CANADIAN AND WORLD MINERAL DEPOSIT DATABASES
Geological Survey of Canada


Deposit number Country Location Names Commodities
74 Sweden (Dalarna) 60.04.46 N -- 014.59.59 E Exportfältet; Grängesberg Fe
 
Database name: World Fe-oxide+/-Cu-Au-U (IOCG) deposits
Compilers: Sunil S. Gandhi
Release date: 2015-03-04
   
Deposit name(s): Exportfältet; Grängesberg
Political location(s): Sweden; Province or state: Dalarna; Nearest community: Ludvika (20 km SW)
Deposit clan (type): Kiruna-type
Deposit (sub) types: stratabound massive magnetite lenses stacked in a sequnece of rhyolite flows and agglomerates; disseminations in the volcanic rocks common; some magnetite occurs as breccia-fillings, veins and dykes; Reference: Magnusson, N. H., 1970: The Origin of the Iron Ores in Central Sweden and the History of their Alterations; Sveriges Geologiska Undersökning, Serie C, Part 1 and 2, Publication code 643, 491 p.
magnetite dominant over hematite; both regarded as primary ore minerals; apatite concentrated on the hanging wall side; range up to 9 % P; hematite altered to magnetite near pegmatite veins; Reference: Magnusson, N. H., 1970: The Origin of the Iron Ores in Central Sweden and the History of their Alterations; Sveriges Geologiska Undersökning, Serie C, Part 1 and 2, Publication code 643, 491 p.
Deposit status: past producer; Size category: 100 Mt
Geologic province: Svecofennian Orogen
Geologic subprovince: Southern Svecofennian
Geologic district: Bergslagen (Ore District)
Commodities: Fe
Mineralization styles: massive magnetite lenses; banded; disseminations around massive bodies
Geological ages: Late Paleoproterozoic (host rocks)
Late Paleoproterozoic (mineralization)
Tectonic setting: continental marginal arc-fore-arc; convergent; Formal name: Late Svecofennian arc (host rocks)
Coincident features: stratification in host sequence (massive ore lenses nearly concordant with the host strata, but some intrusive features like veins and breccia-fillings)
Regional tectonic structure: folded volcanic sequence (late Svecofennian deformation and metamorphism, followed by emplacement of younger granites) Tectonic structure name: Ludvika-Grängesberg fold belt
monoclinal sequence dipping 60 to 65 degrees to the southeast (between two late Svecofenian plutons, a small red granite to the northwest and a large granodiorite to the southeast)
Host rocks: (1) volcanic; felsic volcanic rocks (variably altered potassic and sodic rhyolites); Magma series/sedimentary package/metamorphic group: calc-alkaline; Depositional setting: continental arc; Metamorphic grade: greenschist-amphibolite
External host rock forms:flows, agglomerates
Host rock protoliths:rhyolites (original composition altred by pervasive alkali metasomatism and skarnification)
Internal host rock structures:porphyritic, fine grained granular and gneissic
Individual lithologies:potassic and sodic rhyolites (red potassic rhyolites in the footwall and grey sodic rhyolites in the hanging wall )
Related igneous rocks: (1) intrusive; quartz monzonite-monzogabbro suite (post-ore dykes; up to 40 % of ore zones); Magma series: calc-alkaline; Depositional setting: continental
Individual lithologies:andesite-dacite (dykes postdate the main phase of mineralization; affected by later deformation and granite intrusions)
Country rocks: (1) felsic volcanics; (flows, volcaniclastics and sediments); Metamorphic grade: greenschist-amphibolite
Metallogenic signatures: Fe-P
Alteration signatures: potassic alteration: potash feldspar, biotite, muscovite; What was altered: feldspars
skarn: garnet, diopside, epidote, calcite, apatite; What was altered: calcareous material, calcic silicates
reducing alteration: magnetite; What was altered: hematite
Mineralogy: (alteration): garnet, biotite, chlorite, epidote, muscovite, quartz
(mineralization): magnetite, hematite, apatite, actinolite
Deposit shape: zone of stacked tabular bodies and lenses
Deposit dimensions:strike length: 1,400 metres
thickness: 90 metres
depth: 1,000 metres
Qualified comments: (Applies to: discovery and development) This deposit was mined from the 16th century to 1910 by open pit 100 m deep; then underground mine to 685 m; approximately 100 Mt of ore mined till closure in 1980s; massive and disseminated ores: range 63 to 45 % Fe. remaining resources at deeper levels of the mine and in the deposits nearby, including other past producers Risbergfältet, Strandbergsfältet, Ormbergfältet and Blötberget, amount to some 100 Mt of ore.
References:
Anonymous, 2000
Swedish Database of Mineral Deposits
Email

Frietsch, R., 1973
The Origin of Kiruna Iron Ores
Geologiska Föreningens i Stockholm Förhandlingar, Volume 95, p. 375 - 380

Frietsch, R., 1977
The Iron Ore Deposits in Sweden
in The Iron Ore Deposits of Europe and Adjacent Areas: Explanatory Notes to the International Map of the Iron Ore Deposits of Europe, 1:2,500,000 (Text and Figures), Edited by Walther, H. W.; Zitzmann, A., International Geological Congress, Commission for the Geological Map of the World, Subcommission for the Metallogenic Map of the World, Bundesanstalt fur Geowissenschaften und Rohstoffe, Postfach 51 01 53, D-3000 Hannover 51, Volume I, 418 p, p. 279 - 293

Frietsch, R., 1978
On the Magmatic Origin of Iron Ores of the Kiruna Type
Economic Geology, Volume 73, p. 478 - 485

Frietsch, R.; Papunen, H., 1986
Metallogenesis of the Bergslagen Province and Southwestern Finland
in Mineral Deposits of Southwestern Finland and the Bergslagen Province, Sweden, Edited by Lundström, I.; Papunen, H., Sveriges Geologiska Undersökning, Ser. Ca, International Association on Genesis of Ore Deposits / 7th IAGOD Symposium and Nordkalott Project Meeting, Geological Survey of Sweden, NR 61, 44 p, p. 11 - 16

Magnusson, N. H., 1970
The Origin of the Iron Ores in Central Sweden and the History of their Alterations
Sveriges Geologiska Undersökning, Serie C, Part 1 and 2, Publication code 643, 491 p.

Zitzmann, A. Editor(s)), 1978
The Iron Ore Deposits of Europe and Adjacent Areas: Explanatory Notes to the International Map of the Iron Ore Deposits of Europe, 1:2,500,000 (Lists and Tables)
International Geological Congress, Commission for the Geological Map of the World, Subcommission for the Metallogenic Map of the World, Bundesanstalt fur Geowissenschaften und Rohstoffe, Postfach 51 01 53, D-3000 Hannover 51, Volume II, 386 p.


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