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  • 1.
    Berg, Sylvia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Univ Iceland, Nord Volcanol Ctr, Inst Earth Sci, Sturlugata 7, IS-101 Reykjavik, Iceland.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Harris, Chris
    Univ Cape Town, Dept Geol Sci, ZA-7701 Rondebosch, South Africa.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Riishuus, Morten S.
    Univ Iceland, Nord Volcanol Ctr, Inst Earth Sci, Sturlugata 7, IS-101 Reykjavik, Iceland.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Krumbholz, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Exceptionally high whole-rock delta O-18 values in intra-caldera rhyolites from Northeast Iceland2018Ingår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 82, nr 5, s. 1147-1168Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Icelandic crust is characterized by low delta O-18 values that originate from pervasive high-temperature hydrothermal alteration by O-18-depleted meteoric waters. Igneous rocks in Iceland with delta O-18 values significantly higher than unaltered oceanic crust (similar to 5.7 parts per thousand) are therefore rare. Here we report on rhyolitic intra-caldera samples from a cluster of Neogene central volcanoes in Borgarfjorour Eystri, Northeast Iceland, that show whole-rock delta O-18 values between +2.9 and +17.6 parts per thousand (n = 6), placing them among the highest delta O-18 values thus far recorded for Iceland. Extra-caldera rhyolite samples from the region, in turn, show delta O-18 whole-rock values between +3.7 and +7.8 parts per thousand (n = 6), consistent with the range of previously reported Icelandic rhyolites. Feldspar in the intra-caldera samples (n = 4) show delta O-18 values between +4.9 and +18.7 parts per thousand, whereas pyroxene (n = 4) shows overall low delta O-18 values of +4.0 to +4.2 parts per thousand, consistent with regional rhyolite values. In combination with the evidence from mineralogy and rock H2O contents, the high whole-rock delta O-18 values of the intra-caldera rhyolites appear to be the result of pervasive isotopic exchange during subsolidus hydrothermal alteration with O-18-enriched water. This alteration conceivably occurred in a near-surface hot spring environment at the distal end of an intra-caldera hydrothermal system. and was probably fed by waters that had already undergone significant isotope exchange with the country rock. Alternatively, O-18-enriched alteration fluids may have been produced during evaporation and boiling of standing water in former caldera lakes, which then interacted with the intra-caldera rock suites. Irrespective of the exact exchange processes involved, a previously unrecognized and highly localized delta O-18-enriched rock composition exists on Iceland and thus probably within the Icelandic crust too.

  • 2.
    Bowles, John F. W.
    et al.
    Univ Manchester, Sch Earth & Environm Sci, Manchester, Lancs, England.
    Cook, Nigel J.
    Univ Adelaide, Sch Chem Engn, Adelaide, Australia.
    Sundblad, Krister
    Univ Turku, Dept Geog & Geol, Turku, Finland; St Petersburg State Univ, Inst Earth Sci, St Petersburg, Russia.
    Jonsson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Geol Survey Sweden, Dept Mineral Resources, Uppsala, Sweden.
    Deady, Eimear
    Lyell Ctr, British Geol Survey, Res Ave South, Edinburgh, Midlothian, Scotland; Univ Exeter, Camborne Sch Mines, Penryn Campus, Penryn, England.
    Hughes, Hannah S. R.
    Univ Exeter, Camborne Sch Mines, Penryn Campus, Penryn, England.
    Critical-metal mineralogy and ore genesis: contributions from the European Mineralogical Conference held in Rimini, September 20162018Ingår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 82, s. S1-S4Artikel i tidskrift (Övrigt vetenskapligt)
  • 3. Emeleus, C. H.
    et al.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    The Rum Igneous Centre, Scotland2014Ingår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 78, nr 4, s. 805-839Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The publication of the British Geological Survey memoir on Rum and the Small Isles in 1997 was followed by a period of intense petrological and mineralogical research, leading to some 40 papers, books and other publications. The research progress since then is reviewed here and integrated with the information previously available to provide an overview of the current status of understanding of the centre. New data on the acidic and mixed acid/basic magmas of the early Rum caldera demonstrate that frequent mafic replenishments were the main driver for magmatic activity at Rum right from its initial stages. The caldera is bound by the Main Ring Fault, a structure which probably also exercised an influence on the emplacement of the subsequent basic and ultrabasic intrusions. The later emplacement of gabbros and ultrabasic rocks caused only limited thermal metamorphism of the surrounding Torridonian sandstones, contrasting markedly with the crustal isotope signatures of the early intra-caldera ignimbrite magmas and the intense alteration of uplifted masses of Lewisian gneiss within the ring fault. Rare picritic dykes provide an indication of the possible parent magma for the mafic and ultrabasic rocks, but these, as with most other magmatic rocks on Rum, have undergone varying degrees of crustal contamination, involving both Lewisian granulite and amphibolite-type crust but, notably, no Moine metasedimentary compositions as is the case at the nearby Ardnamurchan centre. Detailed textural studies on the gabbroic and ultrabasic rocks allow a distinction between intrusive peridotites and peridotite that forms part of the classic layered cumulate units of Rum and, furthermore, this work and that on the chromite seams and veins in these rocks shows that movement of trapped magma and magma derived from later intrusions, may produce textures regarded previously as of primary cumulate origin. Sulfides in the chromitite seams and ultrabasic rocks, in turn, show possible influences from assimilated Mesozoic sediments. Igneous activity on Rum was short-lived, possibly only between 0.5 and 1 m.y. in duration and commenced at similar to 60.5 Ma. The Rum Central Complex was extinct by the time the main activity at the nearby Skye Central Complex commenced (similar to 59 Ma). From recent apatite fission-track studies it seems probable that Rum, in common with other Palaeogene centres, underwent a brief, but significantly later heating event (similar to 45 Ma).

  • 4.
    Herbert, Roger B
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Zinc immobilization by zerovalent Fe: surface chemistry and mineralogy and reaction products2003Ingår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 67, nr 6, s. 1285-1298Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In bioreactor systems for the treatment of metal-contaminated water, pretreatment with zerovalent Fe can be exploited for oxygen consumption and H-2 Production. In this study, a column experiment is used to investigate the changes in surface chemistry and solid phase products that result from the reaction of a Zn-sulphate-lactate solution with zerovalent Fe filings. The results of this study indicate that zerovalent Fe is very effective in immobilizing dissolved Zn with a porewater residence time of 1.3-3.1 days. A combination of X-ray diffractometry, X-ray photoelectron spectroscopy, and mineral equilibria calculations indicates that Zn precipitates as Zn(OH)(2) and zincite at PH 9-10. At PH approximate to 6, Zn primarily adsorbs to abundant ferric oxyhydroxides, although incorporation in green rust is also considered. During the course of the experiment, the surface mineralogy changes from magnetite-lepidocrocite-goethite to green rust-akaganeite-goethite. The results suggest that the zerovalent Fe surface becomes passivated by a surface film of ferric oxyhydroxides, green rust and organic material, so that the rate of electron transfer and proton consuming reactions (i.e. oxygen consumption, H-2 generation) declines, resulting in a decrease in solution PH.

  • 5.
    Herbert, Roger
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Winbjörk, Harry
    Pilot-scale barrier system for removal of nitrate in mine drainage2011Ingår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 75, s. 1012-1012Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Undetonated ammonium nitrate is readily soluble in water and quickly enters into the mine water and process water at amine site. In order to investigate the application of nitrate removal by denitrification in the cold climate of northern Sweden, a pilot-scale barrier system was constructed of sheet metal in autumn 2009 at the Malmberget iron ore mine.

    The barrier (9m x 2m x 1.5m) appears as an open basin with three inner dividing walls, and is filled with a reactive mixture consisting of crushed rock, sawdust, and sewage sludge. Water flows through the barrier at ca. 0.45 m3/hour.The chemical analyses of water flowing into and out of thebarrier during 2010 indicate that the degree of nitrate removal generally lay in the range between 11 and 77% of influent nitrate concentrations. Stable isotope analyses of δ15N and δ18O in nitrate demonstrate an enrichment in 15N and 18O in nitrate as water flows through the barrier, supporting theconclusion that denitrification is responsible for nitrateremoval. Ammonium concentrations in the barrier effluents are initially high, but these high levels are subsequently flushed from the barrier.

    In order to increase the degree of nitrate removal by denitrification in the barrier, a reactive carbon source needs to be added to the influent waters; this will be tested during the 2011 field season.

  • 6.
    Majka, Jaroslaw
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Prsek, J.
    Budzyn, B.
    Bacik, P.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Lodzinski, M.
    Fluorapatite-hingganite-(Y) coronas as products of fluid-induced xenotime-(Y) breakdown in the Skoddefjellet pegmatite, Svalbard2011Ingår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 75, nr 1, s. 159-167Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The pre-Caledonian NYF Skoddefjellet pegmatite in Wedel Jarlsberg Land, Svalbard, contains xenotime-(Y) that is partly replaced by fluorapatite-hingganite-(Y) reaction coronas. Hingganitc-(Y) contains up to 2.0 wt.% of Gd2O3, 4.7 wt.% of Dy2O3, 3.3 wt.% of Er2O3 and 5.5 wt.% of Yb2O3. Such unusual, previously undescribed, xenotime-(Y) breakdown was caused by Ca- and F-bearing fluids interacting with the pegmatite. The occurrence of hinnganite-(Y) as a breakdown product of xenotime-(Y) implies that a Be-bearing phase (beryl in this case) was also involved in the reaction. There are few Ca-bearing primary phases in the pegmatite, indicating that the source of fluid was probably located in the generally Ca-richer host rocks (metasediments), though the fluid composition was modified during metasomatism of the pegmatite (i.e. beryl dissolution).

  • 7.
    Skoda, Radek
    et al.
    Masaryk Univ, Fac Sci, Dept Geol Sci, Kotlarska 2, CZ-61137 Brno, Czech Republic.
    Plasil, Jakub
    Inst Phys ASCR, Vvi, Slovance 2, CZ-18221 Prague 8, Czech Republic.
    Copjakova, Renata
    Masaryk Univ, Fac Sci, Dept Geol Sci, Kotlarska 2, CZ-61137 Brno, Czech Republic.
    Novak, Milan
    Masaryk Univ, Fac Sci, Dept Geol Sci, Kotlarska 2, CZ-61137 Brno, Czech Republic.
    Jonsson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Geol Survey Sweden, Dept Mineral Resources, Box 670, SE-75128 Uppsala, Sweden.
    Galiova, Michaela Vasinova
    Masaryk Univ, Fac Sci, Dept Geol Sci, Kotlarska 2, CZ-61137 Brno, Czech Republic;Masaryk Univ, Fac Sci, Dept Chem, Kotlarska 2, CZ-61137 Brno, Czech Republic;Masaryk Univ, Cent European Inst Technol CEITEC, Kamenice 5, CZ-62500 Brno, Czech Republic.
    Holtstam, Dan
    Swedish Res Council, Box 1035, SE-10138 Stockholm, Sweden.
    Gadolinite-(Nd), a new member of the gadolinite supergroup from Fe-REE deposits of Bastnäs-type, Sweden2018Ingår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 82, nr Suppl. 1, s. S133-S145Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new member of the gadolinite supergroup, gadolinite-(Nd), IMA2016-013, ideally Nd2FeBe2Si2O10, was found in the Malmkarra mine, similar to 3.5km WSW of Norberg, south-central Sweden, where it occurs in association with fluorbritholite-(Ce), vastmanlandite-(Ce), dollaseite-(Ce), bastnasite-(Ce) and tremolite. Gadolinite-(Nd) forms anhedral grains up to 150 mu m in size, commonly occurring as aggregates of olive green colour. The crystals are transparent with vitreous to adamantine lustre. Gadolinite-(Nd) is brittle with conchoidal fracture, no cleavage or parting was observed. It has a white streak, the Mohs hardness is 6.5-7 and the calculated density is 4.86gcm(-3). Optically, the mineral is weakly pleochroic in shades of olive green, biaxial (-), n=1.78(1), n((calc.))=1.80, n=1.81(1) measured in white light, 2V((meas.))=62(3)degrees. Electron-microprobe and laser ablation inductively coupled plasma mass spectrometry analysis [in wt.%] provided SiO2 21.77, Y2O3 5.49, La2O3 2.78, Ce-2 O-3 14.04, Pr2O3 3.28, Nd2O3 19.27, Sm2O3 5.30, Eu2O3 0.24, Gd2O3 4.10, Tb2O3 0.36, Dy2O3 1.32, Ho2O3 0.18, Er2O3 0.38, MgO 0.51, CaO 0.14, MnO 0.10, FeO 10.62, B2O3 0.10, BeOcalc. 8.99, H2Ocalc. 0.55 and total 99.52 giving the following empirical formula (based on 2 Si): (Nd0.632Ce0.472Y0.268Sm0.168Gd0.125Pr0.110La0.094Dy0.039Ca0.014Er0.011Tb0.011Eu0.008Ho0.008)(Sigma 1.957)(Fe0.816Mg0.070Mn0.008)(Sigma 0.894)(Be1.984B0.016)(Sigma 2.000)Si2O9.660OH0.337. A weak Raman vibration band at similar to 3525cm(-1) confirms the presence of water in the structure. Gadolinite-(Nd) is monoclinic, P2(1)/c, with a=4.8216(3) angstrom, b=7.6985(4) angstrom, c=10.1362(6) angstrom, beta =90.234(4)degrees, V=376.24(6) angstrom(3) and Z=2. The strongest X-ray diffraction lines are [d(obs) in angstrom (hkl) I-rel]: 4.830 (100) 72, 3.603 (021) 37, 3.191(-112) 52, 3.097 (013) 35, 2.888 (121) 100, 2.607(113) 49, 2.412 (200) 24. Along with the Malmkarra mine, gadolinite-(Nd) was also recorded also at Johannagruvan and Nya Bastnas. The minerals of the gadolinite subgroup together with fluorbritholite-(Ce) incorporate the highest fraction of medium-to-heavy rare-earth elements among associated rare-earth element minerals in the Malmkarra mine and possibly in all Bastnas-type deposits.

  • 8.
    Skoda, Radek
    et al.
    Masaryk Univ, Dept Geol Sci, Fac Sci, CZ-61137 Brno, Czech Republic..
    Plasil, Jakub
    Inst Phys ASCR, Vvi, CZ-18221 Prague 8, Czech Republic..
    Jonsson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Geol Survey Sweden, Dept Mineral Resources, SE-75128 Uppsala, Sweden..
    Copjakova, Renata
    Masaryk Univ, Dept Geol Sci, Fac Sci, CZ-61137 Brno, Czech Republic..
    Langhof, Joergen
    Swedish Museum Nat Hist, Dept Geosci, SE-10405 Stockholm, Sweden..
    Galiova, Michaela Vasinova
    Masaryk Univ, Fac Sci, Dept Chem, CZ-61137 Brno, Czech Republic.;Masaryk Univ, Cent European Inst Technol CEITEC, CZ-62500 Brno, Czech Republic..
    Redefinition of thalenite-(Y) and discreditation of fluorthalenite-(Y): A re-investigation of type material from the Osterby pegmatite, Dalarna, Sweden, and from additional localities2015Ingår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 79, nr 4, s. 965-983Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using type material from the Osterby pegmatite in Dalarna, Sweden, the chemical composition and structural parameters of thalenite-(Y) [ideally Y3Si3O10(OH)] were examined by wavelength dispersive spectroscopy electron microprobe (WDS EMP) analysis and single-crystal X-ray diffraction. High contrast back-scatter electron images of the Osterby material show at least two generations of thalenite-(Y). The formula of the primary thalenite-(Y) normalized to 11 anions is (Y2.58Dy0.11Yb0.09Gd0.06Er0.06Ho0.02 Sm0.02Tb0.02Lu0.02Nd0.01Tm0.01)(Sigma 3.00)Si3.01O10F0.97OH0.03. The secondary thalenite-(Y), replacing the primary material, is weakly enhanced in Y and depleted in the lightest and the heaviest rare-earth elements, yielding the formula (Y2.63Dy0.12Yb0.06Gd0.06Er0.05Ho0.02Sm0.02Tb0.02Tm0.01Nd0.01Lu0.01)(Sigma 3.00) Si3.01O10F0.98OH0.02. Structural data for thalenite-(Y) from Osterby clearly indicate the monoclinic space group P2(1)/n, with a = 7.3464(4), b = 11.1726(5), c = 10.4180(5) angstrom, beta = 97.318(4)degrees, V = 848.13(7) angstrom(3), Z = 4, which is consistent with previous investigations. The structure was refined from single-crystal X-ray diffraction data to R-1 = 0.0371 for 1503 unique observed reflections, and the final chemical composition obtained from the refinement, (Y2.64Dy0.36)(Sigma 3.00)F-0.987[Si3O10], Z = 4, is in good agreement with the empirical formula resulting from electron microprobe (EMP) analysis. Both techniques reveal a strong dominance of F over OH, which means that the type material actually corresponds to the fluorine analogue. Moreover, new EMP analyses of samples of thalenite-(Y) from an additional seven localities (angstrom skagen and Reunavare in Sweden; White Cloud and Snow Flake in Colorado, USA; the Guy Hazel claim in Arizona, USA; Suishoyama and Souri in Japan) clearly show the prevalence of F over OH as well. Based on these observations, the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association has recommended a redefinition of the chemical composition of thalenite-(Y) to represent the F-dominant species with the ideal formula Y3Si3O10F, as it has historical priority. Consequently, the later described fluorthalenite-(Y) has to be discredited.

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