CANADIAN AND WORLD MINERAL DEPOSIT DATABASES
Geological Survey of Canada


Deposit number Country Location Names Commodities
779 Canada (British Columbia) 50.22.25 N -- 127.15.15 W Shamrock; Blackjack; Empire Fe
 
Database name: World Fe-oxide+/-Cu-Au-U (IOCG) deposits
Compilers: Sunil S. Gandhi
Release date: 2015-03-04
   
Deposit name(s): Shamrock; Blackjack; Empire
Political location(s): Canada; Province or state: British Columbia; Nearest community: Port McNeil (30 km SW)
NTS map data: 092L06 (Alice Lake)
Deposit clan (type): Iron Skarn-type
Deposit (sub) types: scattered outcrops of Bonanza rocks at margin of Coast copper stock host vugs carrying quartz and botryoidal magnetite, and nearby Quatsino limestone has some layers selectively replaced by magnetite; 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.
Deposit status: unknown; Size category: very small; Status comments: prospect near open pits of Merry Widow, Kingfisher and Raven deposits
Geologic province: Cordilleran Orogen
Geologic subprovince: Insular Belt
Geologic district: Wrangell Terrane
Commodities: Fe
Mineralization styles: selective replacement of carbonate layers; vuggy
Geological ages: Late Triassic - Early Jurassic (host rocks)
Early Jurassic - Middle Jurassic (mineralization)
Tectonic setting: continental marginal arc-fold belt; transpressive; Formal name: Bonanza magmatic arc (mineralization)
Coincident features: intrusive contact (scattered outcrops of limestone and of Bonanza volcanic rocks host magnetite and botryoidal magnetite, respectively ); Coincident feature name: Quatsino limestone-Coast Copper stock
Regional tectonic structure: wedge of host volcanic rock between limestone and intrusion (margin of intrusion dips 45° west, and limestone beds dip vertical or toward the intrusion) Tectonic structure name: Coast Copper stock margin
Host rocks: (1) sedimentary; carbonate (Late Triassic, well-bedded, gently dipping to west); Magma series/sedimentary package/metamorphic group: carbonate; Depositional setting: arc-back arc basin; Metamorphic grade: lower amphibolite
Host rock protoliths:limestone (gently folded; recrystallized near Coast Copper stock with destruction of bedding features); Host rock protolith name: Quatsino Formation of Vancouver Group
Host rock stratigraphy:Quatsino Formation of Vancouver Group

(2) volcanic; mafic-intermediate volcanic rocks (Early Jurassic; small outcrops); Magma series/sedimentary package/metamorphic group: calc-alkaline; Depositional setting: arc-back arc basin; Metamorphic grade: greenschist
External host rock forms:massive, porphyritic to equigranular
Host rock protoliths:andesite-basalt (volcanic and volcaniclastic rocks; located between Coast Coper stock and Quatsino limestone); Host rock protolith name: Bonanza Group
Internal host rock structures:fine grained to porphyritic
Individual lithologies:basalt-andesite (variable in composition; hornfelsed and skarnified near Coast Copper pluton)
Host rock stratigraphy:Bonanza Group
Related igneous rocks: (1) intrusive; quartz monzonite-monzogabbro suite (Early to Middle Jurassic Island Plutonic Suite); Initials: Coast Copper or Benson Lake stock; Magma series: calc-alkaline; Depositional setting: hypabyssal
Individual lithologies:gabbro-diorite-quartz monzonite (eastern part of the stock near iron deposits is gabbroic, the western part is quartz monzonitic)
Metallogenic signatures: Fe
Alteration signatures: skarn: garnet and diopside; What was altered: volcanic host rocks
Mineralogy: (gangue): quartz
(mineralization): magnetite, magnetite, botryoidal
Deposit shape: irregular - veins
Links to other databases: BC MINFILE; Key value: 092L 040
References:
British Columbia Mines and Energy, 2001
British Columbia MINFILE Database
Government of British Columbia, MINFILE Mineral Inventory, Internet

Carson, D. J. T., 1973
The Plutonic Rocks of Vancouver Island, British Columbia: Their Petrography, Chemistry, Age and Emplacement
Paper, Geological Survey of Canada, Geological Survey of Canada, Department of Energy, Mines and Resources, Ottawa, Canada, Publication code 72-44, 70 p.

Eastwood, G. E. P., 1965
Replacement Magnetite on Vancouver Island, British Columbia
Economic Geology, Volume 60, p. 124 - 148

Gross, G. A., 1996
Skarn Iron
20. Skarn Deposits, Section 20.4 Skarn Iron, in Geology of Canadian Mineral Deposit Types, Edited by Eckstrand, O. R.; Sinclair, W. D.; Thorpe, R. I., Geology of Canada, Decade of North American Geology (DNAG), Geological Survey of Canada, Geological Society of America, Volume 8, 640 p, p. 489 - 495

Hudson, R., 1997
A Field Guide to Gold, Gemstones and Mineral Sites of British Columbia, Volume I, Vancouver Island
Orca Book Publishers, PO Box 5626, Station B, Victoria, British Columbia, Canada, 214 p.

Meinert, L. D., 1984
Mineralogy and Petrology of Iron Skarns in Western British Columbia, Canada
Economic Geology, Volume 79, p. 869 - 882

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.


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