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  • 1.
    Augustsson, Anna
    et al.
    Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden.
    Uddh-Söderberg, Terese
    Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden.
    Filipsson, Monika
    Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden.
    Helmfrid, Ingela
    Occupational and Environmental Medicine Centre, Department of Clinical and Experimental Medicine Linköping University, Linköping, Sweden.
    Berglund, Marika
    Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
    Karlsson, Helen
    Occupational and Environmental Medicine Centre, Department of Clinical and Experimental Medicine Linköping University, Linköping, Sweden.
    Hogmalm, Johan
    Department of Earth Sciences, University of Gothenburg, Gothenburg, Sweden.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Alriksson, Stina
    Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden.
    Challenges in assessing the health risks of consuming vegetables in metal-contaminated environments2018In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 113, p. 269-280Article in journal (Refereed)
    Abstract [en]

    A great deal of research has been devoted to the characterization of metal exposure due to the consumption of vegetables from urban or industrialized areas. It may seem comforting that concentrations in crops, as well as estimated exposure levels, are often found to be below permissible limits. However, we show that even a moderate increase in metal accumulation in crops may result in a significant increase in exposure. We also highlight the importance of assessing exposure levels in relation to a regional baseline. We have analyzed metal (Pb, Cd, As) concentrations in nearly 700 samples from 23 different vegetables, fruits, berries and mushrooms, collected near 21 highly contaminated industrial sites and from reference sites. Metal concentrations generally complied with permissible levels in commercial food and only Pb showed overall higher concentrations around the contaminated sites. Nevertheless, probabilistic exposure assessments revealed that the exposure to all three metals was significantly higher in the population residing around the contaminated sites, for both low-, median- and high consumers. The exposure was about twice as high for Pb and Cd, and four to six times as high for As. Since vegetable consumption alone did not result in exposure above tolerable intakes, it would have been easy to conclude that there is no risk associated with consuming vegetables grown near the contaminated sites. However, when the increase in exposure is quantified, its potential significance is harder to dismiss – especially when considering that exposure via other routes may be elevated in a similar way.

  • 2.
    Barnes, Christopher
    et al.
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Jarosław, Majka
    Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Schneider, David
    Department of Earth and Environmental Sciences, University of Ottawa, Ottawa, Canada.
    Walczak, Katarzyna
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Bukała, Michał
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Kośmińska, Karolina
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Tokarski, Tomasz
    Academic Center for Materials and NanotechnologyAGH University of Science and TechnologyKrakówPoland.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    High-spatial resolution dating of monazite and zircon reveals the timing of subduction–exhumation of the Vaimok Lens in the SeveNappe Complex (Scandinavian Caledonides)2019In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 174, no 1, article id 5Article in journal (Refereed)
    Abstract [en]

    In-situ monazite Th–U–total Pb dating and zircon LA–ICP–MS depth-profiling was applied to metasedimentary rocks from the Vaimok Lens in the Seve Nappe Complex (SNC), Scandinavian Caledonides. Results of monazite Th–U–total Pb dating, coupled with major and trace element mapping of monazite, revealed 603 ± 16 Ma Neoproterozoic cores surrounded byrims that formed at 498 ± 10 Ma. Monazite rim formation was facilitated via dissolution–reprecipitation of Neoproterozoic monazite. The monazite rims record garnet growth as they are depleted in Y2O3 with respect to the Neoproterozoic cores. Rims are also characterized by relatively high SrO with respect to the cores. Results of the zircon depth-profiling revealed igneous zircon cores with crystallization ages typical for SNC metasediments. Multiple zircon grains also exhibit rims formedby dissolution–reprecipitation that are defined by enrichment of light rare earth elements, U, Th, P, ± Y, and ± Sr. Rims also have subdued Eu anomalies (Eu/Eu* ≈ 0.6–1.2) with respect to the cores. The age of zircon rim formation was calculated from three metasedimentary rocks: 480 ± 22 Ma; 475 ± 26 Ma; and 479 ± 38 Ma. These results show that both monazite and zircon experienced dissolution–reprecipitation under high-pressure conditions. Caledonian monazite formed coeval with garnet growth during subduction of the Vaimok Lens, whereas zircon rim formation coincided with monazite breakdown to apatite, allanite and clinozoisite during initial exhumation.

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  • 3.
    Biagioni, Cristian
    et al.
    Università di Pisa, Italy..
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Pasero, Marco
    Università di Pisa, Italy..
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Bosi, Ferdinando
    Sapienza Università di Roma, Italy.
    Hydroxylhedyphane, Ca2Pb3(AsO4)3(OH), a new member of the apatite supergroup from Långban, Sweden2019In: European journal of mineralogy, ISSN 0935-1221, E-ISSN 1617-4011, Vol. 31, no 5-6, p. 1007-1014Article in journal (Refereed)
  • 4.
    Cámara, Fernando
    et al.
    Università degli Studi di Milano,.
    Holtstam, Dan
    Swedish Museum of Natural History, Department of Geology.
    Jansson, Nils
    Jonsson, Erik
    SGU.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Langhof, Jörgen
    Swedish Museum of Natural History, Department of Geology.
    Majka, Jaroslaw
    Zetterqvist, Anders
    Zinkgruvanite, Ba4Mn2+4Fe3+2(Si2O7)2(SO4)2O2(OH)2, a new ericssonite-group mineral from the Zinkgruvan Zn-Pb-Ag-Cu deposit, Askersund, Örebro County, Sweden.2021In: European journal of mineralogy, ISSN 0935-1221, E-ISSN 1617-4011, Vol. 33, no 6, p. 659-673Article in journal (Refereed)
    Abstract [en]

    Zinkgruvanite, ideally Ba4Mn2+4Fe3+2(Si2O7)2(SO4)2O2(OH)2, is a new member of the ericssonite group, found in Ba-rich drill core samples from a sphalerite+galena- and diopside-rich metatuffite succession from the Zinkgruvan mine, Örebro county, Sweden. Zinkgruvanite is associated with massive baryte, barytocalcite, diopside and minor witherite, cerchiaraite-(Al) and sulfide minerals. It occurs as subhedral to euhedral flattened and elongated crystals up to 4 mm. It is almost black, semi-opaque with a dark brown streak. The luster is vitreous to sub-adamantine on crystal faces, resinous on fractures. The mineral is brittle with an uneven fracture. VHN100 = 539 and HMohs ~4½. In thin fragments, it is reddish-black, translucent and optically biaxial (+), 2Vz > 70°. Pleochroism is strong, deep brown-red (E ⊥ {001} cleavage) to olive-pale brown. Chemical point analyses by WDS-EPMA together with iron valencies determined from Mössbauer spectroscopy, yielded the empirical formula (based on 26 O+OH+F+Cl anions): (Ba4.02Na0.03)Σ4.05(Mn1.79Fe2+1.56Fe3+0.42Mg0.14Ca0.10Ni0.01Zn0.01)Σ4.03 (Fe3+1.74Ti0.20Al0.06)Σ2.00Si4(S1.61Si0.32P0.07)Σ1.99O24(OH1.63Cl0.29F0.08)Σ2.00. The mineral is triclinic, space group P–1, with unit-cell parameters a = 5.3982(1) Å, b = 7.0237(1) Å, c = 14.8108(4) Å, α = 98.256(2)º, β = 93.379(2)º, γ = 89.985(2)º and V = 554.75(2) Å3 for Z = 1. The eight strongest X-ray powder diffraction lines are [d Å (I%; hkl)]: 3.508 (70; 103), 2.980(70; 11–4), 2.814 (68; 1–22), 2.777 (70; 121), 2.699 (714; 200), 2.680 (68; 20–1), 2.125 (100; 124, 204), 2.107 (96; –221). The crystal structure (R1 = 0.0379 for 3204 reflections) is an array of TS (titanium silicate) blocks alternating with intermediate blocks. The TS blocks consist of HOH sheets (H = heteropolyhedral, O = octahedral) parallel to (001). In the O sheet, the Mn2+-dominant MO(1,2,3) sites give ideally Mn2+4 pfu. In the H sheet, the Fe3+-dominant MH sites and AP(1) sites give ideally Fe3+2Ba2 pfu. In the intermediate block, SO4 oxyanions and eleven coordinated Ba atoms give ideally 2 × SO4Ba pfu. Zinkgruvanite is related to ericssonite and ferro-ericssonite in having the same topology and type of linkage of layers in the TS block. Zinkgruvanite is also closely compositionally related to yoshimuraite, Ba4Mn4Ti2(Si2O7)2(PO4)2O2(OH)2, via the coupled heterovalent substitution 2 Ti4+ + 2 (PO4)3- →2 Fe3+ + 2 (SO4)2-, but presents a different type of linkage. The new mineral probably formed during a late stage of regional metamorphism of a Ba-enriched, syngenetic protolith, involving locally generated oxidized fluids of high salinity.

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    zinkgruvanite
  • 5.
    Cámara, Fernando
    et al.
    Università degli Studi di Milano,.
    Holtstam, Dan
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Old samples - new amphiboles2022In: Abstracts, International Mineralogical Association 23rd General meeting, Lyon, 2022, Vol. 1, p. 42-42Conference paper (Other academic)
    Abstract [en]

    The scientific value of old and well-preserved collections is priceless. Samples that already have been studied and described can still give very useful information. For instance, minerals with complex solid solutions like amphiboles sometimes show new compositions that are feasible because of crystal-chemistry and charge arrangements, based on the current classification scheme by Hawthorne et al. (2012) for the amphibole supergroup. In the last four years, a fruitful collaboration between the Swedish Museum of Natural History and the Department of Earth Sciences of the University of Milan has allowed the identification of new amphibole species, recognized by CNMNC-IMA. First of all, we identified hjalmarite, [ANaB(NaMn)CMg5TSi8O22W(OH)2], which is related to richterite via the homovalent substitution [B]Ca2+ → [B]Mn2+, and is the second recognized member of the sodium–(magnesium–iron–manganese) subgroup, after ferri-ghoseite. Sjögren (1891) had described a physically similar, MnO-rich sample from Långban, named “astochit”. A related amphibole, although belonging to a different subgroup, that we have formally described is potassic-richterite, [AKB(NaCa)CMg5TSi8O22W(OH)2]. It was found in a sample from the Pajsberg iron and manganese ore mines, which was originally collected by the mineralogist Lars Johan Igelström, probably in the 1850s. The most recent amphibole we have described is ferri-taramite [ANaB(NaCa)C(Mg3Fe3+2)T(Si6Al2)O22W(OH)2], found in a skarn sample from the Jakobsberg manganese mine: it was once examined by Flink (1914), who noted the unusual character of the amphibole and described it as a “strange hornblende”.

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  • 6.
    De Colle, Mattia
    et al.
    KTH Royal Institute of Technology .
    Kielman, Ross
    KTH Royal Institute of Technology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Karasev, Andrey
    KTH Royal Institute of Technology.
    Jönsson, Pär G.
    KTH Royal Institute of Technology.
    Study of the Dissolution of Stainless-Steel Slag Minerals in Different Acid Environments to Promote Their Use for the Treatment of Acidic Wastewaters2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 24, p. 1-19, article id 1210Article in journal (Refereed)
    Abstract [en]

    Several stainless-steel slags have been successfully employed in previous studies as substi-tutes for lime in the treatment of industrial acidic wastewaters. This study deepens the knowledge ofsuch application, by analyzing the neutralizing capacity of different slags related to their mineralcompositions. To do so, firstly the chemical and mineral compositions of all the slag samples areassessed. Then, 0.5 g, 1 g, 2 g of each slag and 0.25 g and 0.5 g of lime are used to neutralize 100 g of0.1 M HCl or HNO3 solutions. After the has neutralization occurred, the solid residues are extractedand analyzed using XRD spectroscopy. Then, the solubility of the minerals is assessed and ranked,by comparing the XRD spectra of the residues with the obtained pH values. The results showthat minerals such as dicalcium silicate and bredigite are highly soluble in the selected experimentalconditions, while minerals such as merwinite and åkermanite, only partially. Moreover, Al-rich slagsseem to perform poorly due to the formation of hydroxides, which generate extra protons. However,when the weight of slag is adequately adjusted, Al-rich slags can increase the pH values to higherlevels compared to the other studied slags.

  • 7.
    Drake, Henrik
    et al.
    Department of Biology and Environmental Science, Linnaeus University, 39231 Kalmar, Sweden.
    Mathurin, Frédéric A.
    Department of Biology and Environmental Science, Linnaeus University, 39231 Kalmar, Sweden.
    Zack, Thomas
    Department of Earth Science, University of Gothenburg, Gothenburg, Sweden.
    Schäfer, Thorsten
    Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, 76021 Karlsruhe, Germany.
    Nick MW, Roberts
    NERC Isotope Geosciences Laboratory, British Geological Survey, Nottingham NG12 5GG, U.K..
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Broman, Curt
    Department of Geological Sciences, Stockholm University, Stockholm 106 91, Sweden.
    Mats E., Åström
    Department of Biology and Environmental Science, Linnaeus University, 39231 Kalmar, Sweden.
    Incorporation of Metals into Calcite in a Deep Anoxic Granite Aquifer2018In: Environmental Science and Technology, ISSN 1086-931X, E-ISSN 1520-6912, Vol. 52, no 2, p. 293-502Article in journal (Refereed)
    Abstract [en]

    Understanding metal scavenging by calcite in deep aquifers in granite is of importance for deciphering and modeling hydrochemical fluctuations and water–rock interaction in the upper crust and for retention mechanisms associated with underground repositories for toxic wastes. Metal scavenging into calcite has generally been established in the laboratory or in natural environments that cannot be unreservedly applied to conditions in deep crystalline rocks, an environment of broad interest for nuclear waste repositories. Here, we report a microanalytical study of calcite precipitated over a period of 17 years from anoxic, low-temperature (14 °C), neutral (pH: 7.4–7.7), and brackish (Cl: 1700–7100 mg/L) groundwater flowing in fractures at >400 m depth in granite rock. This enabled assessment of the trace metal uptake by calcite under these deep-seated conditions. Aquatic speciation modeling was carried out to assess influence of metal complexation on the partitioning into calcite. The resulting environment-specific partition coefficients were for several divalent ions in line with values obtained in controlled laboratory experiments, whereas for several other ions they differed substantially. High absolute uptake of rare earth elements and U(IV) suggests that coprecipitation into calcite can be an important sink for these metals and analogousactinides in the vicinity of geological repositories.

  • 8.
    Drake, Henrik
    et al.
    Institutionen för biologi och miljö, Linneuniversitet.
    Roberts, Nick M. W.
    Geochronology and Tracers Facility, British Geological Survey.
    Reinhardt, Manuel
    Department of Biology and Environmental Science, Linnæus University.
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Kielman-Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield2021In: Communications Earth & Environment, E-ISSN 2662-4435, Vol. 2, no 1, article id 102Article in journal (Refereed)
    Abstract [en]

    Earth’s crust contains a substantial proportion of global biomass, hosting microbial life up to several kilometers depth. Yet, knowledge of the evolution and extent of life in this environment remains elusive and patchy. Here we present isotopic, molecular and morphological signatures for deep ancient life in vein mineral specimens from mines distributed across the Precambrian Fennoscandian shield. Stable carbon isotopic signatures of calcite indicate microbial methanogenesis. In addition, sulfur isotope variability in pyrite, supported by stable carbon isotopic signatures of methyl-branched fatty acids, suggest subsequent bacterial sulfate reduction. Carbonate geochronology constrains the timing of these processes to the Cenozoic. We suggest that signatures of an ancient deep biosphere and long-term microbial activity are present throughout this shield. We suggest that microbes may have been active in the continental igneous crust over geological timescales, and that subsurface investigations may be valuable in the search for extra-terrestrial life.

  • 9. Drake, Henrik
    et al.
    Roberts, Nick M. W.
    Reinhardt, Manuel
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Kielman-Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield2021In: Communications Earth & Environment, E-ISSN 2662-4435, Vol. 2, no 1, article id 102Article in journal (Refereed)
  • 10. Drake, Henrik
    et al.
    Roberts, Nick M. W.
    Reinhardt, Manuel
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Kielman-Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield2021In: Communications Earth & Environment, E-ISSN 2662-4435, Vol. 2, no 1, article id 102Article in journal (Refereed)
  • 11. Drake, Henrik
    et al.
    Roberts, Nick M. W.
    Reinhardt, Manuel
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Karlsson, Andreas
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Kielman-Schmitt, Melanie
    Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield2021In: Communication Earth & Environment, Vol. 2, no 1, article id 102Article in journal (Refereed)
  • 12.
    Hogmalm, Johan K.
    et al.
    Department of Earth Science, University of Gothenburg, Gothenburg, Sweden.
    Zack, Thomas
    Department of Earth Science, University of Gothenburg, Gothenburg, Sweden.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Sjökvist, Axel S.L.
    Department of Earth Science, University of Gothenburg, Gothenburg, Sweden.
    Garbe-Schönberg, Dieter
    CAU Kiel University, Institute of Geosciences, Ludewig-Meyn-Strasse 10, D-24118 Kiel, Germany .
    In situ Rb–Sr and K–Ca dating by LA-ICP-MS/MS: an evaluation of N2O and SF6 as reaction gases2017In: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 32, p. 305-313Article in journal (Refereed)
    Abstract [en]

    In situ dating of K-rich minerals, e.g. micas and K-feldspar, by the Rb–Sr isotopic system is a new development made possible by the ICP-MS/MS technique. Online chemical separation of Rb and Sr is possible in an O2-filled reaction cell, wherein a portion of the Sr reacts to SrO+ while simultaneously no RbO+ is formed. O2 reactions provide stable analytical conditions sufficient for precise and accurate determination of Rb/Sr and Sr/Sr isotopic ratios using 80 micron laser ablation spots. However, to date <10% of the Sr reacts with O2 as reaction gas, leaving room for improvement using more potent reaction gases. With a more efficient reactive transfer, it should be possible to obtain similar results with a smaller laser spot size, hence gaining higher spatial resolution. In this study, we have evaluated N2O and SF6 as reaction gases since they have previously been shown to react strongly with Sr+, without affecting Rb+. Analytical conditions, including cell parameters and reaction gas flow rate were optimized while ablating NIST SRM 610. The main reaction product is SrO+ for N2O reaction and SrF+ for SF6 reaction. Both gases show significantly higher reaction product formation compared to O2 with >85% of Sr reacting with N2O and >70% Sr reacting with SF6; Rb does not react with either gas. As a result, the sensitivity for Sr reaction products is ∼10 times higher with N2O and ∼8 times higher with SF6 compared to O2. With these more reactive gases, the error of mica isochron ages, calibrated against a newly developed nano-particulate pressed powder tablet of mica–Mg, is ∼1% using a 50 μm laser spot. Our tests show that both N2O and SF6 form interfering reaction products, e.g., SrOH (N2O), SiF3 and TiF3 (SF6) that are difficult to handle using single mass spectrometer instruments, but which can be overcome using MS/MS. Using SF6 combined with H2, it is possible to measure 40Ca+ as 40Ca19F+, free from interference of 40Ar+ and 40K+. This facilitates the dating of micas by the K–Ca isotopic system; we present the first in situ K–Ca age determination.

  • 13.
    Holtstam, Dan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bindi, Luca
    University of Florence.
    Förster, Hans-Jürgen
    GFZ German Research Centre for Geosciences .
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Gatedal, Kjell
    Garpenbergite, Mn6□As5+Sb5+O10(OH)2, a new mineral related to manganostibite, from the Garpenberg Zn–Pb–Ag deposit, Sweden2022In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 86, no 1, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Garpenbergite is a new mineral (IMA2020-099) from the Garpenberg Norra mine, Hedemora, Dalarna, Sweden. It occurs with carlfrancisite and minor stibarsen, paradocrasite and filipstadite in a fractured skarn matrix of granular jacobsite, alleghanyite, kutnohorite and dolomite. Crystals are short-prismatic, up to 1.5 mm in length. They have a blackish to greyish brown colour, and are lustrous semi-opaque, with brown streak. Garpenbergite is brittle, with an uneven to subconchoidal fracture. Cleavage is distinct on {010}. Hardness ≈ 5 (Mohs) and VHN100 = 650(40). Dcalc = 4.47(1) g⋅cm−3 , overall ncalc = 1.85. Maximum specular reflectance values (%) obtained are 9.2 (470 nm), 9.1 (546 nm), 9.0 (589 nm) and 8.9 (650 nm). The empirical chemical formula of garpenbergite, based on electron microprobe data, is (Mn2+3.97Mg1.48Mn3+0.26Zn0.296.00(As0.89Fe3+0.04Mn3+0.06Si0.01)Σ1.00(Sb0.98Fe0.02)Σ1.00O10[(OH)1.99Cl0.012.00. The five strongest Bragg peaks in the powder X-ray diffraction pattern [d, Å(I, %) (hkl)] are 3.05 (30) (002), 2.665 (100) (161), 2.616 (40) (301), 2.586 (25) (251) and 1.545 (45) (462). The orthorhombic unit-cell dimensions (in Å) are a = 8.6790(9), b = 18.9057(19) and c = 6.1066(6), with V = 1001.99(18) Å3 for Z = 4. The crystal structure was refined from single-crystal X-ray diffraction data in the space-group Ibmm to R1 = 3.7% for 957 reflections. Garpenbergite, ideally Mn6As5+Sb5+O10(OH)2, is isostructural with manganostibite, Mn7AsSbO12, but possesses a cation vacancy (□) at an octahedrally coordinated structural site; the two minerals are thus related by the exchange Mn2+ + 2O2– → □ + 2(OH) . The presence of hydroxyl groups is supported by vibration bands at 3647 and 3622 cm−1 in the Raman spectrum of garpenbergite, and by bond-valence considerations.

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  • 14.
    Holtstam, Dan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bindi, Luca
    University of Florence.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Langhof, Jörgen
    Swedish Museum of Natural History, Department of Geology.
    Zack, Thomas
    Göteborgs universitet.
    Bonazzi, Paola
    Università degli Studi di Firenze.
    Persson, Anders
    Kesebolite-(Ce), CeCa2Mn(AsO4)[SiO3]3, a new REE-bearing arsenosilicate mineral from the Kesebol mine, Åmål, Västra Götaland, Sweden2020In: Minerals, E-ISSN 2075-163X, Vol. 10, no 385, p. 1-14Article in journal (Refereed)
    Abstract [en]

    Kesebolite-(Ce), ideal formula CeCa2Mn(AsO4)[SiO3]3, is a new mineral (IMA No. 2019-097) recovered from mine dumps at the Kesebol Mn-(Fe-Cu) deposit in Västra Götaland, Sweden. It occurs with rhodonite, baryte, quartz, calcite, talc, andradite, rhodochrosite, K-feldspar, hematite,gasparite-(Ce), chernovite-(Y) and ferriakasakaite-(Ce). It forms mostly euhedral crystals, with lengthwise striation. The mineral is dark grayish-brown to brown, translucent, with light brown streak. It is optically biaxial (+), with weak pleochroism, and ncalc = 1.74. H = 5–6 and VHN100 = 825. Fair cleavage is observed on {100}. The calculated density is 3.998(5) g/cm-3. Kesebolite-(Ce) ismonoclinic, P21/c, with unit-cell parameters from X-ray single-crystal diffraction data: a = 6.7382(3), b = 13.0368(6), c = 12.0958(6) Å, beta = 98.578(2) degr., and V = 1050.66(9) Å3, with Z = 4. Strongest Braggpeaks in the X-ray powder pattern are: [I(%), d(Å) (hkl)] 100, 3.114 (20-2); 92, 2.924 (140); 84, 3.138(041); 72, 2.908 (014); 57, 3.228 (210); 48, 2.856 (042); 48, 3.002 (132). The unique crystal structure wassolved and refined to R1 = 4.6%. It consists of 6-periodic single silicate chains along (001); these are interconnected to infinite (010) strings of alternating, corner-sharing MnO6 and AsO4 polyhedra, altogether forming a trellis-like framework parallel to (100).

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  • 15.
    Holtstam, Dan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bindi, Luca
    University of Florence.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Söderhielm, Johan
    Sveriges Geologiska Undersökning.
    Zetterqvist, Anders
    Zetterqvist Geokonsult AB, Bromma, Sweden.
    Muonionalustaite, Ni3(OH)4Cl2·4H2O, a new mineral formed by terrestrial weathering of the Muonionalusta iron (IVA) meteorite, Pajala, Norrbotten, Sweden2021In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 143, no 1, p. 1-7Article in journal (Refereed)
    Abstract [en]

    Muonionalustaite, ideally Ni3(OH)4Cl2·4H2O, is a new mineral species (IMA 2020-010), found as a terrestrial weathering product of the Muonionalusta iron meteorite, in a fragment excavated 1.5 km NE of Lake Kitkiöjärvi. Muonionalustaite occurs in cavities of corrosion crust, associated with taenite, goethite, maghemite, amorphous Fe-Ni oxy-hydroxides and soil mineral particles. The mineral is green in colour and transparent. It occurs as lath-like crystals up to ca. 5 μm, elongated along [010] and flattened on {001}, forming aggregates and thin crusts. The calculated density and overall refractive index are 2.67(1) g·cm-3 and 1.68, respectively. An empirical formula from point analyses is (Ni2.88Fe0.02S0.02Al0.01Si0.012.94(OH3.73Cl2.276.00·4H2O. The crystal structure was refined in the space-group C2/m from powder X-ray diffraction data to RBragg = 3.55%. The monoclinic unit-cell parameters are a = 15.018(3) Å, b = 3.1490(6) Å, c = 10.502(3) Å, β = 101.535(15)º and V = 486.62(19) Å3 for Z = 2. Muonionalustaite is isostructural with the synthetic compounds Ni3(OH)3.9Cl2.1·4H2O and Mg3(OH)4Cl2·4H2O. The strongest X-ray diffraction lines are [I(%), d(Å), hkl]: 100, 10.30, 001; 67, 5.49, 201; 31, 3.868, 202; 30, 7.36, 200 and 25, 2.409, 60-2. Raman spectra show prominent bands at 3624, 3612, 3571 and 3507 cm-1, respectively, related to O–H-stretching vibrations of OH- groups, and in the region 450–530 cm-1 representing metal–O(H) vibration modes.

  • 16.
    Holtstam, Dan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Casey, Patrick
    Sveriges Geologiska Undersökning.
    Bindi, Luca
    University of Florence.
    Förster, Hans-Jürgen
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Appelt, Oona
    Fluorbritholite-(Nd), Ca2Nd3(SiO4)3F, a new and key mineral for neodymium sequestration in REE skarns2023In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 87, no 5, p. 731-737Article in journal (Refereed)
    Abstract [en]

    Fluorbritholite-(Nd), ideally Ca2Nd3(SiO4)3F, is an approved mineral (IMA 2023-001) and constitutes a new member of the britholite group of the apatite supergroup. It occurs in skarn from the Malmkärra iron mine, Norberg, Västmanland (one of the Bastnäs-type deposits in Sweden), associated with calcite, dolomite, magnetite, lizardite, talc, fluorite, baryte, scheelite, gadolinite-(Nd) and other REE minerals. Fluorbritholite-(Nd) forms anhedral and small grains, rarely up to 250 µm across. They are brownish pink, transparent with a vitreous to greasy luster. The mineral is brittle, with an uneven or subconchoidal fracture, and lacks a cleavage. In thin section, the mineral is nonpleochroic, uniaxial (-). Dcalc = 4.92(1) g·cm-3 and ncalc = 1.795. The empirical chemical formula from electron microprobe (WDS) point analyses is (Ca1.62Nd0.97Ce0.83Y0.52Sm0.30Gd0.23Pr0.17La0.16Dy0.11Er0.03Tb0.03Ho0.01Yb0.01)Σ4.99(Si2.92P0.08As0.013.01O12.00[O0.48F0.26(OH)0.14Cl0.10Br0.02]Σ1.00. The crystal structure of fluorbritholite-(Nd) was refined from single-crystal X-ray diffraction data to R1= 0.043 for 704 unique reflections. It belongs to the hexagonal system, space group P63/m, with unit cell parameters a = 9.5994(3), c = 6.9892(4) Å, V = 557.76(5) Å3 for Z = 2. Fluorbritholite-(Nd) and other britholite-group minerals are a major sink for neodymium in REE-bearing skarns of Bastnäs type. 

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  • 17.
    Holtstam, Dan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Cámara, Fernando
    Università degli Studi di Milano,.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Instalment of the margarosanite group, and data on walstromite–margarosanite solid solutions from the Jakobsberg Mn–Fe deposit, Värmland, Sweden2021In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 85, p. 224-232Article in journal (Refereed)
    Abstract [en]

    The margarosanite group (now officially confirmed by IMA-CNMNC) consists of triclinic Ca-(Ba, Pb) cyclosilicates with three-membered [Si3O9]6- rings (3R), with the general formula AB2Si3O9, where A = Pb, Ba, Ca and B = Ca. A closest-packed arrangement of O atoms parallel to (101) hosts Si and B cations in interstitial sites in alternating layers. The 3R layer has three independent Si sites in each ring. Divalent cations occupy three independent sites: Ca in B occupies two nonequivalent sites, Ca1 (8-fold coordinated), and Ca2 (6-fold coordinated). A (=Ca2) is occupied by Pb2+ (or Ba2+) in 6+4 coordination, or 6+1 when occupied by Ca; this third site occurs within the 3R-layer in a peripheral position. Three minerals belong to this group: margarosanite (ideally PbCa2Si3O9), walstromite (BaCa2Si3O9) and breyite (CaCa2Si3O9). So far, no solid solutions involving the Ca1 and Ca2 sites have been described. Therefore, root names depend on the composition of the Ca3 site only. Isomorphic replacement at the Ca3 sites has been noted. We here report data on a skarn sample from the Jakobsberg Mn-Fe oxide deposit, in Värmland (Sweden), representing intermediate compositions on the walstromite-margarosanite binary, in the range ca. 50–70% mol.% BaCa2Si3O9. The plumbian walstromite is closely associated with celsian, phlogopite, andradite, vesuvianite, diopside and nasonite. A crystal-structure refinement (R1 = 4.8%) confirmed the structure type, and showed that the Ca3 (Ba, Pb) site is split into two positions separated by 0.39 Å, with the Ba atoms found slightly more peripheral to the 3R-layers.

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    margarosanite group
  • 18.
    Holtstam, Dan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Cámara, Fernando
    Università degli Studi di Milano.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Langhofite, Pb2(OH)[WO4(OH)], a new mineral from Långban, Sweden.2020In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 84, p. 381-389Article in journal (Refereed)
    Abstract [en]

    Langhofite, ideally Pb2(OH)[WO4(OH)], is a new mineral from the Långban mine, Värmland, Sweden. The mineral and its name were approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA2019-005). It occurs in a small vug in hematite–pyroxene skarn associated with calcite, baryte, fluorapatite, mimetite and minor sulfide minerals. Langhofite is triclinic, space group P1, and unit-cell parameters a = 6.6154(1) Å, b = 7.0766(1) Å, c = 7.3296(1) Å, α = 118.175(2)°,β = 94.451(1)°, γ = 101.146(1)° and V = 291.06(1) Å3 for Z = 2. The seven strongest Bragg peaks from powder X-ray diffractometry are[dobs, Å (I )(hkl)]: 6.04(24)(010), 3.26(22)(11-2), 3.181(19)(200), 3.079(24)(1-12), 3.016(100)(020), 2.054(20)(3-11) and 2.050(18)(13-2). Langhofite occurs as euhedral crystals up to 4 mm, elongated along the a axis, with lengthwise striation. Mohs hardness is ca. 2½,based on VHN25 data obtained in the range 130–192. The mineral is brittle, with perfect {010} and {100} cleavages. The calculated density based on the ideal formula is 7.95(1) g⋅cm–3. Langhofite is colourless to white (non-pleochroic) and transparent, with a white streakand adamantine lustre. Reflectance curves show normal dispersion, with maximum values 15.7–13.4% within 400–700 nm. Electron microprobe analyses yield only the metals Pb and W above the detection level. The presence of OH-groups is demonstrated with vibration spectroscopy, from band maxima present at ∼3470 and 3330 cm–1. A distinct Raman peak at ca. 862 cm–1 is related to symmetricW–oxygen stretching vibrations. The crystal structure is novel and was refined to R = 1.6%. It contains [W2O8(OH)2]6– edge-sharingdimers (with highly distorted WO6-octahedra) forming chains along [101] with [(OH)2Pb4]6+ dimers formed by (OH)Pb3 triangles. Chains configure (010) layers linked along [010] by long and weak Pb–O bonds, thus explaining the observed perfect cleavage on{010}. The mineral is named for curator Jörgen Langhof (b. 1965), who collected the discovery sample.

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  • 19.
    Holtstam, Dan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Cámara, Fernando
    Università degli Studi di Milano,.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Zack, Thomas
    Göteborgs universitet.
    Ferri-taramite, a new member of the amphibole supergroup, from the Jakobsberg Mn–Fe deposit, Värmland, Sweden2022In: European journal of mineralogy, ISSN 0935-1221, E-ISSN 1617-4011, Vol. 34, no 5, p. 451-462Article in journal (Refereed)
    Abstract [en]

    Ferri-taramite (IMA CNMNC 2021-046), ideally ANaB(CaNa)C(Mg3Fe)T(Si6Al2)O22W(OH)2, occurs in skarn from the Jakobsberg manganese mine, Värmland, Sweden. Associated minerals are celsian, phlogopite, aegirine-augite, andradite, hancockite, melanotekite, microcline (var. hyalophane), calcite, baryte, prehnite, macedonite and oxyplumboroméite. Conditions of formation, close to peak metamorphism (at circa 650∘C and 0.4 GPa), include silica undersaturation, a slightly peralkaline character and relatively high oxygen fugacities. Ferri-taramite forms poikiloblastic crystals up to 5 mm and is dark brownish black with a yellowish grey streak. The amphibole is brittle with an uneven to splintery fracture. Cleavage parallel to {110} is good. Hardness (Mohs) is ∼ 6, and Dcalc=3.227(5) g cm−3. Holotype ferri-taramite has the experimental unit formula A(Na0.79K0.16Pb0.01)Σ0.96B(Ca1.26Na0.72Mn0.02)Σ2C(Mg2.66Mn2+0.58Fe2+0.16Zn0.02Fe3+1.26 Al0.26Ti0.06)Σ5T(Al1.86Si6.14)Σ8O22W(OH)2, based on chemical analyses (EDS, laser-ablation ICP-MS) and spectroscopic (Mössbauer, infrared) and single-crystal X-ray diffraction data. The mineral is optically biaxial (–), with α=1.670(5), β=1.680(5) and γ=1.685(5) in white light and 2Vmeas=70(10)∘ and 2Vcalc=70.2∘. Ferri-taramite is distinctly pleochroic in transmitted light, with X pale yellow, Y dark brown, Z yellowish brown and absorption Y>Z>X. The eight strongest reflections in the X-ray powder pattern (d values (in Å), Irel, hkl) are 8.44, 60, 110; 3.392, 25, 131; 3.281, 39, 240; 3.140, 100, 310; 2.816, 45, 330; 2.7104, 38, 151; 1.3654, 26, 461; and 1.4451, 33, -661. Refined unit-cell parameters from single-crystal diffraction data are a=9.89596(13), b=18.015(2), c=5.32164(7) Å, β=105.003(13)∘ and V=916.38(2) Å3 for Z=2. Refinement of the crystal structure yielded R=2.26 % for 2722 reflections with Io>2σ(I). The Mn2+ and Fe2+ ions show preference for the M1 and M3 octahedrally coordinated sites, whereas Fe3+ is strongly ordered at M2. The A-group cations, K and Na, are split over two subsites, A(m) and A(2), respectively.

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  • 20.
    Holtstam, Dan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Cámara, Fernando
    Università degli Studi di Milano.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Hjalmarite, a new Na-Mn member of the amphibole supergroup, from Mn skarn in the Långban deposit, Värmland, Sweden.2019In: European journal of mineralogy, ISSN 0935-1221, E-ISSN 1617-4011, Vol. 31, p. 565-574Article in journal (Refereed)
    Abstract [en]

    Hjalmarite, ideally ANaB(NaMn)CMg5TSi8O22W(OH)2, is a new root-name member of the amphibole supergroup, discovered in skarn from the Långban Fe-Mn-(Ba-As-Pb-Sb-Be-B) deposit, Filipstad, Värmland, Sweden (IMA-CNMNC 2017-070). It occurs closely associated with mainly rhodonite and quartz. It is grayish white with vitreous luster and non-fluorescent. The crystals are up to 5 mm in length and display splintery fracture and perfect cleavage along {110}. Hjalmarite is colorless (non-pleochroic) in thin section and optically biaxial (-), with α = 1.620(5), β = 1.630(5), γ = 1.640(5). The calculated density is 3.12 Mg/m3. Average VHN100 is 782, corresponding to circa 5½ Mohs. An empirical formula, derived from EPMA analyses in combination with crystal structure refinements, is (Na0.84K0.16)Σ1(Na1.01Mn0.55Ca0.43Sr0.01) Σ2(Mg3.83Mn1.16Al0.01) Σ5(Si7.99Al0.01) Σ8O22(OH1.92F0.08)Σ2. An infra-red spectrum of hjalmarite shows distinct absorption bands at 3673 cm-1 and 3731 cm-1 polarized in the α direction. The eight strongest Bragg peaks in the powder X-ray diffraction pattern are [d (Å), I (%), (hkl)]: 3.164, 100, (310); 2.837, 50, (330); 8.50, 44, (110); 3.302; 40, (240); 1.670, 34, (461); 1.448, 32, (-661); 2.727, 30, (151); 2.183, 18 (261).

    Single-crystal X-ray diffraction data were collected at 298 K and 180 K. The crystal structure was refined in space group C2/m to R1=2.6% [I>2(I)], with observed unit-cell parameters a = 9.9113(3), b = 18.1361(4), c = 5.2831(5) Å, β=103.658(5)° and V = 922.80(9) Å3 at ambient temperature. The A and M(4) sites split into A(m) (K+), A(2) (Na+), and M(4’) (Mn2+) subsites, respectively. Among the octahedrally coordinated C group cations, Mn2+ orders strongly at the M(2) site. No significant violation of C2/m symmetry or change in the structure topology is detected at low temperature (R1=2.1%). The hjalmarite-bearing skarn formed at peak regional metamorphism, T  ≥ 600°C, at conditions of high SiO2 activity and relatively low oxygen fugacity. The mineral name honors the Swedish geologist and mineralogist S.A. Hjalmar Sjögren (1856–1922).

  • 21.
    Holtstam, Dan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Cámara, Fernando
    Università degli Studi di Milano.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Langhof, Jörgen
    Swedish Museum of Natural History, Department of Geology.
    Recognition and approval of potassic-richerite, an amphibole supergroup mineral, from the Pajsberg mines, Filipstad, Sweden.2019In: Mineralogy and Petrology, ISSN 0930-0708, E-ISSN 1438-1168, Vol. 113, p. 7-16Article in journal (Refereed)
    Abstract [en]

    Potassic-richterite, ideally AKB(NaCa)CMg5TSi8O22W(OH)2, is recognized as a valid member of the amphibole supergroup (IMA CNMNC 2017–102). Type material is from the Pajsberg Mn-Fe ore field, Filipstad, Värmland, Sweden, where the mineral occurs in a Mn-rich skarn, closely associated with mainly phlogopite, jacobsite and tephroite. The megascopic colour is straw yellow to grayish brown and the luster vitreous. The nearly anhedral crystals, up to 4 mm in length, are pale yellow (non-pleochroic) in thin section andoptically biaxial (−), with α = 1.615(5), β = 1.625(5), γ = 1.635(5). The calculated density is 3.07 g·cm−1. VHN100 is in the range 610–946. Cleavage is perfect along {110}. EPMA analysis in combination with Mössbauer and infrared spectroscopy yields the empirical formula (K0.61Na0.30Pb0.020.93(Na1.14Ca0.79Mn0.07)Σ2(Mg4.31Mn0.47Fe3+0.20)Σ5(Si7.95Al0.04Fe3+0.01)Σ8O22(OH1.82F0.18)Σ2 for a fragmentused for collection of single-crystal X-ray diffraction data. The infra-red spectra show absorption bands at 3672 cm−1 and 3736 cm−1 for the α direction. The crystal structure was refined in space group C2/m to R1=3.6% [I >2σ(I)], with resulting cellparameters a = 9.9977(3) Å, b = 18.0409(4) Å, c = 5.2794(2) Å, γ = 104.465(4)°, V = 922.05(5) Å3 and Z=2. The A and M(4) sites split into A(m) (K+), A(2/m) (Na+), A(2) (Pb2+), and M(4′) (Mn2+) subsites, respectively. The remaining Mn2+ is strongly ordered at theoctahedrally coordinated M(2) site, possibly together with most of Fe3+. The skarn bearing potassic-richterite formed at peak metamorphism, under conditions of low SiO2 and Al2O3 activities and relatively high oxygen fugacities.

  • 22.
    Holtstam, Dan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    An unusual mineral assemblage of Pb silicates2022In: Geological Society of Sweden, 150 year anniversary meeting, Uppsala, August 17–19 2022, Abstract volume., Uppsala, 2022, Vol. 1, p. 356-357Conference paper (Refereed)
    Abstract [en]

    Rare assemblages of Pb silicates, from skarn in the Långban and Pajsbergs mines, Värmland, Sweden, have been investigated. Minerals observed are alamosite, barysilite, jagoite, joesmithite, melanotekite, nasonite and yangite, together with common metamorphic skarn components like andradite, diopside, hematite and quartz. Jagoite likely formed from primary melanotekite and quartz under the influence of a fluid with high Cl activity. Jagoite is prone to hydrothermal alteration, producing unidentified phases in the system CaO–PbO–SiO2–H2O–(±Cl2).

  • 23.
    Johansson, Åke
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Hurgammal är Stockholmsgraniten? Vad säger forskningen och vad säger folket?2019In: Geologiskt forum, no 101, p. 22-25Article in journal (Other (popular science, discussion, etc.))
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    Stockholmsgranitens ålder
  • 24.
    Johansson, Åke
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    The “intraorogenic” Svecofennian Herräng mafic dyke swarm in east-central Sweden: age, geochemistry and tectonic significance2020In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 142, no 1, p. 1-22Article in journal (Refereed)
    Abstract [en]

    The Herräng mafic dykes form an E-W-trending dyke swarm within the Bergslagen lithotectonic unit of the Svecofennian orogen in east-central Sweden. They intrude the Svecofennian supracrustal rocks and early-orogenic granitoids, but are themselves cut by late Svecofennian pegmatites, and have undergone Svecofennian amphibolite-facies metamorphism, leading to their classification as ‘intraorogenic’ Svecofennian dykes. They can be assigned an age between 1870 and 1850 Ma, with metamorphism of the dykes dated at 1848 ± 13 Ma by U-Pb in titanite. Their current mineralogy is dominated by metamorphic plagioclase and amphibole, with variable amounts of quartz and biotite, and minor to accessory titanite, apatite, epidote, pyrite, magnetite, ilmenite and zircon. Textures range from massive to strongly foliated.

    Twenty samples of dyke rocks from three subareas in the Roslagen region, including the Herräng type area, range in composition from basaltic to andesitic with 47 to 60 wt% SiO2, broadly similar to the Dannemora dykes and the Avesta-Östhammar gabbros and diorites. Initial 87Sr/86Sr ratios (at 1870 Ma) varies between 0.7026 and 0.7038, corresponding to initial εSr between +5 and +21, and initial εNd between -0.4 and +1.3, suggesting a slightly enriched to mildly depleted mantle source, similar to other Svecofennian mafic rocks.

    The dykes dominantly show a calc-alkaline volcanic arc signature related to subduction. They formed during an extensional episode, possibly related to incipient back-arc spreading or subduction roll-back following the main early-orogenic subduction-related Svecofennian magmatism, but penecontemporaneous with amphibolite-facies metamorphism in the area.

  • 25.
    Karlsson, Andreas
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Holtstam, Dan
    Swedish Museum of Natural History, Department of Geology.
    Bindi, Luca
    Dipartimento di Scienze della Terra, Università degli Studi di Firenze.
    Bonazzi, Poala
    Dipartimento di Scienze della Terra, Università degli Studi di Firenze.
    Konrad-Schmolke, Matthias
    Department of Earth Sciences, University of Gothenburg.
    Adding complexity to the garnet supergroup: monteneveite, Ca3Sb5+2(Fe3+2Fe2+)O12, a new mineral from the Monteneve mine, Bolzano Province, Italy2020In: European journal of mineralogy, ISSN 0935-1221, E-ISSN 1617-4011, Vol. 32, no 1, p. 77-87Article in journal (Refereed)
    Abstract [en]

    Monteneveite, ideally Ca3Sb5+2(Fe3+2Fe2+)O12, is a new member of the garnet supergroup (IMA2018-060). The mineral was discovered in a small specimen belonging to the Swedish Museum of Natural History coming from the now abandoned Monteneve Pb–Zn mine in Passiria Valley, Bolzano Province, Alto Adige (South Tyrol), Italy. The specimen consists of mainly magnetite, sphalerite, tetrahedrite-(Fe) and oxycalcioroméite. Monteneveite occurs as black, subhedral crystals with adamantine lustre. They are equidimensionaland up to 400 μm in size, with a subconchoidal fracture. Monteneveite is opaque, grey in reflected light,and isotropic under crossed polars. Measured reflectance values (%) at the four COM wavelengths are 12.6 (470 nm), 12.0 (546 nm), 11.6 (589 nm) and 11.4 (650 nm). The Vickers hardness (VHN100) is 1141 kg mm-2, corresponding to H = 6.5–7, and the calculated density is 4.72(1) g cm-3. A mean of 10 electron microprobe analyses gave (wt %) CaO 23.67, FeO 3.75, Fe2O3 29.54, Sb2O5 39.81, SnO2 2.22, ZnO 2.29, MgO 0.15, MnO 0.03 and CoO 0.03. The crystal chemical formula calculated on the basis of a total of eight cations and 12 anions, and taking into account the available structural and spectroscopic data, is (Ca2.97Mg0.03)Σ=3.00(Sb5+1.73Sn4+0.10Fe3+0.17)Σ=2.00(Fe3+2:43Fe2+0.37Zn0.20)Σ=3.00O12. The most significant chemical variations encounteredin the sample are related to a substitution of the type YSn4+ + ZFe3+  YSb5+ + ZFe2+. Mössbauer data obtained at RT and 77K indicate the presence of tetrahedrally coordinated Fe2+. Raman spectroscopy demonstrates that there is no measurable hydrogarnet component in monteneveite. The six strongest Bragg peaks in the powder X-ray diffraction pattern are [d (Å), I (%), (hkl)]: 4.45, 100, (220); 3.147, 60, (400); 2.814, 40, (420); 2.571, 80, (422); 1.993, 40, (620); 1.683, 60, (642). Monteneveite is cubic, space group Ia-3d, with a =12.6093(2) Å, V = 2004.8(1)Å3, and Z = 8. The crystal structure was refined up to R1 = 0.0197 for 305 reflections with Fo > 4σ (Fo) and 19 parameters. Monteneveite is related to the other Ca-, Sb- and Fe-bearing, nominally Si-free members of the bitikleite group, but it differs in that it is the only known garnet species with mixed trivalent and divalent cations (2:1) at the tetrahedral Z site. Textural and mineralogical evidence suggests that monteneveite formed during peak metamorphism (at ca. 600 ºC) during partial breakdown of tetrahedrite-(Fe) by reactions with carbonate, under relatively oxidizingconditions. The mineral is named after the type locality, the Monteneve (Schneeberg) mine.

  • 26.
    Kasapoğlu, Bülent
    et al.
    The Graduate School of Natural and Applied Sciences, Dokuz Eylül University, TR-35160 İzmir, Turkey.
    Ersoy, Yalçın E.
    Department of Geological Engineering, Dokuz Eylül University, TR-35160 İzmir, Turkey.
    Uysal, İbrahim
    Department of Geological Engineering, Karadeniz Technical University, TR-61080 Trabzon, Turkey.
    Palmer, Martin R.
    School of Ocean and Earth Science, University of Southampton, National Oceanography Centre, European Way, Southampton SO14 3ZH, UK.
    Zack, Thomas
    Department of Earth Science, University of Gothenburg, Gothenburg, Sweden.
    Koralay, Ersin O.
    Department of Geological Engineering, Dokuz Eylül University, TR-35160 İzmir, Turkey.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    The petrology of Paleogene volcanism in the Central Sakarya, Nallıhan Region: Implications for the initiation and evolution of post-collisional, slab break-off-related magmatic activity2015In: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 246-247, p. 81-98Article in journal (Refereed)
    Abstract [en]

    Zircon ages, mineral chemistry, whole-rock major and trace element compositions, as well as Sr–Nd isotopic ratios of basaltic (basanite, basalt, and hawaiite with MgO = 3.90–10.06 and SiO2 = 43.18–48.16) to andesitic (SiO2 = 50.86–61.27) and rhyolitic (SiO2 = 71.11–71.13) volcanic rocks (E-W emplaced Nallıhan volcanics) in the Lower Eocene terrestrial sedimentary units in the Central Sakarya Zone were studied and compared with those of the northerly located E-W-trending Eocene volcanic rocks (the Kızderbent Volcanics with 52.7–38.1 Ma radiometric ages) that are thought to be related to slab break-off process following the continental collision in the NW Anatolia. Zircon U–Pb ages of the Nallıhan volcanics vary from 51.7 ± 4.7 to 47.8 ± 2.4 Ma.

    Clinopyroxene from the basaltic and andesitic rocks record crystallization conditions from ~ 7–8 kbars (~ 23 km) and ~ 1210 °C, to 4.5–1.5 kbars (~ 14–1.5 km) and 1110–1010 °C crystallization conditions, respectively. The olivine-bearing, high-MgO (up to 10 wt%) basaltic rocks of the Nallıhan volcanics have nepheline-normative and Na-alkaline compositions, while the andesitic to rhyolitic rocks show calc-alkaline affinity with mainly sodic character. This is the first time this type of volcanic rock has been described in this region. The initial Sr isotopic ratios of both basaltic and andesitic–rhyolitic samples from the Nallıhan volcanics are similar (~ 0.7040–0.7045), indicating that fractional crystallization processes were not accompanied by crustal contamination and that the magma chambers were likely stored within ophiolitic units. Trace element ratios suggest that the Nallıhan volcanics were derived from E-MORB- or OIB-like enriched mantle sources, while the Kızderbent volcanics had N-MORB-like depleted mantle sources. Both volcanic units were produced by partial melting of spinel-bearing (shallow) mantle sources that had undergone subduction-related enrichment processes, with the degree of enrichment having been greater for the Kızderbent volcanics.

    The geochemical features of both the Nallıhan and Kızderbent volcanics are best explained as the result of slab break-off, in which the Nallıhan volcanics (located closer to the original subduction front) were produced mainly by the melting of upwelling asthenospheric mantle. Further back from the subduction front, the upwelling interacted with more highly metasomatized sub-arc mantle that underwent partial melting to produce the Kızderbent volcanics. This geodynamic scenario can be used for understanding other post-collisional slab break-off-related magmatic activities.

  • 27.
    Kenny, Gavin
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Schmieder, Martin
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Nemchin, Alexander
    Bellucci, Jeremy
    Swedish Museum of Natural History, Department of Geology.
    Recrystallization and chemical changes in apatite in response to hypervelocity impact2020In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 48, no 1, p. 19-23Article in journal (Refereed)
    Abstract [en]

    Despite the wide utility of apatite, Ca5(PO4)3(F,Cl,OH), in the geosciences, including tracing volatile abundances on the Moon and Mars, little is known about how the mineral responds to the extreme temperatures and pressures associated with hypervelocity impacts. To address this deficiency, we here present the first microstructural analysis and chemical mapping of shocked apatite from a terrestrial impact crater. Apatite grains from the Paasselkä impact structure, Finland, display intragrain crystal-plastic deformation as well as pervasive recrystallization—the first such report in terrestrial apatite. A partially recrystallized grain offers the opportunity to investigate the effect of shock recrystallization on the chemical composition of apatite. The recrystallized portion of the fluorapatite grain is depleted in Mg and Fe relative to the remnant non-recrystallized domain. Strikingly, the recrystallized region alone hosts inclusions of (Mg,Fe)2(PO4)F, wagnerite or a polymorph thereof. These are interpreted to be a product of phase separation during recrystallization and to be related to the reduced abundances of certain elements in the recrystallized domain. The shock-induced recrystallization of apatite, which we show to be related to changes in the mineral’s chemical composition, is not always readily visible in traditional imaging techniques (such as backscattered electron imaging of polished interior surfaces), thus highlighting the need for correlated microstructural, chemical, and isotopic studies of phosphates. This is particularly relevant for extraterrestrial phosphates that may have been exposed to impacts, and we urge the consideration of microstructural data in the interpretation of the primary or secondary nature of elemental abundances and isotopic compositions.

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  • 28.
    Langhof, Jörgen
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Holtstam, Dan
    Swedish Museum of Natural History, Department of Geology.
    Långban - a cornucopia for new mineral species?2021Conference paper (Other academic)
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    Långban - cornucopia
  • 29. Larsen, Alf Olav
    et al.
    Langhof, Jörgen
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Fantehullet på Oteröy - lokaliteten for Tellef Dahlls angivelige nye grunnstoff norvegium2019In: Norskt Mineralsymposium 2019 / [ed] Alf Olav Larsen & Torfinn Kjaernet, 2019, p. 93-101Conference paper (Other academic)
  • 30.
    Mulder, Jacob
    et al.
    School of Earth and Environmental Sciences The University of Queensland Queensland Australia;Department of Earth Sciences University of Adelaide Adelaide Australia.
    Hagen‐Peter, Graham
    Department of Geoscience Aarhus University Denmark;Geological Survey of Norway.
    Ubide, Teresa
    School of Earth and Environmental Sciences The University of Queensland Queensland Australia.
    Andreasen, Rasmus
    Department of Geoscience Aarhus University Denmark.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology. Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden.
    Kielman‐Schmitt, Melanie
    The Vegacenter Swedish Museum of Natural History Sweden.
    Feng, Yue‐Xing
    Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) Zhuhai China.
    Paul, Bence
    School of Geography, Earth and Atmospheric Sciences The University of Melbourne Victoria Australia;Elemental Scientific Lasers LLC. Bozeman Montana USA.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology. The Vegacenter Swedish Museum of Natural History Sweden.
    Tegner, Christian
    Department of Geoscience Aarhus University Denmark.
    Lesher, Charles
    Department of Geoscience Aarhus University Denmark;Department of Earth and Planetary Sciences University of California Davis California USA.
    Costa, Fidel
    Institut de Physique du Globe de Paris France.
    New Reference Materials, Analytical Procedures and Data Reduction Strategies for Sr Isotope Measurements in Geological Materials by LA‐MC‐ICP‐MS2023In: Geostandards and Geoanalytical Research, ISSN 1639-4488, E-ISSN 1751-908X, Vol. 47, no 2, p. 311-336Article in journal (Refereed)
    Abstract [en]

    Laser ablation multi-collector mass spectrometry (LA-MC-ICP-MS) has emerged as the technique of choice for in situ measurements of Sr isotopes in geological minerals. However, the method poses analytical challenges and there is no widely adopted standardised approach to collecting these data or correcting the numerous potential isobaric inferences. Here, we outline practical analytical procedures and data reduction strategies to help establish a consistent framework for collecting and correcting Sr isotope measurements in geological materials by LA-MC-ICP-MS. We characterise a new set of plagioclase reference materials, which are available for distribution to the community, and present a new data reduction scheme for the Iolite software package to correct isobaric interferences for different materials and analytical conditions. Our tests show that a combination of Kr-baseline subtraction, Rb-peak-stripping using βRb derived from a bracketing glass reference material, and a CaCa or CaAr correction for plagioclase and CaCa or CaAr + REE2+ correction for rock glasses, yields the most accurate and precise 87Sr/86Sr measurements for these materials. Using the analytical and correction procedures outlined herein, spot analyses using a beam diameter of 100 μm or rastering with a 50–65 μm diameter beam can readily achieve < 100 ppm 2SE repeatability ("internal") precision for 87Sr/86Sr measurements for materials with < 1000 μg g-1 Sr.

  • 31.
    Peillod, Alexandre
    et al.
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Majka, Jaroslaw
    Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Ring, Uwe
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Drüppel, Kirsten
    Department of Petrology, Karlsruhe Institute of Technology, Karlsruhe, Germany.
    Patten, Clifford
    Department of Ore Geology, Karlsruhe Institute of Technology, Karlsruhe, Germany.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Wlodek, Adam
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Tehler, Elof
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Differences in decompression of a high-pressure unit: A case study from the Cycladic Blueschist Unit on Naxos Island, Greece2021In: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 386-387Article in journal (Refereed)
    Abstract [en]

    Determining the tectonic evolution and thermal structure of a tectonic unit that experiences a subduction-related pressure temperature (P-T) loop is challenging. Within a single unit, P-T conditions can vary from top to bottom which can only be revealed by detailed petrological work. We present micropetrological data from the middle section of the Cycladic Blueschist Unit (CBU) in Naxos, Greece, which indicates a different P-T loop than that for the top of the sequence. Using Zr-in-rutile and Ti-in-biotite thermometry coupled with quartz-in-garnet elastic barometry and phase equilibrium thermodynamic modeling, we identify a prograde path from 15.4 ± 0.8 kbar to 19.9 ± 0.6 kbar and from 496 ± 16 °C to 572 ± 7 °C (2σ uncertainty), equilibration during decompression at 8.3 ± 1.5 kbar and 519 ± 12 °C followed by near-isobaric heating to 9.2 ± 0.8 kbar and 550 ± 10 °C (or even 584 ± 19 °C), and a final greenschist-facies equilibration stage at 3.8 ± 0.3 kbar and 520 ± 4 °C. We compare these P-T estimates with published data from the top and also the bottom of the CBU section and find that the bottom half of the CBU on Naxos records higher peak high-pressure (HP) of about 4 kbar than the top of the unit, defining the thickness of the CBU section on Naxos to about 15 km in the Eocene. We determine that crustal thickening of up to ~15% occurs in the upper half of the CBU section during exhumation of the HP rocks in an extrusion wedge in a convergence setting. At about 30 Ma, the bottom half of the CBU was finally thrust onto the radiogenic Cycladic basement. Subsequently this bottom half of the CBU section underwent isobaric heating of 9–96 °C between c. 32–28 and 23–21 Ma. Isobaric heating occurred below the upper CBU section that thickened during decompression and commenced when HP metamorphism in the Cyclades ended. This suggests that thermal relaxation following tectonic accretion in the Cyclades controlled heating of the evolving Cycladic orogen during a tectonically quiescent period before lithospheric extension commenced by 23–20.5 Ma.

  • 32.
    Sjöström, J.K.
    et al.
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Bindler, R.
    Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.
    Martínez Cortizas, A.
    CRETUS, EcoPast (GI-1553), Universidad de Santiago de Compostela, Santiago de Compostela, Spai.
    Björck, S.
    Department of Geology, Lund University, Lund, Sweden.
    Hansson, S.V.
    Laboratoire écologie fonctionnelle et environnement, CNRS Université de Toulouse, Toulouse, France.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Ellerton, D.T.
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Kylander, Malin
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Late Holocene peat paleodust deposition in south-western Sweden - exploring geochemical properties, local mineral sources and regional aeolian activity2022In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 602, p. 1-14, article id 120881Article in journal (Refereed)
    Abstract [en]

    Atmospheric mineral dust not only interacts with the climate system by scattering incoming solar radiation and affecting atmospheric photochemistry, but also contributes critical nutrients to marine and terrestrial ecosystems. In a high-resolution analysis of paleodust deposition, peat development and soil dust sources, we assess the interplay between dust deposition and bog development of the Davidsmosse bog in south-western Sweden. Analyses of the 5400-year record (458 cm) included radiocarbon dating, bulk density, ash content, chemical and mineralogical composition and carbon stable isotopes, subsequently explored using principal component analysis. Fourteen dust events (DEs) were recorded (cal BP) in the peat sequence: 3580–3490; 3280; 3140; 3010–2840; 2740; 2610; 2480; 2340; 2240–2130; 1690; 1240; 960, 890–760, and 620–360. The majority of the DEs were coupled to increases in peat accumulation rates and increased nutrient content (N, P and K) suggesting that the DEs contributed with nutrients to the bog ecosystem, promoting increased accumulation. We also analyzed the chemical and mineral composition of potential mineral source deposits (separated into 6 grain-size fractions) from sites within a 4 km radius as well as aeolian dunes closer to the coast (25 km). The composition deposited on the present-day bog surface indicates that the bulk of the contemporary minerals have a local origin (<1.5 km), but the DEs may be of a more distant origin. The results also indicate that quartz and plagioclase feldspar content consistently increase with increasing grain-size, both in the source samples as well as in the peat sequence, and that the Si/Al ratio can be used to infer grain size changes in the peat. Two longer phases saw numerous DEs, between 2800 and 2130 cal BP and a stepwise increase from 960 towards 360 cal BP. The episodic character of the events, together with the inferred coarse grain size, suggest that the particles were deposited by (winter) storms. Future studies should include grain size analysis as well as a more in-depth comparison with regional paleo dust and storm records to increase knowledge on both transport processes (creep, saltation, suspension) and the climate processes driving late Holocene dust and storm events in Scandinavia.

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  • 33.
    Stockmann, Gabrielle
    Department of Geological Sciences, Stockholm University, Sweden.
    Skelton, Alasdair (Contributor)
    Department of Geological Sciences, Stockholm University, Sweden.
    Brüchert, Volker (Contributor)
    Department of Geological Sciences, Stockholm University, Sweden.
    Balic-Zunic, Tonci (Contributor)
    Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark.
    Langhof, Jörgen (Contributor)
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik (Contributor)
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas (Contributor)
    Swedish Museum of Natural History, Department of Geology.
    Control of a calcite inhibitor (phosphate) and temperature on ikaite precipitation in Ikka Fjord, southwest Greenland2018In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 89, p. 11-22Article in journal (Refereed)
    Abstract [en]

    Ikaite (CaCO3·6H2O) forms submarine tufa columns in Ikka Fjord, SW Greenland. This unique occurrence is thought to relate to aqueous phosphate concentration and low water temperatures (<6 °C). Phosphate ions are well-known inhibitors of calcite precipitation and Ikka Fjord has a naturally high-phosphate groundwater system that when mixing with seawater leads to the precipitation of ikaite. In the study presented here, experiments simulating conditions of Ikka Fjord show that a) the formation of ikaite is unrelated to the aqueous phosphate concentration (0–263 μmol/kg PO43−) in 0.1 M NaHCO3/0.1 M Na2CO3 solutions mixing with seawater at 5 °C and pH 9.6–10.6, and b) ikaite forms at temperatures up to 15 °C without phosphate and in open beakers exposed to air. Instead, supersaturation of ikaite and the seawater composition are the likely factors causing ikaite to precipitate in Ikka Fjord. This study shows that adding Mg2+ to a NaHCO3/Na2CO3 – CaCl2 mixed solution leads to the formation of ikaite along with hydrated Mg carbonates, which points to the high Mg2+ concentration of seawater, another known inhibitor of calcite, as a key factor promoting ikaite formation. In experiments at 10 and 15 °C, increasing amounts of either nesquehonite (Mg(HCO3)(OH)·2H2O) or an amorphous phase co-precipitate with ikaite. At 20 °C, only the amorphous phase is formed. In warming Arctic seawater, this suggests Mg carbonate precipitation could become dominant over ikaite in the future.

  • 34.
    Stockmann, Gabrielle
    Department of Geological Sciences, Stockholm University, Sweden.
    Brüchert, Volker (Contributor)
    Department of Geological Sciences, Stockholm University, Sweden.
    Skelton, Alasdair (Contributor)
    Department of Geological Sciences, Stockholm University, Sweden.
    Balic-Zunic, Tonci (Contributor)
    Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark.
    Langhof, Jörgen (Contributor)
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik (Contributor)
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas (Contributor)
    Swedish Museum of Natural History, Department of Geology.
    Control of a calcite inhibitor (phosphate) and temperature on ikaite precipitation in Ikka Fjord, southwest Greenland2018In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 89, p. 11-22Article in journal (Refereed)
    Abstract [en]

    Ikaite (CaCO3·6H2O) forms submarine tufa columns in Ikka Fjord, SW Greenland. This unique occurrence is thought to relate to aqueous phosphate concentration and low water temperatures (<6 °C). Phosphate ions are well-known inhibitors of calcite precipitation and Ikka Fjord has a naturally high-phosphate groundwater system that when mixing with seawater leads to the precipitation of ikaite. In the study presented here, experiments simulating conditions of Ikka Fjord show that a) the formation of ikaite is unrelated to the aqueous phosphate concentration (0–263 μmol/kg PO43−) in 0.1 M NaHCO3/0.1 M Na2CO3 solutions mixing with seawater at 5 °C and pH 9.6–10.6, and b) ikaite forms at temperatures up to 15 °C without phosphate and in open beakers exposed to air. Instead, supersaturation of ikaite and the seawater composition are the likely factors causing ikaite to precipitate in Ikka Fjord. This study shows that adding Mg2+ to a NaHCO3/Na2CO3 – CaCl2 mixed solution leads to the formation of ikaite along with hydrated Mg carbonates, which points to the high Mg2+ concentration of seawater, another known inhibitor of calcite, as a key factor promoting ikaite formation. In experiments at 10 and 15 °C, increasing amounts of either nesquehonite (Mg(HCO3)(OH)·2H2O) or an amorphous phase co-precipitate with ikaite. At 20 °C, only the amorphous phase is formed. In warming Arctic seawater, this suggests Mg carbonate precipitation could become dominant over ikaite in the future.

  • 35.
    Stockmann, Gabrielle
    et al.
    Department of Geological Sceinces, Stockholm University.
    Tollefsen, Elin
    Department of Geological Sceinces, Stockholm University.
    Skelton, Alasdair
    Department of Geological Sceinces, Stockholm University.
    Brüchert, Volker
    Department of Geological Sceinces, Stockholm University.
    Balic-Zunic, Tonci
    Department of Geosceinces and Natural Resource Management, University of Copenhagen.
    Langhof, Jörgen
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Control of calcite inhibitor (phosphate) and temperature on ikaite precipitation in Ikka Fjord, southwest Greenland2018In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 89, p. 11-22Article in journal (Refereed)
1 - 35 of 35
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