Database name: |
World Fe-oxide+/-Cu-Au-U (IOCG) deposits |
Compilers: |
Sunil S. Gandhi |
Release date: |
2015-03-04 |
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Deposit name(s): |
Prescott; Texada Mines-Prescott |
Political location(s): |
Canada; Province or state: British Columbia; Nearest community: Vancouver (115 km NW) |
NTS map data: |
092F10 (Comox) |
Deposit clan (type): |
Iron Skarn-type |
Deposit (sub) types: |
massive ore lenses plunge steeply south parallel to the limestone-intrusion contact; partial to complete skarn envelope; magnetite veinlets cut skarn in many places; sulphides common near limestone; Reference: Sangster, D. F., 1969: The Contact Metasomatic Magnetite deposits of Southwestern British Columbia; Bulletin, Geological Survey of Canada, Geological Survey of Canada, Department of Energy, Mines and Resources, Ottawa, Canada, Publication code 172, 85 p., 9 maps. distinction between exoskarn and endoskarn often difficult; some lenses at high angle to steep contact of Gillies intrusion; traces of Cu and Au; contacts of unaltered rocks and skarn generally sharp; Reference: Webster, I. C. L..; Ray, G. E., 1990: Geology and Mineral Deposits of Northern Texada Island (92F/9, 10 and 15); Section Mineral Deposit Studies, in Geological Fieldwork 1989: A Summary of Field Activities and Current Research, Edited by Anonymous, Paper, Geological Survey Branch, Mineral Resources Division, British Columbia Ministry of Energy, Mines and Petroleum Resources, Province of British Columbia, Canada, 1990-1, 535 p, p. 257 - 265 |
Deposit status: |
past producer; Size category: 2 Mt |
Geologic province: |
Cordilleran Orogen |
Geologic subprovince: |
Insular Belt |
Geologic district: |
Wrangell Terrane |
Deposit object located: |
open pit |
Commodities: |
Fe; Cu |
Mineralization styles: |
massive magnetite pods in skarn; magnetite veins in skarn; disseminated magnetite around lenses |
Geological ages: |
Late Triassic - Middle Jurassic (host rocks) Middle Jurassic (mineralization) Early Jurassic - Middle Jurassic (mineralization) |
Tectonic setting: |
continental marginal arc-fold belt; transpressive; Formal name: Bonanza magmatic arc (mineralization) |
Coincident features: |
limestone-intrusion contact (group of ore lenses plunge steeply to ythe south parallel to the dip of the limestone-intrusion contact); Coincident feature name: Quatsino Formation-Gillies Intrusion |
Regional tectonic structure: |
northwest-trending open folds (early Jurassic to late Cretaceous; limestone and underlying volcanics folded into north plunging folds) Tectonic structure name: Coast Range orogeny northwest-trending major faults (the faults controlled the emplacement of some Jurassic intrusions and the associated skarn mineralization) Tectonic structure name: Ideal and Holly faults/lineaments |
Host rocks: |
(1) volcanic; mafic-intermediate volcanic rocks (basaltic to andesitic flows); Magma series/sedimentary package/metamorphic group: calc-alkaline; Depositional setting: shallow marine; Metamorphic grade: greenschistExternal host rock forms: | flows, tuffs and agglomerate | Host rock protoliths: | basalt-andesite (flows, some pillowed; folded and altered near the desposit); Host rock protolith name: Karmutsen Group | Internal host rock structures: | massive to porphyritic | Individual lithologies: | basalt-andesitic basalt (faint bedding in tuffaceous beds; clouding of plagioclase and growth of actinolite in hornblende) | Host rock stratigraphy: | Karmutsen Group |
(2) sedimentary; carbonate (limestone completely recrystallized to medium grained marble); Magma series/sedimentary package/metamorphic group: carbonate; Depositional setting: shallow marine; Metamorphic grade: greenschistExternal host rock forms: | well bedded | Host rock protoliths: | limestone (conformably overlies mafic flows of the Karmutsen Group that forms lower part of the Vancouver Group); Host rock protolith name: Quatsino Formation of Vancouver Group | Internal host rock structures: | white and grey beds; some thin dark grey beds | Individual lithologies: | marble (medium grained; folded, recrystallized and intruded by quartz monzonitic Gillies stock) | Host rock stratigraphy: | Quatsino/Marble Bay Formation |
(3) intrusive; quartz monzonite-monzogabbro suite (iron skarns located at intrusive contact); Magma series/sedimentary package/metamorphic group: calc-alkaline; Depositional setting: hypabyssal; Metamorphic grade: unmetamorphosedExternal host rock forms: | crystalline, coarse | Host rock protoliths: | intermediate intrusive rocks (older phase massive grey, younger phase massive to porphyritic, and the youngest aplitic dykes); Host rock protolith name: Gillies Intrusion/Stock | Internal host rock structures: | massive to porphyritic | Individual lithologies: | quartz monzonite (modal composition: plagioclase (An47) 29 %, K-feldspar 14 %, quartz 16 %, augite 8 %, biotite 19 %, opacite 5 %, and accesories 10 %) | Host rock stratigraphy: | Gillies Intrusion/Stock |
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Related igneous rocks: |
(1) intrusive; gabbro-diorite suite (post-ore dykes, up to 15 m wide); Initials: Feldspar Porphyry dykes; Magma series: calc-alkaline; Depositional setting: continentalIndividual lithologies: | porphyritic diorite (phenocrysts of plagioclase, 15 -20 %, and pyroxene, 2 %, in groundmass of plagioclase, hornblende, apatite, sericite and epidote) |
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Metallogenic signatures: |
Fe Cu |
Alteration signatures: |
skarn: andraditic garnet and diopsidic clinopyroxene; What was altered: marble and quartz monzonite epidotization: epidote; What was altered: mafic silicates silicification: quartz; What was altered: silicates carbonatization: calcite; What was altered: marble, silicates |
Mineralogy: |
(alteration): garnet, diopside-hedenbergite, actinolite, epidote (gangue): calcite, quartz (mineralization): magnetite, pyrite, chalcopyrite, pyrrhotite, arsenopyrite, sphalerite |
Radiometric ages: |
Object dated: Related igneous rocks(1); Age - Ma: 176; +2; -2; Dating method: U-Pb; Concentrate: zircon; Source rock: quartz monzodiorite; Formal name: Gillies Intrusion; Event dated: intrusive event; Interpretive comment: age marks time of formation of Fe skarns at contact of the intrusion with limestone and volcanics; Reference: Ettlinger, A. D.; Ray, G. E., 1990: Precious Metal Enriched Skarns in British Columbia: An Overview and Geological Study; Paper, Geological Survey Branch, Mineral Resources Division, British Columbia Ministry of Energy, Mines and Petroleum Resources, Province of British Columbia, Canada, Publication code 1989-3, 128 p., 1 maps. |
Deposit shape: |
zone of lensoid and irregular bodiesDeposit dimensions: | length: 200 metres width: 50 metres depth: 100 metres |
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Qualified comments: |
(Applies to: discovery and development) Discovery in 1873; during 1883-1903 and 1908, 26,213 t of iron ore shipped, except for the 964 t of polymetallic ore from the Lake deposit 1.7 km to the E. Combined production during 1952-1956 from Prescott, Paxton, Lake and Lake Extension open pit and underground mines: 1 997 313 t ore mined, 1 989 996 t ore milled, with recovery of 1 300 466 116 kg Fe. |
Links to other databases: |
BC MINFILE; Key value: 092F 106 |
References: |
British Columbia Mines and Energy, 2001 |
British Columbia MINFILE Database |
Government of British Columbia, MINFILE Mineral Inventory, Internet |
Carson, D. J. T.; Muller, J. E.; Wanless, R. K.; Stevens, R. D., 1971 |
Age of the Contact Metasomatic Copper and Iron Deposits, Vancouver and Texada Islands, British Columbia |
Paper, Geological Survey of Canada, Geological Survey of Canada, Department of Energy, Mines and Resources, Ottawa, Canada, Publication code 71-36, 9 p. |
Ettlinger, A. D.; Ray, G. E., 1990 |
Precious Metal Enriched Skarns in British Columbia: An Overview and Geological Study |
Paper, Geological Survey Branch, Mineral Resources Division, British Columbia Ministry of Energy, Mines and Petroleum Resources, Province of British Columbia, Canada, Publication code 1989-3, 128 p., 1 maps. |
Ray, G. E.; Ettlinger, A. D.; Meinert, L. D., 1990 |
Gold Skarns: Their Distribution, Characteristics and Problems in Classification |
Section Mineral Deposit Studies, in Geological Fieldwork 1989: A Summary of Field Activities and Current Research, Edited by Anonymous, Paper, Geological Survey Branch, Mineral Resources Division, British Columbia Ministry of Energy, Mines and Petroleum Resources, Province of British Columbia, Canada, 1990-1, 535 p, p. 237 - 246 |
Sangster, D. F., 1969 |
The Contact Metasomatic Magnetite deposits of Southwestern British Columbia |
Bulletin, Geological Survey of Canada, Geological Survey of Canada, Department of Energy, Mines and Resources, Ottawa, Canada, Publication code 172, 85 p., 9 maps. |
Webster, I. C. L..; Ray, G. E., 1990 |
Geology and Mineral Deposits of Northern Texada Island (92F/9, 10 and 15) |
Section Mineral Deposit Studies, in Geological Fieldwork 1989: A Summary of Field Activities and Current Research, Edited by Anonymous, Paper, Geological Survey Branch, Mineral Resources Division, British Columbia Ministry of Energy, Mines and Petroleum Resources, Province of British Columbia, Canada, 1990-1, 535 p, p. 257 - 265 |
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Associated group(s): |
Texada Mines (24) |