound Ba-Pb-Zn vein Figure 2. Regional geological map of southeastern Canadian Cordillera showing locations of the sediment-hosted deposits. The projection of the Cathedral escarpment (red dashed-line) corresponds approximately to the western margin location of the Kicking Horse Rim, a paleogeographic high that was initiated in the early middle Cambrian and persisted into the Ordovician [2,3]. Both features mark the change from shallow-water carbonate rocks to the east and continental slope lithofacies to the west during the early Paleozoic. Modified from [4]. Terranes from [5]. Alberta Gp Crowsnest Fm Blairmore Gp Elk Fm Mist Mountain Fm Morissey Fm Fernie Fm Kootenay Gp Spray River Gp Whitehorse Sulfur Mtn Rockie Mtn Supergroup Ranger Canyon Ishbel Gp Spray Lakes Gp Rundle Gp Banff Fm Exshaw Fm Palliser Fm Alexo/Sassenach Fm Fairholme Gp Mount Forster Harrogate Cedared/Burnais Beaverfoot Fm Mount Wilson Fm OwenCk/Skoki/Outram Bison Ck/Mistaya/Survey Peak Waterfowl/Arctomys Fm Sullivan/Lyell/Jubilee Fm Pika/Eldon/ Stephen Fm Cathedral Fm Mt Whyte Fm Miee/Gog Gp Southeast Brish Columbia Quaternary Terary Cretaceous Jurassic Permian Triassic Carb. Miss Pensyl Devonian Silurian Ordovician Cambrian Neo- Proterozoic 2.6 65.5 145.5 201.6 251 299 359 416 444 488 542 1000 Munroe, Alpine, Boivin Monarch Baker Ck, Eldon Shag Hawk Ck Rock Canyon Ck Oldman Rundle Gp Banff Fm Exshaw Fm Palliser Fm Alexo/Sassenach Fm Fairholme Gp Mount Forster Harrogate Cedared/Burnais Beaverfoot Fm Mount Wilson Fm OwenCk/Skoki/ Outram Bison Ck/Mistaya/Survey Peak McKay Group Waterfowl/Arctomys Fm Sullivan/Lyell/Jubilee Fm Pika/Eldon/ Stephen Fm Cathedral Mt Whyte Miee/Gog Gp Kicking Horse Mt Brussilof Island arc volcaniclascs and epiclasc rocks, flows, tuffs, trans-tensional volcanics Fine-grained marine rocks (limestone, dolostone, mudstone, phyllite, schist) Medium- to coarse-grained clasc rocks (sandstone, conglomerate, siltstone, quartzite) Reefal and crystalline carbonates, marbles Unconformity Evaporites and shallow marine carbonates Fine-grained clasc rocks (siltstone, shale, argillite) { Mississippi Valley-type (MVT) Zn-Pb deposit Carbonate-hosted magnesite deposit MVT deposit not studied Unconformity Carbonate-hosted REE-F-Ba deposit Figure 3. Generalized stratigraphy of the Purcell anticlinorium and the Rocky Mountain Foreland Belt with locations of studied deposits indicated by stars. Modified from [4]. Sparry Dol Do frag Sph+Py 100 µm Sph Sph Sph Dol Dol Dol B B A A Figure 4. Kicking Horse MVT deposit. A) Aggregates of sphalerite (Sph)+pyrite (Py) in white sparry dolomite (Do) cement. B) Colloform sphalerite exhibiting colour zonation adjacent to white sparry dolomite; PPL = Plane-Polarized Light. Sph Sph Sph Dol+Qz Dol+Qz Dol+Qz A A Qz Qz (minor Dol) (minor Dol) Qz (minor Dol) B B 1000 µm Sph Sph Sph Qz Qz Qz Figure 5. Shag MVT deposit. A) Sample of Red Bed showing displays alternating bands of white dolomite and quartz and darker dolostone rich in red sphalerite (Sph). B) The C-4 showing with intense replacement by granular sphalerite in a matrix of quartz and dolomite, with minor pyrite and galena (black); PPL. B B Sph 1 Sph 1 Sph 1 Dol 2 Dol 2 Dol 2 Dol 1 Dol 1 Dol 1 500 um 500 um 500 um Figure 7. Hawk Creek MVT deposit. A) Massive layered/banded sphalerite and less pyrite, galena replacing argillites and argillaceous dolostone of the middle Cambrian McKay Group. B) Sphalerite 1 (Sph 1) surrounded by fine crystalline dolomite (Dol 1) and coarse-grained saddle dolomite (Dol 2); PPL. A A 1000 µm Host Do Host Do Host Do Cc Cc Cc Sph Sph Sph 1000 µm Sph Sph Sph Dol Dol Dol Figure 8. Oldman MVT deposit. A) Sphalerite (Sph) interstitial to dolomite (Dol); PPL. B) Colloform sphalerite (Sph) fills open spaces. Smaller grains are interstitial to or replace the dolomite (Host Do); PPL. A A B B Sph Sph Sph Sparry Dol Sparry Dol Sparry Dol Sacch Dol Sacch Dol Sacch Dol Host Do Host Do Host Do Sacch Sacch Dol Dol Sacch Dol Sph Sph Sph 500 µm Dol Dol Dol Figure 6. Munroe MVT deposit. A) Zebra texture created by the alternating bands of dark grey dolostone (Host Do) replaced by saccharoidal dolomite (Sacch Dol) rich in sphalerite (Sph), and white sparry dolomite lenses. B) Nonplanar or planar-e to planar-s dolomite (Dol), coarser-grained saccharoidal dolomite (Sacch Dol) and intergranular sphalerite (Sph); PPL. A A B B Magnesite Sparry Sparry Dol Dol Sparry Dol Frs Frs Frs 100 µm B B A A Figure 9. Mount Brussilof magnesite deposit (Baymag mine). A) Coarse- grained grey magnesite ore. B) Fersmite (Frs) crystal in sparry dolomite (Sparry Dol); PPL. Pyrite Pyrite Pyrite Pyrite Pyrite Pyrite Ferroan dolomite Ferroan dolomite Ferroan dolomite Ferroan dolomite Ferroan dolomite Ferroan dolomite Fluorite Fluorite Fluorite Fluorite Fluorite Fluorite Fluorite Fluorite Fluorite Barite Barite Barite Synchysite Synchysite Synchysite Bastnäsite-Monazite Bastnäsite-Monazite Bastnäsite-Monazite Bastnäsite Bastnäsite Bastnäsite Figure 10. Rock Canyon Creek REE-F-Ba deposit. A) Large euhedral crystals of barite in purple fluorite vein cutting altered dolostone (DDH-09-01 at 38.7 m). B) Backscatter electron image of mineral assemblage from the REE-F-Ba mineralization. A A B B Upper crust Shale curve Orogene Mantle Deposits of the southern Rocky Mountains y = 0.1149x + 13.521 R² = 0.9716 Robb Lake MVT Lead Mountain Pb-Zn deposit Cluster 1 Cluster 2 Cluster 3 “Cordilleran carbonate trend” Includes Zn-Pb occurrences of the northern Rocky Mtns, Mackenzie Mnts, and WCSB (including Robb Lake MVT deposit) 207 204 15.4 15.5 15.6 15.7 15.8 15.9 16.0 16.1 16.2 16.3 16.4 17.0 18.0 19.0 20.0 21.0 22.0 23.0 24.0 25.0 26.0 206 204 Pb/ Pb Pb/ Pb Shag Hawk Creek Mt Brussilof magnesite Munroe Oldman Monarch/Kicking Horse Devonian Palliser Fm Mid-Camb Cathedral Fm and equiv. Upper Camb-Ord McKay Group A) Southern BC carbonatites (Simandl, unpublished data) Primary igneous carbonatites Sediment contamination or high T fractionation RCC: Carbonates associated to mineralization (this study) RCC: Host carbonates (this study) RCC: Altered dolostone (this study) RCC: Saddle dolomite (this study) CMC DMC MVT deposits: Dolomite associated with mineralization (this study) MVT deposits: Host dolostone (this study) -8 -6 -4 -2 0 2 4 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 d (‰) 13 C VPDB (‰) d 18 O VPDB [14] [15] 13 18 Figure 12. Plot of δ C versus δ O . Values for dolomites VPDB VPDB associated with MVT, magnesite, and REE-F-Ba deposits are lower than respective host carbonate rocks. Dolomite associated with Rock 13 Canyon Creek (RCC) REE-F-Ba mineralization has δ C versus VPDB 18 δO values similar to dolomite associated with MVT and VPDB magnesite deposits; these values plot outside the fields of southern British Columbia carbonatite (yellow) and primary igneous carbonatites (defined by [14]). Figure 17. Homogenization temperature (Th) versus salinity (wt. % equiv. NaCl). The data indicate broad ranges of temperature (<80–200°C) and salinity (0.9–28 wt.%), even in some cases for single settings (e.g., Monarch 0.9–20.2 wt. %; Mastodon 3.1–23.1 wt. %). Mastodon and O'Donnell deposits are located in the Kootenay Arc of southern BC [22]. 0 0 50 100 150 200 250 5 10 15 20 25 30 Homogenization Temperature(°C) Salinity (wt% NaCl eq) Robb Lake (RL-2-2) Robb Lake (RL1B-1) Shag Monarch Mastodon O’Donnell -4 0 4 8 12 16 20 -8 -12 -16 -20 200 160 120 80 40 0 4 8 12 16 20 24 28 32 36 40 FCD MCD/CCD/SD Calcite 18 δ O (‰) carbonate o Temperature ( C) 18 Figure 18. Plot of δ O (‰) values for different carbonate types SMOW 18 versus Temperature. The curved lines are δ O values of H2O precipitating fluids calculated using the dolomite-H O fractionation 2 equation of [22]. The dashed black line traces the idealized evolutionary trend of a fluid in a MVT setting [23]. Reeves MacDonald deposit is in the Kootenay Arc of southern BC, and Dawson Oil Field and Great Slave Reef are in the Western Canada Sedimentary Basin. Dawson Oil Field Great Slave Reef Reeves MacDonald Robb Lake Kicking Horse CaCO 3 FeCO 3 MgCO 3 Carbonate types 40% 50% 60% FCD MCD CCD SD Calcite 70 90 80 60 50 40 30 20 10 90 n=109 80 70 60 50 40 20 30 10 90 80 70 60 50 30 40 20 10 Dolomite Ferroan dolomite Ca-dolomite n=76 Figure 16. Ternary plots of CaCO -FeCO -MgCO (in atomic %) for different dolomite 3 3 3 types and calcite from different study areas. Dolomite is generally stoichiometric chemically, but ore-stage types (CCD and SD) are the most Fe-rich (up to 6 mol % FeCO ). Data were collected using SEM-EDS analysis. Abbreviations: FCD = fine- 3 grained crystalline dolostone (~host dolostone), MCD = medium-grained crystalline dolomite, CCD = coarse-grained crystalline dolomite, SD = saddle dolomite [22]. Figure 19. Fluid inclusions (FI) hosted in sphalerite. The inclusions are primary (P), pseudosecondary (PS) and secondary (S) and indeterminate (I) types. A) Kicking Horse: zoned, yellow to clear sphalerite with FI of P types. B) Monarch: zoned yellow to clear sphalerite inundated with opaque FI of P types. C) Monarch: clear to red zoned sphalerite inundated with irregular-shaped FI of P, S and I types. D) & E) Shag: zoned red to clear sphalerite with FI of P and S types. Image E shows an enlarged FI (black arrow) with low vapour phase relative to liquid (V:L ratio) and thus a low Th value (<80°). F) & G) Shag: clear to yellow, zoned sphalerite hosting small to large, equant FI of I type defining a 3D array. Most of the FI are opaque, but inset with outlined black box is a small vapour phase [22]. A A B B C C D D E E F F G G Fluid Inclusions 30 20 10 0 -10 -20 40 500 400 300 600 34 δ S (‰) VCDT Age (Ma) Galena Pyrite Barite Sphalerite Hawk Creek Munroe Rock Canyon Ck Boivin Oldman Shag Kicking Horse Monarch Mt Brussilof Marine sulphate composition [18] Mean sedimentary pyrite composition produced by BSR Likely range of sulphide compositions produced by TSR + + ++ + +++ +++ + + + + + + Figure 14. Sulphur isotope values of carbonate-hosted deposits in relation to age of host rocks. Sulphur in most MVT deposits is consistent with an origin from seawater sulphate, reduced by thermogenic sulphate reduction (TSR) and locally bacterogenic sulphate reduction (BSR) occurred. Modified from [20]. [19] [18] Natural Resources Canada Resources Naturelles Canada Conclusions § Deposits covered by this study are hosted by shallow-water platform carbonate rocks of Ancestral North America (Fig. 1). They are located east of the Rocky Mountain trench along the projection of the Cathedral escarpment (Fig. 2). This escarpment coincides with structurally controlled facies transitions between platform carbonate rocks and deep-water basin rocks. § Dolomite composition is typically stoichiometric; however, ore-stage varieties (“replacive”, coarse-grained sparry and saddle dolomites) are enriched in Fe (up to 6 mol % FeCO ; Fig. 3 16). 18 13 § The δ O and δ C values of hydrothermal dolomites at Rock Canyon Creek REE-F-Ba VPDB VPDB deposit are intermediate between values of carbonatites and host carbonate rocks (Fig. 12). 87 86 Their Sr/ Sr values (0.70588 to 0.70873; Fig. 13) are similar or lower than their host carbonate rocks (0.70866 to 0.70903). This suggests that REE-F-Ba mineralization at Rock Canyon Creek may have formed from distal carbonatite-related fluids interacting with carbonate host rocks and mixing with ambient fluids. § Deposits are associated with syn- to post-depositional dolomitization represented by “replacive”, sparry and saddle dolomites (Fig. 4 to 10). These dolomites resulted from hydrothermal fluid migration along fault systems and strata with enhanced porosity and permeability. § Mineralization occurred intermittently (in more than one stage) during the Paleozoic, i.e. middle to late Cambrian and Late Devonian to middle Carboniferous (Fig. 20). § The homogenization temperatures, measured from fluid inclusions trapped in sphalerite from the Rocky Mountains MVT deposits (~ 160−240ºC, pressure corrected to 1 kbar; Figs. 17, 18, 19), support a hydrothermal origin. § Sulphur isotope values of Sulphide minerals show large variations within a deposit (e.g. +20.5 34 to +32.9‰ at Mount Brussilof) and among different deposits (e.g. across all deposits, δ S VCDT values range from -2.8% to +36.6%, n=53, with most values from +9.9 to +36.6‰, n=51). Reduced sulphur formation predominantly occurred through TSR of coeval seawater sulphate for most deposits (e.g. Kicking Horse, Monarch, and Hawk Creek). However, BSR also occurred locally (e.g. at Boivin; Fig.14). § Lead isotopes suggest a mixing trend involving highly radiogenic and non-radiogenic end members (Fig. 15). 18 13 § The δ O (-20.0 to -9.8‰) and δ C (-8.6 to +1.1‰) values for “replacive”, sparry, and VPDB VPDB saddle dolomites associated with MVT, magnesite, and REE-F-Ba deposits are lower than 18 13 their respective host carbonate rocks (δ O = -15.2 to -7.1‰; δ C = -2.9 to +1.2‰), and VPDB VPDB they compare well with other hydrothermal dolomites in the RMFB (Fig. 11, 12). § Fluids responsible for “replacive”, sparry and saddle dolomites associated with MVT and magnesite deposits were of hydrothermal origin, modified by interaction with siliclastic and carbonate rocks, and were expelled from deep burial settings by tectonic stresses, as 18 exemplified by high temperatures (~ 160−240ºC), low δ O values (-20.0 to -11.5‰), and VPDB 87 86 high Sr/ Sr ratios (0.70879 to 0.71484).