Change search
Refine search result
3456789 251 - 300 of 544
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 251.
    Lund, Cecilia
    et al.
    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.
    Oxide mineralogy and magnetite chemistry of the Malmberget apatite iron ore, Northern Norr2013In: 12th Biennial SGA Meeting: Mineral deposit research for a high-tech world, Uppsala: Geological Society of Sweden , 2013, p. 273-276Conference paper (Refereed)
    Abstract [en]

    The Malmberget deposit has produced morethan 600 Mt of ore and comprises several ore bodies thatexhibit different mineralogical, chemical and structuralfeatures. In the eastern part, the ore bodies occur asmassive lenses of magnetite surrounded by ore breccia,while the western part is characterized by hematitedominated ores. In contrast to most other apatite iron oresin Northern Norrbotten, the Malmberget deposit have beenstrongly affected by deformation, metamorphicrecrystallization and felsic intrusions.Variations in whole rock chemistry of the ores aremainly reflecting primary features with different signaturesfor massive ore and ore breccia, but also indicatingdifferent types of massive ore. Magnetite from ore brecciahave low content of trace elements similar to magnetitefrom IOCG deposits and may have formed byhydrothermal processes while magnetite in massive oreshow chemical characteristics typical for apatite iron ores.The chemistry of magnetite has in various extentsbeen modified due to element redistribution duringmetamorphic recrystallization and oxidation. Mostsignificant is the preferential partition of Ti and to someextent V into porphyroblasts of hematite. The formation ofilmenite and rutile affects the chemistry of magnetite andgives it a lower content of Ti and V and a signatureresembling magnetite from IOCG deposits.

  • 252.
    Lund, Cecilia
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Martinsson, Olof
    Trace-element chemistry of magnetite from the Malmberget apatite-iron deposit2008Conference paper (Other academic)
    Abstract [en]

    Iron is the most used metal and it is mined from several different types of deposits. Those of a chemical-sedimentary origin dominate, but also deposits of hydrothermal or magmatic origin are important in some parts of the world. Due to an expanding market of iron ore and increased customer demands on product quality the producers has to meet this with a more detailed knowledge of their resources, including trace element composition of the iron oxides.Sweden is Europe's most important producer of iron ore with two large underground mines in Kiruna and Malmberget operated by LKAB. Both deposits are apatite iron ores, an ore type that is common in northern Sweden but rare in other parts of the world. These two world class deposits have a similar origin and were formed by magmatic-hydrothermal process at 1.89-1.88 Ga. However, the Malmberget ore is more strongly affected by later metamorphose, deformation and intrusion of granitic rocks.More than 20 different tabular to stock shaped ore bodies are known at Malmberget, occupying an area of 2.5 x 5km. The Malmberget deposit was probably from the beginning a more or less continuous ore lens which were exposed for at least two phases of folding and metamorphism. By strong ductile deformation it was torn into several lenses that today occupy a large-scale fold structure were the individual ore bodies stretches parallel to the fold axis, which plunge 40º-50º towards SSW. Due to the strong metamorphic overprinting of the area, the ore minerals are recrystallised, coarse grained, and elongated in the direction of the lineation of the rocks.The iron ore minerals are both magnetite (Fe3O4) and hematite (Fe2O3) with magnetite as the only iron oxide in most major ore bodies. Hematite dominates some minor ore bodies and is mixed with magnetite in others. The main gangue minerals are apatite, amphibole, pyroxene, feldspars, quartz and biotite. Among the accessory minerals are pyrite, chalcopyrite, titanite, zircons and calcite most common. Each ore body is characterised by its own mineral, chemical and textural properties. Magnetite belongs to the spinel group of minerals and besides the ferrides it may also contain Al and Mg substituting for Fe. Apatite iron ores, including the Malmberget deposit, are characterized by magnetite chemistry different to most other iron deposits. They typically have high vanadium content similar to magmatic segregations of magnetite in mafic rocks but a Ti content that is between magmatic and sedimentary iron deposits. Microprobe analyses of magnetite of different textures and from different ore types indicate that magnetite is not uniform in composition and the content of e.g. Al and Mg seem to be largely controlled by local chemical conditions with Al most enriched in ore of breccia style while Mg is highest in magnetite from massive ore.

  • 253.
    Lund, Cecilia
    et al.
    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.
    Lindberg, Therese
    LKAB, Research & Development, 983 81 Malmberget.
    Mineralogical-textural characterisation of different apatite-iron ore bodies, Malmberget deposit, Sweden, treated in a sorting process in laboratory scale2010Conference paper (Other academic)
    Abstract [en]

    The Malmberget apatite iron ore deposit encloses more than twenty ore bodies which are mined separately but are blended in the mine before it is hoisted up to the sorting plant. The geology of the deposit shows metamorphic overprints and strong alteration which makes each individual ore body heterogeneous in its composition. In this study the aim is to be able to identify and quantify important mineralogical and textural characters of each ore body which will be part and impact the upgrading process. Two different ores bodies were processed in order to simulate a dry sorting process by bench scale measurements. The analytical methods for quantitative characterisation were optical microscopy and QEMSCAN®. Preliminary results show both differences and similarities between the ore bodies. The mineralogy composition differs between the ore bodies but the most important mineral associations for both ore bodies are binary magnetite/feldspar and magnetite/FeTi-oxides. The magnetite liberation is high for both ore bodies.

  • 254.
    Lundberg, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Division of Operation and Maintenance, Luleå University of Technology.
    Rantatalo, Matti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Division of Operation and Maintenance, Luleå University of Technology.
    Wanhainen, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Division of Geosciences and Environmental Engineering, Luleå University of Technology.
    Casselgren, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics. Division of Fluid and Experimental Mechanics, Luleå University of Technology.
    Measurements of friction coefficients between rails lubricated with a friction modifier and the wheels of an IORE locomotive during real working conditions2015In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 324-325, p. 109-117Article in journal (Refereed)
    Abstract [en]

    The real friction coefficients between the rails and the wheels on a 360. t and 10,800. kW IORE locomotive were measured using the locomotive[U+05F3]s in-built traction force measurement system. The locomotive consisted of two pair-connected locomotives had a CoCo+CoCo bogie configuration, and hauled a fully loaded set of 68 ore wagons (120. t/wagon). The measurements were performed both on rails in a dry condition and on rails lubricated with a water-based top-of-rail (ToR) friction modifier on the Iron Ore Line between the cities of Kiruna and Narvik in Northern Sweden and Norway, respectively. Since full-scale measurements like these are costly, the friction coefficients were also measured at the same time and place using a conventional hand-operated tribometer, with and without the ToR friction modifier. The most important results are that the real friction coefficient is definitely not constant and is surprisingly low (0.10-0.25) when the ToR friction modifier is used, and that it is also significantly dependent on the amount of ToR friction modifier. A large amount will reduce the friction coefficient. Furthermore, it is concluded that the real friction coefficients are in general lower than the friction coefficients measured with the hand-operated tribometer. A final remark is thus that the use of a water-based ToR friction modifier can give excessively low friction, which can result in unacceptably long braking distances.

  • 255.
    Lundmark, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Vaikijaur, a palaeoproteroic Cu-Au porphyry style mineralization in the Jokkmokk granitoid at the archaean-proterozoic boundary in northern Sweden2003Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Jokkmokk granitoid is exposed in a plutonic massif northwest of Jokkmokk in northern Norrbotten. It is light grey to white, fine-grained, with megacrysts of feldspar and glomeroporphyritic hornblende and biotite. Small enclaves of mafic rocks and synplutonic mafic dykes are products of mingling with a coeval and possibly cogenetic mafic magma. A couple of smaller occurrences of Jokkmokk-type granitoid are known south of Jokkmokk. All are spatially associated with metasedimentary rocks of the Norvijaur formation. The Jokkmokk granitoid was previously considered to belong to the c.1.8 Ga Lina S-type intrusive suite, but the Jokkmokk granitoid has a unique calc-alkaline to alkali-calcic, metaluminous to weakly peraluminous character with a steep REE-profile, positive Eu-anomaly, and a low Zr content. U-Pb TIMS zircon dating of the Jokkmokk granitoid gives an age of 1882 +-19 Ma which is within limits the same age as that obtained for the Haparanda suite, but contrary to the Haparanda suite it has a positive epsilon Nd value of 2.8, indicating a more juvenile Palaeoproterozoic character similar to the Jörn suite in the Skellefte district. Compared to other granitoids in the Jokkmokk area it is geochemically most similar to the older 1.93 Ga Norvijaur granitoid. This type of magma seems to be restricted to the palaeoboundary between the Archaean craton in the north and Palaeoproterozoic juvenile crust in the south. Spatial correlation with low angle, south dipping, WNW-trending shear zones and NNE-trending subvertical shear zones, highlight the possibility that this unique magma type is related to transtension in the overriding plate and partial melting in sub-arc mantle wedge during NE directed subduction processes related to the early stages of the Svecokarelian orogen. Possibly magma was ponded in shallow chambers below pull-apart basins in a transtensional regime. This type of setting has been advocated as the potentially most favourable tectonic setting for porphyry copper formation. The Cu-Au-(Mo) mineralization at Vaikijaur northwest of Jokkmokk covers an area of 2 by 3 km within the western part of the Jokkmokk granitoid pluton. The mineralization is characterized by dissemination and veinlets of chalcopyrite, pyrite, molybdenite, magnetite, pyrrhotite, and sphalerite. Quartz stockwork with or without sulphides occur in the mineralization. Gold occurs as free grains in silicate matrix, in contact with chalcopyrite, pyrite and sphalerite, or as inclusions within the chalcopyrite. Porphyritic mafic dykes, with phenocrysts of plagioclase and porphyroblasts of magnetite, follow fractures in an almost concentric pattern in the mineralized area. The fabric in the granitoid, dykes, and mineralization shows that the mineralization predates the main regional deformation. Geophysical ground measurements indicate a strong conductive central zone in the mineralized area bordered by both conductive and magnetic zones. Restricted drilling campaigns were carried out in these zones in 1981-83. Chemical and mineralogical analyses of drillcores and outcrops indicate several stages of alteration and a metal zoning at Vaikijaur. The entire mineralized area is affected by potassic alteration. Hornblende is partly or totally replaced by biotite, and plagioclase is partly replaced by microcline. In irregular propylitic alteration zones that overprint the potassic alteration, epidote has replaced plagioclase and hornblende is replaced by epidote and biotite. Biotite is partly chloritized and calcite is common. Light-coloured, irregular phyllic alteration zones overprint the former alteration types, with quartz and sericite replacing plagioclase. A metal zoning can be seen with a pyrite-rich inner part of the mineralized area surrounded by a zone with pyrite, chalcopyrite and gold. Molybdenite occurs in an irregular pattern within the chalcopyrite zone, magnetite is present in both the pyrite and the chalcopyrite zone.

  • 256.
    Lundmark, Christina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Stein, Holly
    Colorado State University.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The geology and Re-Os geochronology of the Palaeoproterozoic Vaikijaur Cu-Au-(Mo) porphyry style deposit in the Jokkmokk granitoid, northern Sweden2005In: Mineralium Deposita, ISSN 0026-4598, E-ISSN 1432-1866, Vol. 40, no 4, p. 396-408Article in journal (Refereed)
    Abstract [en]

    The Vaikijaur Cu–Au–(Mo) deposit is located in the ca. 1.88 Ga calc-alkaline Jokkmokk granitoid near the Archaean–Proterozoic palaeoboundary within the Fennoscandian shield of northern Sweden. The Skellefte VMS district lies immediately to the south and the northern Norrbotten Fe-oxide–Cu–Au deposits to the north. The Vaikijaur deposit occupies an area of 2×3 km within the Jokkmokk granitoid and includes stockwork quartz-sulphide veinlets and disseminated chalcopyrite, pyrite, gold, molybdenite, magnetite, and pyrrhotite. Porphyritic mafic dykes were emplaced along fractures in a ring dyke pattern. The Jokkmokk granitoid, dykes, and the mineralized area are foliated, indicating that mineralization predated the main regional deformation. The mineralized area is characterized by strong potassic alteration. Phyllic and propylitic alteration zones are also present. A pyrite-rich inner core is surrounded by a concentric zone with pyrite, chalcopyrite, and gold. Molybdenite is distributed irregularly throughout the chalcopyrite zone. Geophysical data indicate a strongly conductive central zone in the mineralized area bordered by conductive and high magnetic zones. Five high precision Re–Os age determinations for three molybdenite occurrences from outcrop and drill core samples constrain the age of porphyry-style Cu–Au–(Mo) mineralization to between 1889±10 and 1868±6 Ma. A younger molybdenite is associated with a much later metamorphic event at about 1750 Ma. These data suggest that primary porphyry-style mineralization was associated with calc-alkaline magmatism within the Archaean–Proterozoic boundary zone at ca. 1.89–1.87 Ga.

  • 257.
    Lundmark, Christina
    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.
    Metallogeny associated with accretionary and subduction related processes at 1.9-1.8 Ga in northern Sweden with special emphasis on intrusion-hosted Cu-Au+ or -Fe-oxide mineralizations2001In: 2001: a hydrothermal odyssey; extended conference abstracts / [ed] Patrick J. Williams, James Cook University of North Queensland , 2001, p. 219-220Conference paper (Other academic)
  • 258. Lundmark, Christina
    et al.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Vaikijaur, an intrusion hosted, porphyry style, Palaeoproterozoic Cu-Au mineralization at the Archaean–Proterozoic boundary in northern Sweden2003In: Mineral Exploration and Sustainable Development: Proceedings of the Seventh Biennial SGA Meeting on Mineral Exploration and Sustainable Development / [ed] D.G. Eliopoulos, Rotterdam: Millpress , 2003, p. 1079-1082Conference paper (Refereed)
  • 259. Lundmark, Christina
    et al.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Billström, Kjell
    Swedish Museum of Natural History.
    The Jokkmokk granitoid: an example of 1.88 Ga juvenile magmatism at the Archaean-Proterozoic border in northern Sweden2005In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 127, no 2, p. 83-98Article in journal (Refereed)
    Abstract [en]

    The Jokkmokk granitoid is exposed in a large plutonic massif northwest of Jokkmokk in northern Sweden. It is light grey to white, fine-grained, with megacrysts of feldspar and glomeroporphyritic hornblende and biotite. Small enclaves of mafic rocks and synplutonic mafic dykes are products of mingling with a coeval and possibly cogenetic mafic magma. The Jokkmokk granitoid was previously considered to belong to the c. 1.8 Ga Lina S-type intrusive suite, but the Jokkmokk granitoid has a unique calc-alkaline to alkali-calcic, metaluminous to weakly peraluminous, character with a moderate LREE enrichment and a flat HREE pattern, and a flat to slightly positive Eu-anomaly. U–Pb TIMS zircon dating of the Jokkmokk granitoid gives an age of 1883±15 Ma which is coeval with the emplacement of the Haparanda suite, but contrary to the Haparanda suite it displays a positive _Nd(t) value of 2.8, indicating a more juvenile Palaeoproterozoic character similar to the Jörn suite in the Skellefte district. This type of magma seems to be restricted to the palaeoboundary between the Archaean craton in the north and Palaeoproterozoic juvenile crust in the south. Spatial correlation with low angle, south dipping, WNW-trending shear zones and NNE-trending subvertical shear zones, highlight the possibility that this unique magma type is related to transtension in the overriding plate and partial melting in a sub-arc mantle wedge during NE-directed subduction processes related to the early stages of the Svecokarelian orogen. This type of setting has been advocated as the potentially most favourable tectonic setting for porphyry copper formation

  • 260. Lundquist, T.
    et al.
    Böe, R.
    Kousa, A. J.
    Lukkarinen, H.
    Lutro, O.
    Roberts, D.
    Solli, A.
    Stephens, Michael B.
    Sveriges Geologiska Undersökning.
    Weihed, Pär
    Bedrock map of central Fennoscandia1996Other (Other academic)
  • 261. Lundquist, T.
    et al.
    Böe, R.
    Kousa, A. J.
    Lukkarinen, H.
    Lutro, O.
    Roberts, D.
    Solli, A.
    Stephens, Michael B.
    Sveriges Geologiska Undersökning.
    Weihed, Pär
    Metamorphic, structural and isotope age map of central Fennoscandia1998Other (Other academic)
  • 262. Lundquist, T.
    et al.
    Böe, R.
    Kousa, A. J.
    Lukkarinen, J.
    Lutro, O.
    Roberts, D.
    Solli, A.
    Weihed, Pär
    Bedrock map of the Midnorden area: Scale 1:1 000 0001996Other (Other academic)
  • 263.
    Luth, Stefan
    et al.
    Department of Mineral Resources, Geological Survey of Sweden, Sweden.
    Sahlström, Fredrik
    Department of Earth Sciences, Uppsala University, Sweden.
    Jansson, Nils
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Jönberger, Johan
    Department of Mineral Resources, Geological Survey of Sweden, Sweden.
    Sädbom, Stefan
    Lovisagruvan AB.
    Landström, Erik
    Orexplore AB.
    Bergqvist, Mikael
    Orexplore AB.
    Arvanitidis, Nikolaos
    Department of Mineral Resources, Geological Survey of Sweden, Sweden.
    Arvidsson, Ronald
    Department of Mineral Resources, Geological Survey of Sweden, Sweden.
    Building 3D geomodels using XRF-XRT-generated drillcore data: The Lovisa-Håkansboda base metal- and Stråssa-Blanka iron deposits in Bergslagen, Sweden2019In: Life with Ore Deposits on Earth: Proceedings of the 15th SGA Biennial Meeting 2019, Glasgow, Scotland, 2019, Vol. 3, s. 1282-1485, 2019Conference paper (Refereed)
    Abstract [en]

    3D geological models based on data fromgeological field observations, magnetic airborne surveys and combined XRF-XRT scanning of drill core arepresented for the Lovisa-Håkansboda and the Stråssa-Blanka mineral systems (1.9 - 1.8 Ga). At first, the 3D architecture of several deposits was derived primarilyfrom surface data and mine-level maps. Secondly, geochemical and structural constrains from drill corescanning (XRF-XRT) were used to refine the modelslocally to a detailed, in-mine scale. The constructed models were then placed in a regional context providingvaluable insight on the area’s local and regional deformation pattern. All modelled deposits are plunging 50-60° towards the south-southeast reflecting D2 deformation (vertical shearing) during NW-SE-directed shortening and are locally overprinted by D3 (lateral shearing) during N-S-directed shortening.

  • 264.
    Lutro, O.
    et al.
    Geological Survey of Norway.
    Roberts, D.
    Geological Survey of Norway.
    Solli, A.
    Geological Survey of Norway.
    Lundqvist, T.
    Geological Survey of Sweden.
    Stephens, M. B.
    Geological Survey of Sweden.
    Weihed, Pär
    Kousa, J.
    Geological Survey of Finland.
    Lukkarinen, H.
    Geological Survey of Finland.
    Luukas, J.
    Geological Survey of Finland.
    Metamorphic structural and isotopic age map of central Fennoscandia1995In: Vol. 7, no Suppl. 1, p. 277-277Article in journal (Other academic)
  • 265. Malehmir, A.
    et al.
    Tryggvason, A.
    Juhlin, C.
    Rodriguez, J.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Seismic imaging in the Skellefte ore district, northern Sweden2005In: 20th World Mining Congress, November 7-11, 2005, Tehran, Iran: mining and sustainable development, Teheran: Geological Survey of Iran , 2005, p. 399-404Conference paper (Refereed)
    Abstract [en]

    In the western part of the Skellefte ore district, which is the most important metallogenic zone in Northern Sweden, several world class mines, e.g., the Kristineberg VMS mine (20.1mt, Cu-Zn-Pb-Ag-Au) are situated. In order to understand why these deposits occur where they do, it is important to understand the crustal architecture of the region. One way to understand the contact relationships between the ore bearing volcanic formations and the surrounding rocks is to develop a detailed 3-D geological model of the region. To establish the structural geologic framework at depth, new seismic reflection data were acquired along two profiles in the Kristineberg area in late August and early September 2003. Data along the two seismic profiles (Profile 1 and Profile 5), each about 25 km long and running in parallel, were collected with the purpose of obtaining high resolution images of the top 10 km of the crust. Although the structural geology is very complex, preliminary stacked sections of the data have revealed numerous reflections which can be correlated with surface geology. Results along Profile 1, which passes on top of the Kristineberg mine show the mine to be located in a major synform extending down to about 2.5-3 km depth. The structure and stratigraphy of the Kristineberg area have been debated for many years. Our seismic results suggest that the deposits occur on the northern limb of a regional syncline. The results help to identify new prospective areas, both down-plunge from known ores, and on the southern limb of the ore-bearing syncline. The results for Profile 5 show that the Revsund granite can have a thickness about 3-3.5 km but not more. Ultramafic rocks are imaged clearly. Diffraction patterns can be interpreted as orienting from either a mafic-ultramafic intrusion or a mineralization zone. A detailed study has to be done in order to determine the source of this reflectivity. In this study seismic reflection profiling has been particularly effective for imaging the major structures around the ore body, demonstrating that the seismic-reflection technique can be used for delineating complex structures that are significant in mineral exploration.

  • 266.
    Malehmir, A.
    et al.
    Uppsala University.
    Tryggvason, A.
    Uppsala University.
    Juhlin, C.
    Uppsala University.
    Rodriguez-Tablante, J.
    Uppsala University.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Seismic imaging and potential field modelling to delineate structures hosting VHMS deposits in the Skellefte Ore District, northern Sweden2006In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 426, no 3-4, p. 319-334Article in journal (Refereed)
    Abstract [en]

    Skellefte District in northern Sweden is a roughly 150 by 50 km2 large early Proterozoic massive sulphide belt. Based on high-resolution reflection seismic data along two parallel seismic profiles, potential field modeling has been carried out and two geologic cross sections have been constructed that are consistent with the available geophysical data as well as surface geologic observations. The combined modelling suggests that the Kristineberg deposit occurs on the northern limb of a regional E–W striking syncline. The interpretations help to identify new prospective areas, both down-plunge from known ores, and on the ore-bearing horizon on the southern limb of the syncline. The new results suggest that the post-orogenic Revsund granites can be divided into two major types of intrusives, those which are intruded as domes/stokes with a maximum present day thickness of about 3–3.5 km and those which are intruded as thin sheets, with a maximum thickness of a few hundred meters. The margins of the intrusions are generally inclined inwards, suggesting that the current erosion level is near the middle, or toward the base, of the granites. The contact between the Skellefte volcanic rocks and the Bothnian Basin has been interpreted as a thrust fault. We also suggest that crustal thickening predates the Skellefte volcanism and that the interpreted Bothnian Basin rocks are either a structural basement or a separate terrane to the Skellefte volcanism. Diffraction patterns in the reflection seismic data can be interpreted as originating from either a mafic–ultramafic intrusion or a mineralization zone, similar to observations elsewhere in the world. The results obtained in this study have greatly improved our understanding of the tectonostratigraphic framework and architecture of the poly-deformed c. 1.9 Ga Skellefte VHMS belt and is a key step towards building a 3D geological model in the area.

  • 267.
    Malehmir, Alireza
    et al.
    Department of Earth Sciences, Uppsala University.
    Tryggvason, Ari
    Department of Earth Sciences, Uppsala University.
    Lickorish, Henry
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Regional structural profiles in the western part of the Palaeoproterozoic Skellefte ore district, northern Sweden2007In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 159, no 1-2, p. 1-18Article in journal (Refereed)
    Abstract [en]

    The Kristineberg mining area is situated in the western part of the Palaeoproterozoic Skellefte Ore District, northern Sweden, and is well known for its VHMS base-metal and gold deposits. This paper presents five upper crustal geological cross sections that have been constructed and mainly constrained by seismic reflection data, potential field modeling as well as geological field observations. These profiles are visualized in 3D to highlight the three dimensionality and internal consistency of structures across the region. The resulting structural model for the Skellefte volcanics and overlying metasediments comprises two thrust-sheets that expose the Skellefte volcanics in the cores of hanging-wall anticlinal structures. A shear-zone is imaged as a band of seismic reflectivity terminated by the southern Revsund granite unit. Another shear-zone, possibly a continuation of the Skellefte Shear Zone (SSZ) runs through the centre of the region and accounts for some of the structural complexity and shearing observed between the two anticlinal exposures of the volcanics. Additional smaller scale shear-zones have been identified from geological and geophysical mapping within the main structural blocks of the Skellefte volcanics. The Mala volcanic rocks in the north are separated from the Skellefte volcanics by a fault that cuts discordant to the strike of the Mala volcanics. A structural basement has been proposed to the Skellefte volcanics, constrained by seismic reflection data. Exposures of Bothnian Basin rocks south of the Revsund granite outcrops, suggest that the domain beneath the north dipping reflectivity is associated with Bothnian Basin stratigraphy. The preferred interpretation for the contact between the Skellefte volcanics and the Bothnian Basin rocks is a thrust fault that brings the felsic volcanic rocks over the metasedimentary domain. The Revsund granites are divided into two major groups based on their present day thickness and shapes. Although parts of the Viterliden intrusion are almost undeformed, it is cut by a series of shear-zones, causing the magnetic lineations seen within these rocks. The structural profiles presented demonstrate that the Kristineberg ore is situated in the northern limb of a local synformal structure. The new crustal-scale structural model demonstrates the potential of integrating geophysical and geological data when modelling structures hosting mineralization in a complex region like the Skellefte District. The structural profiles presented in this paper, have greatly improved our understanding of the 3D tectonostratigraphy and architecture of the poly-deformed ca. 1.9 Ga the Skellefte Ore District.

  • 268. Malinovskiy, Dmitry
    et al.
    Hammarlund, Dan
    Lunds universitet.
    Ilyashuk, Boris
    Kola Science Centre, Russian Academy of Sciences, Apatity.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Gelting, Johan
    Variations in the isotopic composition of molybdenum in freshwater lake systems2007In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 236, no 3-4, p. 181-198Article in journal (Refereed)
    Abstract [en]

    Variations in molybdenum isotopic composition, spanning the range of ≈ 2.3‰ in the terms of 97Mo/95Mo ratio, have been measured in sediment cores from three lakes in northern Sweden and north-western Russia. These variations have been produced by both isotopically variable input of Mo into the lakes due to Mo isotopic heterogeneity of bedrock in the drainage basins and fractionation in the lake systems due to temporal variations in limnological conditions. Mo isotope abundances of bedrock in the lake drainage basins have been documented by analysis of Mo isotope ratios of a suite of molybdenite occurrences collected in the studied area and of detrital fractions of the lake sediment cores. The median δ97Mo value of the investigated molybdenites is 0.26‰ with standard deviation of 0.43‰ (n = 19), whereas the median δ97Mo value of detrital sediment fractions from two lakes is - 0.40‰ with standard deviation of 0.36‰ (n = 15). The isotopic composition of Mo in the sediment cores has been found to be dependent on redox conditions of the water columns and the dominant type of scavenging phases. Hydrous Fe oxides have been shown to be an efficient scavenger of Mo from porewater under oxic conditions. Oxidative precipitation of Fe(II) in the sediments resulted in co-precipitation of Mo and significant authigenic enrichment at the redox boundary. In spite of a pronounced increase in Mo concentration associated with Fe oxides at the redox boundary the isotopic composition of Mo in this zone varies insignificantly, suggesting little or no isotope fractionation during scavenging of Mo by hydrous Fe oxides. In a lake with anoxic bottom water a chironomid-inferred reconstruction of O2 conditions in the bottom water through the Holocene indicates that increased O2 concentrations are generally associated with low δ97Mo/95Mo values of the sediments, whereas lowered O2 contents of the bottom water are accompanied by relatively high δ97Mo/95Mo values, thus confirming the potential of Mo isotope data to be a proxy for redox conditions of overlying waters. However, it is pointed out that other processes including input of isotopically heterogeneous Mo and Mn cycling in the redox-stratified water column can be a primary cause of variations in Mo isotopic compositions of lake sediments.

  • 269.
    Marschik, Robert
    et al.
    Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität, München.
    Bauer, Tobias
    Hensler, Anna-Sophie
    Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität, München.
    Skarpelis, Nikos
    Department of Geology and Geoenvironment, University of Athens.
    Hölzl, Stefan
    Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität, München; Bayerische Staatssammlung für Paläontologie und Geologie, München.
    Isotope geochemistry of the Pb-Zn-Ba(-Ag-Au) mineralization at Triades-Galana, Milos Island, Greece2010In: Resource geology (Tokyo. 1998), ISSN 1344-1698, E-ISSN 1751-3928, Vol. 60, no 4, p. 335-347Article in journal (Refereed)
    Abstract [en]

    The Pb-Zn-Ba(-Ag-Au) mineralization in the Triades and Galana mine areas is hosted in 2.5-1.4 Ma pyroclastic rocks, and structurally controlled mostly by NE-SW or N-S trending brittle faults. Proximal pervasive silica and distal pervasive sericite-illite alteration are the two main alteration types present at the surface. The distribution of mineralization-alteration in the district suggests at least two hydrothermal events or that hydrothermal activity lasted longer at Galana. The Sr isotope signature of sphalerite and barite (87Sr/86Sr = 0.709162 to 0.710214) and calculated oxygen isotope composition of a fluid in equilibrium with barite and associated quartz at temperatures of around 230°C are suggestive of a seawater hydrothermal system and fluid/rock interaction. Lead isotope ratios of galena and sphalerite (206Pb/204Pb from 18.8384 to 18.8711; 207Pb/204Pb from 15.6695 to 15.6976; 208Pb/204Pb from 38.9158 to 39.0161) are similar to those of South Aegean Arc volcanic and Aegean Miocene plutonic rocks, and compatible with Pb derived from an igneous source. Galena and sphalerite from Triades-Galana have δ34SVCDT values ranging from +1 to +3.6‰, whereas barite sulfate shows δ34SVCDT values from +22.8 to +24.4‰. The sulfur isotope signatures of these minerals are explained by seawater sulfate reduction processes. The new analytical data are consistent with a seawater-dominated hydrothermal system and interaction of the hydrothermal fluid with the country rocks, which are the source of the ore metals.

  • 270.
    Martinsson, Evy
    Luleå tekniska universitet.
    Geochemistry and petrogenesis of the Palaeoproterozoic, nickel-copper bearing Lainijaur intrusion, northern Sweden1996In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 118, no 2, p. 97-109Article in journal (Refereed)
  • 271.
    Martinsson, Evy
    Luleå tekniska universitet.
    Geokimisk karaktär av sidoberget till Lainejaur Ni-Cu malm1986In: Abstracts: 17e Nordiska geologmötet, Helsingfors universitet, 12-15.5. 1986, 1986Conference paper (Other academic)
  • 272.
    Martinsson, Evy
    Luleå tekniska universitet.
    Lainijaurintrusionens geokemi: En geokemisk studie av sidoberget till Lainijaur Ni-Cu malm1987Licentiate thesis, monograph (Other academic)
  • 273.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Apatite-iron deposits2007In: Metallogeny and tectonic evolution of the Northern Fennoscandian Shield: field trip guidebook, Espoo: Geological Survey of Finland , 2007, p. 20-21Chapter in book (Other academic)
  • 274.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bispbergs järnmalmsfält: En geologisk och geokemisk studie1987Licentiate thesis, monograph (Other academic)
  • 275.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Diversity and character of apatite iron ores and their relation to epigenetic Cu-Au deposits in the Norrbotten Fe-Cu-Au province, northern Sweden2001In: Abstracts with programs (Geological Society of America), ISSN 0016-7592, Vol. 33, no 6, p. 2-Article in journal (Other academic)
    Abstract [en]

    Norrbotten is an important mining province in northern Sweden, which is dominated by Fe- and Cu-Au deposits. Economically most important for the region are the apatite iron ores with an annual production of c. 31 M ton of Fe-ore and a total production of about 1600 M ton of ore the last 100 years. A Paleoproterozoic succession of greenstones, porphyries and clastic sediments that rests unconformably on a 2.7-2.8 Ga old Archean basement is geologically important in this area. Stratigraphically lowest are 2.5-2.0 Ga old rift-related greenstones. They are followed by c. 1.9 Ga Svecofennian volcanic and sedimentary rocks. Synorogenic 1.89-1.87 Ga plutons range in composition from gabbro to granite, while late orogenic intrusions are dominated by c. 1.79 Ga minimum melt granites and pegmatites. The apatite iron ores in Norrbotten shows a considerable variation in host rock relations, P-content, host rock lithology, associated minor components and host rock alterations. Most occurrences are dominated by either magnetite or hematite. Apatite, actinolite, carbonate and quartz are the main gangue minerals. Sulfides are mostly rare within the ores but may occur in the altered wall rocks. The content of Fe and P varies between 30-70% and 0.05-5%, respectively. A typical geochemical feature is the strong enrichment of REE. Epigenetic Cu-Au occurrences are common in Norrbotten. They are of at least two generations (c. 1.88 and 1.77 Ga) and have formed from highly saline fluids. Limited chronological data indicate a similar c. 1.88 Ga age for the older generation of Cu-Au occurrences and some of the apatite iron ores suggesting a possible genetic relation between Fe-oxide and Cu-Au mineralization. A combination of magmatic processes, deep crustal structures and evaporitic units in the lower part of the Paleoproterozoic succession might be genetically important for both types of occurrences.

  • 276.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Exhaliter vid Skelleftefältets malmer: delprojekt Långdal1987Report (Other academic)
  • 277.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Genesis of the Per Geijer Apatite Iron Ores, Kiruna Area, Northern Sweden2015In: Mineral Resources in a Sustainable World / [ed] A.S. Andre-Mayer; M. Cathelineau; P. Muchez; E. Pirard; S. Sindern, 2015, p. 1107-1110Conference paper (Refereed)
    Abstract [en]

    Apatite iron ores are rather uncommon and the genesis of these deposits has been debated for more than a century. In the Kiruna area in northern Sweden the Per Geijer deposits shows a large variation in mineral composition, structures and textures. Apatite, carbonate and quartz are gangue minerals occurring disseminated in varying amounts in the ore as well as segregations in the form of blebs. Larger accumulations of apatite carbonate-quartz exhibit cutting contacts or mingling structures to the ore. The Per Geijer deposits are interpreted as having formed from iron oxide melts with high content of volatiles. During cooling these iron oxide melts underwent unmixing of volatile rich and iron-poor magma that generated apatite-carbonate-quartz rocks. The volatile components expelled during formation of the apatite iron ores also generated extensive hydrothermal brecciation and alteration in the wall rocks. The alteration is mainly developed in the hanging wall and includes K-feldspar, quartz, sericite, chlorite and carbonates

  • 278.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geokemi och faciesuppbyggnad hos Långdalmalmen, en massiv sulfidmalm i Skelleftefältet1986In: Abstracts: 17e Nordiska geologmötet, Helsingfors universitet, 12-15.5. 1986, 1986Conference paper (Other academic)
  • 279.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geological and geochemical evidence for the genesis of the Viscaria Cu-deposit1989In: New ore types in Northern Fennoscandia: September 26-28, 1989, Luleå University of Technology, Luleå, Sweden, Luleå: Högskolan i Luleå , 1989, p. 25-Conference paper (Other academic)
  • 280.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geology and Metallogeny of the Northern Norrbotten Fe-Cu-Au Province2004In: 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)
  • 281.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geotectonic evolution of Paleoproterozoic greenstones in northern Sweden indicated by lithostratigraphic and geochemical data1999In: Geodynamic evolution and metallogeny of the Central Lapland, Kuhmo and Suomussalmi greenstone belts, Finland, Turku: University of Turku , 1999, p. 78-82Chapter in book (Other academic)
  • 282.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kiskamavaara: a shear zone hosted IOCG-style of Cu-Co-Au deposit in Northern Norrbotten, Sweden2011Conference paper (Refereed)
  • 283.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Mesothermal Cu-Au deposits and hydrothermal alterations in Paleoproterozoic greenstones in northern Sweden1999In: Geodynamic evolution and metallogeny of the Central Lapland, Kuhmo and Suomussalmi greenstone belts, Finland, Turku: University of Turku , 1999, p. 107-111Chapter in book (Other academic)
  • 284.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Metallogeny of the northern Norrbotten Fe-Cu-Au-ore province2000In: Abstract volume & Field trip guidebook / [ed] Pär Weihed; Olof Martinsson, Luleå tekniska universitet, 2000, p. 26-28Conference paper (Other academic)
  • 285.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skarn-like iron deposits2007In: Metallogeny and tectonic evolution of the Northern Fennoscandian Shield: field trip guidebook, Espoo: Geological Survey of Finland , 2007, p. 19-Chapter in book (Other academic)
  • 286.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tectonic setting and metallogeny of the Kiruna greenstones1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Paleoproterozoic Kiruna Greenstones belong to a large c. 2.1 Ga tholeiitic province in the north-eastern part of the Baltic Shield. The mainly basaltic volcanism was related to an event of continental rifting, which ended up with continental rupture. The occurrence of komattites, picrites and thick piles of tholeiites in the northern parts of Sweden, Norway and Finland is in contrast to the sedimentary dominated areas in central-eastern Finland. This suggests the location of a mantle plume to the northern area, which generated the large volumes of mantle melts. The stratigraphical record of the well preserved Kiruna Greenstone Group demonstrates a change from initial clastic sedimentation, evaporate deposition and WPB-type volcanism to later extensive volcanism of flood basalt character. Subsequent crustal thinning generated MORB-type magmas by decompressional mantle melting. The later development of a subaqueous basin was accompanied by a change to explosive volcanism, and large amounts of volcaniclastic material was formed by Surtseyan eruptions. During ocean opening along a line from Ladoga to Lofoten a NNE-directed failed rift-arm was formed. This is expressed by rapid basin subsidence and voluminous eruption of MORB-type pillowlava, which created an anomalous environment of local extent within the greenstone domain. Basin shoaling and subsequent uplift and erosion of the rifted margin marks an end of the rift event. Two different types of economic sulfide deposits occur in the Kiruna Greenstones, syngenetic Cu-(Zn) ores of exhalative origin (Viscaria-type), and epigenetic Cu-Au ores (Pahtohavare-type). Both types are formed from highly saline hydrothermal fluids, but they are clearly different in metal association, ore related alteration and ore character. Conspicuous for the Viscaria-type is the occurrence of stacked blanket-shaped mineralizations of magnetite and sulfides, and the layered structure of high-grade Cu-ore, which is explained by repeated exhalative activity and deposition of the ores in brinepools. The most productive ore was formed in association with the main stage of basin subsidence and MORB-type volcanism in the failed rift. Faults parallel with the rift axis acted as channels for the ore fluids, and controlled the shape and location of brine-pool in which the ore was precipitated. Ores of the Pahtohavare-type have formed in zones of active ductile to brittle shearing. In detail the location of ores are mainly lithologically controlled by black schists, which has acted as chemical traps. The ores are hosted by albite felsites, and surrounded by characteristic zones of scapolite-biotite alteration. Calcopyrite and pyrite are the main ore minerals and they occur mainly as veinlets, veins and matrix to brecciated albite felsite. Ferro-dolomite is a characteristic ore related mineral formed in several generations from early dissemination in albite felsite, gangue to ore minerals and late barren veins. The Viscaria and Pahtohavare deposits are different in many respects to typical massive sulfide deposits and Au-ores in most other greenstone terrains. This is mainly due to their formation from highly saline solution, which is a common feature of both exhalative and epigenetic sulfide deposits formed in continental rift environments. Thus, the existence of evaporitic sediments at the base of the Kiruna Greenstones may be of major metallogenetic importance for this region, serving as a source for saline hydrothermal fluids.

  • 287.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The Narken iron oxide-(Cu) deposits: a link between Kiruna-type iron ore and IOCG-style of mineralization2009In: Smart science for exploration and mining: proceedings of the 10th Biennial SGA Meeting, Townsville, Australia 17th-20th August / [ed] Patrick Williams, James Cook University of North Queensland , 2009Conference paper (Refereed)
    Abstract [en]

    The Northern Norrbotten Ore Province is the type area for iron deposits of Kiruna-type (apatite iron ores). These deposits are mainly hosted by 1.9 Ga Svecofennian porphyries and occur as massive lenses or as breccia style of mineralisation in the Kiruna and Malmberget regions. Just outside this area an unusual type of apatite iron ore occur at Narken. Euhedral crystals of hematite altered magnetite, apatite, and pyrite occur as breccia infill together with tabular hematite, epidote, chlorite and some quartz. The occurrences of iron oxide mineralization are enriched in REE, and contain up to 0.5% Cu but are low in Au. The wall rocks and clasts of these rocks within the breccia bodies are strongly altered by silicification, epidotization and chloritization. Sulphur isotope data and mineral paragenesis indicate increasingly oxidizing conditions during development of the mineralization. Magnetite, apatite and pyrite are early formed minerals, transported to higher levels in the crust by a fluidized hydrothermal system and deposited in breccia bodies where they occur in a xenocrystic manner in a breccia infill of flaky hematite, epidote, chlorite, quartz and minor chalcopyrite. In many respects the Narken deposits are transitional in character to apatite iron ores and IOCG-style mineralization.

  • 288.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The northern Norrbotten ore province, northern Sweden1997In: Research and exploration - where do they meet?: excursion guidebook - B1 - Ore deposits of Lapland in Northern Finland and Sweden / [ed] Esko A. Korkiakoski; Peter Sorjonen-Ward, Espoo: Geological Survey of Finland , 1997, p. 33-36Conference paper (Refereed)
  • 289.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The Pahtohavare Cu-Au deposit and related geological excursion stops in the Kiruna area1997In: Research and exploration - where do they meet?: excursion guidebook : B1 : Ore deposits of Lapland in Northern Finland and Sweden / [ed] Esko A. Korkiakoski; Peter Sorjonen-Ward, Espoo: Geological Survey of Finland , 1997, p. 37-39Conference paper (Refereed)
  • 290.
    Martinsson, Olof
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Allan, Åsa
    Envipro Miljöteknik AB, Linköping.
    Niiranen, Tero
    Northland Exploration Finland.
    Wanhainen, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Eilu, Pasi
    GTK.
    Ojala, Juhani
    GTK.
    Nykänen, Vesa
    GTK.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Iron oxide-Cu-Au deposits in the northern part of the Fennoscandian shield2008Conference paper (Other academic)
    Abstract [en]

    The northern part of the Fennoscandian Shield, which formed during repeated extensional and compressional events at 3.1-1.8 Ga, is an ore province characterized by regionally developed albite and scapolite alteration and the occurrence of world class Fe-oxide (Kiirunavaara) and Cu-Au deposits (Aitik). It host several styles of Fe-oxide-Cu-Au deposits, including skarn and apatite-iron style deposits, many of them with features that also warrant classification as iron oxide-copper-gold (IOCG) deposits.The apatite-iron ores are economically most important with a total production of c. 1900 Mt from 10 mines during the last 100 years and with a total pre-mining resource of c. 4100 Mt. In these deposits, the Fe and P content vary between 30-70 % and 0.05-5 %, respectively. The ore minerals magnetite and hematite occur in lenses or as breccia infill. The ores are usually enriched in LREE, sulphides are rare but subeconomic amounts of Cu may occur.Skarn-like iron occurrences consisting of magnetite and Mg and Ca-Mg silicates have been less important with c. 20 Mt mined from 6 deposits and a pre-mining resource of 760 Mt. Most of them occur as conformable lenses with a banded internal structure. Pyrite, pyrrhotite and minor chalcopyrite are commonly present disseminated or as veinlets. Typical grades are 30-55% Fe, 0.2-3.5 % S, 0.05-0.3% Cu, 0.005-1g/t Au and 0.02-0.2% P. A few of the deposits are also enriched in LREE. Epigenetic Cu±Au occurrences include the porphyry-style giant Aitik deposit with a pre-mining resource of 2000 Mt at 0.3% Cu and 0.2 g/t Au and a total production of 465 Mt. Other deposits vary in style from disseminated to breccia infill or veins. Chalcopyrite is the most important ore mineral but bornite, pyrite, pyrrhotite, magnetite, molybdenite and native gold may occur in varying amounts. The skarn-like ores occur in 2.1Ga Karelian greenstones in association to carbonate rocks, BIF and graphite schist. The apatite iron ores are hosted by 1.9 Ga Svecofennian intermediate to felsic porphyries. The epigenetic Cu±Au deposits occur in both Karelian and Svecofennian volcanic and sedimentary rocks and 1.9 Ga intrusive rocks. The two last type of deposits show similar alteration styles including albite, K-feldspar, biotite, scapolite, carbonate, amphibole and tourmaline, whereas the skarn-like deposits are associated with diopside, amphibole, scapolite and biotite alteration.Deposit studies and geochronological data reveal a multiphase origin of the Fe oxide and Cu±Au occurrences with multiple sources of the ore fluids and peaks of mineralization at c. 1.88 and 1.77 Ga. These events are temporally related to major orogenic stages in the evolution of the Fennoscandian Shield. This implies that mineralization formed in different tectonic settings, and with different magmatic associations. Thus, the IOCG deposits are not uniform in origin, which may well explain their diverse features and also makes a simple genetic model for them dubious.

  • 291.
    Martinsson, Olof
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bergman, Stefan
    Geological Survey of Sweden.
    Day 4: Regional geology of norrbotten, Sweden, Skarn iron ores and the Kiirunavaara apatite Fe-deposit2007In: Metallogeny and tectonic evolution of the Northern Fennoscandian Shield: field trip guidebook, Espoo: Geological Survey of Finland , 2007, p. 71-76Chapter in book (Other academic)
  • 292.
    Martinsson, Olof
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Billström, Kjell
    Swedish Museum of Natural History.
    Links between epigenetic Cu-Au mineralizations and agmatism/deformation in the Norrbotten county, Sweden2000In: Abstract volume & Field trip guidebook / [ed] Pär Weihed; Olof Martinsson, Luleå: Luleå tekniska universitet, 2000, p. 6-Conference paper (Other academic)
  • 293.
    Martinsson, Olof
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Billström, Kjell
    Plume related MORB and high-Ti basalts in the Kalix greenstones, northern Sweden2006In: The 27th Nordic Geological Winter Meeting, January 9-12, 2006, Oulu, Finland: abstract volume / [ed] Petri Peltonen ; Antti Pasanen, Helsinki: Geological Society of Finland , 2006, p. 98-Conference paper (Other academic)
    Abstract [en]

    Paleoproterozoic greenstones are widely distributed in the northeastern part of the Fennoscandian Shield. Due to obvious similarities of the local stratigraphy and the mainly tholeiitic character of the mafic volcanic rocks, Pharaoh (1985) suggested these greenstone areas to be coeval and representing a major tholeiitic province. Based on petrological and chemical studies of the mafic volcanic rocks and associated sediments, a continental rift setting is favoured for these greenstones. According to the present distribution of Archean rocks the paleocontinent was rifted in a northwest-southeast direction from Lofoten to Ladoga and a passive margin with deposition of greywacke developed at 2.1-2.0 Ga.In the Kalix area in northern Sweden well preserved Paleoproterozoic greenstones occur 100 km inland from the rift margin. Basaltic lava interlayered with volcanoclastic rocks and dolomite is exposed in a more than two km thick sequence that is overlain by graywackes. The chemostratigraphy of the Kalix greenstones including Sm-Nd isotopes suggest variable magma sources and progressive changes during magma evolution. Most of the basaltic lava and the volcanoclastic rocks have a depleted mantle source, a low to moderate content of Ti, and a chemical composition resembling MORB. However, extremely TiO2 rich (5.0-6.0 %) basaltic lava and tuff occur in a 150 m thick unit in the upper part of the greenstone pile. These are succeeded by basalt with a transitional character interlayered with stromatolitic dolomite. A major change in depositional environment is then recorded by the overlying graywackes. The lithostratigraphy and the chemostratigraphy of the greenstones are suggested to monitor the magmatic evolution during the final stage of continental break up and the interaction with a mantle plume that caused extrusion of thick units of volcanic rocks in the Kalix-Kiruna-Kautokeino-Kittili area.

  • 294.
    Martinsson, Olof
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Billström, Kjell
    Laboratory for Isotope Geology. Swedish Museum of Natural History, Stockholm, Laboratoriet för Isotopgeologi, Naturhistoriska Riksmuseet, Stockholm, Swedish Museum of Natural History, Department of Geosciences.
    Broman, Curt
    Department of Geology and Geochemistry, Stockholm University, Stockholms Universitet, Stockholm University, Department of Geological Sciences, Stockholm University.
    Weihed, Pär
    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.
    Metallogeny of the Northern Norrbotten Ore Province, northern Fennoscandian Shield with emphasis on IOCG and apatite-iron ore deposits2016In: Ore Geology Reviews, ISSN 0169-1368, E-ISSN 1872-7360, Vol. 78, p. 447-492Article in journal (Refereed)
    Abstract [en]

    The Northern Norrbotten Ore Province in northernmost Sweden includes the type localities for Kiruna-type apatite iron deposits and has been the focus for intense exploration and research related to Fe oxide-Cu-Au mineralisation during the last decades. Several different types of Fe-oxide and Cu-Au ± Fe oxide mineralisation occur in the region and include: stratiform Cu ± Zn ± Pb ± Fe oxide type, iron formations (including BIF's), Kiruna-type apatite iron ore, and epigenetic Cu ± Au ± Fe oxide type which may be further subdivided into different styles of mineralisation, some of them with typical IOCG (Iron Oxide-Copper-Gold) characteristics. Generally, the formation of Fe oxide ± Cu ± Au mineralisation is directly or indirectly dated between ~ 2.1 and 1.75 Ga, thus spanning about 350 m.y. of geological evolution.The current paper will present in more detail the characteristics of certain key deposits, and aims to put the global concepts of Fe-oxide Cu-Au mineralisations into a regional context. The focus will be on iron deposits and various types of deposits containing Fe-oxides and Cu-sulphides in different proportions which generally have some characteristics in common with the IOCG style. In particular, ore fluid characteristics (magmatic versus non-magmatic) and new geochronological data are used to link the ore-forming processes with the overall crustal evolution to generate a metallogenetic model.Rift bounded shallow marine basins developed at ~ 2.1–2.0 Ga following a long period of extensional tectonics within the Greenstone-dominated, 2.5–2.0 Ga Karelian craton. The ~ 1.9–1.8 Ga Svecofennian Orogen is characterised by subduction and accretion from the southwest. An initial emplacement of calc-alkaline magmas into ~ 1.9 Ga continental arcs led to the formation of the Haparanda Suite and the Porphyrite Group volcanic rocks. Following this early stage of magmatic activity, and separated from it by the earliest deformation and metamorphism, more alkali-rich magmas of the Perthite Monzonite Suite and the Kiirunavaara Group volcanic rocks were formed at ~ 1.88 Ga. Subsequently, partial melting of the middle crust produced large volumes of ~ 1.85 and 1.8 Ga S-type granites in conjunction with subduction related A −/I-type magmatism and associated deformation and metamorphismIn our metallogenetic model the ore formation is considered to relate to the geological evolution as follows. Iron formations and a few stratiform sulphide deposits were deposited in relation to exhalative processes in rift bounded marine basins. The iron formations may be sub-divided into BIF- (banded iron formations) and Mg-rich types, and at several locations these types grade into each other. There is no direct age evidence to constrain the deposition of iron formations, but stable isotope data and stratigraphic correlations suggest a formation within the 2.1–2.0 Ga age range. The major Kiruna-type ores formed from an iron-rich magma (generally with a hydrothermal over-print) and are restricted to areas occupied by volcanic rocks of the Kiirunavaara Group. It is suggested here that 1.89–1.88 Ga tholeiitic magmas underwent magma liquid immiscibility reactions during fractionation and interaction with crustal rocks, including metaevaporites, generating more felsic magmatic rocks and Kiruna-type iron deposits. A second generation of this ore type, with a minor economic importance, appears to have been formed about 100 Ma later. The epigenetic Cu-Au ± Fe oxide mineralisation formed during two stages of the Svecofennian evolution in association with magmatic and metamorphic events and crustal-scale shear zones. During the first stage of mineralisation, from 1.89–1.88 Ga, intrusion-related (porphyry-style) mineralisation and Cu-Au deposits of IOCG affinity formed from magmatic-hydrothermal systems, whereas vein-style and shear zone deposits largely formed at c. 1.78 Ga.The large range of different Fe oxide and Cu-Au ± Fe oxide deposits in Northern Norrbotten is associated with various alteration systems, involving e.g. scapolite, albite, K feldspar, biotite, carbonates, tourmaline and sericite. However, among the apatite iron ores and the epigenetic Cu-Au ± Fe oxide deposits the character of mineralisation, type of ore- and alteration minerals and metal associations are partly controlled by stratigraphic position (i.e. depth of emplacement). Highly saline, NaCl + CaCl2 dominated fluids, commonly also including a CO2-rich population, appear to be a common characteristic feature irrespective of type and age of deposits. Thus, fluids with similar characteristics appear to have been active during quite different stages of the geological evolution. Ore fluids related to epigenetic Cu-Au ± Fe oxides display a trend with decreasing salinity, which probably was caused by mixing with meteoric water. Tentatively, this can be linked to different Cusingle bondAu ore paragenesis, including an initial (magnetite)-pyrite-chalcopyrite stage, a main chalcopyrite stage, and a late bornite stage.Based on the anion composition and the Br/Cl ratio of ore related fluids bittern brines and metaevaporites (including scapolite) seem to be important sources to the high salinity hydrothermal systems generating most of the deposits in Norrbotten. Depending on local conditions and position in the crust these fluids generated a variety of Cu-Au deposits. These include typical IOCG-deposits (Fe-oxides and Cu-Au are part of the same process), IOCG of iron stone type (pre-existing Fe-oxide deposit with later addition of Cu-Au), IOCG of reduced type (lacking Fe-oxides due to local reducing conditions) and vein-style Cu-Au deposits. From a strict genetic point of view, IOCG deposits that formed from fluids of a mainly magmatic origin should be considered to be a different type than those deposits associated with mainly non-magmatic fluids. The former tend to overlap with porphyry systems, whereas those of a mainly non-magmatic origin overlap with sediment hosted Cu-deposits with respect to their origin and character of the ore fluids.

  • 295.
    Martinsson, Olof
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Broman, C.
    Billström, Kjell
    Wanhainen, Christina
    Character and origin of Cu-Au deposits in the northern Norrbotten ore province2001In: A Hydrothermal Odyssey: Extended Conference Abstracts / [ed] Patrick J. Williams, James Cook University of North Queensland , 2001, p. 128-129Conference paper (Other academic)
  • 296.
    Martinsson, Olof
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hansson, Karl-Enar
    Apatite iron ores in the Kiruna area: day seven 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. 173-Chapter in book (Other academic)
  • 297.
    Martinsson, Olof
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Perdahl, J-A
    Luleå tekniska universitet.
    Different types of Paleoproterozoic mafic to felsic volcanism in northernmost Sweden: products of underplating and subduction1994In: Terra Nova, ISSN 0954-4879, E-ISSN 1365-3121, Vol. 6, no Suppl. 2Article in journal (Refereed)
  • 298.
    Martinsson, Olof
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Söderholm, Krister
    Viscaria AB.
    The Greenstone hosted Pahtohavare Cu-Au deposit at Kiruna, northern Sweden1993In: Abstracts of lectures and posters: 21:a Nordiska geologiska vintermötet 10-13 Januari 1994 Luleå / [ed] Jan-Anders Perdahl, Luleå: Högskolan i Luleå , 1993, p. 137-Conference paper (Other academic)
  • 299.
    Martinsson, Olof
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Vaasjoki, Matti
    Geologian Tutkimuskeskus, Finland.
    Persson, Per-Olof
    Naturhistoriska Riksmuseet.
    U-Pb zircon ages of Archaean to Palaeoproterozoic granitoids in the Tornetrask-Rastojaure area, northern Sweden1999In: Radiometric dating results: Division of Bedrock Geology, Geological Survey of Sweden, Uppsala: Sveriges Geologiska Undersökning , 1999, p. 70-90Chapter in book (Other academic)
  • 300.
    Martinsson, Olof
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Virkkunen, Risto
    Apatite iron ores in the Gällivare, Svappavaara and Jukkasjärvi areas: day six 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. 167-Chapter in book (Other academic)
3456789 251 - 300 of 544
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf