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  • 1. Ahl, Martin
    et al.
    Bergman, Stefan
    Bergström, Ulf
    Eliasson, Thomas
    Ripa, Magnus
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Geochemical classification of plutonic rocks in central and northern Sweden2001Report (Other academic)
  • 2.
    Alakangas, Lena
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Bark, Glenn
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Ericsson, Magnus
    Luleå tekniska universitet, Samhällsvetenskap.
    Martinsson, Olof
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Söderholm, Patrik
    Luleå tekniska universitet, Samhällsvetenskap.
    Wanhainen, Christina
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Widerlund, Anders
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Öhlander, Björn
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    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.

  • 3.
    Allen, Rodney
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Martinsson, OlofWeihed, PärUppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    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)
  • 4. Allen, Rodney
    et al.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Global comparisons of volcanic-associated massive sulphide districts2002In: The timing and location of major ore deposits in an evolving Orogen / [ed] D.J. Blundell; F. Neubauer; A. von Quadt, 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.

  • 5.
    Allen, Rodney
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet, Geovetenskap och miljöteknik.
    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)
  • 6.
    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.

  • 7.
    Antal, Ildiko
    et al.
    Sveriges Geologiska Undersökning.
    Bergström, Ulf
    Sveriges Geologiska Undersökning.
    Kathol, Benno
    Sveriges Geologiska Undersökning.
    Lundström, Ingmar
    Sveriges Geologiska Undersökning.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Kartbladen 23J Norsjö2000In: Regional berggrundsgeologisk undersökning: sammanfattning av pågående undersökningar 2000 / [ed] Hans Delin, Uppsala: Sveriges Geologiska Undersökning , 2000, p. 38-47Chapter in book (Other academic)
  • 8.
    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 tekniska universitet, Geovetenskap och miljöteknik.
    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, p. 58-61Conference paper (Refereed)
  • 9.
    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 tekniska universitet, Geovetenskap och miljöteknik.
    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, p. 54-57Conference paper (Refereed)
  • 10.
    Bark, Glenn
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Broman, C.
    Stockholms Universitet.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    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.

  • 11.
    Bark, Glenn
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Broman, Curt
    Stockholms Universitet.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    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.

  • 12.
    Bark, Glenn
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet, Geovetenskap och miljöteknik.
    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.

  • 13.
    Bark, Glenn
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    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).

  • 14. Bark, Glenn
    et al.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet, Geovetenskap och miljöteknik.
    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)
  • 15. Bauer, Tobias E
    et al.
    Tavakoli, Saman
    Weihed, Pär
    Luleå tekniska universitet.
    Skytta, Pietari
    Hermansson, Tobias
    Allen, Rodney
    Dehghannejad, Mahdieh
    García Juanatey, María de los Ángeles
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    A regional scale 3D-model of the Skellefte mining district, northern Sweden2013In: Proceedings of the 12th SGA Biennial Meeting 2013., Uppsala, 2013, p. 62-65Conference paper (Refereed)
  • 16.
    Bauer, Tobias
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Skyttä, Pietari
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Allen, Rodney
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    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

  • 17.
    Bauer, Tobias
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Skyttä, Pietari
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Allen, Rodney
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet, Geovetenskap och miljöteknik.
    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.

  • 18.
    Bauer, Tobias
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Skyttä, Pietari
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Dehghannejad, Mahdieh
    Uppsala University.
    Tavakoli, Saman
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    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

  • 19.
    Bauer, Tobias
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Skyttä, Pietari
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Hermansson, Tobias
    Boliden Mineral AB.
    Allen, Rodney
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Correlation between distribution and shape of VMS deposits, and regional deformation patterns, Skellefte district, northern Sweden2014In: Mineralium Deposita, ISSN 0026-4598, E-ISSN 1432-1866, Vol. 49, no 5, p. 555-573Article in journal (Refereed)
    Abstract [en]

    The Skellefte district in northern Sweden is host to abundant volcanogenic massive sulphide (VMS) deposits comprising pyritic, massive, semi-massive and disseminated Zn–Cu–Au ± Pb ores surrounded by disseminated pyrite and with or without stockwork mineralisation. The VMS deposits are associated with Palaeoproterozoic upper crustal extension (D1) that resulted in the development of normal faults and related transfer faults. The VMS ores formed as sub-seafloor replacement in both felsic volcaniclastic and sedimentary rocks and partly as exhalative deposits within the uppermost part of the volcanic stratigraphy. Subsequently, the district was subjected to deformation (D2) during crustal shortening. Comparing the distribution of VMS deposits with the regional fault pattern reveals a close spatial relationship of VMS deposits to the faults that formed during crustal extension (D1) utilising the syn-extensional faults as fluid conduits. Analysing the shape and orientation of VMS ore bodies shows how their deformation pattern mimics those of the hosting structures and results from the overprinting D2 deformation. Furthermore, regional structural transitions are imitated in the deformation patterns of the ore bodies. Plotting the aspect ratios of VMS ore bodies and the comparison with undeformed equivalents in the Hokuroko district, Japan allow an estimation of apparent strain and show correlation with the D2 deformation intensity of the certain structural domains. A comparison of the size of VMS deposits with their location shows that the smallest deposits are not related to known high-strain zones and the largest deposits are associated with regional-scale high-strain zones. The comparison of distribution and size with the pattern of high-strain zones provides an important tool for regional-scale mineral exploration in the Skellefte district, whereas the analysis of ore body shape and orientation can aid near-mine exploration activities.

  • 20.
    Bauer, Tobias
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Skyttä, Pietari
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Hermansson, Tobias
    Boliden Mineral AB.
    Weihed, Pär
    Ore body shapes versus regional deformation patterns as a base for 3D prospectivity mapping in the Skellefte Mining District, Sweden2012Conference paper (Refereed)
  • 21.
    Bauer, Tobias
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Skyttä, Pietari
    Hermansson, Tobias
    Boliden Mineral AB, Luleå tekniska universitet.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    The comparison of ore body shapes and regional deformat patterns as a base for prospectivity mapping in the Skellefte mining district, Sweden2012Conference paper (Refereed)
  • 22.
    Bauer, Tobias
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Skyttä, Pietari
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Tavakoli, Saman
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Dehghannejad, Mahdieh
    Uppsala University, Uppsala universitet, Department of Earth Sciences, Uppsala University.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    From deposit to regional scale: 4-dimensional geological modelling in the Skellefte Mining District, Sweden2011Conference paper (Refereed)
  • 23.
    Bauer, Tobias
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Skyttä, Pietari
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Allen, Rodney
    3D-modelling of the Central Skellefte District, Sweden2009In: Smart science for exploration and mining: proceedings of the 10th Biennial SGA Meeting, Townsville, Australia 17th-20th August 2009 / [ed] Patrick Williams, James Cook University of North Queensland , 2009Conference paper (Refereed)
    Abstract [en]

    The central part of the Palaeoproterozoic Skellefte District in northern Sweden is host to several VMS deposits. This area is dominated by upright folds with axial surfaces trending WNW - ESE. Northeast - SW trending faults crosscut WNW - ESE trending faults and impart a distinct fault pattern. Subvertical stretching as expressed by subvertical mineral lineations as well as gently W-plunging mineral lineations parallel to the F2 fold axes indicate not only significant vertical movement, but also pronounced lateral movement. The faults formed in an extensional stage and were reactivated during a compressional stage oblique to the earlier phase. This crustal shortening caused folding and development of the main foliation. Overturned, tight to isoclinal folds within the Vargfors meta-sediments coincide with 1st and 2nd order faults and are considered to be related to reactivation of the early normal and transfer faults. A three dimensional model taking into account the structures was constructed using the GoCAD 3D-modelling software.

  • 24.
    Bauer, Tobias
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Tavakoli, Saman
    Dehghannejad, Mahdieh
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Garcia Juanatey, Maria de los Angeles
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Weihed, Pär
    4-dimensional geological modelling of the Skellefte district, Sweden2010In: The international archives of the photogrammetry, remote sensing and spatial information sciences, ISPRS Commission IV - Working Group 8 , 2010, p. 93-96Conference paper (Other academic)
  • 25.
    Bauer, Tobias
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Crustal Scale Shear Zones Controlling Grade and Tonnage of VMS Deposits in the Skellefte District, Northern Sweden2015In: Mineral Resources in a Sustainable World / [ed] A.S. Andre-Mayer; M. Cathelineau; P. Muchez; E. Pirard; S. Sindern, 2015, p. 45-48Conference paper (Refereed)
    Abstract [en]

    The Skellefte district in northern Sweden hosts abundant Paleoproterozoic, volcanic-hosted massive sulfide (VMS) deposits. The deposits formed due to pull apart basin formation in a volcanic arc setting and utilized the syn-extensional faults as fluid conduits. By comparing the structural setting in distinct structural domains with the tonnage and Cu, Au, and Ag grades a clear coupling between VMS deposits and the size of structures becomes evident. This shows how major crustal fault zones acted as fluid conduits for the ore forming hydrothermal fluids during an extensional phase. The same structures were subsequently re-activated as shear zones and possibly enhanced secondary enrichment processes.

  • 26. Bejgarn, Therese
    et al.
    Nylander, Juhani
    Boliden AB.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Årebäck, Hans
    Boliden AB.
    The Älgtrask intrusive-hosted Au (-Cu) deposit, Sweden2008Conference paper (Other academic)
    Abstract [en]

    The Algtrask gold deposit is located in the northern part of the Skellefte mining district, northern Sweden. It constitutes a major gold and copper exploration target for the mining company Boliden Mineral AB with an inferred mineral resource of 1.6 Mt grading 3 g/t Au. The deposit is situated in the southern margin of the Jorn Granitoid Complex (JGC), a composite, I-type, calc-alkaline batholith, which intruded into an island arc or continental margin arc volcanic succession in the early Proterozoic. The area has been affected by regional metamorphism of lower greenschist facies.Mineralization occurs as veins and disseminations in meter wide, steeply dipping, sub-parallel ENE-NE striking deformation zones within a coarse grained quartz-porphyritic granodiorite. The deposit has proximal silicic/phyllic and distal propylitic alteration. The altered zones commonly show ductile deformation, and where they are sulphide bearing, form IP-anomalies. Gabbro, equigranular tonalite, quartz-feldspar porphyritic dacitic dykes, basaltic dykes, aplitic dykes, quartz-calcite veins and episyenite have been recognized close to mineralization. The quartz-feldspar porphyritic dykes are in part altered and mineralized in a similar manner to the granodiorite.Two main mineralized zones have been distinguished at Algtrask; both contain pyrite, chalcopyrite, sphalerite and arsenopyrite and minor molybdenite, bornite, pyrrhotite, magnetite, gold and tellurides (e.g. petzite, hessite, altaite, coloradoite). Traces of native silver and bismuth have also been observed. The gold occurs as electrum (ca 80% Au) and calaverite closely associated with other tellurides. Gold and tellurides commonly occur as inclusions or in fractures in pyrite, within quartz-calcite veins or zones of phyllic-silicic alteration. Thicker bands of arsenopyrite are common in the southern zone, but do not occur in the northern zone, which suggests that the chemistry and sulphur fugacity of the ore forming fluids were different in the two mineralised zones.The Tallberg porphyry copper deposit is situated only 3 km west of Algtrask. Tallberg is characterized by quartz stockworks with disseminated pyrite, chalcopyrite, pyrrhotite and magnetite, hosted in propylitic and phyllic altered equigranular tonalite of the JGC. The similar settings, alteration and close spatial relationship, suggest a genetic link between the two deposits. The Algtrask deposit might represent a higher level epithermal system genetically linked to the Tallberg porphyry system. Ductile deformation took place during subsequent tectonic events, probably causing remobilization of sulphides and precious metals. Alternatively, a syntectonic model can be proposed in which the Algtrask deformation zones have overprinted an earlier porphyry copper system. In this model, syntectonic hydrothermal fluids may have "leached" gold from the earlier porphyry system during deformation and deposited gold in the deformation zones.

  • 27.
    Bejgarn, Therese
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Söderlund, Ulf
    Lunds universitet.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Årebäck, Hans
    Boliden Mineral AB.
    Ernst, Richard E.
    Carleton University, Ottawa.
    Palaeoproterozoic porphyry Cu-Au, intrusion-hosted Au and ultramafic Cu-Ni deposits in the Fennoscandian Shield: temporal constraints using U-Pb geochronology2013In: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 174, p. 236-254Article in journal (Refereed)
    Abstract [en]

    The Skellefte district, northern Sweden, is known for the occurrence of 1.89 Ga Palaeoproterozoic volcanogenic massive sulphide (VMS) deposits. The deposits are hosted by the older part of a volcanosedimentary succession, which was intruded at 1.88-1.86 Ga by multiple phases of the syn-volcanic, early orogenic Jörn intrusive complex (JIC). The oldest phase of the JIC hosts different styles of mineralisation, among them porphyry Cu-Mo-Au, intrusion-related Au, and mafic-hosted Fe and Cu-Ni deposits. To discriminate between the different intrusive and ore related events, U-Pb ages of zircons have been obtained for nine intrusive phases and from Na-Ca alteration spatially related to mineralisation, while U-Pb ages of baddeleyite (ZrO2) have been used to constrain intrusive ages of three mineralised and barren mafic-ultramafic intrusive rocks.The two main JIC intrusive phases of a granodioritic-tonalitic composition in the southern study area intruded at 1887 ± 3 Ma and 1886 ± 3 Ma, respectively, and were succeeded by the intrusion of layered mafic-ultramafic intrusive rocks in the northern and southern study area at 1879 ± 1 Ma and 1884 ± 2 Ma, respectively. Emplacement of porphyry dykes took place at ca. 1877 Ma in the southern, western and northern JIC. The dykes are spatially and temporally associated with formation of porphyry style mineralisation, alteration and Au-mineralisation, as inferred from 1879 ± 5 Ma zircons in adjacent Na-Ca alteration zones. High SiO2 and Al2O3 content together with high Sr/Y ratios, mingling structures, mafic xenoliths and hornblende phenocrysts in the porphyry dykes suggest that the magma originated from hydrated partial melts, possibly from the base of the crust at a mature stage of subduction. Local extension resulted in intrusion of mafic-ultramafic rocks around 1.88 Ga prior to and after, the porphyry dykes and associated mineralisation, approximately 10 Ma after the formation of the spatially related 1.89 Ga VMS deposits in the Skellefte district. This 1.88 Ga event correlates with other 1.88 Ga mafic-ultramafic units widespread around the world, and could possibly be interpreted as a large scale response to supercontinent formation.

  • 28.
    Bejgarn, Therese
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Luleå tekniska universitet.
    Broman, Curt
    Stockholm University.
    Söderlund, Ulf
    Lund University.
    Large, Ross
    University of Tasmania.
    Årebäck, Hans
    Boliden Mineral AB.
    Nylander, Juhani
    Boliden Mineral AB.
    The Älgträsk Au±Cu deposit, northern Sweden: a Palaeoproterozoic porphyry-related hydrothermal system?2011Conference paper (Refereed)
  • 29.
    Bejgarn, Therese
    et al.
    Luleå tekniska universitet, Geoteknologi.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Nylander, Juhani
    Boliden Mineral AB.
    Årebäck, Hans
    Boliden Mineral AB, Earth Sciences Centre – Geology, Göteborg University.
    Söderlund, Ulf
    Lund Universitet, Department of Geology, GeoBiosphere Science Centre, Lund University.
    Ernst, Richard E.
    Geological Survey of Canada, Carleton University, Ottawa.
    Tectonomagmatic aspects of intrusive hosted Cu-Au-Mo deposits in the Skellefte District, northern Sweden2013In: Mineral deposit research for a high-tech world: proceedings / [ed] Erik Jonsson, Uppsala: Sveriges Geologiska Undersökning , 2013, p. 770-773Conference paper (Refereed)
    Abstract [en]

    The Algtrask gold deposit and several low grade base metal deposits, e.g. the Tallberg porphyry deposit, are hosted by the Jam intrusive complex in the northern part of the Skellefte District, northern Sweden. The intrusive complex was emplaced at 1.89-1.86 Ga in a continental margin volcanic arc setting, and the oldest 1.89 Ga phase is coeval with volcanic rocks within the Skellefte Group, a complex volcano-sedimentary succession hosting numerous VMS deposits. The intrusive hosted deposits are associated with 1.88 Ga quartz-feldspar porphyritic intrusive rocks, which formed from 1.89 Ga recycled crust. Hence, it is interpreted that the intrusive hosted deposits formed when the arc was under transpression-compression, 10 Myr after the spatially related VMS deposits, which formed when the arc was under extension.

  • 30.
    Bejgarn, Therese
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Luleå tekniska universitet.
    Årebäck, Hans
    Boliden Mineral AB.
    Nylander, Juhani
    Boliden Mineral AB.
    Intrusion-related mineralization in the Palaeo-proterozoic Jörn Granitoid Complex, northern Sweden2009In: Smart science for exploration and mining: proceedings of the 10th Biennial SGA Meeting, Townsville, Australia, 17th-20th August 2009 / [ed] Patrick Williams, James Cook University of North Queensland , 2009, p. 921-923Conference paper (Refereed)
    Abstract [en]

    Immediately north of the Skellefte mining district, northern Sweden, the early orogenicsynvolcanic Jörn granitoid complex hosts several mineral deposits. The Jörn granitoid batholith intruded into a continental margin arc or island arc volcanic succession during the early Proterozoic, and comprises a composite, I-type, calc-alkaline batholith, ranging from granite to gabbro in composition. Several mineral deposits occur in the heterogeneous margin of the complex, i.e. the Tallberg porphyry Cu-Au-Mo, the Älgträsk Au and the Älgliden Ni-Cu-Au deposits in the south and the Näsberg Fe±PGE and Granberg porphyry Cu mineralization in the north. The known deposits indicate that the intrusion is fertile for further exploration activities and that Palaeoproterozioc synvolcanic intrusions close to VMS districts should be studied more closely to further develop genetic models which can be used to reconstruct the ore forming environments and tectonic evolution. This knowledge might be used as guidelines when exploring for new districts with economic potential in Palaeoproterozoic terrains.

  • 31. Bejgarn, Therese
    et al.
    Årebäck, Hans
    Boliden Mineral AB.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Nylander, Juhani
    Boliden Mineral AB.
    Geology, petrology and alteration geochemistry of the Palaeoproterozoic intrusive hosted Ägträsk Au deposit, Northern Sweden2011In: Geological Society Special Publication, ISSN 0305-8719, E-ISSN 2041-4927, no 350, p. 105-132Article in journal (Refereed)
    Abstract [en]

    The Ägträsk intrusive hosted Au deposit, Skellefte district, northern Sweden, is situated in the oldest, most heterogeneous part of the c. 1.89-1.86 Ga Jörn granitoid complex, which intruded a complex volcano-sedimentary succession in an island arc or continental margin arc environment. The Tallberg porphyry Cu deposit, situated only 3 km west of Ägträsk, is associated with quartz feldspar porphyritic dykes. These dykes are suggested to be genetically related to similar porphyry dykes in Älgträsk and the tonalitic host rock in Tallberg. The granodiorite hosting the Ägträsk Au-deposit does not appear to be genetically related to the tonalite or the porphyry dykes.

  • 32. Berglund, J.
    et al.
    Bergström, U.
    Bolvede, P.
    Bäck, J.
    Egagha, E.
    Grönberg, H.
    Lindberg, E.
    Nilsson, S.
    Nömtak, V.
    Olsson, E.
    Tillman, K.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    A petrological study of an east-west vertical crossection, Oia harbour, Thea (Santorini), Greece1983Report (Other academic)
  • 33. Berglund, J.
    et al.
    Bergström, U.
    Bolvede, P.
    Bäck, J.
    Egagha, E.
    Grönberg, H.
    Lindberg, E.
    Nilsson, S.
    Nömtak, V.
    Olsson, E.
    Tillman, K.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    A petrological study of an east-west vertical crossection, Oia harbour, Thea (Santorini), Greece1983Report (Other academic)
  • 34. Berglund, J.
    et al.
    Bergström, U.
    Bolvede, P.
    Bäck, J.
    Egagha, E.
    Grönberg, H.
    Lindberg, E.
    Nilsson, S.
    Nömtak, V.
    Olsson, E.
    Tillman, K.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Tektonisk och bergmekanisk studie över Nordön, södra Bohuslän1983Report (Other academic)
  • 35. Bergman, J.
    et al.
    Bergström, U.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Genesis and structural evolution of early Proterozoic gold lode deposits in the Skellefte district, northern Sweden1989In: Abstracts: 28th International geological congress, 1989, p. 459-460Conference paper (Other academic)
  • 36.
    Bergman, J.
    et al.
    Uppsala University.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Shear zones in the Proterozoic rocks of northern Västerbotten1993Report (Other academic)
  • 37. Bergman, J.
    et al.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Volcanotectonic evolution of the central part of the early Proterozoic Skellefte volcanic arc, northern Sweden1989In: 28th international geological congress: Abstracts, 1989, p. 135-Conference paper (Other academic)
  • 38.
    Bergman, Stefan
    et al.
    Geological Survey of Sweden.
    Weihed, Pär
    Luleå tekniska universitet.
    Martinsson, Olof
    Eilu, Pasi
    Geological Survey of Finland.
    Geological and tectonic evolution of the northernpart of the Fennoscandian Shield2007In: Metallogeny and tectonic evolution of the Northern Fennoscandian Shield: field trip guidebook / [ed] Juhani Ojala; Pär Weihed; Pasi Eilu; Markku Iljina, Espoo: Geological Survey of Finland , 2007, p. 6-15Chapter in book (Other academic)
  • 39.
    Bergström, U.
    et al.
    Sveriges Geologiska Undersökning.
    Lundin, I. Antal
    Sveriges Geologiska Undersökning.
    Winnes, K.
    Sveriges Geologiska Undersökning.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Berggrundskartan 23J Norsjö NO2003Other (Other academic)
  • 40.
    Bergström, U.
    et al.
    Sveriges Geologiska Undersökning.
    Lundin, I. Antal
    Sveriges Geologiska Undersökning.
    Winnes, K.
    Sveriges Geologiska Undersökning.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Berggrundskartan 23J Norsjö SO2003Other (Other academic)
  • 41.
    Bergström, U.
    et al.
    Sveriges Geologiska Undersökning.
    Lundin, I. Antal
    Sveriges Geologiska Undersökning.
    Winnes, K.
    Sveriges Geologiska Undersökning.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Berggrundskartan 23J Norsjö SV2003Other (Other academic)
  • 42.
    Bergström, U.
    et al.
    Sveriges Geologiska Undersökning.
    Lundin, I. Antal
    Sveriges Geologiska Undersökning.
    Winnes, K.
    Sveriges Geologiska Undersökning.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Berggrundskartan Norsjö 23J NV2003Other (Other academic)
  • 43.
    Bergström, U.
    et al.
    University of Gothenburg.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Structural aspects of some gold mineralizations in the Skellefte District, northern Sweden1991In: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 113, no 1, p. 42-44Article in journal (Refereed)
  • 44.
    Billström, Kjell
    et al.
    Museum of Natural History.
    Eilu, Pasi
    Geological Survey of Finland.
    Martinsson, Olof
    Niiranen, Tero
    Geological Survey of Finland.
    Broman, Curt
    Stockholm University.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Wanhainen, Christina
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Ojala, Juhani
    Geological Survey of Finland.
    IOCG and related mineral deposits of the northern Fennoscandian Shield2011In: Hydrothermal iron oxide copper-gold & related topics: a global perspective / [ed] T.M. Porter, Adelaide: PGC Publishing , 2011, p. 381-414Chapter in book (Other academic)
    Abstract [en]

    The northernmost Fennoscandian shield comprises Archaean and Palaeoproterozoic rocks. Unlike most other shield areas, economic mineral deposits are largely restricted to its Palaeoproterozoic parts. The latter are characterised by intracratonic basin evolution between ca. 2.5 and 2.0 Ga, involving recurrent mantle hotspot activity with numerous layered intrusions, komatiite and picrite eruptions, but no signs of accretionary phases or formation of major new felsic crust. Accretion and continent-continent collision followed from ca. 1.9 to 1.8 Ga, during the Svecofennian orogeny. A range of mineralisation styles are hosted by extensive ca. 2.5 to 2.0 Ga greenstone belts and younger, subduction-related 1.9 to 1.8 Ga Svecofennian intrusive and extrusive settings. These mineralisation styles partially overlap, and individual deposits may not readily be placed into genetic classification schemes. A provisional grouping of observed mineralisation styles comprises (1) stratiform-stratabound sulphide, (2) apatite-iron, (3) skarn-related iron and BIF, and (4) epigenetic(±syngenetic?) Au and Cu-Au deposits. The descriptive section of this paper also highlights features that may relate to orogenic-gold, IOCG and 'atypical metal association' categories of mineralisation. The assumption made is that the deposition of a diverse range of ore deposits was made possible by a long and complex geological evolution. This involved an initial (sowing) stage where iron, and to some extent copper and gold, were concentrated during 2.3 to 2.1 Ga (Karelian) rock-forming processes. Following this, ore elements were mobilised during two younger (Svecofennian) stages at 1.92 to 1.87 and 1.85 to 1.79 Ga, respectively. The latter were triggered by metamorphic and magmatic episodes, and fluids liberated during these stages precipitated IOCG and related deposits when fluids met structural and chemical traps in suitable host rocks. Ore fluids are generally saline, and their development probably involved incorporation of evaporates and, at least locally, also felsic magmatism may have played a role. Skarn-related mineralisation, hosted by ca. 2.1 Ga greenstones, occurs both as a BIF type in Sweden (formed at around 2.1 Ga), and as a gold-copper enriched variety (the result of Svecofennian epigenetic processes) in the Kolari region of Finland. The huge Kiirunavaara deposit is the type example of apatite iron ores, and is here considered to have formed from a magma at ca. 1.88 Ga, although it also has features best explained by a magmatic-hydrothermal overprint. A younger, less prominent, stage of apatite iron ore formation took place at approximately 1.78 Ga. Epigenetic gold and copper-gold deposits are particularly hard to classify as these show mixed ore characteristics, and to some extent this is likely to be due to multiple mineralisation stages (cf. the huge, low grade Aitik deposit in Sweden which is interpreted to be a hybrid porphyry-IOCG-type of ore). Structurally controlled, orogenic-gold mineralisation is common in the Central Lapland greenstone belt, although there are also gold deposits with enhanced contents of e.g., copper, cobalt and uranium (e.g., at Saatopoora). The latter, sometimes referred to as being of an 'atypical metal association' type, could potentially also include syngenetic mineralisation (e.g., at Juomasou). The range of epigenetic (±syngenetic) gold and copper-gold deposits could possibly be related to a vague east-west trend defined by gold-rich deposits in the east (Finland), followed by IOCG (copper±gold) and more iron-dominant ore types near the Finnish-Swedish border and further west into Sweden.

  • 45.
    Billström, Kjell
    et al.
    Swedish Museum of Natural History.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Age and provenance of host rocks and ores in the Paleoproterozoic Skellefte District, northern Sweden1996In: Economic geology and the bulletin of the Society of Economic Geologists, ISSN 0361-0128, E-ISSN 1554-0774, Vol. 91, no 6, p. 1054-1072Article in journal (Refereed)
    Abstract [en]

    The Skellefte district in northern Sweden is a ca. 1.9 Ga, extensively mineralized, mainly felsic, submarine volcanic belt. Within the district, the volcanic rocks (Skellefte Group) are overlain by turbiditic sedimentary rocks and coarser clastic rocks, as well as younger, mainly mafic, volcanic rocks (Vargfors Group). To the north, subaerial volcanic rocks of the Arvidsjaur Group are probably coeval with the Vargfors Group. The sedimentation in the Bothnian basin, south of the Skellefte district, appears to have started at ca. 2.0 Ga and continued until ca. 1.86 Ga, as indicated by the presence of granitoids spanning this time interval. The first main magmatic episode in the Skellefte district was a felsic stage at around 1.89 Ga as confirmed by two new U-Pb zircon ages from volcanic rocks situated in the central and eastern part of the district (Bjurvattnet, 1884 + or - 6 Ma; Melestj rn, 1889 + or - 4 Ma). No basement is known to the felsic magmatism, but granitoids occurring to the south of the district, which have been dated at 2.0 to 1.9 Ga, could constitute remnants of a basement which was destroyed by 1.89 Ga arc volcanism within the Skellefte district. The Vargfors Group overlies the Skellefte Group with no major unconformity, and one new age from an ignimbrite in the Vargfors Group (1875 + or - 4 Ma) confirms the temporal relationship with the deposition of subaerial volcanic rocks of the Arvidsjaur Group.An evaluation of age data for the early, synvolcanic (ca. 1890 Ma) Joern-type granitoids suggests that these should be further subdivided. Three different generations of Joern-type granitoids may exist. The GI phase has an age of about 1.89 Ga, the GII and GIII phases within the major Joern batholith probably formed at around 1.87 Ga, and the Siktr sk intrusion in the southern part of the district, has a crystallization age of ca. 1.86 Ga.A number of distinctive isotopic characteristics have been observed, e.g., significant data scatter for Sr whole-rock data, reversely discordant zircon data, and unusually young lower intercept ages for zircon discordia. These features seem to relate preferentially to volcanic rocks, and it is suggested that this behavior is due to Phanerozoic hydrothermal processes that have mobilized elements at different scales. Upper intercepts for zircon discordia, however, are with one exception thought to represent true crystallization ages. The 1847 + or - 3 Ma age for a mass flow at Petiktr sk, as defined by a three-point discordia, is for geologic reasons too young, but a considerably higher (super 207) Pb/ (super 206) Pb age at 1890 Ma for one zircon fraction is more consistent with the field relationships.Volcanic-hosted massive sulfide ores occur in the upper part of the volcanic sequence of the Skellefte Group and, in some cases, also in the lower part of the Vargfors Group. A good approximation of the age of massive ore formation is provided by the age of the host rocks. It is suggested that two main depositional stages of massive ore occurred at ca. 1885 to 1880 Ma and at ca. 1875 Ma. Gold occurs in two principal settings, as a constituent in the volcanic-hosted massive sulfide ores, and related to quartz veins found both in intrusive and supracrustal rocks. In the massive ores, gold was probably emplaced in connection with the hydrothermal processes which concentrated the base metals. Gold in some major intrusive-related Au deposits (e.g., Bjoerkdal) is likely to have concentrated at a premetamorphic stage, tentatively at 1.87 Ga, and still other Au ores (e.g., Boliden) may be epithermal in origin and were possibly formed at a relatively late stage at ca. 1.85 Ga. Later, during peak metamorphic conditions, some mesothermal Au-As vein deposits (e.g., Grundfors) formed at ca. 1.84 to 1.82 Ga.

  • 46.
    Björklund, Lennart
    et al.
    Gothenburg University.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Geochemistry and tectonic setting of the Orvar Hill mafic volcanic rocks of the Tiveden area, south-central Sweden1997In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 119, no 2, p. 127-134Article in journal (Refereed)
    Abstract [en]

    The Orvar Hill formation in Tiveden, south-central Sweden, constitutes a unique low-strain window of well preserved Svecofennian mafic volcanic rocks on the southwestern border of the Svecokarelian orogen. The area can be considered as the southwestern border of the Bergslagen region of the Svecokarelian orogen. The Orvar Hill formation consists of coherent pillowed and non-pillowed basalts alternating with mafic volcaniclastic racks in the lower part of the Lindberga supracrustal succession. Only minor felsic volcanic rocks occur in the upper part. Quartz-bearing metagreywackes comprise the top part of the Lindberga supracrustal succession. Geochemistry of lavas and volcaniclastic rocks suggests that the Orvar Hill mafic volcanic rocks were emplaced in a volcanic-are setting. This demonstrates that the Tiveden supracrustal units probably formed in response to volcanism related to subduction. The Tiveden area may thus represent a 1.89 Ga primitive, sediment-starved volcanic are at the margin of the continental volcanic are of the Bergslagen district. The relationship between Tiveden and Bergslagen at the time of formation is not clear and Tiveden may represent a remnant of an are that accreted to a continent at c. 1.88-1.86 Ga.

  • 47.
    Chmielowski, Riia
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Jansson, Nils
    Persson, Mac Fjellerad
    Boliden Mines.
    Fagerström, Pia
    Boliden Mines.
    Weihed, Pär
    Luleå tekniska universitet.
    3D geochemical modelling of hydrothermal alteration related to 1.89 Ga VHMS-type deposits, Kristineberg area, Skellefte District2013In: 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. 66-69Conference paper (Refereed)
    Abstract [en]

    A 3D geochemical model of the Kristineberg area of the Skellefte District, Sweden, is currently under construction, utilizing data from more than 1600 regionally distributed whole-rock lithogeochemical samples. The model will improve our understanding of the formation the VHMS deposits in this area. The model is built by mapping geochemical variations in 3D, and using this as a basis for modelling hydrothermal alteration in the unsampled portions of the rock column. A better understanding of the geometry, intensity, vectors of transport, and zonation of the hydrothermal zones in 3D will aid deep exploration for massive sulphide deposits in the Kristineberg area, and may potentially lead to new discoveries.

  • 48.
    Dehghannejad, A.
    et al.
    Uppsala University.
    Juhlin, C.
    Uppsala University.
    Malehmir, A.
    Uppsala University.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    High-resolution reflection seismic imaging in the Kristineberg mining area, Northern Sweden2010In: 72nd European Association of Geoscientists and Engineers conference and exhibition 2010: Barcelona, 14 - 17 June 2010, Curran Associates, Inc. , 2010, p. 5368-5371Conference paper (Refereed)
    Abstract [en]

    The Kristineberg mining area is located in the western part of the Skellefte Ore District, one of the most important mining districts in Europe. As a part of a 4D geologic modeling project, two new reflection seismic profiles were acquired. Although the structural geology is complex, the processed seismic data reveal a series of steeply dipping to sub-horizontal reflections, some of which reach the surface and allow correlation with surface geology. Reflection modeling was carried out to obtain the 3D orientation of the main reflections and to provide insight into the possible contribution of out-of-the-plane reflections. The new reflection seismic profiles have improved our understanding of shallow geological structures in the area and in conjunction with recently acquired potential field data, magnetotelluric data and geological observations will help to refine previous 3D geologic modeling interpretations that were aimed at larger scale structures.

  • 49.
    Dehghannejad, M.
    et al.
    Uppsala universitet.
    Juhlin, C.
    Uppsala universitet.
    Malehmir, A.
    Uppsala universitet.
    Weihed, Pär
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    High-resolution reflection seismic imaging in the Skellefte ore district: a contribution to 4D geologic modeling2009In: Geophysical Research Abstracts: Vol. 11, EGU2009-4894, 2009, 2009Conference paper (Other academic)
    Abstract [en]

    The Kristineberg VHMS (volcanic-hosted massive sulfide) mining area is located in the western part of the Skellefte Ore District, the most important metallogenic zone in northern Sweden. The area has been the subject of several geological and geophysical studies with the aim of understanding the contact relationships between the ore bearing volcanic and volcanosedimentary formations and the surrounding rocks. To establish the structural geologic framework at depth, two new reflection seismic profiles, a N-S directed high resolution one with a length of about 6.3 km and an E-W directed one perpendicular to the high-resolution profile with a length of about 13 km were acquired in 2008. Although the structural geology is complex, a preliminary stacked section of the high-resolution profile reveals a series of steeply dipping to sub-horizontal reflections in the southern and northern parts of the profile, many of which can be traced to the surface for correlation with surface geology. Several reflections appear to be consistent with reflections observed in two previously acquired profiles in the study area. The new reflection seismic results will be integrated with the previous reflection seismic results, potential field modeling, magnetotelluric data and geological observations to improve earlier geological interpretations that led to a pilot 3D geologic model of the study area.

  • 50.
    Dehghannejad, M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Weihed, P.
    Luleå University of Technology.
    High-resolution reflection seismic imaging in the Kristineberg mining area, Northern Sweden2010In: Society of Petroleum Engineers - 72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010 - Incorporating SPE EUROPEC 2010, Barcelona: Curran Associates, Inc., 2010, Vol. 7, p. 5368-5371Conference paper (Refereed)
    Abstract [en]

    The Kristineberg mining area is located in the western part of the Skellefte Ore District, one of the most important mining districts in Europe. As a part of a 4D geologic modeling project, two new reflection seismic profiles were acquired. Although the structural geology is complex, the processed seismic data reveal a series of steeply dipping to sub-horizontal reflections, some of which reach the surface and allow correlation with surface geology. Reflection modeling was carried out to obtain the 3D orientation of the main reflections and to provide insight into the possible contribution of out-of-the-plane reflections. The new reflection seismic profiles have improved our understanding of shallow geological structures in the area and in conjunction with recently acquired potential field data, magnetotelluric data and geological observations will help to refine previous 3D geologic modeling interpretations that were aimed at larger scale structures.

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