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  • 201.
    Jansson, Nils
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Zetterqvist, Anders
    Zetterqvist Geokonsult AB.
    Allen, Rodney
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik. Boliden Mineral AB, Exploration Department.
    Malmström, Lars
    Zinkgruvan Mining AB.
    Geochemical vectors for stratiform Zn-Pb-Ag sulfide and associated dolomite-hosted Cu mineralization at Zinkgruvan, Bergslagen, Sweden2018Ingår i: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 190, s. 207-228Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Zinkgruvan deposit is the largest stratiform Zn-Pb-Ag mineralization in Sweden. The most recent genetic model attributes ore formation to the discharge of oxidized, near-neutral pH, metalliferous brines into a reduced basin, forming laterally extensive, stratiform sulfide mineralization on the seafloor. It has a known strike extent of 5 km and is underlain by a regionally extensive zone of K-altered metavolcanic rock and dolomitic marble, the latter hosting Cu-(Co-Ni) replacement mineralization near the inferred hydrothermal vent to the stratiform sulfides. The deposit is stratigraphically overlain by migmatized,  pyrrhotite- and graphite-rich pelite that is in turn overlain by a banded almandine-biotite-quartz-ferrosilite-bearing unit at the base of an regionally extensive metasedimentary succession. These laterally continuous units are interpreted as metamorphosed organic-rich sulphidic mudstone and silicate-dominated Fe formation, respectively.

    The favorable stratigraphic interval contains anomalously high Zn, Pb, Ag, Cu, K2O/(K2O+Na2O), Mn, Co, Tl, Ba and B relative to adjacent metatuffite. However, only Zn, Pb, Ag, K2O/(K2O+Na2O) and Mn are significantly enriched relative to adjacent strata beyond the known lateral extent of the ore. Elevated copper, Co and Tl only occur in the vent-proximal part of the deposit, whereas anomalous enrichments of Ba and B are sporadic and occur mainly in the stratigraphic footwall. Many elements such as Si, Fe, Mg, Ca and Cs are of limited use in vectoring due to low enrichment factors relative to inferred background compositions and/or strong lithological controls on their distribution.

    Although ore metal (Zn, Pb and Ag) enrichments are the best quantitative and qualitative guides to ore, K, Mn and Co enrichments also provide corroborative support. The most useful elements for vectoring have been synthesized into exploration indices. The Modified Sedex Metal Index (MSMI; Zn+3Pb+100Ag) is a vector towards stratiform Zn-Pb-Ag mineralization, whereas MSMI2 [Zn+3Pb+10(Cu+Co)] alsoallows targeting of proximal Cu mineralization.

    The banded iron formation and the pyrrhotite- and graphite-rich pelite of the stratigraphic hangingwall are consistently enriched in base metals (e.g. 500-1000 ppm Zn), total S and Mn throughout the entire Zinkgruvan area. However, these units are not known to grade laterally along strata into economic base metal sulfide mineralization, and they are not obviously products of the same hydrothermal system which formed the stratiform Zn-Pb-Ag deposit.

    In a vent-distal setting, the somewhat spurious metal anomalies of the hangingwall units can be difficult to distinguish from those of the favorable interval. The favorable stratigraphic interval can, however, be recognized by also taking into account that positive Zn anomalies are mainly coincident with positive anomalies in both K and Mn only in the favorable interval. Furthermore, samples from the favorable interval generally have Co/Ni > 1 and displays a positive Co/Ni vs. Zn trend, whereas samples of the pyrrhotite- and graphite-rich pelite have Co/Ni < 1 and define a negative Co/Ni vs. Zn trend. Thus, the index (Co/Ni)*Zn allows easy detection of weak Zn anomalies associated with the stratiform Zn-Pb-Ag mineralization.

  • 202.
    Jansson, Nils
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Zetterqvist, Anders
    Zetterqvist Geokonsult AB, Bromma.
    Allen, Rodney
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Malmström, Lars
    Zinkgruvan Mining.
    Oxidized Brines Inferred in the Formation of c. 1.9 Ga Stratiform Zn-Pb-Ag and Dolomite-Hosted Cu Ores, Zinkgruvan, Bergslagen, Sweden2015Ingår i: Mineral Resources in a Sustainable World / [ed] A.S. Andre-Mayer; M. Cathelineau; P. Muchez; E. Pirard; S. Sindern, 2015, s. 1925-1928Konferensbidrag (Refereegranskat)
    Abstract [en]

    Zinkgruvan is an elusive Palaeoproterozoic stratiform Zn-Pb-Ag deposit which has been discussed in the context of sediment-hosted Zn-Pb (SEDEX), volcanic-hosted massive sulphide (VHMS) and Broken Hill-type (BHT) deposits. In this contribution, we address the chemistry of the ore-forming fluid, the nature of the depositional environment and the controls on ore formation based on a review of previous work complemented with new geological data from a stratigraphically underlying dolomite-hosted, zinciferous, cobaltiferous and nickeliferous Cu ore. We conclude that both deposit types can be explained as the product of a saline, oxidizing metalliferous brine which formed Cu mineralization by interaction with reduced pore waters, prior to exhalation into an anoxic brine pool, forming the stratiform Zn-Pb-Ag deposit. Our inference of fluid composition differs from many inferences on the chemistry of hydrothermal fluids involved in the formation of typical VHMS and BHT deposits, but is similar to that inferred for Proterozoic sediment-hosted Zn-Pb deposits in the McArthur basin, Australia.

  • 203.
    Jansson, Nils
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Zetterqvist, Anders
    Zetterqvist Geokonsult AB.
    Allen, Rodney
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Malmström, Lars
    Zinkgruvan Mining.
    Oxidized Brines Inferred in the Formation of c. 1.9 Ga Stratiform Zn-Pb-Ag and Dolomite-Hosted Cu Ores, Zinkgruvan, Bergslagen, Sweden2015Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Zinkgruvan is an elusive Palaeoproterozoic stratiform Zn-Pb-Ag deposit which has been discussed in the context of sediment-hosted Zn-Pb (SEDEX), volcanic-hosted massive sulphide (VHMS) and Broken Hill-type (BHT) deposits. In this contribution, we address the chemistry of the ore-forming fluid, the nature of the depositional environment and the controls on ore formation based on a review of previous work complemented with new geological data from a stratigraphically underlying dolomite-hosted, zinciferous, cobaltiferous and nickeliferous Cu ore. We conclude that both deposit types can be explained as the product of a saline, oxidizing metalliferous brine which formed Cu mineralization by interaction with reduced pore waters, prior to exhalation into an anoxic brine pool, forming the stratiform Zn-Pb-Ag deposit. Our inference of fluid composition differs from many inferences on the chemistry of hydrothermal fluids involved in the formation of typical VHMS and BHT deposits, but is similar to that inferred for Proterozoic sediment-hosted Zn-Pb deposits in the McArthur basin, Australia

  • 204.
    Johansson, Björn
    et al.
    Boliden Mineral AB.
    Wanhainen, Christina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Flotation and leach tests performed within a geo-metallurgical project on gold in the Aitik Cu-Au-Ag-(Mo) deposit2010Ingår i: Conference in Minerals Engineering: Luleå, 2 -3 februari 2010 / [ed] Johanna Alatalo, Luleå: Luleå tekniska universitet, 2010, s. 73-84Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Laboratory flotation tests were done with all samples after 7 and 11 minutes of grinding. Tail products from the laboratory flotation tests were leached for Au using cyanide. Different ore types could be distinguished from their particle size distribution after grinding. Similar mineralogical structures could be tied to samples with a lower than expected Cu-recovery and mineralogical explanations for high and low Au recoveries are given in this paper.

  • 205.
    Johansson, Kurt
    et al.
    Swedish Stone Industries Federation.
    Larsen, Rune B
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Lehtinen, Markku J
    Nordkalk Oy.
    Persson, Lars
    SGU.
    Räisänen, Mika
    GTK.
    Pedersen, Stig A Schack
    GEUS.
    Weihed, Pär
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Wik, Nils-Gunnar
    SGU.
    Industrial minerals and rocks, aggregates and natural stones in the Nordic countries2008Ingår i: Episodes, ISSN 0705-3797, Vol. 31, nr 1, s. 133-138Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Nordic countries, including Greenland, have a long tradition in mining. The industrial minerals sector is expanding in most Nordic countries and extensive development has taken place during the last few years. The main commodities mined are carbonate rocks, quartz, feldspar, apatite, olivine and talc. A number of different types of dimension stones are quarried in all countries. Rock aggregates are increasingly important, replacing sand and gravel aggregate as construction materials in some countries due to the need to protect ground water supplies.

  • 206.
    Johansson, Simon
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Ore mineralogy and silver distribution at the Rävliden N volcanogenic massive sulphide deposit, Skellefte district, Sweden2017Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The Rävliden North deposit (Rävliden N) is a volcanogenic massive sulphide (VMS) deposit in the western part of the Skellefte district, northern Sweden. The district is one of Sweden’s major metallogenic provinces with a significant amount of VMS deposits. The Rävliden N deposit, discovered in 2011, contains copper, zinc, lead, silver and subordinate gold and occurs close to the largest VMS deposit in the district, the Kristineberg deposit, which has been mined for more than 70 years. The purpose of this master thesis is to study the composition, mineralogy and paragenetic relationships in different types of sulphide mineralization from the Rävliden N deposit. Emphasis is placed on characterizing the distribution and paragenetic relationships of silver-bearing minerals. The methods include core logging, sampling and mineralogical studies through light optical microscopy (LOM), scanning electron microscopy (SEM) and quantitative evaluation of mineralogy by scanning electron microscopy (QEMSCAN). Lastly, electron microprobe analysis (EMPA) was used to determine the chemical composition of silver-bearing minerals and sulphides.

    Mineralization types studied include 1: the main massive to semi-massive sulphide mineralization, 2: stratigraphically underlying stringer mineralization and 3: local, vein- and/or fault-hosted silver-rich mineralization in the stratigraphic hanging wall. The massive to semi-massive sulphide mineralization is dominated by sphalerite with lesser galena and pyrrhotite. In contrast, the stringer mineralization is dominated by chalcopyrite and pyrrhotite. The major minerals show evidence of a coeval formation and textural as well as structural evidence suggest that ductile deformation has affected the mineralization types. Notable evidence includes ball-ore textures, accumulation of minerals in pressure shadows and brittle fracturing of competent arsenopyrite and pyrite porphyroblasts and infilling by more incompetent sulphide minerals. The silver-bearing minerals identified are commonly spatially associated with galena and the major species is freibergite ((Ag,Cu,Fe)12(Sb,As)4S13), which also occur as inclusions in chalcopyrite mainly in the stringer mineralization. The stringer mineralization also contains notable amounts of hessite (Ag2Te). Notably, galena, pyrrhotite, freibergite and other sulphosalt minerals are commonly accumulated in pressure shadows near host rock fragments in the massive to semi-massive sulphide mineralization. The only gold-bearing mineral identified in this study is electrum (Au, Ag) in the stringer mineralization.

    The hanging wall mineralization locally comprises faulted and/or sheared massive sulphide mineralization which is compositionally similar to the main massive to semi-massive sulphide mineralization, besides a significantly higher content of freibergite. However, parts of the hanging wall mineralization are entirely dominated by sulphides and sulphosalts of silver, such as pyrargyrite (Ag3SbS3), pyrostilpnite (Ag3SbS3), argentopyrite (AgFe2S4), sternbergite (AgFe2S3) and stephanite (Ag5SbS4). These occur in structurally late settings, which along with consideration of their temperature stabilities suggest a late origin. Since the silver-bearing minerals in the massive to semi-massive sulphide mineralization and the two varieties of hanging wall mineralization contains the same metals, the mineralization in the hanging wall may have formed by late-stage remobilization of ore components from the underlying Rävliden N deposit. This negates the need for multiple mineralization events to explain the local silver-enriched zones in the hanging wall. The paragenetically late mineralization types contains high content of Ag-bearing minerals in relation to base metal sulphides. This suggests that remobilisation processes were important for locally upgrading the Ag-content.  

     

  • 207.
    Johansson, Åke
    et al.
    Swedish Museum of Natural History, Department of Geosciences.
    Stephens, Michael
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Timing of magmatism and migmatization in the 2.0–1.8 Ga accretionary Svecokarelian orogen, south-central Sweden2017Ingår i: International journal of earth sciences, ISSN 1437-3254, E-ISSN 1437-3262, Vol. 106, nr 3, s. 783-810Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Palaeoproterozoic (2.0–1.8 Ga) Svecokarelian orogen in central Sweden consists of a low-pressure, predominantly medium-grade metamorphic domain (central part of Bergslagen lithotectonic unit), enclosed to the north and south by low-pressure migmatite belts. Two periods of metamorphism (1.87–1.85 and 1.83–1.79 Ga) are known in the migmatite belts. In this study, new U–Th–Pb ion microprobe data on zircon and monazite from twelve samples of locally migmatized gneisses and felsic intrusive bodies determine both protolith and metamorphic ages in four sample areas north of Stockholm, inside or immediately adjacent to the medium-grade metamorphic domain. Two orthogneiss samples from the Rimbo area yield unusually old protolith ages of 1909 ± 4 and 1908 ± 4 Ma, while three orthogneisses from the Skutskär and Forsmark areas yield more typical protolith ages between 1901 ± 3 and 1888 ± 3 Ma. Migmatized paragneiss samples from this and two earlier studies contain a significant detrital component sourced from this 1.9 Ga magmatic suite. They are interpreted to be deposited contemporaneously with or shortly after this magmatism. Migmatization of the paragneiss at Rimbo was followed by intrusion of leucogranite at 1846 ± 3 Ma. Even in the other sample areas to the north (Hedesunda-Tierp, Skutskär and Forsmark), metamorphism including migmatization is constrained to the 1.87–1.85 Ga interval and penetrative ductile deformation is limited by earlier studies in the Forsmark area to 1.87–1.86 Ga. However, apart from a metamorphic monazite age of 1863 ± 1 Ma, precise ages were not possible to obtain due to the presence of only partially reset recrystallized domains in zircon, or highly discordant U-rich metamict and altered metamorphic rims. Migmatization was contemporaneous with magmatic activity at 1.87–1.84 Ga in the Bergslagen lithotectonic unit involving a mantle-derived component, and there is a spatial connection between migmatization and this magmatic phase in the Hedesunda-Tierp sample area. The close spatial and temporal interplay between ductile deformation, magmatism and migmatization, the P–T metamorphic conditions, and the continuation of similar magmatic activity around and after 1.8 Ga support solely accretionary rather than combined accretionary and collisional orogenic processes as an explanation for the metamorphism. The generally lower metamorphic grade and restricted influence of the younger metamorphic episode, at least at the ground surface level, distinguishes the central part of the Bergslagen lithotectonic unit from the migmatite belts further north and south.

  • 208.
    Jonsson, Linus
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Seismic tomography as an instrument for structural evaluation in the Printzsköld and Alliansen ore bodies, Malmberget2017Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Gruvan i Malmberget är belägen i norra Norrbotten och utgör en av de största apatitjärnmalmerna i Europa. Med tiden försätter brytningen i Malmberget på allt större djup. Det innebär en större utmaning med stabiliteten i gruvan då spänningarna i berget kan tänkas öka längre ner. När bergsspänningarna överskrider bergets hållfasthet sker en frigörelse av energi i form av seismiska vågor. I Malmberget finns ett system av 200 geofoner som detekterar alla seismiska vågor i området. Baserat på data som mottagits från övervakningssystemet har LKAB lyckats framställa en seismisk tomografimodell över de seismiska vågornas hastighetsvariationer när de breder ut sig i bergmassan.

    I studien granskas hur den seismiska tomografin kan användas som ett verktyg för att utvärdera geologiska strukturer i de två malmkropparna Printzsköld och Alliansen. Syftet är att klargöra om seismisk tomografi kan kombineras med strukturdata för att öka den geologiska kunskapen i Malmbergets gruvområde.

    På basis av mätta strukturer i gruvan i kombination med geoteknisk data (RQD, Jr, Ja) konstruerades två strukturgeologiska modeller i syfte att jämföra modellerna mot den seismiska tomografin.

    Resultatet från studien visar att foliationen i Printzsköld har en NÖ-SV orientering med en brant stupning. I den östra delen som förbinder till Alliansen ändras orienteringen succesivt till NV-SÖ, vilket indikerar en veckning av foliationen. De dominerande riktningarna för sprickor och frakturer i Printzsköld och Alliansen uppträdde som 4 set. Ett set var orienterat parallellt med foliationen och ett vinkelrätt mot det förevarande. De två andra sprick riktningarna var orienterade Ö-V nästintill vinkelrätt mot varandra med en flack stupning. Bergskvalitén i Printzsköld visade ett mönster av att förbättras djupare ner. Zoner med lägre bergskvalité följer malmkroppen. Den seismiska tomografin uppvisade korrelation med storskaliga strukturer samt stora områden med minskad berghållfasthet. Den tidigare identifierade deformations zonen DZ031 uppträder också som en viktig struktur instabila områden i Printzsköld.

    Utvärderandet av resultaten tyder på att den seismiska tomografin behöver fortsatt mer undersökningsarbete men visar lovande resultat av att fungera som ett vägledande instrument för att definiera storskaliga strukturer och större områden med sämre bergskvalité.

  • 209.
    Juanatey, Maria Garcia
    et al.
    Uppsala University.
    Hübert, Juliane
    Uppsala University.
    Tryggvason, Ari
    Uppsala University.
    Juhlin, Christopher
    Uppsala University.
    Pedersen, Laust
    Uppsala University.
    Dehghannejad, Mahdieh
    Uppsala University.
    Bauer, Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Weihed, Pär
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Skyttä, Pietari
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Magnetotelluric measurements in the Skellefte ore district, northern Sweden2013Ingår i: Mineral depostits for a high-tech world: Proceedings of the 12th SGA Biennial Meeting 2013, 12-15 August 2013, Uppsala, Sweden, Uppsala, 2013, Vol. 1, s. 138-141Konferensbidrag (Refereegranskat)
  • 210.
    Juanatey, María A. García
    et al.
    Uppsala University, Sweden.
    Hübert, Juliane
    Uppsala University, Sweden.
    Tryggvason, Ari
    Uppsala University, Sweden.
    Juhlin, Christopher
    Uppsala University, Sweden.
    Pedersen, Laust B.
    Bauer, Tobias E.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Dehghannejad, Mahdieh
    Uppsala University, Sweden. Ramboll Sweden..
    2D and 3D MT in the central Skellefte Ore District, northern Sweden2019Ingår i: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 764, s. 124-138Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    New broadband magnetotelluric (MT) data have been acquired along two parallel profiles in the central part of the metallogenic Skellefte district in northern Sweden. The data were recorded as part of the Swedish 4D modelling of mineral belts project and cover an area with several economical and sub-economical deposits. The dimensionality and quality of the data were carefully analyzed and new error floors were systematically determined prior to inverse modelling in 2D and 3D. The algorithms used were EMILIA and WSINV3DMT. For the 2D inversion, only the determinant of the impedance tensor was used, while for the 3D inversion all elements were considered. The obtained models fit the inverted data, and image the main regional features. A detailed comparison reveals the superiority of the 3D model, both in model structures and data fit. After assessing the main features in the model, an interpretation is proposed and refined with the support of previous geophysical studies. The most interesting features are large and medium-sized conductors associated with crustal-scale shear zones and faults within the Skellefte Group rocks. These may be depicting a network of fossil pathways for hydrothermal fluid transport and as such, provide new insight into past processes in the area.

  • 211.
    Juhlin, C.
    et al.
    Uppsala University.
    Elming, Sten-åke
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Mellqvist, C.
    SGAB Analytica.
    Öhlander, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Weihed, Pär
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Wikström, A.
    Geological Survey of Sweden.
    Crustal reflectivity near the Archean-Proterozoic boundary in northern Sweden and implications for the tectonic evolution of the area2002Ingår i: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 150, nr 1, s. 180-197Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sm–Nd isotope ratios of 1.9–1.8 Ga granitoids delineate the Archaean–Proterozoic boundary in northern Sweden, an important feature in the Fennoscandian Shield. The boundary strikes approximately WNW–ESE and is defined as a c. 20 km wide zone with juvenile Palaeoproterozoic rocks to the SSW and Archaean and Proterozoic rocks, derived to a large extent from Archaean sources, to the NNE. It therefore constitutes the strongly reworked margin of the old Archaean craton. Extrapolation of the boundary offshore into the Bothnian Bay and correlation with the marine reflection seismic BABEL Lines 2 and 3/4 indicates that the boundary dips to the south-southwest, consistent with interpretation of the Sm–Nd data. In order to tie the BABEL results with onshore surface geology and obtain detailed images of the uppermost crust a short (30 km of subsurface coverage) pilot profile was acquired in the Luleå area of northern Sweden during August 1999. The profile consisted of a high-resolution shallow component (1 kg shots) and a lower-resolution deep component (12 kg shots). Both components image most of the reflective crust, with the deep component providing a better image below 10 s. Comparison of signal penetration curves with data acquired over the Trans-Scandinavian Igneous Belt (a large batholith) indicate the transparent nature of the crust there to be caused by geological factors, not acquisition parameters. Lower crustal reflectivity patterns on the Luleå test profile are similar to those observed on the BABEL lines, suggesting the same lower crust onshore as offshore. Interpreted Archaean reflective upper crust in the NE extends below more transparent Proterozoic crust in the SW. This transparent crust contains a number of high-amplitude reflectors that may represent shear zones and/or mafic rock within granite intrusions. A marked boundary in the magnetic field in the SW has been interpreted as being the result of a gently west-dipping contact zone between meta-sediments and felsic volcanic rocks, however, the seismic data indicate a near-vertical structure in this area. By correlating the onshore and offshore seismic data we have better defined the location of the Archaean–Proterozoic boundary on the BABEL profiles. Our new interpretation of the crustal structure along the northern part of the BABEL Line 2 shows a more bi-vergent geometry than previous interpretations. Comparison of the re-interpreted crustal structure in northern Sweden with that found in the Middle Urals shows several similarities, in particular the accretion of a series of arcs to a stable craton. Based on this similarity and geological data, we deduce that a continental arc accreted to the southwestern margin of the Archaean craton at c. 1.87 Ga. Shortly thereafter, the Skellefte island arc underthrust the continental arc owing to a collision further to the southwest resulting in the bi-vergent crustal structure observed today.

  • 212.
    Kampmann, Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Age, Origin and Tectonothermal Modification of the Falun Pyritic Zn-Pb-Cu-(Au-Ag) Sulphide Deposit, Bergslagen, Sweden: Supplementary data tables2017Dataset
  • 213.
    Kampmann, Tobias Christoph
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    3D structural framework and constraints on the timing of hydrothermal alteration and ore formation at the Falun Zn-Pb-Cu-(Au-Ag) sulphide deposit, Bergslagen, Sweden2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, situated in the Palaeoproterozoic (1.9–1.8 Ga) Bergslagen lithotectonic unit in the south-western part of the Fennoscandian Shield, is one of the major base and minor precious metal sulphide deposits in Sweden. Host rocks to the deposit as well as the ores and altered rocks were metamorphosed and affected by heterogeneous ductile strain during the Svecokarelian orogeny the total duration of which was 2.0–1.8 Ga. These processes both reworked the mineral assemblages of the original hydrothermal alteration system and reshaped the structural geometry of the deposit, following formation of the ores and the associated hydrothermal alteration.In order to study primary geological and ore-forming processes at Falun, it is necessary firstly to investigate the nature of the tectonothermal modification. In this licentiate thesis, a three-dimensional modelling approach is used in order to evaluate geometric relationships between lithologies at the deposit. This study demonstrates the polyphase character (D1 and D2) of the strong ductile deformation at Falun. The major rock-forming minerals in the silicate alteration rocks are quartz, biotite/phlogopite, cordierite, anthophyllite, chlorite, and minor almandine and andalusite. On the basis of microstructural investigations, it is evident that these minerals grew during distinct periods in the course of the tectonic evolution, with major static grain growth between D1 and D2, and also after D2. Furthermore, the occurrence of F2 sheath folds along steeply south-south-east plunging axes is suggested as a key deformation mechanism, forming cylindrical, rod-shaped ore bodies which pinch out at depth. The sheath folding also accounts for the same stratigraphic level (footwall) on both the eastern and western sides of the massive sulphide ores. A major, sulphide-bearing high-strain zone defines a tectonic boundary at the deposit and bounds the massive sulphide ores to the north.The geological evolution in the Falun area involved emplacement of felsic sub-volcanic intrusive and volcanic rocks and some carbonate sedimentation; followed by hydrothermal alteration, ore formation and the intrusion of dykes and plutons of variable composition after burial of the supracrustal rocks. Secondary Ion Mass Spectrometry (SIMS) U-Pb (zircon) geochronology of key lithologies in and around the Falun base metal sulphide deposit indicates a rapid sequence of development of different magmatic pulses with individual age determinations overlapping within their uncertainties. The intense igneous activity, as well as the feldspar-destructive hydrothermal alteration and ore formation are constrained by two 207Pb-206Pb weighted average (zircon) ages of 1894 ± 3 Ma for a sub-volcanic host rock not affected by this type of alteration and 1891 ± 3 Ma for a felsic dyke, which cross-cuts the hydrothermally altered zone and is also unaffected by this alteration. All other ages, including the granitic plutonic rocks, fall in the interval between these ages.The lithological, structural and geochronological observations have implications for the environment and the conditions of ore formation at the Falun deposit. Several aspects argue for an ore system resembling a classic volcanogenic massive sulphide (VMS) system in terms of type of alteration, metal zonation, the pyritic character of massive sulphides and an inferred vent-proximal location in relation to the convection-driving magmatic system. The bowl-shaped, sub-seafloor feeder part of such a system might have served as an initial inhomogeneity in the strata for the later development of strong stretching along steep axes and sheath fold formation during ductile strain. Possible discordant relationships along the margins of the massive sulphide ores, coupled with the syn-magmatic, pre-tectonic timing of ore formation are in accordance with a general VMS-type model for the Falun base metal sulphide deposit. These results provide a compromise solution to the previous debate around two opposing models of strictly syn-genetic vs. epigenetic, post-deformational carbonate-replacement processes for ore formation at the deposit.

  • 214.
    Kampmann, Tobias Christoph
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik. Lund University.
    Age, origin and tectonothermal modification of the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, Bergslagen, Sweden2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, situated in the Palaeoproterozoic (1.9–1.8 Ga) Bergslagen lithotectonic unit in the south-western part of the Fennoscandian Shield, is one of the major base and precious metal sulphide deposits in Sweden. Felsic volcanic rocks and limestone hosting the deposit, as well as their hydrothermally altered equivalents and the mineralization, were affected by heterogeneous ductile strain and metamorphism under low-pressure, lower amphibolite-facies conditions during the Svecokarelian orogeny (2.0–1.8 Ga). These processes reworked the mineral assemblages of the original hydrothermal system and the mineralization, and also reshaped the structural geometry of the deposit.

    A three-dimensional modelling approach has been used in order to evaluate geometric relationships between lithologies at the deposit. The polyphase character (D1 and D2) of the strong ductile deformation at Falun is apparent. The main rock-forming minerals in the altered silicate-rich rocks are quartz, biotite and anthophyllite with porphyroblasts of cordierite and garnet, as well as retrogressive chlorite. Major static grain growth occurred between D1 and D2, inferred to represent the peak of metamorphism, as well as after D2 with growth (or recrystallization) of anthophyllite. A major shear zone with chlorite, talc and disseminated sulphides bounds the pyritic Zn-Pb-Cu-rich massive sulphide mineralization to the north, the latter being surrounded elsewhere by disseminated to semi-massive Cu-Au mineralization. F2 sheath folding along axes plunging steeply to the south-south-east is suggested as a key deformation mechanism, accounting for the cone-shaped mineralized bodies, which pinch out at depth, and explaining the similar character of intensely altered rocks on all sides of the massive sulphide mineralization. Immobile-element lithogeochemistry suggests that they share a common volcanic precursor. These relationships are consistent with a model in which the pyritic massive sulphide mineralization is located in the core of a sheath fold structure, surrounded by the same altered stratigraphic footwall rocks with Cu-Au mineralization.

    The geological evolution in the metavolcanic inlier that hosts the Falun deposit, constrained by secondary ion mass spectrometry (SIMS) U–Pb (zircon) geochronology, involved emplacement of a felsic volcanic and sub-volcanic rock suite at 1894±3 Ma, followed by hydrothermal alteration and mineralization. Subsequent burial and intrusion of late- to post-mineralization dykes occurred between 1896±3 Ma and 1891±3 Ma, followed by further burial and emplacement of plutons with variable composition during the time span 1894±3 Ma to 1893±3 Ma. The age determinations for all these magmatic suites overlap within their uncertainties, indicating a rapid sequence of continuous burial and different magmatic pulses. A metamorphic event, herein dated at 1831±8 Ma and 1822±5 Ma (SIMS U–Pb monazite), falls in the age range of a younger Svecokarelian metamorphic episode (M2). U-Th-Pb isotope systematics in monazite was completely reset during this event.

    During hydrothermal alteration and mineralization, a hot, reducing and acidic fluid carrying metals and sulphur together flowed upward along syn-volcanic faults, leading to intense chloritization, sericitization and silicification of calc-alkaline volcanic rocks in the stratigraphic footwall to the deposit. This resulted in proximal siliceous associations including Fe-rich chlorite, and dominant Mg-rich chlorite and sericite in more peripheral parts. Cu-Au stockwork mineralization formed in the siliceous core of the hydrothermal system as result of fluid cooling. Neutralization of the metal-bearing fluids upon carbonate interaction stratigraphically higher in the sub-seafloor regime led to formation of Zn-Pb-Cu-rich massive sulphide mineralization, the space for which was created by a combination of carbonate dissolution, primary porosity in the overlying volcanic rocks and secondary porosity produced during syn-volcanic faulting. A hybrid model for mineralization is suggested by alteration styles, metal zoning and textures indicating replacement of carbonate rock or highly porous pumice breccia by pyritic massive sulphide. Aspects of a sub-seafloor volcanogenic massive sulphide (VMS) system and carbonate replacement are both present. Partly Zn-Pb-(Ag) mineralized skarns comprise a separate and subordinate type of mineralization, probably formed after burial of the hydrothermal system to the contact-metasomatic regime.

    Textures and microstructures in the massive sulphide mineralization indicate that the ductile deformation and metamorphism resulted in internal mechanical and chemical remobilization of sulphide minerals. Laser ablation inductively coupled mass spectrometry (LA-ICP-MS) analysis of the main sulphide minerals suggests, for example, that trace elements (including Au) were liberated from pyrite during metamorphism. A system of auriferous quartz veins, affected by D2 ductile strain, occurs in intensely altered and mineralized rocks on the eastern side of the deposit. It is suggested that they formed after the peak of metamorphism and prior to the completion of the D2 tectonic event, as a result of fluid-assisted remobilization of sulphides and Au in the disseminated to semi-massive Cu-Au mineralization and possibly also the massive sulphide mineralization.

  • 215.
    Kampmann, Tobias Christoph
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Djupt nere i Falu Gruva: Hur det går till att leta efter värdefulla mineral.2018Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 216.
    Kampmann, Tobias Christoph
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Ny mineralutställning på gång2019Ingår i: Geologiskt Forum, ISSN 1104-4721, Vol. 101, s. 9-9Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    På Luleå tekniska universitet håller vi just nu på med att skapa en modern mineralutställning som visar den geologiska forskningen vid universitetet, men som också ska väcka intresse för prospektering och industriprocesser kopplade till mineral och metallurgi.

  • 217.
    Kampmann, Tobias Christoph
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    The Falun deposit – genetic constraints from geology, geochemistry and U-Pb isotope systematics2018Konferensbidrag (Övrigt vetenskapligt)
  • 218.
    Kampmann, Tobias Christoph
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Bauer, Tobias E.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Visual3D: A European network of infrastructure with focus on 3D/4D geomodelling2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    While the territory of the EU in many parts shows a very high exploration potential and many EU countries remain attractive to investors (e.g. Fraser Institute, 2015), a mere 4% of global exploration expenditure is currently invested within European countries. One tool to trigger a higher degree of investment in exploration and to secure the domestic supply of both main commodities and critical raw materials (CRM) is to enhance our three-dimensional geometric understanding of the Earth’s crust.

    For these reasons, EIT Raw Materials decided to fund a network of infrastructure (NoI) –Visual3D – for three years (2017–2019). Visual3D involves to-date 14 partner organisations from nine EU countries. The NoI aims to integrate expertise within exploration and 3D modelling from industry, academia and research institutes, with the ambition to increase the understanding of geological bodies in 3D and 4D through improved visualisation techniques.

    During its first year, Visual3D has worked to identify common issues in the field of geomodelling, the solutions to which may be facilitated by a Pan-European network approach:

    1. Data compatibility. The vast majority of European mining companies are currently working with 3D solutions for mine planning, resource estimation and production, utilizing a vast variety of expert programs (e.g. Leapfrog, Vulcan, Surpac, gOcad, MOVE). This leads to a wide range in character of 3D-models, as well as various types of data and file formats. Especially the combination of models on different scales, such as the incorporation of deposit scale models into regional-scale models, often necessitates simplifications and may lead to a loss of data. Therefore, a NoI that improves the interchangeability of models and furthermore enables full data integration will increase the usability of geomodels in exploration and research.
    2. Communication of geomodels. Commonly, specific expert software in order to make different data formats readable and communicate geomodels between collaborators, clients, stakeholders and decision makers. This limits the group of possible co-workers in a modelling project and the group of people that can utilize such models to the amount of available and often expensive licenses. A network of 3D-modelling users can substantially widen the possibilities to make geomodels accessible to a wider audience.
    3. Complexity and variety of CAM software. Software packages for computer-aided modelling (CAM) for geology and for industry standard mineral resource and reserve models are rather complex. Furthermore, there is a wide variety of available CAM software, each yielding individual functions, advantages and disadvantages. Changing a software or personnel within an organisation necessitates investment in additional training and causes downtimes. Implementing work flows for data interoperability may minimize expenditures on software and training for mining and exploration companies. Hence the NoI aims to work on solutions in order to optimize the generation, interpretation and application of geomodels, and improve the time and cost efficiency of these processes.

    Integration and improved outward communication of the available visualisation tools at the NoI partners will support better targeting of new mineral resources at depth, and eventually reduce environmental impacts and costs by enhancing the efficiency of exploration workflows. The distribution and possible commercialization of the NoI´s outcomes among stakeholders of the extractive industry will improve the competitiveness of European exploration and mining.

  • 219.
    Kampmann, Tobias Christoph
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Cwiertnia, Tomasz
    AGH University of Science and Technology, Cracow, Poland.
    The 6th Annual Baltic Student Chapter meeting 2015: A journey to the active and historical mines in Poland2015Ingår i: SGA News, nr 37, s. 1,10-11Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 220.
    Kampmann, Tobias Christoph
    et al.
    Lund University.
    Gumsley, Ashley Paul
    Lund University.
    Kock, Michiel Olivier de
    University of Johannesburg.
    Söderlund, Ulf
    Department of Geology, GeoBiosphere Science Centre, Lund University, Lund University.
    U-Pb geochronology and paleomagnetism of the Westerberg Sill Suite, Kaapvaal Craton – support for a coherent Kaapvaal–Pilbara Block (Vaalbara) into the Paleoproterozoic?2015Ingår i: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 269, s. 58-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Precise geochronology, combined with paleomagnetism on mafic intrusions, provides first-order information for paleoreconstruction of crustal blocks, revealing the history of supercontinental formation and break-up. These techniques are used here to further constrain the apparent polar wander path of the Kaapvaal Craton across the Neoarchean–Paleoproterozoic boundary. U–Pb baddeleyite ages of 2441 ± 6 Ma and 2426 ± 1 Ma for a suite of mafic sills located on the western Kaapvaal Craton in South Africa (herein named the Westerberg Sill Suite), manifests a new event of magmatism within the Kaapvaal Craton of southern Africa. These ages fall within a ca. 450 Myr temporal gap in the paleomagnetic record between 2.66 and 2.22 Ga on the craton. Our older Westerberg Suite age is broadly coeval with the Woongarra magmatic event on the Pilbara Craton in Western Australia. In addition, the Westerberg Suite on the Kaapvaal Craton intrudes a remarkably similar Archean-Proterozoic sedimentary succession to that on the Pilbara Craton, supporting a stratigraphic correlation between Kaapvaal and Pilbara (i.e., Vaalbara). The broadly coeval Westerberg–Woongarra igneous event may represent a Large Igneous Province. The paleomagnetic results are more ambiguous, with several different possibilities existing. A Virtual Geomagnetic Pole obtained from four sites on the Westerberg sills is 18.9°N, 285.0°E, A95 = 14.1°, K = 43.4 (Sample based VGP, n = 34: 16.8°N, 2879.9°E, dp = 4.4°, dm = 7.7°). If primary (i.e., 2441–2426 Ma), it would provide a further magmatic event within a large temporal gap in the Kaapvaal Craton's Paleoproterozoic apparent polar wander path. It would suggest a relatively stationary Kaapvaal Craton between 2.44 Ga and 2.22 Ga, and ca. 35° of latitudinal drift of the craton between ca. 2.66 Ga and 2.44 Ga. This is not observed for the Pilbara Craton, suggesting breakup of Vaalbara before ca. 2.44 Ga. However, it is likely that the Woongarra paleopole represents a magnetic overprint acquired during the Ophtalmian or Capricorn Orogeny, invalidating a paleomagnetic comparison with the Westerberg Sill Suite. Alternatively, our Westerberg Virtual Geographic Pole manifests a 2.22 Ga magnetic overprint related to Ongeluk volcanism. The similarity between Ongeluk and Westerberg paleopoles however may also infer magmatic connections if both are primary directions, despite the apparent 200 million year age this difference.

  • 221.
    Kampmann, Tobias Christoph
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Jansson, Nils F.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Stephens, Michael B.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Olin, Paul H.
    CODES ARC Centre of Excellence and TMVC ARC Research Hub, University of Tasmania.
    Gilbert, Sarah
    CODES ARC Centre of Excellence and TMVC ARC Research Hub, University of Tasmania.
    Wanhainen, Christina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Syn-tectonic sulphide remobilization and trace element redistribution at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, Bergslagen, Sweden2018Ingår i: Ore Geology Reviews, ISSN 0169-1368, E-ISSN 1872-7360, Vol. 96, s. 48-71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mineralization types at the Palaeoproterozoic Falun base metal sulphide deposit are predominantly pyritic Zn-Pb-Cu-rich massive sulphide mineralization, disseminated to semi-massive Cu-Au mineralization, auriferous quartz veins, and mineralized shear zones of talc-chlorite-dominated schist. The massive and disseminated to semi-massive sulphide mineralization types were subject to polyphase ductile deformation (D1 and D2) and metamorphism under low-P, lower-amphibolite facies conditions, which led to the development of ore textures and paragenetic relationships indicating both mechanical and chemical remobilization of sulphides. In the massive sulphide mineralization, rare inclusion-rich pyrite occurs as relic cores inside inclusion-poor metamorphosed pyrite. Imaging and spot analysis using multielement laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) reveal that inclusion-poor pyrite was depleted in trace elements, which were originally present as non-stoichiometric lattice substitutions or in mineral inclusions. The inclusion-rich pyrite was shielded from depletion and, at least partly, retained its initially higher trace element concentrations, including Au.

    Gold is also associated with chalcopyrite in the disseminated to semi-massive Cu-Au mineralization and in the system of auriferous quartz veins hosted therein, the latter being also affected by the D2 ductile strain. It is inferred that emplacement of the vein system took place after the peak of metamorphism, which occurred between D1 and D2, but prior to and possibly even shortly after completion of the D2 deformational event. Similarities in trace element signatures in chalcopyrite are compatible with the interpretation that the quartz veins formed by local chemical remobilization of components from the Cu-Au mineralization. Transport of liberated Au from pyrite during grain growth in the massive sulphide mineralization may have upgraded the Au endowment in the quartz veins, leading to the additional formation of native gold in the veins. A strong correspondence between elements liberated from pyrite (e.g. Pb, Bi, Se and Au) and those forming discrete and characteristic mineral phases in the quartz veins (Pb-Bi sulphosalts, native gold) supports this hypothesis.

    Trace element signatures for the main sulphide minerals pyrite, chalcopyrite, sphalerite and galena are similar to previously published data from other metamorphosed massive sulphide deposits. The association of the Falun mineralization with elevated Bi is reflected by its occurrence in sulphide minerals (e.g. galena) and in abundant mineral inclusions of Pb-Bi sulphosalts (e.g. weibullite), especially in the disseminated to semi-massive Cu-Au mineralization. Elevated Sn concentrations in the lattice and/or as cassiterite inclusions in chalcopyrite, sphalerite and galena are compatible with a hot, acidic and reducing fluid during formation of the syn-volcanic, base metal sulphide mineralization and associated host-rock alteration.

  • 222.
    Kampmann, Tobias Christoph
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Jansson, Nils
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Stephens, Michael
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Majka, Jarosław
    Uppsala universitet, AGH University of Science and Technology, Mickiewicza.
    Lasskogen, Jonas
    Boliden Mineral AB.
    Systematics of Hydrothermal Alteration at the Falun Base Metal Sulfide Deposit and Implications for Ore Genesis and Exploration, Bergslagen ore district, Fennoscandian Shield, Sweden2017Ingår i: Economic geology and the bulletin of the Society of Economic Geologists, ISSN 0361-0128, E-ISSN 1554-0774, Vol. 112, nr 5, s. 1111-1152Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Paleoproterozoic Falun Zn-Pb-Cu-(Au-Ag) pyritic sulfide deposit in the Bergslagen ore district, Sweden, is enveloped by hydrothermally altered rocks metamorphosed to the lower amphibolite facies. Immobile-element ratios suggest that the alteration precursors were volcanic rocks of mainly rhyolitic to dacitic composition. Least altered examples of these rocks plot along magmatic fractionation trends outlined by late- to post-ore feldspar-phyric metadacite dikes and post-ore granitoid plutons, consistent with a comagmatic relationship between these calc-alkaline, coeval (<10-m.y.) suites. Dolomite or calcite marble, as well as diopside-hedenbergite or tremolite skarn, form subordinate but important lithologic components in the hydrothermally altered zone. Marble occurs as fragments in the massive pyritic sulfide mineralization, suggesting that at least some mineralization formed by carbonate replacement.

    Mass-change calculations suggest that the hydrothermally altered volcanic rocks gained Mg and Fe and generally lost Ca, K, and Na. Proximal, quartz-anthophyllite-rich altered rocks additionally gained Si, whereas several types of biotite-rich altered rocks lost this element. These mass changes along with mineral chemical data for anthophyllite, biotite, cordierite, and garnet, and the common occurrence of quartz indicate that chloritization, sericitization, and silicification were the dominant premetamorphic alteration styles. A zonation from distal sericitized and silicified volcanic rocks to intermediate sericitized rocks, partly overprinted by chloritization (Mg-rich chlorite), and proximal siliceous and intensely chloritized (Fe-rich chlorite) rocks has been identified. Furthermore, mass changes in more peripheral parts of the altered zone toward the southeast of the deposit suggest that the alteration weakens gradationally toward the volcanic and subvolcanic rocks surrounding the deposit. These patterns represent vectors toward mineralization.

    Intensely chloritized rocks, largely represented by a single, rhyolitic precursor, envelop the central pyritic massive sulfide bodies to the east, south, and west, supporting a structural model in which the massive sulfide mineralization formed the stratigraphically highest preserved unit in the center, surrounded in a tubular manner by stratigraphic footwall rocks. The northern side represents a portion of the footwall, which was separated by a major shear zone. These spatial relationships also have implications for near-mine exploration, since quartz-rich footwall rocks locally host disseminated to semimassive stockwork Cu-Au mineralization.

    Cooling of a hot (300°–400°C), acidic (pH ≤4) and reducing fluid carrying metals and sulfur is suggested for formation of stockwork Cu-Au vein mineralization and hydrothermal alteration in the stratigraphic footwall. The Zn-Pb-Cu-rich massive sulfide mineralization is inferred to have formed by fluid neutralization upon interaction with carbonates and mixing with cooler seawater upon fluid entry into porous pumice breccia in a subseafloor setting. Dissolution processes, primary porosity in the pumice breccia, and secondary porosity produced during synvolcanic faulting are all suggested to have contributed to the creation of space necessary for the formation of the massive sulfide mineralization. Falun differs from other deposits of the same type in Bergslagen mainly in the high pyrite content of the massive sulfide mineralization, the absence of related Fe oxide deposits, as well as the dominant replacement of volcaniclastic sediments compared to carbonates. The types of host rocks, the inferred premetamorphic feldspar-destructive alteration types, and the style of mineralization and alteration zonation at the deposit are reminiscent of pyritic volcanogenic massive sulfide (VMS) deposits. However, the importance of chemical trapping by fluid-limestone interaction, as well as the spatial association with subordinate skarn alteration constitute important differences to a classic VMS model.

  • 223.
    Kampmann, Tobias Christoph
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Skyttä, Pietari
    University of Turku.
    Bauer, Tobias E.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Lynch, Edward P.
    Geological Survey of Sweden.
    Ore Deposits and 3D/4D modelling in Northern Fennoscandia: Fruitful knowledge exchange about one of Europe’s most prospective regions for metal exploration2016Ingår i: SGA News, nr 39, s. 26-27Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 224.
    Kampmann, Tobias Christoph
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Stephens, Michael
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Structural geology and spatial patterns of hydrothermal alteration at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, Bergslagen region, south-central Sweden2014Konferensbidrag (Refereegranskat)
  • 225.
    Kampmann, Tobias Christoph
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Stephens, Michael
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Weihed, Pär
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    3D modelling and sheath folding at the Falun Zn-Pb-Cu-(Au-Ag) massive sulphide deposit and implications for exploration in a 1.9 Ga ore district, Fennoscandian Shield, Sweden2016Ingår i: Mineralium Deposita, ISSN 0026-4598, E-ISSN 1432-1866, Vol. 51, nr 5, s. 665-680Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Falun pyritic Zn-Pb-Cu-(Au-Ag) deposit, situated in the Palaeoproterozoic (1.9–1.8 Ga) Bergslagen lithotectonic unit in the south-western part of the Fennoscandian Shield, is one of the major base metal sulphide deposits in Sweden. Altered rocks and ore types at Falun have been metamorphosed and deformed in a heterogeneous ductile manner, strongly modifying mineral assemblages in the original hydrothermal alteration system and the geometry of the deposit. Using a combined methodological approach, including surface mapping of lithologies and structures, drill core logging and microstructural investigation, the polyphase character (D1 and D2) of the ductile deformation is demonstrated and a 3D model for the deposit created. F2 sheath folding along axes that plunge steeply to the south-south-east, parallel to a mineral stretching lineation and the dip direction of the S2 foliation, is suggested as a key deformation mechanism forming steeply plunging, rod-shaped ore bodies. This is in contrast to previous structural models involving fold interference and, in turn, has implications for near-mine exploration, the occurrence of hanging-wall components to the ore body being questioned. Typical rock-forming minerals in the Falun alteration aureole include quartz, biotite/phlogopite, cordierite, anthophyllite and minor almandine, andalusite and chlorite, as well as dolomite, tremolite and actinolite. Where observable, the silicate minerals in the alteration rocks show growth patterns during different phases of the tectonothermal evolution, considerable static grain growth occurring between D1 and D2 and even after D2. A major high-strain zone, characterized by the mineral assemblage talc-chlorite-(quartz-biotite/phlogopite) defines a boundary between northern and southern structural domains at the deposit, and is closely spatially associated with the polymetallic massive sulphide ores. A possible role as a metal-bearing fluid conduit during ore genesis is discussed.

  • 226.
    Kampmann, Tobias Christoph
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Stephens, Michael
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Weihed, Pär
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Hydrothermal alteration, 3D modeling and sheath folding at the volcanic-hosted Falun Zn-Pb-Cu-(Au-Ag) deposit – implications for exploration in a 1.9 Ga ore district, Fennoscandian Shield, central Sweden2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Paleoproterozoic (1.9 Ga), volcanic-hosted Zn-Pb-Cu-(Au-Ag) sulfide deposit at Falun is located in the Bergslagen lithotectonic unit, central Sweden, which includes one of the major ore districts in the Fennoscandian Shield, northern Europe. The Falun deposit is known mainly as one of the world’s leading copper suppliers over many centuries. During the 20th century, the mine was a major base (Zn, Pb, Cu) and precious (Ag, Au) metal producer until it closed during 1992.This study has the following four aims: (i) Identify the style and spatial distribution of hydrothermal alteration; (ii) determine the geometry of the different types of ore bodies; (iii) provide a mechanism for the structure of the deposit; and (iv) address broader implications for the Bergslagen ore district. Petrographic and structural data were collected during surface mapping and microscope work; modeling of the different ore bodies in 3D space was completed using available mine level maps and data collected during new logging of available drill cores. The Falun deposit is affected by polyphase ductile deformation and metamorphism under amphibolite facies conditions. The metamorphosed alteration rocks are dominated by distal quartz-mica-cordierite-(anthophyllite) and proximal quartz-anthophyllite assemblages, interpreted to represent Si-, Fe-, Mg-metasomatism of felsic volcanic rocks. Dolomite and calc-silicate (tremolite, actinolite, diopside)-skarn assemblages are interpreted as the equivalent alteration of carbonate rocks. Surface mapping in the open pit indicates that the ore bodies are completely enveloped by these altered rocks. Structural data suggest the presence of a reclined F2 fold that plunges steeply to the southeast, with a stretching component defined by a linear grain-shape fabric sub-parallel to the fold axis. Modeling in 3D space reveals the presence of several rod-shaped ore bodies that also plunge steeply to the southeast and thicken and merge upwards into a single ore body that is up to 270 m in diameter at the ground surface. The ore body close to this surface is zoned in a concentric pattern, from a massive, pyritic Zn-Pb-Cu-sulfide core in the inner part to a more Cu-rich sulfide zone and then a semi-massive to disseminated Cu-Au mineralization in the outer part. The cone-shaped and zoned ore bodies are interpreted as steeply-plunging megascopic sheath folds, formed in a ductile, high-strain tectonic regime. The viscosity contrast between competent, strongly silicified and metamorphosed felsic volcanic host rock and softer massive sulfide ore is suggested to have enhanced the development of these sheath folds. Steeply plunging, rod-shape geometries have commonly been reported for several volcanic-hosted sulfide and Fe oxide ore deposits in the Bergslagen lithotectonic unit and megascopic sheath folds have been identified in a high-strain belt in the northern part of this unit. If sheath fold formation can be confirmed as a key deformation mechanism for ore bodies in this mineral district, in contrast to the classical model of dome and basin fold interference structure, this will influence near-mine exploration strategies. Previous structural concepts and models for footwall/hanging wall relationships will need radical revision and areas previously considered as barren hanging wall lithologies may have a higher exploration potential.

  • 227.
    Kampmann, Tobias Christoph
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Weihed, Pär
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Debatt: Falu gruvas 1,9 miljarder år gamla geologiska processer kan säkra samhällets framtida behov av metaller2017Ingår i: Dala-Demokraten, ISSN 1103-9183, artikel-id 20 majArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 228.
    Kampmann, Tobias Christoph
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Weihed, Pär
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Stephens, Michael B.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Structural investigation and 3D modelling of the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, Bergslagen region, south-central Sweden2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the prominent ore deposits of the Bergslagen region in south-central Sweden is located in Falun in the northern part of this mining district. A belt of 1.91-1.89 Ga metavolcanic rocks hosts both the ores and an alteration aureole of several hundreds to thousands of metres in extent at the ground surface. Analysis of the structures in the area reveals a polyphase ductile deformational history and a major, steeply plunging F2 reclined fold. 3D modelling of the boundary surface to the pyritic Zn-Pb-Cu sulphide ore has been used to visualize the geometry of this ore body at depth, constraining its steeply plunging rod-like and NW-SE elongate shape and a geometric control by the F2 fold structure.

  • 229.
    Kampmann, Tobias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Jansson, Nils
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Stephens, Michael
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Majka, Jarosław
    Uppsala universitet.
    Systematics of hydrothermal alteration at the volcanic-hosted Falun Zn-Pb-Cu-(Au-Ag) deposit: implications for ore genesis, structure and exploration in a 1.9 Ga ore district, Fennoscandian Shield, Sweden2016Ingår i: Geophysical Research Abstracts, ISSN 1029-7006, E-ISSN 1607-7962, Vol. 18Artikel i tidskrift (Refereegranskat)
  • 230.
    Kampmann, Tobias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Stephens, Michael
    Sveriges Geologiska Undersökning.
    Ripa, Magnus
    Sveriges Geologiska Undersökning.
    Hellström, Fredrik
    Sveriges Geologiska Undersökning.
    Timing of Magmatism and Mineralisation at Falun, a Major Base Metal Sulphide Deposit in the Fennoscandian Shield, Sweden2015Ingår i: Mineral Resources in a Sustainable World / [ed] A.S. Andre-Mayer; M. Cathelineau; P. Muchez; E. Pirard; S. Sindern, 2015, s. 591-594Konferensbidrag (Refereegranskat)
    Abstract [en]

    U-Pb (zircon) ion probe geochronology on key lithologies at the Palaeoproterozoic Falun Zn-Pb-Cu-(Au-Ag) sulphide deposit in the south-western part of the Fennoscandian Shield has been carried out. Results suggest that dominantly felsic sub-volcanic intrusion, hydrothermal alteration, ore formation and intrusion by dykes and plutons took place in a short time interval between 1894 +/- 3 Ma and 1891 +/- 3 Ma. Analogues to intra-arc VMS mineralisation in Peru are discussed.

  • 231.
    Kampmann, Tobias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Stephens, Michael
    Sveriges Geologiska Undersökning.
    Ripa, Magnus
    Sveriges Geologiska Undersökning.
    Hellström, Fredrik
    Sveriges Geologiska Undersökning.
    Timing of magmatism and mineralisation at Falun, a major base metal sulphide deposit in the Fennoscandian Shield, Sweden2015Konferensbidrag (Refereegranskat)
  • 232.
    Kampmann, Tobias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Stephens, Michael
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik. Sveriges Geologiska Undersökning.
    Ripa, Magnus
    Sveriges Geologiska Undersökning.
    Hellström, Fredrik
    Sveriges Geologiska Undersökning.
    Majka, Jarosław
    Uppsala universitet.
    Time constraints on magmatism, mineralisation and metamorphism at the Falun base metal sulphide deposit, Sweden, using U-Pb geochronology on zircon and monazite2016Ingår i: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 278, s. 52-68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    U–Th–Pb (zircon and monazite) ion probe data have provided constraints on the timing of emplacement and metamorphism of magmatic rocks close to the Palaeoproterozoic, Falun base metal sulphide deposit in the Bergslagen lithotectonic unit, Fennoscandian Shield, Sweden, and, thereby the timing of mineralisation. Hydrothermal alteration and mineralisation at Falun are constrained to a short interval of several million years between a 207Pb/206Pb weighted average age of 1894 ± 3 Ma for a rhyolitic sub-volcanic rock in the felsic volcanic to sub-volcanic host rock suite, and a 207Pb/206Pb weighted average age of 1891 ± 3 Ma for a post-sulphide, porphyritic dacite dyke. Magmatism also included the emplacement of granite plutons with igneous crystallization ages of 1894 ± 3, 1894 ± 2 Ma and 1893 ± 3 Ma. The felsicsub-volcanic to volcanic activity and the emplacement of dacite dykes and granite plutons overlap in age within their respective analytical uncertainties, indicating hydrothermal alteration and sulphide mineralisation inside a narrow time span of intense magmatic activity, and burial of the supracrustal rocks.Two distinct patchy and homogeneous metamorphic monazite types in a felsic volcanic rock around and hydrothermally altered rocks at the Falun deposit yield 207Pb/206Pb weighted average ages of 1831 ± 8 Ma and 1822 ± 5 Ma, respectively. These ages fall well within the temporal range of a younger1.84–1.81 Ga (M2) metamorphic episode during the 2.0–1.8 Ga Svecokarelian orogeny, with the older episode (M1) inside the Bergslagen lithotectonic unit at around 1.86 Ga. This shows the major influence of the M2 event in the north-western part of this unit, leading to a complete resetting of the U–Th–Pb isotopesystem in monazite.

  • 233. Kathol, B.
    et al.
    Weihed, Pär
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Regional geological and geophysical maps of the Skellefte District and surrounding areas2004Ingår i: The 26th Nordic Geological Winter Meeting: abstract volume / [ed] Joakim Mansfeld, Uppsala: Geological Society of Sweden , 2004, s. 150-Konferensbidrag (Refereegranskat)
  • 234.
    Klapp, Rasmus
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    The presence of REE in titanite, garnet and epidote from the Aitik mine tailings2018Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The aim of this thesis is to investigate the rare earth element (REE) distribution within titanite, garnet and epidote from the Aitik mine tailings, the waste material of a large porphyry-copper deposit mined in northern Sweden. The mine is an open pit operation with a low grade – high tonnage ore that generates roughly 36 Mt of tailings annually. REE are considered critical metals as they are very important for the industry and the society. They are also only extracted in a few locations around the world which implies a substantial risk of supply shortage. It is therefore necessary to increase the exploration and understanding of REE in many types of deposits, including the Aitik deposit. Linking the REE distribution of these minerals with the geological evolution of the Aitik deposit is a second aim of this thesis, in order to further increase the knowledge of the Aitik deposit and the behaviour of REE.  

    A sample taken from the Aitik tailings material was examined by micro-analytical techniques including optical microscope, SEM and finally LA-ICP-MS, generating REE distribution maps of titanite (5 grains), garnet (2 grains) and epidote (2 grains). The results show that REE are present in all titanite grains, with varying abundance within certain areas of the grains. The garnet end epidote showed lower REE signature, mostly bound to fractures within the grains. It is concluded that further investigations on the concentrations of REE should be conducted, and that innovative mineral processing methods will have to be examined before a potential extraction would be considered. Also, based on the REE distribution, the titanite grains are suggested to have undergone trace element migration, consistent with Svecofennian magmatism and metamorphism established for the area.

  • 235.
    Knipfer, Sebastian
    et al.
    Boliden AB.
    Nordin, Roger
    Boliden AB.
    Wasström, Annika
    Boliden AB.
    Höglund, Sofia
    Boliden Mineral AB.
    Joslin, Gregory
    Boliden AB.
    Wanhainen, Christina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    The Aitik porphyry Cu-Au-Ag-(Mo) deposit in Sweden2011Konferensbidrag (Refereegranskat)
  • 236.
    Kock, Michiel Olivier de
    et al.
    University of Johannesburg.
    Kampmann, Tobias Christoph
    Lund University.
    Söderlund, Ulf
    Department of Geology, GeoBiosphere Science Centre, Lund University, Lund University.
    U-Pb geochronology and paleomagnetism of the Westerberg sill, Kaapvaal Craton - Support for Vaalbara into the Paleoproterozoic2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Precise geochronology combined with paleomagnetism provides first-order information necessary for paleoreconstructions of crustal blocks and for revealing the history of supercontinent formation and break-up. These techniques are used here in an attempt to further constrain the apparent polar wander path of the Kaapvaal craton through the Neoarchean and Paleoproterozoic. A new baddeleyite U-Pb age of 2440.2 ± 5.9 Ma for the intracratonic Westerberg sill manifests a new event of mafic magmatism within the Kaapvaal Craton of southern Africa and falls in the center of a ca. 450 Ma gap in the paleomagnetic record, between 2.66 and 2.22 Ga. The Westerberg sill is coeval with the Woongarra sills on the Pilbara craton and intrudes into a remarkably similar sedimentary succession, hence supporting a coherent Kaapvaal-Pilbara block (i.e., Vaalbara) spanning the Archean-Proterozoic boundary interval. The coeval Westerberg-Woongarra igneous event may represent a large igneous province, here recognized for the first time on the Kaapvaal craton. The virtual geomagnetic pole obtained for the Kaapvaal craton for the Westerberg sill fits well into a large gap of the craton’s apparent polar wander path. Furthermore, combined with a coeval Pilbara pole, it allows for a reconstruction of Vaalbara that places Pilbara in relative close proximity and to the north of the Kaapvaal craton.

  • 237.
    Kontturi, Monika
    et al.
    Boliden AB.
    Martinsson, Olof
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Gold in the Aitik Cu-Au deposit, Gellivare area, Northern Sweden2000Ingår i: Abstract volume & Field trip guidebook / [ed] Pär Weihed; Olof Martinsson, Luleå: Luleå tekniska universitet, 2000, s. 22-Konferensbidrag (Övrigt vetenskapligt)
  • 238.
    Krispinsson, Joel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    A GIS-based re-evaluation of the surface geology of the Storuman area, northern Sweden2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The Canadian gold mining company Agnico Eagle Mines Limited (hereafter Agnico Eagle) is actively exploring for gold and other metals in the vicinity of Barsele in the Storuman municipality, northern Sweden. The most recent version to the geological map of the project area was done in 2007 and during the exploration campaign plenty of new information and data about the surface geology have been collected. A large extent of the geological interpretations of the older map is mainly based on geophysics and a small amount of field observations. With this new data available a re-evaluation of the surface geology of the project area was necessary.

    The in-data that was used for the project were retrieved from the company and included infield outcrop observations, bottom till drill data, geochemical analysis, geophysical and structural measurements.  The project has been performed by analysing the available bedrock data together with geophysical and structural measurements. Based upon this data a new interpretation of the geology has been made, with additions and modifications to previous geological borders where possible. These changes have later been digitized in the geographical information system (GIS) software ArcMap.

    The resulting updated geological map has been evaluated and compared with the previous version. The results show that a significant amount of what has previously been interpreted as metasedimentary rocks now can be classified as mafic metavolcanic rocks instead. Felsic metavolcanic rocks that might be of interest are more frequent than previously thought. The data also confirms the geological interpretations of the previous map in several areas, proving that the accuracy of the map in these areas is of good quality.  

  • 239.
    Kronsell, Ida
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Structural control on the Peña del Seo tungsten-greisen vein deposit, northwest Spain2019Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Tungsten is listed on the European Commission list of critical raw materials that are crucial to Europe’s economy. By raising awareness of tungsten as a critical raw material the EU can prioritise to enhance exploration, mining and recycling of tungsten. In this thesis the structural relationship between wall rock and veins, in a greisen-tungsten vein deposit, were analysed with the intention to interpret how tectonic deformation events control the emplacement of tungsten-bearing veins. The objective of this thesis is to investigate if and how structures controlled hydrothermal fluid flow and ore formation in the Peña del Seo tungsten-greisen vein deposit.

    Greisen systems are associated with tin and tungsten-bearing minerals and are related to intrusive magmatic bodies of granitic composition. Greisen-related granites (leucogranites), form at shallow depths in the crust (1.5-4 km) generally in intracontinental tectonic settings such as orogenic belts.

    The study site is located in the West Asturian-Leonese Zone in northwest Spain. This zone marks the transition between the foreland and the hinterland and is recognized as being part of a continental margin, where Palaeozoic rocks were deposited unconformably. These rocks were subsequently subjected to folding during the Variscan orogeny (370-290 Ma). Three main types of structures were generated due to three deformational phases (D1, D2 and D3) during the Variscan orogeny. D1 resulted in east-verging recumbent folding and formation of a related axial-planar parallel cleavage (S1), D2 resulted in displacement along large thrust sheets and D3 produced upright folding and refolding of F1 folds.

    Geological mapping with a focus on structural geology was carried out in March 2019, covering an area of approximately 0.25 km2. Structural measurements and oriented rock samples for microstructural study in thin sections were collected in the field. Additionally, photogrammetric mapping of structures was performed on a 3D photogrammetry model derived from a UAS survey.

    The geometry of the Peña del Seo tungsten-greisen vein deposit is interpreted to result from two major deformation events. The axial planar foliation (S1) at Peña del Seo is correlated to the regional fabric that developed during D1 of the Variscan orogeny. The related F1 folds are caused by buckling accompanied by flexural slip folding mechanism during D1. Forceful intrusion of the granite underlying the Peña del Seo deposit caused bending of the overlying rocks layers during D2. Layer-parallel stretching is likely to have caused tension fractures perpendicular to bedding in the outer arc of the F2 fold hinge. The formation of local crenulation and related spaced cleavage can be explained by layer-parallel shortening in the inner arc of the F2-fold. Local transposition of S1-foliation occurred during emplacement of quartz veins and explains the different orientation of strike of foliation between the northern and southern parts of the area. Fractures forming during formation of F2-fold are likely to have worked as conduits for ascending hydrothermal, ore-bearing fluids forming the Peña del Seo tungsten-greisen vein deposit.

  • 240.
    Lager, Ingemar
    Luleå tekniska universitet.
    Bevis for peritidal paleomiljö i Kalix grönstenbälte1986Ingår i: Abstracts: 17e Nordiska geologmötet, Helsingfors universitet, 12-15.5. 1986, 1986Konferensbidrag (Övrigt vetenskapligt)
  • 241.
    Lamberg, Pertti
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Rosenkranz, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Wanhainen, Christina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Lund, Cecilia
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Minz, Friederike
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Mwanga, Abdul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Parian, Mehdi
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Building a Geometallurgical Model in Iron Ores using a Mineralogical Approach with Liberation Data2013Ingår i: Geomet13: The Second AusIMM International Geometallurgy Conference 2013 / [ed] Simon Dominy, Parkville, Victoria: The Australasian Institute of Mining and Metallurgy, 2013, s. 317-324Konferensbidrag (Refereegranskat)
    Abstract [en]

    A geometallurgical model is currently built in two different ways. The first and the most common way relies on geometallurgical testing, where a large number of samples are analysed for metallurgical response using small-scale laboratory tests, eg Davis tube testing. The second, mineralogical approach focuses on collecting mineralogical information over the orebody and building the metallurgical model based on mineralogy. At Luleå University of Technology,Sweden, the latter method has been adopted and taken further in four ongoing PhD studies. The geological model gives modal composition by the help of element-to-mineral conversion and Rietveld X-ray diffraction. Texturally, the orebody is divided into different archetypes, and liberation measurements for each of them are carried out in processing fineness using IncaMineral, a SEM-based technique. The grindability and liberation spectrum of any given geological unit (sample, ore block, domain) are extrapolated from the archetypes. The process model is taken into a liberation level by mass balancing selected metallurgical tests using the particle tracking technique. The approach is general and can be applied to any type of ores. Examples of ongoing studies on iron and massive sulfide ores are given.

  • 242.
    Lindblom, S.
    et al.
    Department of Geology and Geochemistry, Stockholm University.
    Broman, C.
    Department of Geology and Geochemistry, Stockholm University.
    Martinsson, Olof
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Magmatic-hydrothermal fluids in the Pahtohavare Cu-Au deposit in greenstone at Kiruna, Sweden1996Ingår i: Mineralium Deposita, ISSN 0026-4598, E-ISSN 1432-1866, Vol. 31, nr 4, s. 307-318Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Proterozoic Pahtohavare Cu-Au deposit is located in the greenstone belt near Kiruna, northern Sweden. The greenstone consists of mafic volcanic rocks with pillow lavas, mafic sills and albitized rocks, including tuffites, black schists and mafic sills, together with carbonates and mineralized zones. Mineralization occurs as impregnations, epigenetic quartz-rich breccias and fracture fillings with pyrite, chalcopyrite, pyrrhotite and gold in a complex tectonic environment. Fluid inclusions indicate an early formation of quartz and pyrite at temperatures initially near 500°C and a pressure of 2-2.4 kbar from a supersaturated aqueous solution of magmatic origin. In addition to halite cubes, daughter minerals of sylvite, calcite, hematite, graphite and two unknown phases are found. The main stage of chalcopyrite and gold deposition is characterized by aqueous fluids of variable salinity (up to 30 eq. wt.% NaCl including CaCl2), at temperatures below 350°C and pressures between 1 and 2 kbar. A minor CO2 phase with some N2 accompanies this stage. Gold was transported as a chloride complex which destabilized due to an increase in pH (as a consequence of the CO2 loss) as well as cooling and dilution of the solution. The ore deposition occurred as a result of mixing with a low salinity aqueous solution during tectonic fracturing with pressure fluctuations and CO2 unmixing. Late oxidation of ores was caused by low to moderately saline (3 to 13 eq. wt.% NaCl) low temperature aqueous solutions.

  • 243.
    Lindblom, S.
    et al.
    University of Stockholm, Department of Geological Sciences Ore Research Group.
    Martinsson, Olof
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Fluids associated with Cu-Au mineralization in the Kiruna greenstone belt at Viscaria and Pahtohavare, northern Sweden1991Ingår i: Greenstone gold and crustal evolution: NUNA conference volume : Proceedings of a workshop held at Val d'Or, Québec, May 24-27, 1990 / [ed] Francois Robert; Patricia A. Sheahan; Stephen B. Green, St. Johns, Nfld: Geological and Mineralogical Association of Canada, 1991Konferensbidrag (Refereegranskat)
  • 244.
    Lu, Jinmei
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Alakangas, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Wanhainen, Christina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Metal mobilization under alkaline conditions in ash-covered tailings2014Ingår i: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 139, s. 38-49Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study was to determine element mobilization and accumulation in mill tailings under alkaline conditions. The tailings were covered with 50 cm of fly ash, and above a sludge layer. The tailings were geochemically and mineralogically investigated. Sulfides, such as pyrrhotite, sphalerite and galena along with gangue minerals such as dolomite, calcite, micas, chlorite, epidote, Mn-pyroxene and rhodonite were identified in the unoxidized tailings. The dissolution of the fly ash layer resulted in a high pH (close to 12) in the underlying tailings. This, together with the presence of organic matter, increased the weathering of the tailings and mobilization of elements in the uppermost 47 cm of the tailings. All primary minerals were depleted, except quartz and feldspar which were covered by blurry secondary carbonates. Sulfide-associated elements such as Cd, Fe, Pb, S and Zn and silicate-associated elements such as Fe, Mg and Mn were released from the depletion zone and accumulated deeper down in the tailings where the pH decreased to circum-neutral. Sequential extraction suggests that Cd, Cu, Fe, Pb, S and Zn were retained deeper down in the tailings and were mainly associated with the sulfide phase. Calcium, Cr, K and Ni released from the ash layer were accumulated in the uppermost depletion zone of the tailings

  • 245.
    Lund, Cecilia
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Mineralogical, chemical and textural characterisation of the Malmberget iron ore deposit for a geometallurgical model2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The northern Norrbotten ore province is an intensely mineralised area and has traditionally been a very important mining district. It contains Fe, Cu-Au, Au, and Ag deposits ranging from world-class ore deposits to small and uneconomic ones (Martinsson 2004). The most important are the Kiruna and Malmberget iron ores and the Aitik Cu-Au deposit.The cross-discipline approach called geometallurgy connects two different but closely related areas in the mining industry, namely geology and mineral processing. It involves understanding and measurements of the ore properties significant for its successful processing. Geometallurgy takes both the geological and mineral processing information to create a spatially-based (3D) predictive model for product management in mining operations (Lamberg, 2011).This case study investigates how to establish a geometallurgical model using the Malmberget iron ore deposit as a case study. A mineralogical approach (Lamberg 2011) was selected meaning that the focus is on mineralogy, and therefore parameters like modal mineralogy, mineral textures, mineral associations, mineral grain sizes and their relation to liberation characteristics are important. The main effort is to deliver a geological model which gives quantitative rather than descriptive information to be used in a process submodel.The ore characterisation (Papers I and II) gives new information on the chemical composition of minerals, mineralogical composition of both ore and host rocks, as well as the variation within the individual ore bodies. This sets a firm basis for the quantitative methods developed for routine analysis of modal mineralogy (Paper III) and mineral textures (Paper IV). Also, this increases the understanding regarding the primary origin and metamorphic evolution of the deposit, which is important since the origin of the apatite iron ore of the Kiruna type is still controversial.Based on the modal composition, preliminary geometallurgical (GEM) ore types were established for the Malmberget ore body. Each of these GEM-types describes quantitatively: the minerals present, their chemical composition, rules how to calculate the modal composition from routine chemical assays (element to mineral conversion, EMC rules) and a textural archetype in a library of archetypes. Using these GEM-types it is possible to calculate the modal mineralogy and the liberation distribution for every geological unit from the sample level to GEM-types to be further used in building a GEM block model of the ore.The applicability of the geological model was tested by developing a liberation based process model of simple one stage dry magnetic separation for the GEM-types. The model returns the metallurgical response, in terms of grade and recovery, of each of the developed GEM-types. The model was validated with another ore sample representing the same archetype from a different ore body and with a different grade. The model forecasted the recovery and concentrate grade within 2%-unit accuracy.This is the first published study where a full predictive geometallurgical model is entirely based on the mineralogy. The approach is a generic approach and valid not only for iron ores but also for other metallic mines.

  • 246.
    Lund, Cecilia
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Mineralogical, chemical and textural properties of the Malmberget iron deposit: a process mineralogically characterisation2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    I den här avhandlingen förenas två olika, men i en gruvprocess närliggande discipliner, malmgeologi och processmineralogi. Det sker genom att studera de mineralogiska-texturella egenskaperna om hur malmen ser ut i fast klyft och hur malmkoncentratet beter sig i en anrikningsprocess. Fyndigheten som studerats är LKAB:s apatitjärnmalm i Malmberget. Apatitjärnmalmer (av Kirunatyp) finns på ett fåtal platser runt om i världen och de två mest betydande fyndigheterna bryts idag av LKAB i Kiruna och Malmberget. Sett till den globala järnmalm marknaden är produktionen liten men i en lokal skala är dessa höghaltiga järnmalmer av största ekonomiska vikt. Tre olika malmkroppar ingår i denna studie Hens, ViRi och Fabian. Dessa är karaktäriserade i avseende på mineralogi, kemi och texturella egenskaper. Det första manuskriptet (Paper І) beskriver malmmineralen kemiskt och texturellt med tyngdpunkten på inverkan av den metamorfa överpräglingen. Mineralogiskt är ViRi och Fabian liknande, med avseende på förekomsten av Ti-mineral, pyrit och kopparkis. Hens skiljer sig från dessa två malmkroppar genom förekomsten av hematit. Magnetit från olika malmkroppar och malmtyper visar en kemisk variation mellan elementen TiO2, V2O3, Al2O3 och MgO. Magnetit från den massiva delen av Fabian malmkropp har kemiska likheter med andra apatitjärnmalmer och kan ursprungligen ha bildats genom kristallisation från en järnoxidmagma eller genom hydrotermala processer under höga temperaturer. Magnetit från malmbreccia har bildats under lägre temperatur och andra hydrotermala förhållanden. Det andra och tredje manuskriptet handlar om processmineralogi. I manuskript två (Paper ІІ) görs en kvantitativ mineralogisk karaktärisering av malmkroppen Fabian mineralogiskt genom att använda ett automatiserat SEM baserat system kallat QEMSCAN®. Två olika malmtyper massiv malm och malmbreccia har nedkrossats och siktats i tre fraktioner 150µm, 75µm och 38µm. Det är stor skillnad mellan malmtyperna både i avseende på mineralogin men även deras texturella egenskaper. Den modala mineralogin visar att malm breccia innehåller högre andel gångartsmineral. Magnetit från malm har en hög frikrossningsgrad medan den är lägre för malmbreccia. Båda malmtyperna visar en minskande frikrossningsgrad i finare fraktioner. Detta är ett resultat av kornstorlek, mineralogi och textur av både magnetit och gångartsmineral. Mineralassociationerna i malmbreccia är fler och mer komplexa än i malm och oavsett om mineralassociationer med magnetit hamnar i koncentratet eller avfallet så ökar kiselhalten i koncentratet eller så ökar järnhalten i avfallet. Manuskript tre (Paper ІІІ) beskriver en metod att hitta spårbarhet i anrikningsprocessen i Malmberget genom att påvisa och identifiera signifikanta mineralogiska signaturer både i malmen (fast klyft) och i anrikningskoncentratet. Två möjliga mineralogiska signaturer påvisades. Det är dels en enkel association med halvkorn bestående av magnetit och apatit och dels en mer komplicerad textur där små magnetitkorn sitter som inneslutningar inne i fältspatskorn. Dessa identifierade signaturer kan förmodligen fungera som "fingeravtryck" för olika malmtyper, partikel fraktioner och malningskretsar och kan därigenom användas till spårbarhet genom processen.

  • 247.
    Lund, Cecilia
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Lamberg, Pertti
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Lindberg, Therese
    LKAB, Research & Development, 983 81 Malmberget.
    Practical way to quantify minerals from chemical assays at Malmberget iron ore operations: an important tool for the geometallurgical program2013Ingår i: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 49, s. 7-16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This is the first step in establishing a geometallurgical program for the Malmberget iron ore deposit, northern Sweden. Geometallurgy captures geological and metallurgical (processing) information into a spatially-based predictive model of mineral processing characteristics. This paper describes the development of a practical, fast and inexpensive technique to quantify minerals from routine chemical assays. Ore samples and process samples from two different orebodies were used in the process of developing this element to mineral conversion technique that involved electron microprobe (EPMA), X-ray fluorescence (XRF) and SATMAGAN analyses. The method was validated against QEMSCAN analyses. From the calculated modal mineralogy an ore classification system was established based on the iron mineralogy, iron mineral grades and gangue mineralogy to create a preliminary geological/geometallurgical model of the ore. However, in a geometallurgical context the modal composition is not sufficient and the geological model requires information on mineral textures, too.

  • 248.
    Lund, Cecilia
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Martinsson, Olof
    A characterising of the ore minerals due to mineralogical, chemical and textural properties in Malmberget2008Ingår i: Conference in Minerals Engineering 2008, Luleå: Luleå tekniska universitet, 2008, s. 71-80Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This study was an attempt to find a way of characterising an iron ore body both mineralogical and textural in a quantitative manner by using analytical methods like optical microscopy, microprobe (EMPA) and an automatic SEM based system, Particle Texture Analysis (PTA). The source of this study is an iron ore body, called Fabian, located in Malmberget, Sweden. Two types of ores were identified and analysed in this study named "orebreccia" and "ore". The Particle Texture Analysis was made on two fractions of crushed ore. The mineralogy was evaluated and characterized as mineral liberation and mineral association. Magnetite has a simple outline and straight grain boundaries and the gangue minerals have a finer particle size with a more complicated texture. The liberation of magnetite in "ore" and "ore breccia" is high. The ore quality for both "ore" and "ore breccia" does have similarities in a process technique perspective.

  • 249.
    Lund, Cecilia
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Martinsson, Olof
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Oxide mineralogy and magnetite chemistry of the Malmberget apatite iron ore, Northern Norr2013Ingår i: 12th Biennial SGA Meeting: Mineral deposit research for a high-tech world, Uppsala: Geological Society of Sweden , 2013, s. 273-276Konferensbidrag (Refereegranskat)
    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.

  • 250.
    Lund, Cecilia
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Martinsson, Olof
    Trace-element chemistry of magnetite from the Malmberget apatite-iron deposit2008Konferensbidrag (Övrigt vetenskapligt)
    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.

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