Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Genesis and tectonic setting of the hypozonal Fäboliden orogenic gold deposit, northern Sweden
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.ORCID iD: 0000-0001-9846-1793
2005 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The well-known Skellefte Ore District, northern Sweden, hosts a large number of massive sulphide deposits, a few porphyry-type-deposits and a number of gold deposits in different geological settings. Southwest of this district a new ore province, the so called Gold Line, is presently being uncovered. During the past decade a number of gold occurrences have been discovered in this area. Only one deposit is in production, the Svartliden gold deposit (2 Mton at 4.3 ppm Au). However, with regards to tonnage the Fäboliden gold deposit stands out with a known mineral resource of c. 16 Mton with 1.33 ppm Au. Additional 24.5 Mton with 1.5 ppm Au is indicated down to a depth of 350 m. The late- to post-orogenic, c. 1.81-1.77 Ga, Revsund granite constitutes the main rock type in the Fäboliden area and surrounds a narrow belt of metavolcanic rocks and metagreywackes. The metasedimentary rocks are strongly deformed, within a roughly N-S trending subvertical shear zone, with boudinaged competent horizons that indicate E-W shortening and a suggested dextral sense of shear within the shear zone. The mineralization at Fäboliden constitutes a 30-50 m wide, N-S striking, steeply dipping ore zone. The mineralization is commonly hosted in arsenopyrite-bearing quartz-veins, which parallel the main foliation, within the metagreywackes in the shear zone. The fine-grained (2-40 µm) gold is closely associated with arsenopyrite-löllingite and stibnite and found in fissures and as intergrowths in the arsenopyrite-löllingite. Gold is also seen as free grains in the silicate matrix of the metagreywacke host rock. Microprobe analysis shows that the gold occurs as electrum (Au:Ag 2:1). The proximal ore zone display enrichment in Ca, total S, As, Ag, Au, Sb, Sn, W, Pb, Bi, Cd, Se, and Hg, whereas K and Na are slightly depleted. The hydrothermal alteration assemblage in the proximal ore zone is diopside, calcic amphibole, biotite, and minor andalusite and tourmaline. This type of assemblage is commonly recognized in hypozonal orogenic gold deposits worldwide. The c. 1.3 km long ore body (lode) is steeply dipping and known to a depth of 150 m, with a few deeper boreholes indicating a continuation of the mineralization towards depth. The mineralization is also open towards north and south. The fabric that hosts the mineralization is also found in the outer margin of the surrounding Revsund granite. It is therefore suggested that at least the final stages of the gold mineralization are late- or post-orogenic in age, and the maximum age for the mineralization is constrained at c. 1.80 Ga (Revsund age). The mineralizing fluids were composed of CO2-CH4-H2S. Gold, arsenopyrite- löllingite, and graphite were precipitated from this fluid. The crystal structure of the graphite, enclosed in the gold related quartz veins, indicates a maximum temperature of 520-560ºC for the mineralizing event, temperature conditions equal to mid-amphibolite facies. These temperatures indicate pressure conditions of c. 4 kbar for the mineralizing event. During deformation mineralizing fluids are often concentrated into deformation zones. Therefore, the potential for economic mineralization in the Lycksele-Storuman region is regarded as very high since the initial results from this project have indicated the existence of several larger ductile to semi-ductile shear zones and accompanied silica alteration in the studied area. During 2004 the project strongly assisted in locating a new gold target in the Gold Line area. For more effective future exploration in this area a better understanding of the structural conditions and evolution is a key factor.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2005. , p. 7
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757 ; 2005:73
National Category
Geology
Research subject
Ore Geology
Identifiers
URN: urn:nbn:se:ltu:diva-17200Local ID: 22337e90-8b56-11db-8975-000ea68e967bOAI: oai:DiVA.org:ltu-17200DiVA, id: diva2:990200
Note
Godkänd; 2005; 20061214 (haneit)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-03-15Bibliographically approved

Open Access in DiVA

fulltext(4821 kB)53 downloads
File information
File name FULLTEXT01.pdfFile size 4821 kBChecksum SHA-512
859ca22562f5e110601aad036a6b675474e0954a3a2621ea0124b0d50a4056624bc1b20e18bc655289481b78739485bd03107175861cd8f1a155e4b0c0c1ea49
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Bark, Glenn
By organisation
Geosciences and Environmental Engineering
Geology

Search outside of DiVA

GoogleGoogle Scholar
Total: 53 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

urn-nbn

Altmetric score

urn-nbn
Total: 77 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf