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  • 1.
    Abdelnasser, Amr
    et al.
    Geological Engineering Department, Faculty of Mines, Istanbul Technical University; Geology Department, Faculty of Science, Benha University, Benha .
    Kumral, Mustafa
    Geological Engineering Department, Faculty of Mines, Istanbul Technical University.
    Zoheir, Basem
    Geology Department, Faculty of Science, Benha University.
    Karaman, Muhittin
    Geological Engineering Department, Faculty of Mines, Istanbul Technical University.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    REE geochemical characteristics and satellite-based mapping of hydrothermal alteration in Atud gold deposit, Egypt2018In: Journal of African Earth Sciences, ISSN 0899-5362Article in journal (Refereed)
    Abstract [en]

    New geochemical data of the hydrothermal alteration zones associated with gold-bearing quartz veins at Atud mine are used for better understanding the ore evolution and exploration vectoring. ASTER and Landsat 8 OLI data are used to elucidate the distribution of gold-associated alteration zones. Three alteration zones are defined; zone 1 (sericite-kaolinite-quartz-pyrite), zone 2 (quartz-sericite-albite-pyrite), and zone 3 (chlorite-carbonate-epidote ± pyrite). Sericite and hydrothermal quartz are confined to the mineralized quartz veins. Fe-OH and OH-bearing minerals are observed along NW- and NE-trending shear zones in the Main Atud mine. The association of gold-bearing quartz veins and sericite alteration is constrained by processing ASTER- and OLI-imagery data. The geochemical data of the ore-enveloping hydrothermally altered rocks are used to assess the behavior of the REEs during the mineralization process. Mild enrichment in LREE and significant enrichment in the HREE are associated with sericite in zones (1) and (2) alterations. Carbonate alteration (zone 3) is enriched in LREE and in immobile HREE. Moreover, LREE and Eu anomalies have negative correlated with the Alteration Index (A.I.) and K2O index (K.I.) in zones 1 and 2, suggesting high mobility of LREE in K-rich hydrothermal fluids. On the other hand, HREE anomalies with increasing MgO index (M.I.) in alteration zone 3 may imply low solubility of these elements in alkaline solutions. Au anomalies linked to sericite/silica alteration is a rather meaningful vector for further exploration in the area.

  • 2. Ahl, Martin
    et al.
    Bergman, Stefan
    Bergström, Ulf
    Eliasson, Thomas
    Ripa, Magnus
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geochemical classification of plutonic rocks in central and northern Sweden2001Report (Other academic)
  • 3.
    Aiglsperger, Thomas
    et al.
    Department of Crystallography, Mineralogy, and Ore Deposits, University of Barcelona.
    Proenza, Joaquín A.
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona.
    Font-Bardia, Mercé
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Universitat de Barcelona .
    Baurier-Aymat, Sandra
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Universitat de Barcelona .
    Galí, Salvador
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Universitat de Barcelona .
    Lewis, John F.
    Department of Earth and Environmental Sciences, George Washington University, .
    Longo, Francisco
    Faculty of Engineering, Universidad Católica Tecnológica del Cibao (UCATECI), La Vega.
    Supergene neoformation of Pt-Ir-Fe-Ni alloys: multistage grains explain nugget formation in Ni-laterites2016In: Mineralium Deposita, ISSN 0026-4598, E-ISSN 1432-1866, p. 1-15Article in journal (Refereed)
    Abstract [en]

    Ni-laterites from the Dominican Republic host rare but extremely platinum-group element (PGE)-rich chromitites (up to 17.5 ppm) without economic significance. These chromitites occur either included in saprolite (beneath the Mg discontinuity) or as ‘floating chromitites’ within limonite (above the Mg discontinuity). Both chromitite types have similar iridium-group PGE (IPGE)-enriched chondrite normalized patterns; however, chromitites included in limonite show a pronounced positive Pt anomaly. Investigation of heavy mineral concentrates, obtained via hydroseparation techniques, led to the discovery of multistage PGE grains: (i) Os-Ru-Fe-(Ir) grains of porous appearance are overgrown by (ii) Ni-Fe-Ir and Ir-Fe-Ni-(Pt) phases which are overgrown by (iii) Pt-Ir-Fe-Ni mineral phases. Whereas Ir-dominated overgrowths prevail in chromitites from the saprolite, Pt-dominated overgrowths are observed within floating chromitites. The following formation model for multistage PGE grains is discussed: (i) hypogene platinum-group minerals (PGM) (e.g. laurite) are transformed to secondary PGM by desulphurization during serpentinization; (ii) at the stages of serpentinization and/or at the early stages of lateritization, Ir is mobilized and recrystallizes on porous surfaces of secondary PGM (serving as a natural catalyst) and (iii) at the late stages of lateritization, biogenic mediated neoformation (and accumulation) of Pt-Ir-Fe-Ni nanoparticles occurs. The evidence presented in this work demonstrates that in situ growth of Pt-Ir-Fe-Ni alloy nuggets of isometric symmetry is possible within Ni-laterites from the Dominican Republic.

  • 4.
    Aiglsperger, Thomas
    et al.
    Department of Crystallography, Mineralogy, and Ore Deposits, University of Barcelona.
    Proenza, Joaquín A.
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona.
    Galí, Salvador
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Universitat de Barcelona .
    Rius, Jordi
    Institut de Ciència de Materials de Barcelona, CSIC, Campus de la Universitat Autònoma de Barcelona.
    Longo, Francisco
    Falcondo Glencore, Santo Domingo .
    Domènech, Cristina
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB).
    The supergene origin of ruthenian hexaferrum in Ni-laterites2017In: Terra Nova, ISSN 0954-4879, E-ISSN 1365-3121, Vol. 29, no 2, p. 106-116Article in journal (Refereed)
    Abstract [en]

    For two decades, the nature of Fe‐rich, oxygen‐bearing, Ru–Os compounds found in the supergene environment has been debated. Ru–Os–Fe‐oxides and nano‐intergrowths of ruthenium with magnetite have been proposed. We applied FE‐SEM, EMPA, μ‐Raman spectroscopy and synchrotron tts‐μXRD to Ru–Os–Fe compounds recovered from Ni‐laterites from the Dominican Republic. The results demonstrate that a significant portion of Fe exists in a common structure with the Ru–Os alloy, that is, ruthenian hexaferrum. This mineral occurs both as nanoparticles and as micrometric patches within a matrix of Fe‐oxide(s). Our data suggest that supergene ruthenian hexaferrum with a (Ru0.4(Os,Ir)0.1Fe0.5)Ʃ1.0 stoichiometry represents the most advanced weathering product of primary laurite within Ni‐laterites from the Dominican Republic.

  • 5.
    Aiglsperger, Thomas
    et al.
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona .
    Proenza, Joaquín A.
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona .
    Lewis, John F.
    Department of Earth and Environmental Sciences, George Washington University, .
    Labrador, Manuel
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona.
    Svojtka, Martin
    Institute of Geology, Academy of Sciences.
    Rojas-Purón, Arturo
    Departamento de Geología, Instituto Superior Minero Metalúrgico de Moa.
    Longo, Francisco
    Falcondo Glencore Nickel.
    Ďurišová, Jana
    Institute of Geology, Academy of Sciences.
    Critical metals (REE, Sc, PGE) in Ni laterites from Cuba and the Dominican Republic2016In: Ore Geology Reviews, ISSN 0169-1368, E-ISSN 1872-7360, Vol. 73, p. 127-147Article in journal (Refereed)
    Abstract [en]

    Ni laterites are considered worthy targets for critical metals (CM) exploration as Rare Earth Elements (REE), Sc and platinum group elements (PGE) can be concentrated during weathering as a result of residual and secondary enrichment. In this contribution geochemical and mineralogical data of CM from two different nickel laterite types (i) from the Moa Bay mining area in Cuba (oxide type) and (ii) from the Falcondo mining area in the Dominican Republic (hydrous Mg silicate type) are presented. Emphasis is given on examining their potential to accumulate CM and on processes involved. Results show that CM are concentrated towards the surface in specific zones: (i) REE in clay minerals rich horizons and within zones composed of secondary Mn oxide(s), (ii) Sc within zones rich in secondary Fe and Mn bearing oxide(s) and (iii) PGE in zones with high concentrations of residual chromian spinel and secondary Fe and Mn bearing oxide(s) at upper levels of the Ni laterite profiles. Concentration factors involve (i) residual enrichment by intense weathering, (ii) mobilization of CM during changing Eh and pH conditions with subsequent reprecipitation at favourable geochemical barriers and (iii) interactions between biosphere and limonitic soils at highest levels of the profile (critical zone) with involved neoformation processes. Total contents of CM in both Ni laterite types are low when compared with conventional CM ore deposits but are of economic significance as CM have to be seen as cost inexpensive by-products during the Ni (+ Co) production. Innovative extraction methods currently under development are believed to boost the significance of Ni laterites as future unconventional CM ore deposits.

  • 6.
    Aiglsperger, Thomas
    et al.
    Department of Crystallography, Mineralogy, and Ore Deposits, University of Barcelona.
    Proenza, Joaquín A.
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona.
    Longo, Francisco
    Falcondo Glencore, Santo Domingo .
    Font-Bardia, Mercé
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Universitat de Barcelona .
    Galí, Salvador
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Universitat de Barcelona .
    Roqué, Josep
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona.
    Baurier-Aymat, Sandra
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Universitat de Barcelona .
    Fibrous Platinum-Group Minerals in “Floating Chromitites” from the Loma Larga Ni-Laterite Deposit, Dominican Republic2016In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 6, no 4, article id 126Article in journal (Refereed)
    Abstract [en]

    This contribution reports on the observation of enigmatic fibrous platinum-group minerals (PGM) found within a chromitite body included in limonite (“floating chromitite”) from Ni-laterites in the Dominican Republic. Fibrous PGM have a Ru-Os-Ir-Fe dominated composition and are characterized by fibrous textures explained by grain-forming fibers which are significantly longer (1–5 _m) than they are wide (~100 nm). Back-scattered electron (BSE) images suggest that these nanofibers are platinum-group elements (PGE)-bearing and form <5 _m thick layers of bundles which are oriented orthogonal to grains’ surfaces. Trace amounts of Si are most likely associated with PGE-bearing nanofibers. One characteristic fibrous PGM was studied in detail: XRD analyses point to ruthenian hexaferrum. However, the unpolished fibrous PGM shows numerous complex textures on its surface which are suggestive for neoformation processes: (i) features suggesting growth of PGE-bearing nanofibers; (ii) occurrence of PGM nanoparticles within film material (biofilm?) associated with PGE-bearing nanofibers; (iii) a Si-rich and crater-like texture hosting PGM nanoparticles and an Ir-rich accumulation of irregular shape; (iv) complex PGM nanoparticles with ragged morphologies, resembling sponge spicules and (v) oval forms (<1 _m in diameter) with included PGM nanoparticles, similar to those observed in experiments with PGE-reducing bacteria. Fibrous PGM found in the limonite may have formed due to supergene (bio-)weathering of fibrous Mg-silicates which were incorporated into desulphurized laurite during stages of serpentinization.

  • 7.
    Aiglsperger, Thomas
    et al.
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona, .
    Proenza, Joaquín A.
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona.
    Zaccarini, Frederica
    Department of Applied Geosciences and Geophysics, University of Leoben.
    Lewis, John F.
    Department of Earth and Environmental Sciences, George Washington University .
    Garuti, Giorgio
    Department of Applied Geosciences and Geophysics, University of Leoben.
    Labrador, Manuel
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona, .
    Longo, Francisco
    Falcondo Glencore, Santo Domingo .
    Platinum group minerals (PGM) in the Falcondo Ni-laterite deposit, Loma Caribe peridotite (Dominican Republic)2014In: Mineralium Deposita, ISSN 0026-4598, E-ISSN 1432-1866, Vol. 50, no 1, p. 105-123Article in journal (Refereed)
    Abstract [en]

    Two Ni-laterite profiles from the Loma Caribe peridotite (Dominican Republic) have been investigated for their platinum group element (PGE) geochemistry and mineralogy. One profile (Loma Peguera) is characterized by PGE-enriched (up to 3.5 ppm total PGE) chromitite bodies incorporated within the saprolite, whereas the second profile is chromitite-free (Loma Caribe). Total PGE contents of both profiles slightly increase from parent rocks (36 and 30 ppb, respectively) to saprolite (∼50 ppb) and reach highest levels within the limonite zone (640 and 264 ppb, respectively). Chondrite-normalized PGE patterns of saprolite and limonite reveal rather flat shapes with positive peaks of Ru and Pd. Three types of platinum group minerals (PGM) were found by using an innovative hydroseparation technique: (i) primary PGM inclusions in fresh Cr-spinel (laurite and bowieite), (ii) secondary PGM (e.g., Ru-Fe-Os-Ir compounds) from weathering of preexisting PGM (e.g., serpentinization and/or laterization), and (iii) PGM precipitated after PGE mobilization within the laterite (neoformation). Our results provide evidence that (i) PGM occurrence and PGE enrichment in the laterite profiles is independent of chromitite incorporation; (ii) PGE enrichment is residual on the profile scale; and (iii) PGE are mobile on a local scale leading to in situ growth of PGM within limonite, probably by bioreduction and/or electrochemical metal accretion.

  • 8.
    Aiglsperger, Thomas
    et al.
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona, .
    Proenza, Joaquín A.
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona.
    Zaccarini, Frederica
    Department of Applied Geological Sciences and Geophysics, University of Leoben.
    Lewis, John F.
    Department of Earth and Environmental Sciences, George Washington University, .
    Garuti, Giorgio
    Department of Applied Geosciences and Geophysics, University of Leoben.
    Labrador, Manuel
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona, .
    Longo, Francisco
    Falcondo Glencore, Santo Domingo .
    Platinum group minerals (PGM) in the Falcondo Ni-laterite deposit, Loma Caribe peridotite (Dominican Republic)2015In: Mineralium Deposita, ISSN 0026-4598, E-ISSN 1432-1866, Vol. 50, no 1, p. 105-123Article in journal (Refereed)
    Abstract [en]

    Two Ni-laterite profiles from the Loma Caribe peridotite (Dominican Republic) have been investigated for their platinum group element (PGE) geochemistry and mineralogy. One profile (Loma Peguera) is characterized by PGE-enriched (up to 3.5 ppm total PGE) chromitite bodies incorporated within the saprolite, whereas the second profile is chromitite-free (Loma Caribe). Total PGE contents of both profiles slightly increase from parent rocks (36 and 30 ppb, respectively) to saprolite (∼50 ppb) and reach highest levels within the limonite zone (640 and 264 ppb, respectively). Chondrite-normalized PGE patterns of saprolite and limonite reveal rather flat shapes with positive peaks of Ru and Pd. Three types of platinum group minerals (PGM) were found by using an innovative hydroseparation technique: (i) primary PGM inclusions in fresh Cr-spinel (laurite and bowieite), (ii) secondary PGM (e.g., Ru-Fe-Os-Ir compounds) from weathering of preexisting PGM (e.g., serpentinization and/or laterization), and (iii) PGM precipitated after PGE mobilization within the laterite (neoformation). Our results provide evidence that (i) PGM occurrence and PGE enrichment in the laterite profiles is independent of chromitite incorporation; (ii) PGE enrichment is residual on the profile scale; and (iii) PGE are mobile on a local scale leading to in situ growth of PGM within limonite, probably by bioreduction and/or electrochemical metal accretion.

  • 9.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bark, Glenn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ericsson, Magnus
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Söderholm, Patrik
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Wanhainen, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Widerlund, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Norrbottens malm- och mineralresurs och dess potentiella betydelse för innovation, samhälle och miljö2014Report (Other academic)
    Abstract [sv]

    Gruvindustrins betydelse för samhällsutveckling och infrastruktur i Sverige och inte minst i Norrbottens län är mycket stor. De geologiska förutsättningarna att hitta nya brytvärda förekomster i Norrbotten är goda. Länet är tillsammans med Västerbotten en av Europas viktigaste regioner för utvinning av metaller. Det syns också i den nyligen framtagna regionala mineralstrategin för Norrbotten och Västerbotten. Visionen för den regionala mineralstrategin: ”Genom långsiktigt hållbart nyttjande av Norrbottens och Västerbottens läns mineralresurser har ytterligare tillväxt skapats i regionen och hela Sverige. Vi har utvecklat och stärkt vår ställning som ledande gruv- och mineralnation.”Eftersom framtidspotentialen för gruvnäringen är mycket god men okunnigheten hos både allmänhet och beslutsfattare om näringens betydelse för innovation och samhällsutveckling är stor, kopplat med en utbredd oro för miljöpåverkan, måste dessa viktiga framtidsfrågor belysas. Med finansiering från Länsstyrelsen i Norrbotten bedrevs därför under första hälften av 2014 en förstudie som syftade till att sammanfatta kunskapsläget om framtidens gruvindustri i Norrbotten. Resultaten av förstudien redovisas i den här rapporten. En viktig slutsats är att det under nästa strukturfondsperiod (med start 2015) behövs ett framtidsinriktat forskningsprogram för att belysa de möjligheter som finns. Denna förstudie utgör grund för en kommande ansökan till strukturfonderna. Kompetensen som finns vid Luleå tekniska universitet, Sveriges centrum för gruvrelaterad forskning och utbildning, bör användas för att studera troliga framtidsmöjligheter och hur de ska kunna användas för att få en så positiv utveckling som möjligt för länet. Projektet bör innehålla följande tre huvudinriktningar, som naturligtvis hör ihop:Vilka malm- och mineralresurser finns det potential för i Norrbotten, och vilka kommer sannolikt att exploateras i framtiden?Vad kommer den exploateringen att ha för betydelse för innovation och samhällsutveckling?Vad kommer den exploateringen att få för miljöeffekter och hur ska man göra för att minska miljöbelastningen?En annan slutsats är att nedlagda gruvområden inte måste ses som förstörd natur. Betydande mervärden som gruvturism skulle kunna skapas om vilja, kreativitet och beslutsamhet finns. Detta är ett givet utvecklingsområde där småföretag och entreprenörer kan göra stor insats om de politiska och myndighetsmässiga förutsättningarna finns. Dessa aspekter skulle också kunna belysas i det föreslagna forskningsprogrammet eller i ett eget projekt.

  • 10.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sandström, Åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Rosenkranz, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hällström, Lina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Improve Resource Efficiency and Minimize Environmental Footprint2016Other (Other (popular science, discussion, etc.))
    Abstract [en]

    The REMinE project is organized in five work packages that comprise: detailedcharacterization and risk assessment of the mine wastes selected (WP2), identification of new processing methods for mine waste (WP3), characterization and risk assessment of the remaining residuals (WP4), outlining business opportunities and environmental impact in a conceptual model for sustainable mining (WP5). The project comprises case studies of historical mine wastes from three different European countries, namely Portugal, Romania and Sweden. The interdisciplinary research collaboration in this project is innovative in the sense that separation of minerals and extraction of metals not only are basedon technical and economic gain but also considers the environmental perspective.

  • 11.
    Allen, Ann
    et al.
    Boliden Mineral, Garpenberg.
    Allen, Rodney
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kaiser, Majka C.
    Boliden Mineral, Garpenberg.
    Geochemistry as a Tool for Exploration at the Renstrom Zn-Pb-Cu-Au-Ag VMS Camp, Skellefte District, Sweden2015In: Mineral Resources in a Sustainable World / [ed] A.S. Andre-Mayer; M. Cathelineau; P. Muchez; E. Pirard; s. Sindern, 2015, p. 2047-2050Conference paper (Refereed)
    Abstract [en]

    The Skellefte mining district in northern Sweden contains over 85 pyritic Zn-Cu-Au-Ag massive sulphide deposits. The Renstrom area, one of the most intensely mineralized parts of the Skellefte district, contains five zinc-and gold-rich deposits, three of which are confined to a specific continuous stratigraphic unit, the "Renstrom ore host unit". The great structural complexity of the area made it difficult to locate and follow the ore horizon to generate new exploration targets. A new study in the Kyrkvagen area, based on stratigraphic correlations, structural interpretations and lithogeochemical and geophysical data interpretation, revealed several NW-trending faults which separate five structural blocks. The rocks of the area could be characterized in terms of geochemistry, stratigraphy and their position in the hanging or footwall with respect to the ore horizon. Moreover, alteration patterns allowed predictions of possible extensions of the ore horizon. This increased knowledge of the Kyrkvagen area led to the identification of five new drilling targets for further exploration in one of Boliden's most important mining areas.

  • 12. Allen, Rodney
    et al.
    Cas, R.A.F.
    Yamagishi, H.
    Ishikawa, Y.
    Ohguchi, T.
    Submarine silicic volcanoes associated with Miocene Kuroko mineralization, northern Japan1989Conference paper (Other academic)
  • 13.
    Allen, Rodney
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Martinsson, OlofWeihed, Pär
    Svecofennian Ore-Forming Environments Field Trip Volcanic-associated Zn-Cu-Au-Ag and magnetite-apatite, sediment-hosted Pb-Zn, and intrusion-associated Cu-Au deposits in northern Sweden2004Collection (editor) (Other academic)
  • 14.
    Allen, Rodney
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Montelius, Cecilia
    Schlatter, Denis
    Imana, Marcello
    Barrett, T.
    Svenson, Sven-Åke
    Boliden Mineral AB.
    Application of volcanology to understanding massive sulphide deposits in the 1.9 Ga Skell2004In: The 26th Nordic Geological Winter Meeting: abstract volume / [ed] Joakim Mansfeld, Uppsala: Geological Society of Sweden , 2004, p. 45-Conference paper (Refereed)
  • 15.
    Allen, Rodney
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Montelius, Cecilia
    Svenson, Sven-Åke
    Geology of the Maurliden Area, Central Skellefte District, and Visit to the West Maurliden Zn-Cu-Au Massive Sulfide Deposit: Day three field guide2004In: Svecofennian Ore-Forming Environments Field Trip Volcanic-associated Zn-Cu-Au-Ag and magnetite-apatite, sediment-hosted Pb-Zn, and intrusion-associated Cu-Au deposits in northern Sweden, Littleton, Colorado: Society of Economic Geologists, 2004, p. 111-Chapter in book (Other academic)
  • 16.
    Allen, Rodney
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ohguchi, Takeshi
    Volcanic setting of kuroko massive sulphide deposits, Hokuroku Basin, Japan2006In: 12th Quadrennial IAGOD Symposium, Taylor and Francis Group , 2006Conference paper (Other academic)
  • 17.
    Allen, Rodney
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Svenson, Sven-Åke
    1.9 Ga Volcanic Stratigraphy, Structure, and Zn-Pb-Cu-Au-Ag Massive Sulfide Deposits of the Renström area, Skellefte District, Sweden2004In: Svecofennian Ore-Forming Environments Field Trip Volcanic-associated Zn-Cu-Au-Ag and magnetite-apatite, sediment-hosted Pb-Zn, and intrusion-associated Cu-Au deposits in northern Sweden, Society of Economic Geologists, 2004Chapter in book (Other academic)
  • 18.
    Allen, Rodney
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Svenson, Sven-Åke
    Day one field guide: Overview of the Stratigraphy, Structure, and Volcanology of the Skellefte Mining District2004In: Svecofennian Ore-Forming Environments Field Trip Volcanic-associated Zn-Cu-Au-Ag and magnetite-apatite, sediment-hosted Pb-Zn, and intrusion-associated Cu-Au deposits in northern Sweden, Society of Economic Geologists, 2004Chapter in book (Other academic)
  • 19.
    Allen, Rodney
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Svenson, Sven-Åke
    Boliden Mineral AB.
    Jonsson, Rolf
    Day two field guide: Volcanic Stratigraphy and Structure of the Renström Area and Mine Tour of the Petiknäs South Zn-Pb-Cu-Au-Ag Massive Sulfide Deposit2004In: Svecofennian Ore-Forming Environments Field Trip Volcanic-associated Zn-Cu-Au-Ag and magnetite-apatite, sediment-hosted Pb-Zn, and intrusion-associated Cu-Au deposits in northern Sweden, Society of Economic Geologists, 2004Chapter in book (Other academic)
  • 20.
    Allen, Rodney
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tornos, F.
    Peter, J.
    Cagatay, N.
    Links between volcanism and massive sulphide deposits: a global perspective2005In: GAC-MAC-CSPG-CSSS [joint Meeting], Halifax, 2005: building bridges - across science, through time, around the world : abstracts, St. John's: Geological and Mineralogical Association of Canada, 2005, p. 3-Conference paper (Other academic)
  • 21.
    Allen, Rodney
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tornos, F.
    Instituto Geológico y Minero de España.
    Peter, J. M.
    Geological Survey of Canada.
    A thematic issue on the geological setting and genesis of volcanogenic massive sulfide (VMS) deposits2011In: Mineralium Deposita, ISSN 0026-4598, E-ISSN 1432-1866, Vol. 46, no 5, p. 429-430Article in journal (Other academic)
  • 22.
    Allen, Rodney
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tornos, F.
    Instituto Geológico y Minero de España.
    Peter, J.
    Geological Survey of Canada.
    Çagatay, N.
    Istanbul Technical University.
    Links between volcanism and the distribution and timing of massive sulphide (VMS) deposits2006In: The 27th Nordic Geological Winter Meeting, January 9-12, 2006, Oulu, Finland: abstract volume / [ed] Petri Peltonen; Annti Pasanen, Helsinki: Geological Society of Finland , 2006, p. 7-Conference paper (Other academic)
    Abstract [en]

    The links between volcanism and massive sulphide deposits are being studied as part of the "Global Volcanic-hosted Massive Sulphide (VMS) Project", which is IGCP project 502. Different types and settings of VMS deposit show different degrees of influence from volcanic or magmatic processes, with the most distinct genetic connection shown by some felsic-hosted deposits. These influences include:(1) Basin-wide volcano-tectonic events cause deposition of VMS on specific time-stratigraphic horizons. (2) With the exception of mid-ocean ridge settings, major VMS deposits are mainly associated with felsic volcanic rocks, even where felsic rocks form a minor component of the region. (3) Most VMS deposits form in proximal volcanic settings. (4) Most VMS deposits form at a particular stage in the evolution of their host volcanoes, typically late in the magmatic-hydrothermal cycle following a significant felsic eruptive event. The specific relationship in time and place implied by these last two points indicate that either the magmatic-hydrothermal cycle creates an important part of the ore solution, or controls when and where a metal-bearing geothermal solution can be focused and expelled to the sea floor, or both.(5) VMS deposits occur preferentially at times and places where both felsic and mafic magmas were erupted. In felsic-dominated regions, eruption of the mafic rocks commonly closely followed deposition of the ore-host felsic package. (6) Volcanic host rocks influence the morphology and stratigraphic position of VMS. Volcaniclastic and especially pumiceous strata promote deposition of VMS below the sea floor via replacement, whereas coherent lava flows and intrusions promote deposition of VMS on the sea floor. (7) Volcanic rocks and/or magmas are probably the source of metals in most VMS deposits.

  • 23. Allen, Rodney
    et al.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Global comparisons of volcanic-associated massive sulphide districts2002In: The timing and location of major ore deposits in an evolving Orogen, London: Geological Society of London, 2002, p. 13-37Chapter in book (Other academic)
    Abstract [en]

    Although volcanic-associated massive sulphide (VMS) deposits have been studied extensively, the geodynamic processes that control their genesis, location and timing remain poorly understood. Comparisons among major VMS districts, based on the same criteria, have been commenced in order to ascertain which are the key geological events that result in high-value deposits. The initial phase of this global project elicited information in a common format and brought together research teams to assess the critical factors and identify questions requiring further research. Some general conclusions have emerged. (1) All major VMS districts relate to major crustal extension resulting in graben subsidence, local or widespread deep marine conditions, and injection of mantle-derived mafic magma into the crust, commonly near convergent plate margins in a general back-arc setting. (2) Most of the world-class VMS districts have significant volumes of felsic volcanic rocks and are attributed to extension associated with evolved island arcs, island arcs with continental basement, continental margins, or thickened oceanic crust. (3) They occur in a part of the extensional province where peak extension was dramatic but short-lived (failed rifts). In almost all VMS districts, the time span for development of the major ore deposits is less than a few million years, regardless of the time span of the enclosing volcanic succession. (4) All of the major VMS districts show a coincidence of felsic and mafic volcanic rocks in the stratigraphic intervals that host the major ore deposits. However, it is not possible to generalize that specific magma compositions or affinities are preferentially related to major VMS deposits world-wide. (5) The main VMS ores are concentrated near the top of the major syn-rift felsic volcanic unit. They are commonly followed by a significant change in the pattern, composition and intensity of volcanism and sedimentation. (6) Most major VMS deposits are associated with proximal (near-vent) rhyolitic facies associations. In each district, deposits are often preferentially associated with a late stage in the evolution of a particular style of rhyolite volcano. (7) The chemistry of the footwall rocks appears to be the biggest control on the mineralogy of the ore deposits, although there may be some contribution from magmatic fluids. (8) Exhalites mark the ore horizon in some districts, but there is uncertainty about how to distinguish exhalites related to VMS from other exhalites and altered, bedded, fine grained tuffaceous rocks. (9) Most VMS districts have suffered fold-thrust belt type deformation, because they formed in short-lived extensional basins near plate margins, which become inverted and deformed during inevitable basin closure. (10) The specific timing and volcanic setting of many VMS deposits, suggest that either the felsic magmatic-hydrothermal cycle creates and focuses an important part of the ore solution, or that specific types of volcanism control when and where a metal-bearing geothermal solution can be focused and expelled to the sea floor, or both. This and other questions remain to be addressed in the next phase of the project. This will include in-depth accounts of VMS deposits and their regional setting and will focus on an integrated multi-disciplinary approach to determine how mineralisation, volcanic evolution and extensional tectonic evolution are interrelated in a number of world-class VMS districts.

  • 24.
    Allen, Rodney
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Gold deposit types in Palaeoproterozoic greenstone belts and accretionary complexes in northern Sweden1999In: Gold '99 Trondheim: Precambrian gold in the Fennoscandian and Ukrainian shields and related areas : abstract volume / [ed] Nigel J. Cook; Krister Sundblad, Trondheim: American Speech-Language-Hearing Association, 1999, p. 115-118Conference paper (Other academic)
  • 25. Allen, Rodney
    et al.
    Weihed, Pär
    Geological Survey of Sweden.
    Svenson, S. A.
    Jonsson, Rolf
    Evolution of the Skellefte massive sulphide district, Sweden, and facies analysis of mineralized silicic submarine intrusive dome-hyaloclastite-tuff cone volcanoes1993In: IAVCEI abstracts: ancient volcanism & modern analogues, Australian Geological Survey Organisation , 1993Conference paper (Other academic)
  • 26.
    Allen, Rodney
    et al.
    Volcanic Resources Ltd, Stavanger.
    Weihed, Pär
    Geological Survey of Sweden.
    Svensson, S. Å.
    Boliden AB.
    Setting of Zn-Cu-Au-Ag massive sulfide deposits in the evolution and facies architecture of a 1.9 Ga marine volcanic arc: Skellefte district, Sweden1996In: Economic geology and the bulletin of the Society of Economic Geologists, ISSN 0361-0128, E-ISSN 1554-0774, Vol. 91, no 6, p. 1022-1053Article in journal (Refereed)
    Abstract [en]

    Skellefte mining district occurs in an Early Proterozoic, mainly 1.90-1.87 Ga (Svecofennian) magmatic province of low to medium metamorphic grade in the Baltic Shield in northern Sweden. The district contains over 85 pyritic Zn-Cu-Au-Ag massive sulfide deposits and a few vein Au deposits and subeconomic porphyry Cu-Au-Mo deposits, The massive sulfide deposits mainly occur within, and especially along the top of: a regional felsic-dominant volcanic unit attributed to a stage of intense, extensional, continental margin are volcanism. From facies analysis we interpret the paleogeography of this stage to have comprised many scattered islands and shallow-water areas. surrounded by deeper seas. All the major massive sulfide ores occur in below-wave base facies associations: however, some ores occur close to stratigraphic intervals of above-wave base facies associations, and the summits of some volcanoes that host massive sulfides emerged above sea level. Intense marine volcanism was superceded at different times in different parts of tile district by a stage of reduced volcanism, uplift resulting in subregional disconformities, and then differential uplift and subsidence resulting in a complex horst and graben paleogeography. Uplift of the are is attributed to the relaxation of crustal extension and the emplacement of granitoids to shallow crustal levels. A few massive sulfide ores formed within the basal strata of this second stage. The horst and graben system was filled by prograding fluvial-deltaic sediments and mainly mafic lavas, and during this stage the Skellefte district was a transitional area between renewed are volcanism of more continental character to the north, and subsidence and basinal mudstone-turbidite sedimentation to the south. This whole volcanotectonic cycle occurred within 10 to 15 m.y. We define 26 main volcanic, sedimentary, and intrusive facies in the Skellefte district. The most abundant facies are (1) normal-graded pumiceous breccias, which are interpreted as syneruptive subaqueous mass flow units of pyroclastic debris, (2) porphyritic intrusions, and (3) mudstone and sandstone turbidites. Facies associations define seven main volcano types, which range from basaltic shields to andesite cones and rhyolite calderas. Despite this diversity of volcano types, most massive sulfide ol es are associated with one volcano type: subaqueous rhyolite cryptodome-tuff volcanoes. These rhyolite volcanoes are 2 to 10 km in diameter, 250 to 1,200 m thick at the center, and are characterized by a small to moderate volume rhyolitic pyroclastic unit, intruded by rhyolite cryptodomes, sills, and dikes. Massive sulfide ores occur near the top of the proximal (near vent) facies association The remarkable coincidence in space and time between the ores and this volcano type indicates an intimate, genetic relationship between the ores and the magmatic evolution of the volcanoes.Many of the massive sulfide ores occur within rapidly emplaced volcaniclastic facies and are interpreted to have formed by infiltration and replacement of these facies. Some of the ore deposits have characteristics of both marine massive sulfides and subaerial epithelial deposits. We suggest that massive sulfides in the Skellefte district span a range in ore deposit style from deep-water sea floor ores, to subsea-floor replacements, to shallow-water and possible subaerial synvolcanic replacements. Facies models are provided for the mineralized rhyolite volcanoes and volcanological guides are provided for exploration for blind ores within these volcanoes.

  • 27.
    Andersson, L. Christer
    Luleå tekniska universitet.
    The application of landsat data on geological structure interpretation1981In: Vol. 19, no 2, p. 143-144Article in journal (Other academic)
  • 28.
    Antal, Ildiko
    et al.
    Sveriges Geologiska Undersökning.
    Bergström, Ulf
    Sveriges Geologiska Undersökning.
    Kathol, Benno
    Sveriges Geologiska Undersökning.
    Lundström, Ingmar
    Sveriges Geologiska Undersökning.
    Weihed, Pär
    Kartbladen 23J Norsjö2000In: Regional berggrundsgeologisk undersökning: sammanfattning av pågående undersökningar 2000, Uppsala: Sveriges Geologiska Undersökning , 2000, p. 38-47Chapter in book (Other academic)
  • 29.
    Arvanitidis, N
    et al.
    Institute of Geology and Mineral Exploration (IGME).
    Michael, C
    Institute of Geology and Mineral Exploration (IGME).
    Christidis, C
    National and Kapodistrian University of Athens.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Gaal, Gabor
    Geological Survey of Finland, P.O.Box 96, 02151 Espoo.
    Royer, J.J.
    Université de Lorraine, CNRS, Nancy.
    Perantonis, G
    Hellas Gold S.A..
    Bakalis, V
    Hellas Gold S.A..
    Ballas, D
    Hellas Gold S.A..
    Using 3D/4D modelling tools in exploration for epithermal gold potential areas in Eastern Rhodope zone (Western Thrace, NE Greece)2013In: Mineral deposit research for a high-tech world: Proceedings of the 12th Biennial SGA Meeting, 12–15 August 2013, Uppsala, Sweden, Uppsala: Sveriges Geologiska Undersökning , 2013, Vol. 1, p. 58-61Conference paper (Refereed)
  • 30.
    Arvanitidis, N
    et al.
    Institute of Geology and Mineral Exploration (IGME).
    Michael, C
    Institute of Geology and Mineral Exploration (IGME).
    Christidis, C
    National and Kapodistrian University of Athens.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Gaal, Gabor
    Geological Survey of Finland.
    Royer, J.J.
    Université de Lorraine, CNRS, Nancy.
    Perantonis, G
    Hellas Gold S.A..
    Bakalis, V
    Hellas Gold S.A..
    Ballas, D
    Hellas Gold S.A..
    Using 3D/4D modelling tools in exploration for porphyry and manto-polymetallic potential areas in Eastern Chalkidiki peninsula2013In: Mineral deposit research for a high-tech world: Proceedings of the 12th SGA Biennial Meeting 2013, 12-15 August 2013, Uppsala, Sweden, Uppsala: Sveriges Geologiska Undersökning , 2013, Vol. 1, p. 54-57Conference paper (Refereed)
  • 31.
    Asani, Besnik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Investigation of bedrock quality for use as aggregates in Umeå municipality2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 32.
    Ask, Maria
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ask, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. FracSinus Rock Stress Measurement AB, Luleå.
    Cornet, Francois
    University of Strasbourg, School and Observatory of Earth Sciences, Strasbour.
    Nilsson, Tommy
    University of Strasbourg, School and Observatory of Earth Sciences, Strasbourg.
    A hydraulic stress measurement system for deep borehole investigations2017In: Geophysical Research Abstracts, ISSN 1029-7006, E-ISSN 1607-7962, Vol. 19Article in journal (Refereed)
    Abstract [en]

    Lulea University of Technology (LTU) is developing and building a wire-line system for hydraulic rock stress measurements, with funding from the Swedish Research Council and Lulea University of Technology. In this project, LTU is collaborating with University of Strasbourg and Geosigma AB. The stress state influences drilling and drillability, as well as rock mass stability and permeability. Therefore, knowledge about the state of in-situ stress (stress magnitudes, and orientations) and its spatial variation with depth is essential for many underground rock engineering projects, for example for underground storage of hazardous material (e.g. nuclear waste, carbon dioxide), deep geothermal exploration, and underground infrastructure (e.g. tunneling, hydropower dams). The system is designed to conduct hydraulic stress testing in slim boreholes. There are three types of test methods: (1) hydraulic fracturing, (2) sleeve fracturing and (3) hydraulic testing of pre-existing fractures. These are robust methods for determining in situ stresses from boreholes. Integration of the three methods allows determination of the three-dimensional stress tensor and its spatial variation with depth in a scientific unambiguously way. The stress system is composed of a downhole and a surface unit. The downhole unit consists of hydraulic fracturing equipment (straddle packers and downhole imaging tool) and their associated data acquisition systems. The testing system is state of the art in several aspects including: (1) Large depth range (3 km), (2) Ability to test three borehole dimensions (N=76 mm, H=96 mm, and P=122 mm), (3) Resistivity imager maps the orientation of tested fracture; (4) Highly stiff and resistive to corrosion downhole testing equipment; and (5) Very detailed control on the injection flow rate and cumulative volume is obtained by a hydraulic injection pump with variable piston rate, and a highly sensitive flow-meter. At EGU General Assembly 2017, we would like to present this new and unique stress measurement system and some initial test results from a 1200 m long borehole in crystalline rock

  • 33.
    Bark, Glenn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Genesis and tectonic setting of the hypozonal Fäboliden orogenic gold deposit, northern Sweden2005Licentiate 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.

  • 34.
    Bark, Glenn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    On the origin of the Fäboliden orogenic gold deposit, northern Sweden2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A new promising ore province, the Gold Line, southwest of the well- known Skellefte District, northern Sweden, is currently under exploration. This province hosts, so far, one operating mine, the Svartliden Au mine, and the recently closed Blaiken Zn-Pb-Au-Ag mine. The largest known gold deposit, the hypozonal Fäboliden orogenic gold deposit, in the area was recently granted mining permits. The deposit holds c. 54 Mt at 1.2 g/t Au, with a planned production of 4.6 Mt of ore/year. The mineralization at Fäboliden is commonly hosted in arsenopyrite-bearing quartz-veins, within a roughly N-S striking, steeply dipping shear zone in amphibolite facies volcano- sedimentary host rocks. The narrow belt of supracrustal rocks is surrounded by late- to post-orogenic Revsund granite. The gold is fine-grained (2-40 µm) and closely associated with arsenopyrite- löllingite and stibnite. Gold is found in fractures and as inclusions in the arsenopyrite-löllingite. Gold is also seen as free grains in the silicate matrix of the host rock. The hydrothermal mineral assemblage in the proximal alteration 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 lateral extent of the proximal alteration zone is estimated to 30-50 meters, and there is a good agreement between diopside- amphibole-biotite alteration, quartz veining, and gold mineralization. The mineral assemblage in the distal alteration zone is characterised by the presence of Ca- and Fe-Mg amphiboles, hedenbergite, biotite, and quartz. The transition from the distal alteration into the regional metamorphic assemblage is diffuse, and the only discernable feature appears to be a gradual decrease of amphibole away from the mineralization. The ductile gold-hosting fabric progresses laterally across the Revsund granite contact and then disappears after a few meters inside the granite, suggesting that at least the final stages of mineralization syn- to postdate the emplacement of the c. 1.81-1.77 Ga Revsund granite. Relationships between garnet-biotite and graphite geothermometry, together with these field relationships, indicate that the late stages of mineralization at Fäboliden post-date regional peak-metamorphism in the area, which is estimated at c. 1.80 Ga. The Fäboliden gold mineralization is hosted by a reverse, mainly dip-slip, high-angle shear zone with a relatively small horizontal shear movement. The mineralization constitutes two sets of mineralized quartz veins, one steep fault-fill vein system that is parallel to the regional foliation and one flat-lying extensional vein system. Both vein sets are suggested to have been generated from the same stress field, during E-W shortening at c. 1.80 Ga. At least two types of ore shoot are present at Fäboliden, intersections between the fault-fill vein set and the extensional vein set and bends in the shear zone system both show elevated gold content, similar to many gold- quartz vein deposits globally. The fluids involved in the precipitation of gold at Fäboliden shows characteristics similar to other hypozonal orogenic gold deposits, such as a CO2-CH4-H2S fluid composition and pressure-temperature conditions of c. 4 kbar and 520-560°C. Sulphur isotope data ranges between -1.5 and +3.6‰. Oxygen and hydrogen isotope data ranges between +10.6 and 13.1‰, and -120 to -67‰, respectively. The hydrothermal fluids at Fäboliden are interpreted to have originate from a crustally contaminated magmatic source. The potential for future orogenic gold discovery in the Fennoscandian Shield is considered good. From this PhD study it is suggested that interesting targets, concerning exploration for orogenic gold in at least the Gold Line, would be areas associated with roughly N-S striking tectonic zones that were active at around 1.80 Ga.

  • 35.
    Bark, Glenn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Orogenic gold in the late stages of the Svecokarelian orogen: with emphasis on the Palaeoproterozoic Fäboliden orogenic gold deposit2004In: The 26th Nordic Geological Winter Meeting: abstract volume / [ed] Joakim Mansfeld, Uppsla: Geological Society of Sweden , 2004, p. 146-Conference paper (Refereed)
  • 36.
    Bark, Glenn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Broman, C.
    Stockholms Universitet.
    Weihed, Pär
    Fluid chemistry of the hypozonal Fäboliden orogenic gold deposit, northern Sweden2006In: The 27th Nordic Geological Winter Meeting, January 9-12, 2006, Oulu, Finland: abstract volume / [ed] Petri Peltonen; Antti Pasanen, 2006, p. 13-Conference paper (Other academic)
    Abstract [en]

    Southwest of the well-known Skellefte District in northern Sweden a new ore province is presently being explored, the so called Gold Line. Today the largest known gold deposit in the Gold Line is the Fäboliden orogenic gold deposit.The gold mineralization is commonly hosted in quartz veins, which parallel the steep main foliation, within a shear zone in the metagreywacke host rocks. The fine-grained (2-40 μm) gold is closely associated with arsenopyrite in the quartz veins.Two main groups of fluid inclusions are present in the Fäboliden quartz veins. 1) Primary inclusions with a CO2-CH4 or a H2S (±CH4) composition (the latter recognized for the first time in a Swedish ore deposit). 2) Secondary fluid inclusions composed of pure CH4 and low-salinity aqueous fluids. The primary fluid inclusions are associated with arsenopyrite (+gold) and the CO2-CH4 fluid was also involved in precipitation of graphite. The graphite-forming reactions should generate a H2O phase as well. However, the presence of a H2O phase was not detected in any of the primary fluid inclusions and is suggested to have been consumed by wall rock reactions, generating hydrated alteration minerals such as Ca-amphibole, biotite, and minor tourmaline. Fluid inclusion data indicate arsenopyrite and graphite deposition at a pressure condition of ~4 kbars. Graphite is useful as an indicator of the metamorphic grade because the graphitization process is irreversible with no effects on the graphite structure during retrogression (Beyssac et al., 2002). Graphite in the mineralized quartz veins at Fäboliden indicates maximum temperatures of 520-560°C for the hydrothermal alteration system.Pyrrhotite was deposited after a subsequent pressure decrease and a later input of pure CH4 and low-salinity aqueous fluids, as suggested by the secondary fluid inclusions. These later fluids were trapped at a substantially lower pressure of ~0.3 kbars and a temperature of ~400°C.

  • 37.
    Bark, Glenn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Broman, Curt
    Stockholms Universitet.
    Weihed, Pär
    Fluid chemistry of the Palaeoproterozoic Fäboliden hypozonal orogenic gold deposit, northern Sweden: evidence from fluid inclusions2007In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 129, no 3, p. 197-210Article in journal (Refereed)
    Abstract [en]

    A new ore province, the Gold Line, southwest of the Skellefte District, northern Sweden, is currently under exploration. The largest known deposit in the Gold Line is the hypozonal Fäboliden orogenic gold deposit. The mineralization is hosted by arsenopyrite-bearing quartz veins, within a steep shear zone in amphibolite facies metagreywacke host rocks. Gold occur in fractures and as intergrowths in arsenopyrite-löllingite, and as free grains in the silicate matrix of the host rock. The hydrothermal mineral assemblage in the proximal alteration zone is diopside, calcic amphibole, biotite, and minor andalusite and tourmaline. Primary fluid inclusions in the Fäboliden quartz veins show a CO2-CH4 or a H2S (±CH4) composition (the latter recognized for the first time in a Swedish ore deposit). The primary fluid inclusions are associated with arsenopyrite-löllingite (+gold) and the CO2-CH4 fluid was also involved in precipitation of graphite. A prevalence of carbonic over aqueous fluid inclusions is characteristic for a number of hypozonal high-temperature orogenic gold deposits. The Fäboliden deposit, thus, shows fluid compositions similar to other hypozonal orogenic gold deposits. The proposed main mechanism for precipitation of gold from the fluids, is a mixing between H2S-rich and H2O?-CO2±CH4 fluids. Fluid inclusion data indicate arsenopyrite-löllingite and graphite deposition at a pressure condition of about 4 kbar. Graphite thermometry indicates maximum temperatures of 520-560°C for the hydrothermal alteration at Fäboliden, suggesting that at least the late stages of the mineralizing event took place shortly after peak-metamorphism in the area, i.e. at c. 1.80 Ga.

  • 38.
    Bark, Glenn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Wanhainen, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Textural setting of gold and its implications on mineral processing: preliminary results from three gold deposits in northern Sweden2013In: Mineral deposit research for a high-tech world: Proceedings of the 12th Biennial SGA Meeting, 12–15 August 2013, Uppsala, Sweden, Uppsala: Sveriges Geologiska Undersökning , 2013, p. 302-305Conference paper (Refereed)
    Abstract [en]

    Within the European Union (EU27) the two most important gold producers are Finland and Sweden, covering more than two thirds of the European market. Due to the high gold prize mining companies are looking to extract more of the metal by improving recovery. We have done textural analysis on three gold-bearing deposits to better understand how the gold-textures seen in drill cores might affect the processing of different gold-ore types. In the Nautanen IOCG deposit, gold deportment is different whether gold is associated with pyrite or magnetite, and this must be considered when optimising the future mine and process planning. In the VMS-type Kristineberg deposit, the gold is associated with pyrite, sphalerite, and galena. Low gold recoveries from flotation could be explained by the occurrence of gold-inclusions in the pyrite. In the epigenetic Svartliden lode gold deposit, the gold is rather coarse-grained and associated with arsenopyrite-löllingite, and silicates. The relatively large grain size of gold can result in incomplete breakdown of the largest gold grains in the cyanide leaching process. To properly understand gold deportment in ores and to be able to improve mine planning and predict metal recoveries a comprehensive textural analysis of gold in drill core-samples is essential.

  • 39.
    Bark, Glenn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geodynamic settings for Paleoproterozoic gold mineralization in the Svecofennian domain: a tectonic model for the Fäboliden orogenic gold deposit, northern Sweden2012In: Ore Geology Reviews, ISSN 0169-1368, E-ISSN 1872-7360, Vol. 48, p. 403-412Article in journal (Refereed)
    Abstract [en]

    Northern Sweden is currently experiencing active exploration within a new gold ore province, the so called Gold Line, situated southwest of the well-known Skellefte VMS District. The largest known deposit in the Gold Line is the hypozonal Fäboliden orogenic gold deposit. Mineralization at Fäboliden is hosted by arsenopyrite-rich quartz veins, in a reverse, mainly dip-slip, high-angle shear zone, in amphibolite facies supracrustal host rocks. The timing of mineralization is estimated, from field relationships, at ca. 1.8 Ga.The gold mineralization is hosted by two sets of mineralized quartz veins, one steep fault-fill vein set and one relatively flat-lying extensional vein set. Ore shoots occur at the intersections between the two vein sets, and both sets could have been generated from the same stress field, during the late stages of the Svecofennian orogen.The tectonic evolution during the 1.9–1.8 Ga Svecofennian orogen is complex, as features typical of both internal and external orogens are indicated. The similarity in geodynamic setting between the contemporary Svecofennian and Trans-Hudson orogens indicate a potential for world-class orogenic gold provinces also in the Svecofennian domain.The Swedish deposits discussed in this paper are all structurally associated with roughly N-S striking shear zones that were active at around 1.8 Ga, when gold-bearing fluids infiltrated structures related to conditions of E-W shortening.

  • 40.
    Bark, Glenn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Weihed, Pär
    Orogenic gold in the new Lycksele-Storuman ore province, northern Sweden: the Palaeoproterozoic Fäboliden deposit2007In: Ore Geology Reviews, ISSN 0169-1368, E-ISSN 1872-7360, Vol. 32, no 1-2, p. 431-451Article in journal (Refereed)
    Abstract [en]

    Southwest of the well-known Skellefte District, northern Sweden, a new gold ore province, the so called Gold Line, is presently being explored. During the past decade a number of gold occurrences have been discovered in this area. The largest known gold occurrence is the Fäboliden deposit. Late-to post-orogenic, ca. 1.81 to 1.77 Ga, Revsund granite constitutes the main rock type in the Fäboliden area and surrounds a narrow belt of mineralized metagreywackes and metavolcanic rocks. The supracrustal rocks are strongly deformed within a roughly N-S trending subvertical shear zone. The mineralization constitutes a 30 to 50 m wide, N-S striking, steeply dipping zone. The mineralization is commonly hosted by arsenopyrite-bearing quartz-veins within the supracrustal rocks. The quartz veins parallel the main foliation in the shear zone. Gold is closely associated with arsenopyrite-löllingite and stibnite and found in fractures and as intergrowths in the arsenopyrite-löllingite. Gold is also seen as free grains in the silicate matrix of the host rock. The proximal alteration zone displays positive correlation with Ca, S, As, Ag, Sb, Sn, W, Pb, Bi, Cd, Se, and Hg, whereas K and Na show a slightly negative correlation. The hydrothermal mineral assemblage in the proximal alteration zone is diopside, calcic amphibole, biotite, and minor andalusite and tourmaline. This type of assemblage is commonly recognized in hypozonal orogenic gold deposits worldwide. Garnet-biotite geothermometry indicates amphibolite facies in the Fäboliden area. The ductile fabric that hosts the mineralization is also found in the margin of the surrounding Revsund granitoid. It is therefore suggested that at least the final stages of the gold mineralization are syn- to late-kinematic, and the minimum age for the mineralization is thus constrained at ca. 1.80 Ga (Revsund age).

  • 41. Bark, Glenn
    et al.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The new Lycksele-Storuman gold ore province, northern Sweden; with emphasis on the early Proterozoic Fäboliden orogenic gold deposit.2003In: Mineral exploration and sustainable development: proceedings of the Seventh Biennial SGA Meeting, Athens, Greece, 24-28 August 2003, Rotterdam: Millpress , 2003, p. 1061-1064Conference paper (Refereed)
  • 42.
    Bauer, Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Structural and sedimentological reconstruction of the inverted Vargfors basin: a base for 4D-modelling2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Palaeoproterozoic Skellefte mining district in northern Sweden covers an area of 120 by 30 km and is one of the most important mining districts in Europe, producing mainly Zn, Cu, Pb, As and Au from volcanogenic massive sulfide (VMS) and orogenic gold deposits.Detailed mapping of structures and stratigraphy within the sedimentary Vargfors Group combined with a structural analysis revealed a syn-extensional fault pattern of NW-SE-trending normal faults and associated NE-SW-trending transfer faults, creating the segmented sedimentary Vargfors basin. It comprises distinct fault-bound compartments, which incluence the sedimentary stratigraphy in each of these compartments.Syn-rift subsidence affected the sedimentary conditions from near-shore to shallow submarine environment.Intensive fault movements associated with mafic volcanic activity along these faults resulted in the rapid uplift of the oldest phase of the Jörn intrusive complex and/or subsidence of its surrounding areas. Subsequent erosion of the intrusive rocks led to the formation of a tonalite to granodiorite bearing conglomeratic sequence, representing an alluvial fan. Further uplift to the north of the district resulted in the erosion of Arvidsjaur volcanic rocks and the formation of a braided river system. Subsidence of the intrusive complex and/or a sedimentary coverage on top of the same caused a break in sedimentation of tonalite to granodiorite clasts. Stratigraphical evolution of the sedimentary rocks and the Vargfors Group - Skellefte Group contact relationships show that rifting started in the centre and proceeded with time towards SE and NW. Subsequent basin inversion resulted in the reactivation of the existing normal faults along a carbonate-rich basal layer forming asymmetric synclines. Primary geometries of sedimentary strata within each fault-bound compartment controlled their deformation styles. Furthermore, strain was partitioned into the faults, forming high strain zones along the basin margins, where foliations parallel the main faults, and low strain domains in the core of the basin, where foliation is oblique to the main structural grain of the basin. This oblique foliation is either a result of a rotating stress field or a transpressional regime. This case study on basin inversion gives implications for accretion processes along the Svecokarelian Craton margin as well as forthe formation of VMS-deposits and their possible transposition. Basic modelling of the main geological boundaries in the central Skellefte district was performed by integrating data from regional to outcrop scale using the GoCAD (Paradigm) software platform. Available data included geographical and geological data, which were imported from ArcGIS (ESRI) as well as drill-hole data, seismic profiles, resistivity and gravimetry profiles and EM-profiles. Creation of the main geological boundaries utilized GoCAD and SPARSE (Mirageoscience) algorithms, whereas structural geological data was exclusively modelled with SPARSE. Furthermore, this study provides a base for refining the 3-dimensional model and developing a 4-dimensional model, showing the geological evolution of the Skellefte district.

  • 43.
    Bauer, Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    VISUAL3D: an EIT network on visualization of geomodels2017In: Geophysical Research Abstracts, ISSN 1029-7006, E-ISSN 1607-7962, Vol. 19Article in journal (Refereed)
    Abstract [en]

    When it comes to interpretation of data and understanding of deep geological structures and bodies at different scales then modelling tools and modelling experience is vital for deep exploration. Geomodelling provides a platform for integration of different types of data, including new kinds of information (e.g., new improved measuring methods). EIT Raw Materials, initiated by the EIT (European Institute of Innovation and Technology) and funded by the European Commission, is the largest and strongest consortium in the raw materials sector worldwide. The VI-SUAL3D network of infrastructure is an initiative by EIT Raw Materials and aims at bringing together partners with 3D-4D-visualisation infrastructure and 3D-4D-modelling experience. The recently formed network collaboration interlinks hardware, software and expert knowledge in modelling visualization and output. A special focus will be the linking of research, education and industry and integrating multi-disciplinary data and to visualize the data in three and four dimensions. By aiding network collaborations we aim at improving the combination of geomodels with differing file formats and data characteristics. This will create an increased competency in modelling visualization and the ability to interchange and communicate models more easily. By combining knowledge and experience in geomodelling with expertise in Virtual Reality visualization partners of EIT Raw Materials but also external parties will have the possibility to visualize, analyze and validate their geomodels in immersive VR-environments. The current network combines partners from universities, research institutes, geological surveys and industry with a strong background in geological 3D-modelling and 3D visualization and comprises: Lulea University of Technology, Geological Survey of Finland, Geological Survey of Denmark and Greenland, TUBA Freiberg, Uppsala University, Geological Survey of France, RWTH Aachen, DMT, KGHM Cuprum, Boliden, Montan Universitat Leoben, Slovenian National Building and Civil Engineering Institute, Tallinn University of Technology and Turku University. The infrastructure within the network comprises different types of capturing and visualization hardware, ranging from high resolution cubes, VR walls, VR goggle solutions, high resolution photogrammetry, UAVs, lidar-scanners, and many more.

  • 44.
    Bauer, Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Andersson, Joel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. LKAB, Malmberget.
    Sarlus, Zmar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lund, Cecilia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Kearney, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Structural controls on the setting, shape and hydrothermal alteration of the Malmberget IOA deposit, northern Sweden2018In: Economic geology and the bulletin of the Society of Economic Geologists, ISSN 0361-0128, E-ISSN 1554-0774, Vol. 113, no 2, p. 377-395Article in journal (Refereed)
    Abstract [en]

    The Malmberget iron oxide-apatite (IOA) deposit in northern Sweden is one of the largest underground iron ore mine operations in the world with estimated ore reserves in 2015 of 346 million metric tons (Mt) at 42.5% Fe. The underground operation is concentrated in 10 orebodies of 5 to 245 Mt each, which currently produce 17.4 Mt of apatite iron ore per year. Structural investigations were combined with data on hydrothermal mineral assemblages in order to reconstruct the relative timing of ore-forming, deformation, and overprinting hydrothermal events. The results improve the understanding of structural geometries, relationships, and control on orebody transposition in the deposit. A first compressional event (D1) around 1.88 Ga represents the main metamorphic event (M1) in the area and was responsible for a strong transposition of potential primary layering and the orebodies and led to the formation of a composite S0/1 fabric. A subsequent F2 folding event around 1.80 Ga resulted in the formation of an open, slightly asymmetric synform with a steeper southeast limb and a roughly SW-plunging fold axis. The result of structural modeling implies that the ore formed at two separate horizons. The folding was accompanied by stretching, resulting in boudinage of the iron orebodies. D2-related high-strain zones and syntectonic granites triggered the remobilization of amphibole, biotite, magnetite, and hematite and controlled the formation of iron oxide-copper-gold (IOCG)-type hydrothermal alteration, including an extensive K-feldspar alteration accompanied with sulfides, scapolite, and epidote. This shows a distinct time gap of at least 80 m.y. between the formation of iron oxides and sulfides. Brittle structures and the lack of an axial planar parallel fabric in conjunction with previous results suggest upper crustal, low-pressure, and high-temperature conditions during this D2 deformation phase, indicating a hydrothermal event rather than a purely regional metamorphic compression. It is proposed in the present study that the Malmberget IOA deposit was deformed and metamorphosed during a 1.88 Ga crustal shortening event. Moreover, the Malmberget IOA deposit was affected by a 1.8 Ga folding and hydrothermal event that is related to a regional IOCG overprint.

  • 45.
    Bauer, Tobias E.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The crustal architecture of the central Skellefte district, Sweden: Structural analysis, setting of VMS deposits and 3D-modelling2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Skellefte district in northern Sweden is a Palaeoproterozoic volcanic arc hosting abundant volcanogenic massive sulphide (VMS) deposits. The dominating rocks in the district are submarine volcanic and volcaniclastic rocks of the Skellefte Group deposited in an extensional regime at 1.89–1.88 Ga. Structural analysis and facies analysis combined with reflection seismic investigations in the central part of the Skellefte district revealed a pronounced pattern of WNW–ESE-striking normal faults and NE–SW-striking transfer faults that developed synchronously with volcanic activity. Dextral strike-slip movement along regional-scale NE-SW-striking faults favoured the opening of a pull-apart system. VMS deposits formed as sub-seafloor replacement and partly exhalative deposits mainly in the uppermost parts of Skellefte Group but also in the lowermost parts of the overlying Vargfors Group. Furthermore, the VMS deposits show a close spatial relationship to faults indicating that the ore-forming hydrothermal fluids utilized the synextensional faults as fluid conduits. The Vargfors Group sedimentary rocks form a distinct sub-basin in the central Skellefte district, the so called Vargfors basin or Vargfors syncline. Syn-extensional faulting created fault-bound compartments within the Vargfors basin. Syn-tectonic sedimentation of the Vargfors Group within the sub-basin is responsible for changes in stratigraphy between the individual compartments. Progressive opening of the sub-basin from the centre towards north-west and south-east is evident from the change of sedimentary facies associations. The onset of Vargfors Group deposition is characterized by turbiditic sedimentation with intercalated sandstones and monomict conglomerates derived from eroded and/or reworked Skellefte Group volcanic rocks. These facies associations are unconformably overlain by polymict conglomerates of alluvial fan and braided systems caused by the uplift of the Jörn intrusive complex and the subsequent formation of the Arvidsjaur volcanic arc, respectively. It is unclear if the polymict series formed during the latest stages of crustal extension or at the onset of subsequent crustal shortening. Crustal shortening at around 1.87 Ga is attributed to basin inversion and accretionary processes at the Svecokarelian craton margin and is assumed to result in inversion of normal and transfer faults and the formation of upright, fault-bound syn- and anticlines. A rheologically weak carbonate-rich layer at the base of the sedimentary sequence is suggested to favour the fault inversion over more distributed shortening as the controlling deformation mechanism in the Vargfors syncline. Furthermore, VMS deposits were transposed along the faults, and the deformation style of the ore bodies generally mimics the deformation styles of the hosting high-strain zones. Moreover, the size of the VMS deposits is coupled to the size of the associated high-strain zone with large-tonnage deposits associated with regional-scale high-strain zones and their splays. Progressive crustal shortening led to the formation of N-dipping break-back and shortcut faults. Mafic volcanic rocks are commonly observed along early, inverted faults and later break-back and short-cut faults indicating a long history of mafic volcanic activity both during extension and crustal shortening in the central Skellefte district.Three-dimensional geological multi-scale modelling combined results from geological and geophysical investigations in order to visualise the crustal architecture in the Skellefte district. Modelling was carried out in different scales ranging from detailed deposit-scale models of 21 VMS ore bodies to a semi-regional scale model of the Vargfors syncline and a simplified regional scale model of the central Skellefte district.

  • 46.
    Bauer, Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sarlus, Zimer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Multi-scale 4-dimensional geological modelling of the Gällivare area2013Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Due to an increasing demand on metals the production of iron and copper will rise during the next years. While the Gällivare area is one of the most active exploration areas in Europe, hosting two of Europe’s most important metal mines, the Aitik Cu-Au-Ag-(Mo) deposit and the Malmberget Fe-deposit, the northern Norrbotten ore province is still underexplored. In a multi-disciplinary project we intend to unravel the structural setting of ore deposits in the Gällivare area in close cooperation with both active mining companies LKAB and New Boliden AB. By reconstructing the geological history and especially the structural evolution of the region we aim at understanding the history of the ore deposits from their formation to their deformation and transposition into their present day position. Structural geological studies will be combined with geochemical and geochronological studies in order to reconstruct the structural evolution through time. These geological investigations will be furthermore accomplished by geophysical studies for constraining the 3D-geometries of the subsurface. Based on these results geological multi-scale 3D- and 4D-models will be produced aiding the prospecting and exploration of unknown ore deposits.

  • 47.
    Bauer, Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sarlus, Zimer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nordin, Roger
    Boliden Mineral AB.
    Andersson, Joel
    LKAB.
    The three dimensional crustal architecture of the Aitik Cu-Au-Ag-(Mo)-deposit and the Malmberget Fe-deposit2014Conference paper (Other academic)
  • 48.
    Bauer, Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skyttä, Pietari
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Allen, Rodney
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Fault-controlled sedimentation in a progressively opening extensional basin: the Palaeoproterozoic Vargfors basin, Skellefte mining district, Sweden.2013In: International journal of earth sciences, ISSN 1437-3254, E-ISSN 1437-3262, Vol. 102, no 2, p. 385-400Article in journal (Refereed)
    Abstract [en]

    The Vargfors basin in the central part of the Skellefte mining district is an inverted sedimentary basin within a Palaeoproterozoic (1. 89 Ga) marine volcanic arc. The fault-segmented basin formed from upper-crustal extension and subsequent compression, following a period of intense sub-marine volcanism and VMS ore formation. New detailed mapping reveals variations in stratigraphy attributed to syn-extensional sedimentation, as well as provenance of conglomerate clasts associated with tectonic activity at the transition from extension to compression. The onset of fan delta to alluvial fan sedimentation associated with basin subsidence indicates that significant dip-slip displacement accommodating rapid uplift of the intrusive complex and/or subsidence of the adjacent volcano-sedimentary domain took place along a major fault zone at the southern margin of the intrusive complex. Subsidence of the Jörn intrusive complex and/or its burial by sedimentary units caused a break in erosion of the intrusion and favoured the deposition of a tonalite clast-barren conglomerate. Clast compositions of conglomerates show that the syn-extensional deposits become younger in the south-eastern parts of the basin, indicating that opening of the basin progressed from north-west to south-east. Subsequent basin inversion, associated with the accretion to the Karelian margin, involved reverse activation of the normal faults and development of related upright synclines. Progressive crustal shortening caused the formation of break-back faults accompanied by mafic volcanic activity that particularly affected the southern contact of the Jörn intrusive complex and the northern contact of the Vargfors basin

  • 49.
    Bauer, Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skyttä, Pietari
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Allen, Rodney
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Syn-extensional faulting controlling structural inversion: Insights from the Palaeoproterozoic Vargfors syncline, Skellefte mining district, Sweden2011In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 191, no 3-4, p. 166-183Article in journal (Refereed)
    Abstract [en]

    The Vargfors basin in the central Skellefte district, Sweden, is an inverted sedimentary sub-basin within a Palaeoproterozoic (1.89 Ga) marine volcanic arc. The sub-basin formed from upper-crustal extension and subsequent compression, following a period of intense marine volcanism and VMS ore formation. Detailed mapping and structural analysis reveals a pattern of SE–NW-striking normal faults and interlinked NE–SW-striking transfer faults, which define distinct fault-bound compartments, each with an individual structural geometry and stratigraphy. Constraints on the deformation style and mechanisms achieved by 2D forward modelling are in agreement with the previously inferred inversion of the early normal faults during a regional crustal shortening event. A rheologically weak carbonate-rich layer at the base of the sedimentary sequence favoured the fault inversion over more distributed shortening as the controlling deformation mechanism. Transposition of sedimentary strata into the approximately SE–NW faults led to formation of asymmetric synclines that were tightened during progressive shortening. Structural analysis infers a progressive opening of the basin towards SE and NW with time. Furthermore, it is inferred that a displacement gradient was developed along the main structural grain, with decreasing dip-slip displacements towards SE and NW, both during the extension and the structural inversion.VMS deposits in the vicinity of the contact between the volcanic and the overlying sedimentary rocks were formed along early normal faults, which reacted as fluid conduits. Subsequently, the deposits were transposed into the inverted faults during crustal shortening. Consequently, the inverted faults provide a useful tool for mineral exploration in the district.

  • 50.
    Bauer, Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skyttä, Pietari
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Dehghannejad, Mahdieh
    Uppsala University.
    Tavakoli, Saman
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geological multi-scale modelling as a tool for modern ore exploration in the Skellefte mining district, Sweden2011In: Proceedings IAMG 2011 Salzburg: Mathematical Geosciences at the crossroads of theory and practice, 2011, p. 759-Conference paper (Other academic)
    Abstract [en]

    The Palaeoproterozoic Skellefte Mining District is host to abundant ore deposits. Geological 3Dmodelling was performed using the gOcad software platform. Geological methods such as field mapping, structural analysis and facies analysis combined with geophysical techniques such as reflection seismic investigations, resistivity, magnetic, electromagnetic and gravimetric studies and analysis of potential field data provide a framework for the reconstruction of the crustal geometry and geological history of the district as a tool for modern ore exploration. Results will be furthermore utilized for kinematic 4-dimensional modelling

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