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Sullivan |
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British Columbia, Canada |
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Zn Pb Ag Sn
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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SUMMARY
Sullivan is a stratabound, massive iron-lead-zinc sulphide orebody that lies conformably near the top of the Mesoproterozoic Lower Aldridge Formation. This unit is dominantly composed of fine grained siliciclastic rocks, mainly a rhythmic succession of thin to medium bedded, typically graded, very fine wackes and quartzitic wackes with associated tourmalinites. The northern two-thirds of the orebody is underlain by up to 125 m of intraformational conglomerate. Cross-cutting zones of chaotic breccia disrupt well bedded sedimentary rock and conglomerates under the western half of the orebody. Ore occurs as a convex, gently east dipping tabular lens with lateral dimensions of approximately 2000 x 1600 m. The western part, which is up to 100 m thick, can be divided into three approximately equal intervals. The lower is composed of predominantly pyrrhotite massive sulphides, while the middle layer is also massive sulphides, but mainly galena and sphalerite. The upper part is delicately banded galena, pyrrhotite and sphalerite, with intercalated siliciclastic beds near the top. The eastern part of the orebody consists of five distinct bedded sulphide intervals totalling up to 27 m in thickness, that are intercalated with four siliciclastic bands which are together up to 10 m thick. A funnel shaped tourmaline zone some 1400 x 950 m in plan area at the orebody footwall extends downwards for more than 450 m below the western part of the sulphide deposit. Production + reserves totalled 170 Mt @ 6.1% Zn, 4.9% Pb, 50 g/t Ag.
DETAIL
The Sullivan mine is located on the western edge of the Rocky Mountain Trench, in south-eastern British Columbia, near the town of Kimberley, and has been owned and operated by Cominco Ltd (later Teck-Cominco) since 1913. The reserves were exhausted and the mine closed in 2001. Published reserve and production figures include:
Original resource - 160 Mt @ 5.6% Zn, 6.5% Pb, 67 g/t Ag, 25.9% Fe (Leitch, et al., 1995),
Production to 1981 - 115.97 Mt @ 5.8% Zn, 6.7% Pb, 79 g/t Ag (Hamilton, et al., 1983),
Reserve, 1981 - 46.00 Mt @ 6.0% Zn, 4.5% Pb, 38 g/t A (Hamilton, et al., 1983)
Reserve, 1993 - 17 Mt @ 7.9% Zn, 4.7% Pb, 25 g/t Ag (Belluz and Knapp, 1994).
The Sullivan deposit was discovered in 1892 by four prospectors lured to the district by stories of rich Ag-Pb mineralisation at the North Star prospect some 2.5 km to the SSW. The deposit was worked intermittently by various syndicates and companies from 1892. Via amalgamation with several other mines, Cominco was formed and finally fully purchased the Sullivan Claims in 1913. After years of metallurgical and underground access development, the mine commenced operation in 1920 (Belluz and Knapp, 1994).
The North Star mine was first worked in 1892 and produced 77 500 t of hand-sorted ore averaging 995 g/t Ag, 46% Pb and <1% Zn. It occurs at the same stratigraphic level as Sullivan, at the top of erratically tourmalinised fragmental sediments, and is composed mainly of stratabound sulphides. The Stemwinder vein is located midway between North Star and Sullivan, with the three aligned along a NNE trend, generally parallel to the Sullivan Fault a few hundred metres to the west. It comprises a large, cross-cutting pyrrhotite body which contained 1.7 Mt of pyrrhotite grading 30% Fe, and dipped at 60° to the south. In addition to the pyrrhotite it included a smaller economic zone of 0.1225 Mt @ 75 g/t Ag, 3.1% Pb, 16.6% Zn, which was found 150 m below the Sullivan stratigraphic position (Belluz and Knapp, 1994).
The Estella property, some 15 km to the east, across the Rocky Mountain Trench, is a cross-cutting, fault controlled vein deposit, occurring in sediments similar to those found around the Sullivan deposit, but at a facies change in the basin. It yielded 0.1095 Mt @ 60 g/t Ag, 9% Zn, 4.7% Pb. The Kootenay King deposit, which is 3 km to the south of Estella, was a small lens of stratabound sulphides occurring in sediments that are stratigraphically over 1500 m higher than the hosts to Sullivan. The orebody contained 0.022 Mt @ 110 g/t Ag, 8.7% Zn, 5.5% Pb. Further south again the St Eugene deposit is a fault controlled sulphide vein system consisting chiefly of galena, some 900 m stratigraphically above the Sullivan host level. It contained approximately 1 Mt @ 200 g/t Ag, 5% Zn, 15% Pb. The deposit was discovered in 1893 and was Cominco's first mine when purchased in 1906 (Belluz and Knapp, 1994).
Geological Setting
Click here for a regional setting image.
The Sullivan deposit is an iron-lead-zinc-silver sulphide body that lies conformably near the top of the Mesoproterozoic Lower Aldridge Formation. This formation comprises a sequence of dominantly fine grained siliciclastic rocks, mainly a rhythmic succession of thin to medium bedded, typically graded, very fine wackes and quartzitic wackes. Towards the top of the Lower Aldridge, matrix is more abundant and the grain size decreases. Typical internal structures are grading, even parallel laminations and local crossbedding. The Lower Aldridge is the lowest of the three members that make up the 4000 m thick Aldridge Formation, which in turn is part of the locally 10 000 m thick Purcell Supergroup, the Canadian equivalent of the Belt Supergroup of the north-western US (Hamilton, et al., 1983). The main massive sulphides are overlain by a quartzite, marking the base of the Middle Aldridge which is generally characterised by thicker, coarser, silt to sand-sized wackes (Leitch, et al., 1995).
Mesoproterozoic gabbros of two ages, 1433 and 1075 Ma, intrude the Purcell Supergroup. These intrusives are present as dykes and sills and are common in the vicinity of the Sullivan orebody (Hamilton, et al., 1983).
The orebody is located on the eastern side of the Purcell Anticlinorium, a broad zone of dominantly east-verging thrust and fold structures. North and north-east trending transcurrent faults along the boundaries of the east-verging thrust plates of the Purcell Anticlinorium trend from the east, across the Rocky Mountain Trench and merge with north and north-west striking thrusts in the Western Rocky Mountains in the Sullivan area (Hamilton, et al., 1983). The deposit also lies over the south-westerly extension of the major NE-SW trending Snowbird Tectonic Zone which separates the Rae and Hearne Archaean Provinces to the east, and can be traced in geophysical data below the intervening Interior Platform cover and eastern Cordillera.
The Sullivan ore deposit falls within the north-south trending Sullivan-North Star corridor, an elongate, north-south to NNW trending graben within which the Proterozoic host rocks contain abundant fragmental and disrupted sediments. The corridor is some 6 km long, 1 to 3 km in width, and occurs over a stratigraphic thickness of 500 m. It is truncated to the north at it widest section by the major east-west trending Kimberley Fault, with the Sullivan orebody being over its north-eastern extremity (Turner, et al., 1995).
Three gabbro sills with an aggregate thickness of 650 m, have been intersected below the Sullivan deposit, as mentioned above. They are the upper part of a widespread sill complex intruded into the host Lower Aldridge Formation. The uppermost sill forms a discordant arch-like feature, roughly coincident with the corridor, and contains a core of more silicic plagioclase-quartz-biotite granophyre. The top of the arch is at the same stratigraphic level as the Sullivan orebody (Turner, et al., 1995).
The "fragmental" rocks within the corridor include bedded conglomerates, semi-concordant bodies of massive pebble-wacke, clastic dykes of conglomerate and breccia, and disrupted strata. Bedded conglomerate immediately underlies the Sullivan deposit and extends across the width of the corridor. It is composed of beds up to 5 m thick which have graded tops. It is generally 30 to 50 m thick, but gets up to 300 m thick to the west of the orebody. Bedded conglomerate is commonly underlain by disrupted strata and clastic dykes. The clastic dykes are centimetres to metres in thickness and have highly varied textures, including angular breccia, conglomerate and pebble-wacke. Major clastic dykes are commonly associated with sulphide veins. Disrupted strata extend throughout the corridor and are generally identified by abundant small displacement faults, variable bedding attitudes, contorted beds, small clastic dykes and elevated sulphide contents as veinlets and disseminations. Pebble-wackes are massive and are conformable to semi-conformable with rounded lithic fragments up to 10 mm in diameter in a wacke matrix. Individual units are tens to hundreds of metres thick and grade laterally into disrupted strata (Turner, et al., 1995).
The northern two-thirds of the Sullivan orebody is underlain by up to 125 m of intraformational conglomerate that thins rapidly to the west, north and south, but less rapidly to the east. Crosscutting zones of chaotic breccia disrupt well bedded sedimentary rocks and conglomerates under the western half of the orebody (Hamilton, et al., 1983).
Mineralisation
Ore mineralisation occurs as a convex, gently east dipping tabular lens with lateral dimensions of approximately 2000 x 1600 m. The western part, which ranges from 10m, up to 100 m in thickness, can be divided into three approximately equal intervals. The lowest of these intervals is around 35 m thick and 350 m long and is composed of massive sulphides, primarily pyrrhotite, with minor fracture fillings, disseminations and wispy layers of galena and sphalerite. The pyrrhotite zone also carries cassiterite, averaging around 0.4% Sn. The middle layer is also composed of massive sulphides, although a layering defined by pyrrhotite, galena and sphalerite is more pronounced. The upper part is delicately banded galena, pyrrhotite and sphalerite, with minor pyrite and intercalated siliciclastic beds near the top (Hamilton, et al., 1983).
Below the pyrrhotite zone there is a sulphide stringer zone, parts of which contained sufficient Pb and Zn to be mined as ore (Belluz & Knapp, 1994).
The eastern part of the orebody consists of five distinct bedded sulphide intervals totalling up to 27 m in thickness, that are intercalated with four siliciclastic bands which are together up to 10 m thick. This ore zone thins progressively to the east. The eastern and western parts of the orebody are joined by a narrow transition zone of deformation across which stratigraphic correlation is difficult (Hamilton, et al., 1983).
Metal distribution is generally concentric around the central part of the ore complex, above the main zone of hydrothermal tourmalinisation. High Ag:Pb and Pb:Zn ratios are found in the massive western part of the orebody, while Pb:Zn ratios decrease towards the bedded eastern sections. Essentially the orebody was a Pb-Ag deposit to the west with by-product Zn, while to the east it became Zn ore with Pb & Ag by-products. In the western part of the orebody, Pb and Zn grades increase upwards, with decreasing Fe; while to the east Zn and Pb decrease upwards and Fe rises (Belluz & Knapp, 1994).
Alteration
Sandstones and siltstones of the Lower Aldridge Formation are characterised by 15 to 20% detrital plagioclase. However within the Sullivan-North Star corridor altered rocks are distinguished by the near absence of feldspar and the presence of abundant muscovite, sulphides, chlorite, epidote and garnet. Sulphides include abundant pyrite and pyrrhotite, lesser sphalerite and galena, and trace chalcopyrite and arsenopyrite. Major alteration includes tourmalinite, muscovite-pyrite, garnet, albite-biotite-chlorite, biotite-plagioclase-hornfels and quartz-plagioclase-biotite granophyre. There is no evidence for the addition of hydrothermal silica, while the intensity of alteration is highly variable, related to a number of discrete hydrothermal centres, the major ones being below the Sullivan deposits and the Stemwinder Vein System, some 2 km to the south (Turner, et al., 1995).
Tourmalinite alteration bodies occur as pipes underlying the western portion of the Sullivan deposit; as an envelope around the Stemwinder vein; as a cluster of small bodies extending south-west for around 1 km from the Stemwinder vein to the North Star deposit; and as an isolated small body at the southern extremity of the corridor. Pyrrhotite commonly accompanies tourmaline alteration, although pyrite is generally absent (Turner, et al., 1995).
The tourmaline pipe below the western apart of the main Sullivan sulphide deposit is a funnel shaped zone some 1400 x 950 m in plan area at the orebody footwall, extending downwards for more than 450 m. Contacts between the tourmalinite and laterally equivalent unaltered footwall rocks, although serrated in detail, have moderately to steep dips overall. Rocks rich in albite, chlorite, pyrite and carbonate occur in restricted, highly discordant zones in footwall tourmalinite and locally in the orebody (Hamilton, et al., 1983).
Muscovite alteration resulted in the destruction of feldspar and the lack of biotite formation in later regional metamorphism. It is widespread throughout the corridor, accompanied by veinlet and disseminated sulphides, mainly both pyrrhotite and pyrite. Disseminated garnet porphyroblasts occur throughout the corridor and accompany banded sulphides at Sullivan and North Star. Three large albite bodies are found within the corridor, namely: 1). overlying the western Sullivan orebody; 2). approximately 1 km to the west of the Stemwinder vein, immediately above the footwall gabbro; and 3). three kilometres to the west of the Sullivan orebody in the conglomerate horizon (Turner, et al., 1995).
For more detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2001.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Beaudoin G 1997 - Proterozoic Pb isotope evolution in the Belt-Purcell Basin: constraints from syngenetic and epigenetic Sulfide deposits: in Econ. Geol. v92 pp 343-350
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Campbell FA, Ethier VG and Krouse HR 1980 - The massive sulphide zone: Sullivan orebody: in Econ. Geol. v75 pp 916-926
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del bel Belluz N, Knapp M E 1994 - The evolution of the Sullivan Mine: in 100 th Annual, Northwest Mining Association Convention, Spokane, Washington, Nov 29-Dec 2, 1994 18p
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Hoy T 1982 - Stratigraphic and structural setting of stratabound lead-zinc deposits in southeastern B.C.: in CIM Bull v75, no. 840 pp 114-134
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Jiang S Y, Palmer M R, Slack J F, Shaw D R 1998 - Paragenesis and Chemistry of multistage Tourmaline Formation in the Sullivan Pb-Zn-Ag deposit, British Columbia: in Econ. Geol. v93 pp 47-67
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Leitch C H B, Turner R J W, Ransom P W and Sullivan Mine Staff 1995 - Day 3 - Sullivan Deposit: in Hoy T, Turner R, Leitch C (Eds.), 1995 Field Trip Guidebook - Depositional Environment, Alteration and Associated Magmatism, Sullivan and related Massive Sulphide Deposits, Southeastern B.C. GAC/MAC Annual Meeting, Victoria 95, May 17-19 pp 59-80
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McClay K R 1983 - Structural evolution of the Sullivan Fe-Pb-Zn-Ag orebody, Kimberley, British Columbia, Canada: in Econ. Geol. v78 pp 1398-1424
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Slack, J.F., 2020 - Potential for Sullivan-type Pb-Zn-Ag deposits in modern sedimentary basins: in Mineralium Deposita v.55, pp. 1271–1278.
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Slack. J.F., Neymark, L.A., Moscati, R.J., Lowers, H.A., Ransom, P.W., Hauser, R.L. and Adams, D.T., 2020 - Origin of Tin Mineralization in the Sullivan Pb-Zn-Ag Deposit, British Columbia: Constraints from Textures, Geochemistry, and LA-ICP-MS U-Pb Geochronology of Cassiterite: in Econ. Geol. v.115, pp. 1699-1724.
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Turner R J W, Leitch C H B, Hoy T 1995 - Day 2 PM - Sullivan-North Star corridor: in Hoy T, Turner R, Leitch C (Eds.), 1995 Field Trip Guidebook - Depositional Environment, Alteration and Associated Magmatism, Sullivan and related Massive Sulphide Deposits, Southeastern B.C. GAC/MAC Annual Meeting, Victoria 95, May 17-19 1995 pp 50-58
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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