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  • 51.
    Bosi, Ferdinando
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Reznitskii, Leonid
    Russian Academy of Science, Irkutsk.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Vanadio-oxy-dravite, NaV3(Al4Mg2)(Si6O18)(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup2014In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 99, p. 218-224Article in journal (Refereed)
  • 52.
    Bosi, Ferdinando
    et al.
    Sapienza Università di Roma, Italy.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Fregola, Rosa Anna
    Università di Bari Aldo Moro, Italy.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Crystal chemistry of spinels in the system MgAl2O4-MgV2O4-Mg2VO42016In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 101, p. 580-586Article in journal (Refereed)
    Abstract [en]

    Eight spinel single-crystal samples belonging to the spinel sensu stricto-magnesiocoulsonite series (MgAl2O4-MgV2O4) were synthesized and crystal-chemically characterized by X‑ray diffraction, electron microprobe and optical absorption spectroscopy. Site populations show that the tetrahedrally coordinated site (T) is populated by Mg and minor Al for the spinel sensu stricto compositions, and only by Mg for the magnesiocoulsonite compositions, while the octahedrally coordinated site (M) is populated by Al, V3+, minor Mg, and very minor amounts of V4+. The latter occurs in appreciable amounts in the Al-free magnesium vanadate spinel, T(Mg)M(Mg0.26V3+1.48V4+0.26)O4, showing the presence of the inverse spinel VMg2O4. The studied samples are characterized by substitution of Al3+ for V3+ and (Mg2++V4+) for 2V3+ described in the system MgAl2O4-MgV2O4-VMg2O4.

    The present data in conjunction with data from the literature provide a basis for quantitative analyses of two solid-solution series MgAl2O4-MgV23+O4 and MgV23+O4-V4+Mg2O4. Unit-cell parameter increases with increasing V3+ along the series MgAl2O4-MgV2O4 (8.085–8.432 Å), but only slightly increases with increasing V3+ along the series VMg2O4-MgV2O4 (8.386–8.432 Å). Although a solid solution could be expected between the MgAl2O4 and VMg2O4 end-members, no evidence was found. Amounts of V4+ are nearly insignificant in all synthetic Al-bearing vanadate spinels, but are appreciable in Al-free vanadate spinel.

    An interesting observation of the present study is that despite the observed complete solid-solution along the MgAl2O4-MgV2O4 and MgV2O4-VMg2O4 series, the spinel structure seems to be unable to stabilize V4+ in any intermediate members on the MgAl2O4-Mg2VO4 join even at high oxygen fugacities. This behavior indicates that the accommodation of specific V-valences can be strongly influenced by crystal-structural constraints, and any evaluation of oxygen fugacities during mineral formation based exclusively on V cation valence distributions in spinel should be treated with caution. The present study underlines that the V valency distribution in spinels is not exclusively reflecting oxygen fugacities, but also depends on activities and solubilities of all chemical components in the crystallization environment.

  • 53.
    Bosi, Ferdinando
    et al.
    Sapienza Università di Roma, Italy.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Oxy-foitite, □(Fe2+Al2)Al6(Si6O18)(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup2017In: European journal of mineralogy, ISSN 0935-1221, E-ISSN 1617-4011, Vol. 29, no 5, p. 889-896Article in journal (Refereed)
    Abstract [en]

    Oxy-foitite, □(Fe2+Al2)Al6(Si6O18)(BO3)3(OH)3O, is a new mineral of the tourmaline supergroup. It occurs in high-grade migmatitic gneisses of pelitic composition at the Cooma metamorphic Complex (New South Wales, Australia), in association with muscovite, K-feldspar and quartz. Crystals are black with a vitreous luster, sub-conchoidal fracture and gray streak. Oxy-foitite has a Mohs hardness of ∼7, and has a calculated density of 3.143 g/cm3. In plane-polarized light, oxy-foitite is pleochroic (O= dark brown and E = pale brown), uniaxial negative. Oxy-foitite belongs to the trigonal crystal system, space group R3ma = 15.9387(3) Å, c = 7.1507(1)Å and V = 1573.20(6)Å3,Z = 3. The crystal structure of oxy-foitite was refined to R1 = 1.48% using 3247 unique reflections from single-crystal X-ray diffraction using MoKα radiation. Crystal-chemical analysis resulted in the empirical structural formula: X(□0.53Na0.45Ca0.01K0.01)Σ1.00Y(Al1.53Fe2+1.16Mg0.22Mn2+0.05Zn0.01Ti4+0.03)Σ3.00Z(Al5.47Fe3+0.14Mg0.39)Σ6.00[(Si5.89Al0.11)Σ6.00O18](BO3)3V(OH)3W[O0.57F0.04(OH)0.39]Σ1.00. Oxy-foitite belongs to the X-site vacant group of the tourmaline-supergroup minerals, and shows chemical relationships with foitite through the substitution YAl3++WO2-YFe2++W(OH)1–.

  • 54.
    Bosi, Ferdinando
    et al.
    Sapienza Università di Roma, Rome, Italy.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Thermally induced cation redistribution in Fe‑bearing oxy‑dravite and potential geothermometric implications2016In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 171, no 5, p. 1-14, article id 47Article in journal (Refereed)
    Abstract [en]

    Iron-bearing oxy-dravite was thermally treated in air and hydrogen atmosphere at 800 °C to study potential changes in Fe, Mg and Al ordering over the octahedrally coordinated Y and Z sites and to explore possible applications to intersite geothermometry based on tourmaline. Overall, the experimental data (structural refinement, Mössbauer, infrared and optical absorption spectroscopy) show that heating Fe-bearing tourmalines results in disordering of Fe over Y and Z balanced by ordering of Mg at Y, whereas Al does not change appreciably. The Fe disorder depends on temperature, but less on redox conditions. The degree of Fe3+–Fe2+ reduction is limited despite strongly reducing conditions, indicating that the fO2 conditions do not exclusively control the Fe oxidation state at the present experimental conditions. Untreated and treated samples have similar short- and long-range crystal structures, which are explained by stable Al-extended clusters around the O1 and O3 sites. In contrast to the stable Al clusters that preclude any temperature-dependent Mg–Al order– disorder, there occurs Mg diffusion linked to temperaturedependent exchange with Fe. Ferric iron mainly resides around O2− at O1 rather than (OH), but its intersite disorder induced by thermal treatment indicates that Fe redistribution is the driving force for Mg–Fe exchange and that its diffusion rates are significant at these temperatures. With increasing temperature, Fe progressively disorders over Y and Z, whereas Mg orders at Y according to the order–disorder reaction: YFe + ZMg → ZFe + YMg. The presented findings are important for interpretation of the post-crystallization history of both tourmaline and tourmaline host rocks and imply that successful tourmaline geothermometers may be developed by thermal calibration of the Mg– Fe order–disorder reaction, whereas any thermometers based on Mg–Al disorder will be insensitive and involve large uncertainties.

  • 55.
    Bosi, Ferdinando
    et al.
    Sapienza Università di Roma, Italy.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Ciriotti, Marco
    Associazione Micromineralogica Italiana,Torino, Italy.
    Experimental cation redistribution in the tourmaline lucchesiite, CaFe2+3Al6(Si6O18)(BO3)3(OH)3O2018In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 45, no 7, p. 621-632Article in journal (Refereed)
    Abstract [en]

    Natural Mg-rich lucchesiite was thermally treated in air and hydrogen atmosphere up to 800 °C to study potential changes in Fe-, Mg- and Al ordering over the octahedrally coordinated Y-  and Z -sites, and to explore possible applications to intracrystalline geothermometry based on tourmaline. Overall, the experimental data (structural refinement, Mössbauer, infrared and optical absorption spectroscopy) show that thermal treatment of lucchesiite results in an increase of Fetot contents at Z balanced by an increase of Mg and Al at Y . This process is accompanied by a significant deprotonation of the O3 anion site. The Fe order–disorder reaction depends more on temperature, than on redox conditions. During heat treatment in H2 ,reduction of Fe3+ to Fe2+ was not observed despite strongly reducing conditions, indicating that the fO2  conditions do not exclusively control the Fe oxidation state at the present experimental conditions. On the basis of this and previous studies, the intersite order–disorder process induced by thermal treatment indicates that Fe redistribution is an important factor for Fe–Mg–Al-exchange and is significant at temperatures around 800 °C. As a result, Fe–Mg–Al intersite order–disorder is sensitive to temperature variations, whereas geothermometers based solely on Mg–Al order–disorder appear insensitive and involve large uncertainties. The presented findings are important for interpretation of the post-crystallization history of both tourmaline and tourmaline host rocks, and indicate that successful tourmaline geothermometers may be developed by thermal calibration of the Fe-Mg–Al order–disorder reaction.

  • 56.
    Bosi, Ferdinando
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Reznitskii, Leonid
    Russian Academy of Science, Irkutsk.
    Crystallographic and spectroscopic characterization of Fe-bearing chromo-alumino-povondraite and its relationships with oxy-chromium-dravite and oxy-dravite2013In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 98, p. 1557-1564Article in journal (Refereed)
  • 57.
    Bosi, Ferdinando
    et al.
    Sapienza Universita di Roma.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Lazor, Peter
    Uppsala Universitet.
    Reznitskii, Leonid
    Russian Academy of Sciences.
    Atomic arrangements around the O3 site in Al- and Cr-rich oxytourmalines: a combined EMP, SREF, FTIR and Raman study2015In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 42, p. 441-453Article in journal (Refereed)
  • 58. Bouvier, Laura
    et al.
    Costa, Maria
    Connelly, James
    Jensen, Ninna
    Wielandt, Daniel
    Storey, Michael
    Nemchin, Alexander
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Snape, Joshua
    Swedish Museum of Natural History, Department of Geology.
    Bellucci, Jeremy
    Swedish Museum of Natural History, Department of Geology.
    Moynier, Frederic
    Agranier, Arnaud
    Gueguen, Bleuenn
    Schonbachler, Maria
    Bizzarro, Martin
    Evidence for extremely rapid magma ocean crystallization and crust formation on Mars2018In: Nature, ISSN 1476-4687, Vol. 558, p. 586-589Article in journal (Refereed)
    Abstract [en]

    The formation of a primordial crust is a critical step in the evolution of terrestrial planets but the timing of this process is poorly understood. The mineral zircon is a powerful tool for constraining crust formation because it can be accurately dated with the uranium-to-lead (U–Pb) isotopic decay system and is resistant to subsequent alteration. Moreover, given the high concentration of hafnium in zircon, the lutetium-to-hafnium (176Lu–176Hf) isotopic decay system can be used to determine the nature and formation timescale of its source reservoir (1,2,3) Ancient igneous zircons with crystallization ages of around 4,430 million years (Myr) have been reported in Martian meteorites that are believed to represent regolith breccias from the southern highlands of Mars (4,5) These zircons are present in evolved lithologies interpreted to reflect re-melted primary Martian crust4, thereby potentially providing insight into early crustal evolution on Mars. Here, we report concomitant high-precision U–Pb ages and Hf-isotope compositions of ancient zircons from the NWA 7034 Martian regolith breccia. Seven zircons with mostly concordant U–Pb ages define 207Pb/206Pb dates ranging from 4,476.3 ± 0.9 Myr ago to 4,429.7 ± 1.0 Myr ago, including the oldest directly dated material from Mars. All zircons record unradiogenic initial Hf-isotope compositions inherited from an enriched, andesitic-like crust extracted from a primitive mantle no later than 4,547 Myr ago. Thus, a primordial crust existed on Mars by this time and survived for around 100 Myr before it was reworked, possibly by impacts (4,5) to produce magmas from which the zircons crystallized. Given that formation of a stable primordial crust is the end product of planetary differentiation, our data require that the accretion, core formation and magma ocean crystallization on Mars were completed less than 20 Myr after the formation of the Solar System. These timescales support models that suggest extremely rapid magma ocean crystallization leading to a gravitationally unstable stratified mantle, which subsequently overturns, resulting in decompression melting of rising cumulates and production of a primordial basaltic to andesitic crust (6,7).

  • 59. Brengman, L.
    et al.
    Fedo, C.M.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Micro-scale silicon isotope heterogeneity observed in hydrothermal quartz precipitates from the >3.7 Ga Isua Greenstone Belt, SW Greenland.2016In: Terra Nova, ISSN 0954-4879, E-ISSN 1365-3121, Vol. 28, p. 70-75Article in journal (Refereed)
    Abstract [en]

    Pillow basalt and chert form integral lithologies comprising many Archean greenstone belt packages. To investigate details of these lithologies in the >3.7 Ga Isua Greenstone Belt, SW Greenland, we measured silicon isotope compositions of quartz crystals, by secondary ion mass spectrometry, from a quartz-cemented, quartz-amygdaloidal basaltic pillow breccia, recrystallized chert and chert clasts thought to represent silica precipitation under hydrothermal conditions. The recrystallized chert, chert clasts and quartz cement have overlapping δ30Si values, while the δ30Si values of the quartz amygdules span nearly the entire range of previously published values for quartz precipitates of any age, despite amphibolite facies metamorphism. We suggest that the heterogeneity is derived from kinetic isotope fractionation during quartz precipitation under disequilibrium conditions in a hydrothermal setting, consistent with the pillow breccia origin. On the basis of the present data, we conclude that the geological context of each sample must be carefully evaluated when interpreting δ30Si values of quartz.

  • 60.
    Bruschini, Enrico
    et al.
    Sapienza Università di Roma.
    Speziale, Sergio
    Geoforschungszentrum, Potsdam.
    Andreozzi, Giovanni
    Sapienza Università di Roma.
    Bosi, Ferdinando
    Sapienza Università di Roma.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    The elasticity of MgAl2O4-MnAl2O4 spinels by Brillouin scattering and an empirical approach for bulk modulus prediction2015In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 100, p. 644-651Article in journal (Refereed)
  • 61. Budd, D.A.
    et al.
    Troll, V.R.
    Deegan, F.M.
    Jolis, E.M.
    Smith, V.C.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Harris, C.
    Freda, C.
    Hilton, D.R.
    Halldorsson, S.A.
    Bindemann, I.N.
    Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 40624Article in journal (Refereed)
    Abstract [sv]

    Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ18O values. Overall, Toba quartz crystals exhibit comparatively high δ18O values, up to 10.2‰, due to magma residence within, and assimilation of, local granite basement. However, some 40% of the analysed quartz crystals display a decrease in δ18O values in outermost growth zones compared to their cores, with values as low as 6.7‰ (maximum ∆core−rim = 1.8‰). These lower values are consistent with the limited zircon record available for Toba, and the crystallisation history of Toba quartz traces an influx of a low-δ18O component into the magma reservoir just prior to eruption. Here we argue that this late-stage low-δ18O component is derived from hydrothermally-altered roof material. Our study demonstrates that quartz isotope stratigraphy can resolve magmatic events that may remain undetected by whole-rock or zircon isotope studies, and that assimilation of altered roof material may represent a viable eruption trigger in large Toba-style magmatic systems.

  • 62. Cabral, R.A.
    et al.
    Jackson, M.G.
    Koga, K.T.
    Rose-Koga, E.F.
    Hauri, E.H.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Price, A.A:
    Day, J.M.D.
    Shimizu, N.
    Kelley, K.A.
    Volatile cycling of H2O, CO2, F, and Cl in the HIMU mantle: A new window provided by melt inclusions from oceanic hotspot lavas at Mangaia, Cook Islands.2014In: Geochemistry, Geophysics, Geosystems, ISSN 1525-2027, Vol. 15, p. 4445-4467Article in journal (Refereed)
    Abstract [en]

    Mangaia hosts the most radiogenic Pb-isotopic compositions observed in ocean island basalts and represents the HIMU (high µ = 238U/204Pb) mantle end-member, thought to result from recycled oceanic crust. Complete geochemical characterization of the HIMU mantle end-member has been inhibited due to a lack of deep submarine glass samples from HIMU localities. We homogenized olivine-hosted melt inclusions separated from Mangaia lavas and the resulting glassy inclusions made possible the first volatile abundances to be obtained from the HIMU mantle end-member. We also report major and trace element abundances and Pb-isotopic ratios on the inclusions, which have HIMU isotopic fingerprints. We evaluate the samples for processes that could modify the volatile and trace element abundances postmantle melting, including diffusive Fe and H2O loss, degassing, and assimilation. H2O/Ce ratios vary from 119 to 245 in the most pristine Mangaia inclusions; excluding an inclusion that shows evidence for assimilation, the primary magmatic H2O/Ce ratios vary up to ∼200, and are consistent with significant dehydration of oceanic crust during subduction and long-term storage in the mantle. CO2 concentrations range up to 2346 ppm CO2 in the inclusions. Relatively high CO2 in the inclusions, combined with previous observations of carbonate blebs in other Mangaia melt inclusions, highlight the importance of CO2 for the generation of the HIMU mantle. F/Nd ratios in the inclusions (30 ± 9; 2σ standard deviation) are higher than the canonical ratio observed in oceanic lavas, and Cl/K ratios (0.079 ± 0.028) fall in the range of pristine mantle (0.02–0.08).

  • 63.
    Charette, M
    et al.
    Woods Hole Oceanographic Institution, USA.
    Lam, P.J.
    University of California Santa Cruz, USA.
    Lohan, M.C.
    University of Southhampton, UK.
    Kwon, E.Y.
    Seoul National University,Korea.
    Hatje, V
    Universidade Federal da Bahia, Brazil.
    Jeandel, C
    University of Toulouse, France.
    Shiller, A.M.
    University of Southern Mississippi, USA.
    Cutter, G.A.
    Old Dominion University, USA.
    Thomas, A
    University of Edinburgh, UK.
    Boyd, P.W.
    University of Tasmania, Australia.
    Homoky, W.B.
    University of Oxford, UK.
    Milne, A.
    Plymoth University, UK.
    Thomas, H.
    Dalhousie University, Canada.
    Andersson, P.S.
    Swedish Museum of Natural History, Department of Geology.
    Porcelli, D.
    University of Oxford,Uk.
    Tanaka, T
    University of Tokyo, Japan.
    Geibert, W
    Alfred Wegener Institute, Germany.
    Dehairs, F.
    Vrije Universiteit, Belgium.
    Garcia-Orellana, J.
    Universitat Autonoma de Barcelona, Spain.
    Coastal ocean and shelf-sea biogeochemical cycling of trace elements and isotopes: lessons learned from GEOTRACES2016In: Philosopical Transactions of the Royal Society A, ISSN 1364–503X, Vol. 374, no 2081Article, review/survey (Refereed)
    Abstract [en]

    Continental shelves and shelf seas play a central role in the global carbon cycle. However,

    their importance with respect to trace element and isotope (TEI) inputs to ocean basins

    is less well understood. Here, we present major findings on shelf TEI biogeochemistry

    from the GEOTRACES programme as well as a proof of concept for a new method to

    estimate shelf TEI fluxes. The case studies focus on advances in our understanding of TEI

    cycling in the Arctic, transformations within a major river estuary (Amazon), shelf sediment

    micronutrient fluxes and basin-scale estimates of submarine groundwater discharge. The

    proposed shelf flux tracer is 228-radium (T1/2 =5.75 yr), which is continuously supplied to

    the shelf from coastal aquifers, sediment porewater exchange and rivers. Model-derived shelf

    228Ra fluxes are combined with TEI/ 228Ra ratios to quantify ocean TEI fluxes from the

    western North Atlantic margin. The results from this new approach agree well with previous

    estimates for shelf Co, Fe, Mn and Zn inputs and exceed published estimates of atmospheric

    deposition by factors of approximately 3–23. Lastly, recommendations are made for additional

    GEOTRACES process studies and coastal margin-focused section cruises that will help refine

    the model and provide better insight on the mechanisms driving shelf-derived TEI fluxes

    to the ocean.

    This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element

    chemistry’.

  • 64. Chi Fru, E.
    et al.
    Ivarsson, M.
    Swedish Museum of Natural History, Department of Geology.
    Kilias, S. P.
    Frings, Patrick J
    Swedish Museum of Natural History, Department of Geology.
    Hemmingsson, C.
    Broman, C.
    Bengtson, S.
    Swedish Museum of Natural History, Department of Paleobiology.
    Chatzitheodoridis, E.
    Biogenicity of an Early Quaternary iron formation, Milos Island, Greece2015In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 13, no 3, p. 225-244Article in journal (Refereed)
    Abstract [en]

    A ~2.0-million-year-old shallow-submarine sedimentary deposit on Milos Island, Greece, harbours an unmetamorphosed fossiliferous iron formation (IF) comparable to Precambrian banded iron formations (BIFs). This Milos IF holds the potential to provide clues to the origin of Precambrian BIFs, relative to biotic and abiotic processes. Here, we combine field stratigraphic observations, stable isotopes of C, S and Si, rock petrography and microfossil evidence from a ~5-m-thick outcrop to track potential biogeochemical processes that may have contributed to the formation of the BIF-type rocks and the abrupt transition to an overlying conglomerate-hosted IF (CIF). Bulk δ13C isotopic compositions lower than -25‰ provide evidence for biological contribution by the Calvin and reductive acetyl–CoA carbon fixation cycles to the origin of both the BIF-type and CIF strata. Low S levels of ~0.04 wt.% combined with δ34S estimates of up to ~18‰ point to a non-sulphidic depository. Positive δ30Si records of up to +0.53‰ in the finely laminated BIF-type rocks indicate chemical deposition on the seafloor during weak periods of arc magmatism. Negative δ30Si data are consistent with geological observations suggesting a sudden change to intense arc volcanism potentially terminated the deposition of the BIF-type layer. The typical Precambrian rhythmic rocks of alternating Fe- and Si-rich bands are associated with abundant and spatially distinct microbial fossil assemblages. Together with previously proposed anoxygenic photoferrotrophic iron cycling and low sedimentary N and C potentially connected to diagenetic denitrification, the Milos IF is a biogenic submarine volcano-sedimentary IF showing depositional conditions analogous to Archaean Algoma-type BIFs.

  • 65.
    Chi Fru, Ernest
    et al.
    Stockholm University, Department of Geological Sciences.
    Rodríguez, Nathalie
    Stockholm University Department of Geological Sciences.
    Partin, Camille
    University of Saskatchewan, Canada.
    Lalonde, Stefan
    Université de Bretagne Occidentale, France.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Weiss, Dominik
    Imperial College, London, UK.
    El Albani, Abderrazak
    Université de Poitiers, France.
    Rodushkin, Ilia
    ALS Scandinavia, Sweden.
    Konhauser, Kurt
    University of Alberta, Canada.
    Cu isotopes in marine black shales record the Great Oxidation Event2016In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 113, no 18, p. 4941-4946Article in journal (Refereed)
    Abstract [en]

    The oxygenation of the atmosphere ∼2.45–2.32 billion years ago (Ga) is one of the most significant geological events to have affected Earth’s redox history. Our understanding of the timing and processes surrounding this key transition is largely dependent on the development of redox-sensitive proxies, many of which remain unexplored. Here we report a shift from negative to positive copper isotopic compositions (δ65CuERM-AE633) in organic carbon-rich shales spanning the period 2.66–2.08 Ga. We suggest that, before 2.3 Ga, a muted oxidative supply of weathering-derived copper enriched in 65Cu, along with the preferential removal of 65Cu by iron oxides, left seawater and marine biomass depleted in 65Cu but enriched in 63Cu. As banded iron formation deposition waned and continentally sourced Cu became more important, biomass sampled a dissolved Cu reservoir that was progressively less fractionated relative to the continental pool. This evolution toward heavy δ65Cu values coincides with a shift to negative sedimentary δ56Fe values and increased marine sulfate after the Great Oxidation Event (GOE), and is traceable through Phanerozoic shales to modern marine settings, where marine dissolved and sedimentary δ65Cu values are universally positive. Our finding of an important shift in sedimentary Cu isotope compositions across the GOE provides new insights into the Precambrian marine cycling of this critical micronutrient, and demonstrates the proxy potential for sedimentary Cu isotope compositions in the study of biogeochemical cycles and oceanic redox balance in the past.

  • 66.
    Claesson, Stefan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bibikova, Elena
    Vernadsky Institute of Geochemistry and Analytical Chemistry RAS, Kosygin St 19, 119991 Moscow, Russia.
    Shumlyanskyy, Leonid
    M. P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation, Palladina Ave. 34, 03142 Kyiv, Ukraine.
    Dhuime, Bruno
    Department of Earth and Environmental Sciences, University of St Andrews, North Streeet, St Andrews KYI6 9AL, UK.
    Hawkesworth, C. H.
    Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8, 1RJ, UK.
    The oldest crust in the Ukrainian Shield - Eoarchaean U-Pb ages and Hf-Nd constraints from enderbites and metasediments2014In: Continent Formation Through Time / [ed] Roberts, N. M. W., van Kranendonk, M., Parman, S., Shirey, S. and Clift, P. D., London: The Geological Society Publishing House, 2014, Vol. 389Chapter in book (Refereed)
    Abstract [en]

    The oldest crust in the Ukrainian Shield occurs in the Podolian and Azov domains which both include Eoarchaeanarchaean components. U-Pb age data for Dniestr-Bug enderbites, Podolian Domain, indicate these are ca. 3.75 Ga old, and Lu-Hf isotope date indicate extraction from chondritic to mildly isotopically depleted sources with εHf up to ca. +2. Nd model ages support their Eoarchaeanarchaean age, while model ages for Dniestr-Bug metasedimentary gneisses indicate that these also include younger crustal material. Most of the Hf-age data for metasedimentary zircon from the Soroki greenstone belt, Azov Domain, reflects Eoarchaeanarchaean primary crustal sources with chondritic to mildly depleted Hf isotope signatures at 3.75 Ga. A minor portion is derived from Mesoarchaeanarchaean crust with a depleted εHf signature of ca. +4 at 3.1 Ga. U-Pb zircon ages from Fedorivka greenstone belt metasediments are consistent with the Soroki age data, but also include a 2.7‒2.9 Ga component. Nd whole rock model ages provide support for a younger crustal component in the latter. Both domains have been subject to Neoarchaeanarchaean, ca. 2.8 Ga, and Palaeoproterozoic, ca. 2.0 Ga metamorphism. The spatial distribution indicates that the Podolian and Azov domains have evolved independently of each other before the amalgamation of the Ukrainian Shield.

  • 67.
    Claesson, Stefan
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bibikova, Elena V.
    Vernadsky Institute of Geochemistry and Analytical Chemistry, R.A.S., Moscow, Russia.
    Shumlyanskyy, Leonid
    M.P Semenenko Institute of Geochemistry, Mineralogy and Ore Formation, Palladina Ave. 34, 03680 Kyiv, Ukraine.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Billström, Kjell
    Swedish Museum of Natural History, Department of Geology.
    Can oxygen isotopes in magmatic zircon be modified by metamorphism? A case study from the Eoarchean Dniester-Bug Series, Ukrainian Shield2016In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 273, p. 1-11Article in journal (Refereed)
  • 68. Clymans, W.
    et al.
    Conley, D. J.
    Battles, J. J.
    Frings, Patrick J
    Swedish Museum of Natural History, Department of Geology.
    Koppers, M. M.
    Likens, G. E.
    Johnson, C. E.
    Silica uptake and release in live and decaying biomass in a northern hardwood forest2016In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 97, no 11, p. 3044-3057Article in journal (Refereed)
    Abstract [en]

    In terrestrial ecosystems, a large portion (20-80%) of the dissolved Si (DSi) in soil solution has passed through vegetation. While the importance of this terrestrial Si filter is generally accepted, few data exist on the pools and fluxes of Si in forest vegetation and the rate of release of Si from decomposing plant tissues. We quantified the pools and fluxes of Si through vegetation and coarse woody debris (CWD) in a northern hardwood forest ecosystem (Watershed 6, W6) at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire, USA. Previous work suggested that the decomposition of CWD may have significantly contributed to an excess of DSi reported in stream-waters following experimental deforestation of Watershed 2 (W2) at the HBEF. We found that woody biomass (wood+bark) and foliage account for approximately 65% and 31%, respectively, of the total Si in biomass at the HBEF. During the decay of American beech (Fagus grandifolia) boles, Si loss tracked the whole-bole mass loss, while yellow birch (Betula alleghaniensis) and sugar maple (Acer saccharum) decomposition resulted in a preferential Si retention of up to 30% after 16yr. A power-law model for the changes in wood and bark Si concentrations during decomposition, in combination with an exponential model for whole-bole mass loss, successfully reproduced Si dynamics in decaying boles. Our data suggest that a minimum of 50% of the DSi annually produced in the soil of a biogeochemical reference watershed (W6) derives from biogenic Si (BSi) dissolution. The major source is fresh litter, whereas only similar to 2% comes from the decay of CWD. Decay of tree boles could only account for 9% of the excess DSi release observed following the experimental deforestation of W2. Therefore, elevated DSi concentrations after forest disturbance are largely derived from other sources (e.g., dissolution of BSi from forest floor soils and/or mineral weathering).

  • 69. Conley, Daniel
    et al.
    Frings, Patrick J
    Swedish Museum of Natural History, Department of Geology.
    Fontorbe, Guillaume
    Clymans, Wim
    Stadmark, Johanna
    Hendry, Katherine
    Marron, Alan
    De La Rocha, Christina
    Biosilicification drives a decline of dissolved Si in the oceans through geologic time2017In: Frontiers in Marine Science, E-ISSN 2296-7745Article in journal (Refereed)
    Abstract [en]

    Biosilicification has driven variation in the global Si cycle over geologic time. The evolution of different eukaryotic lineages that convert dissolved Si (DSi) into mineralized structures (higher plants, siliceous sponges, radiolarians and diatoms) has driven a secular decrease in DSi in the global ocean leading to the low DSi concentrations seen today. Recent studies, however, have questioned the timing previously proposed for the DSi decreases and the concentration changes through deep time, which would have major implications for the cycling of carbon and other key nutrients in the ocean. Here, we combine relevant genomic data with geological data and present new hypotheses regarding the impact of the evolution of biosilicifying organisms on the DSi inventory of the oceans throughout deep time. Although there is no fossil evidence for true silica biomineralization until the late Precambrian, the timing of the evolution of silica transporter genes suggests that bacterial silicon-related metabolism has been present in the oceans since the Archean with eukaryotic silicon metabolism already occurring in the Neoproterozoic. We hypothesize that biological processes have influenced oceanic DSi concentrations since the beginning of oxygenic photosynthesis.

  • 70.
    Cooper, Mark
    et al.
    University of Manitoba, Winnipeg, Canada.
    Hawthorne, Frank
    University of Manitoba, Winnipeg, Canada.
    Langhof, Jörgen
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Holtstam, Dan
    Swedish Museum of Natural History, Department of Geology.
    Wiklundite, ideally Pb2[4](Mn2+,Zn)3(Fe3+,Mn2+)2(Mn2+,Mg)19(As3+O3)2[(Si,As5+)O4]6 (OH)18Cl6, a new mineral from Långban, Filipstad, Värmland, Sweden: Description and crystal structure2017In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 81, no 4, p. 841-855Article in journal (Refereed)
  • 71.
    Cornacchia, Irene
    et al.
    Dipartimento di Scienze della Terra, Sapienza Universita di Roma.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Agostine, Samuele
    Instituto di Geosciencze e Georisorse, CNR, Pisa.
    Brandanao, Marco
    Dipartimento di Scienze della Terra, Sapienza Universita di Roma.
    Strontium stratigraphy of the upper Miocene Lithothamnion Limestone in the Majella Mountain, central Italy, and its palaeoenvironmental implications2017In: Lethaia: an international journal of palaeontology and stratigraphy, ISSN 0024-1164, E-ISSN 1502-3931, Vol. 50, no 4, p. 561-575Article in journal (Refereed)
    Abstract [en]

    The87Sr/86Sr isotope ratio has been widely used as aphysical tool to date and correlate carbonate successions due to the long Srresidence time in comparison with the ocean mixing time. If this method workson oceanic successions, marginal basins may show different Sr isotope recordsin comparison with the coeval ocean one due to sea-level variations,continental run-off and restricted water exchanges. In this work, we present the87Sr/86Sr isotope record of the upper Miocene carbonateramp of the Lithothamnion Limestone(Majella Mountain, central Apennines), as an example of the onset of restrictedwater exchanges between a marginal basin and the ocean water masses. The overalllatemost Tortonian–earlyMessinian Sr isotope record of the Lithothamnion Limestonefits below the global reference line. This deviation has been interpreted as dueto the strong control that freshwater input and enhanced continental run-off,linked to the migration of the Apennine accretionary wedge and foredeep system,have had on the central Adriatic water chemistry. These results imply that anaccurate oceanographic and geodynamic framework along with diagenetic overprintinvestigation has to be taken into consideration prior to apply SIS oncarbonate successions on marginal basins, even when facies analyses indicatefully marine conditions. This seems to be the case for the upper MioceneCentral Mediterranean carbonate successions, but may have more general validityand be extended to other recent or past marginal basins.

  • 72. Crémière, A.
    et al.
    Lepland, A.
    Chand, S.
    Sahy, D.
    Kirsimäe, K.
    Bau, M.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Noble, S.R.
    Martma, T.
    Thorsnes, T.
    Brunstad, H.
    Fluid source and methane-related diagenetic processes recorded in cold seep carbonates from the Alvheim channel, central North Sea2016In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 432, p. 16-33Article in journal (Refereed)
    Abstract [en]

    Integrated petrography, mineralogy, geochronology and geochemistry of cold seep carbonate crusts and free gas from the Alvheim channel elucidate diagenetic carbonate precipitation and related seepage histories in the central North Sea. Free gas isotope characteristics coupled with carbonate δ13C values as low as − 66‰ VPDB, indicate a predominantly microbial methane source with minor thermogenic contribution. We estimate that ~ 70% of the carbon sequestered into carbonate precipitates was derived from local oxidation of methane. The early stage of crust growth is represented by microcrystalline aragonite and Mg-calcite (10 to 40% mol MgCO3) cementing seafloor sediments consisting of clays, quartz, feldspar, and minor detrital low Mg-calcite and dolomite. Typical association of aragonite cement with coarse-grained detritus may reflect elevated fluid flow and flushing of fine particles prior to cementation close to the seafloor. Middle rare earth element enrichment in early generation microcrystalline cements containing framboidal pyrite indicates diagenetic precipitation within the zone of anaerobic methane oxidation contiguous to iron reduction. The later generation diagenetic phase corresponds to less abundant radial fibrous and botryoidal aragonite which lines cavities developed within the crusts. In contrast to early generation cements, late generation cavity infills have rare earth elements and Y patterns with small negative Ce anomalies similar to seawater, consistent with carbonate precipitation in a more open, seawater dominated system. Aragonite U–Th ages indicate carbonate precipitation between 6.09 and 3.46 kyr BP in the northern part of the channel, whereas in the southern part precipitation occurred between 1.94 and 0.81 kyr BP reflecting regional changes in fluid conduit position.

  • 73.
    Cuss, Chad
    et al.
    Trent University Canada.
    Guéguen, Celine
    Trent University Canada.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Porcelli, Don
    University of Oxford UK.
    Maximov, Trofim
    North-Eastern Federal University Yakutsk, Russia.
    Kutscher, Liselott
    Swedish Museum of Natural History, Department of Geology.
    Advanced residuals analysis for determining the number of PARAFAC components in dissolved organic matter2016In: Applied Spectroscopy, ISSN 0003-7028, E-ISSN 1943-3530, Vol. 70, no 2, p. 334-346Article in journal (Refereed)
  • 74.
    Dahlin, Peter
    et al.
    Uppsala Universitet.
    Johansson, Åke
    Swedish Museum of Natural History, Department of Geology.
    Andersson, Ulf Bertil
    LKAB.
    Source character, mixing, fractionation and alkali metasomatism in Palaeoproterozoic greenstone dykes, Dannemora area, NE Bergslagen region, Sweden2014In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 151, no 4, p. 573-590Article in journal (Refereed)
    Abstract [en]

    The geochemical and isotopic characteristics of metamorphosed Svecofennian mafic dykes from the Dannemora area in the NE part of the Bergslagen region in central Sweden were investigated and compared to mafic intrusive rocks in their vicinity. The dykes, with an inferred age of c. 1860–1870 Ma, are calc-alkaline, sub-alkaline and basaltic in composition and have a mixed subduction and within-plate geochemical affinity. They are the result of mixing of at least three mantle source components with similar basaltic major element composition, but different concentrations of incompatible trace elements. Magma M1 is strongly enriched both in Rare Earth Elements (REE) and High-Field-Strength Elements (HFSE); magma M2 is highly enriched in Large-Ion Lithophile Elements (LILE, except Sr) with only moderate enrichment in HFSE and REE (particularly low in Heavy Rare Earth Elements); and magma M3 is enriched in Sr and has a flat REE profile. Magma M3 also has a somewhat more positive (depleted) initial εNd value of +1.8, compared to +0.4 to +0.5 for magmas M1 and M2. The magma evolution was controlled by a mixture of fractionation (mainly affecting the compatible elements) and mixing, best seen in the incompatible element concentrations and the Nd isotope data. The basaltic overall composition indicates little or no wholesale contamination by upper continental crust, but the dykes have undergone later metasomatic changes mainly affecting the alkali elements.

  • 75.
    De La Rosa, Nathaly
    et al.
    Lunds universitet.
    Kristiansson, Per
    Lunds universitet.
    Nilsson, Charlotta
    Lunds universitet.
    Ros, Linus
    Lunds universitet.
    Pallon, Jan
    Lunds universitet.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Quantification of lithium at ppm level in geological samples using nuclear reaction analysis2018In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 317, p. 253-259Article in journal (Refereed)
  • 76.
    de Vries, Bernard
    et al.
    Stockholms universitet.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Waters, L.B.F.M.
    University of Amsterdam.
    Min, M
    University of Amsterdam.
    Laboratory mid-IR spectra of equilibrated and igneous meteorites. Searching for observables of planetesimal debris2018In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 307, p. 400-416Article in journal (Refereed)
  • 77. Deegan, F.M.
    et al.
    Troll, V.R.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Jolis, E.M.
    Freda, C.
    Boron isotope fractionation in magma via crustal carbonate dissolution.2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 30774Article in journal (Refereed)
    Abstract [en]

    Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ11B values down to −41.5‰, reflecting preferential partitioning of 10B into the assimilating melt. Loss of 11B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports 11B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ11B melt values in arc magmas could flag shallow-level additions to the subduction cycle.

  • 78. Deegan, F.M.
    et al.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Troll, V.R.
    Budd, D.A.
    Harris, C.
    Geiger, H.
    Hålenius, U.
    Swedish Museum of Natural History, Department of Geology.
    Pyroxene standards for SIMS oxygen isotope analysis and their application to Merapi volcano, Sunda arc, Indonesia2016In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 447, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Measurement of oxygen isotope ratios in common silicate minerals such as olivine, pyroxene, feldspar, garnet, and quartz is increasingly performed by Secondary Ion Mass Spectrometry (SIMS). However, certain mineral groups exhibit solid solution series, and the large compositional spectrum of these mineral phases will result in matrix effects during SIMS analysis. These matrix effects must be corrected through repeated analysis of compositionally similar standards to ensure accurate results. In order to widen the current applicability of SIMS to solid solution mineral groups in common igneous rocks, we performed SIMS homogeneity tests on new augite (NRM-AG-1) and enstatite (NRM-EN-2) reference materials sourced from Stromboli, Italy and Webster, North Carolina, respectively. Aliquots of the standard minerals were analysed by laser fluorination (LF) to establish their δ18O values. Repeated SIMS measurements were then performed on randomly oriented fragments of the same pyroxene crystals, which yielded a range in δ18O less than ± 0.42 and ± 0.58‰ (2σ) for NRM-AG-1 and NRM-EN-2, respectively. Homogeneity tests verified that NRM-AG-1 and NRM-EN-2 do not show any crystallographic orientation bias and that they are sufficiently homogeneous on the 20 μm scale to be used as routine mineral standards for SIMS δ18O analysis. We subsequently tested our new standard materials on recently erupted pyroxene crystals from Merapi volcano, Indonesia. The δ18O values for Merapi pyroxene obtained by SIMS (n = 204) agree within error with the LF-derived δ18O values for Merapi pyroxene but differ from bulk mineral and whole-rock data obtained by conventional fluorination. The bulk samples are offset to higher δ18O values as a result of incorporation of mineral and glass inclusions that in part reflects crustal contamination processes. The Merapi pyroxene SIMS data, in turn, display a frequency peak at 5.8‰, which allows us to estimate the δ18O value of the primary mafic magma at Merapi to ~ 6.1‰ when assuming closed system differentiation.

  • 79.
    Dekov, Vesselin
    et al.
    University of Sofia.
    Boycheva, Tanya
    University of Sofia.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Billström, Kjell
    Swedish Museum of Natural History, Department of Geology.
    Kamenov, George D.
    University of Florida.
    Shanks, Wayne C.
    U.S. Geological Survey, Denver.
    Stummeyer, Jens
    Bundesanstalt für Geowissenschaften, Hannover.
    Mineralogical and geochemical evidence for recent hydrothermal activity at the west wall of 12°50´N core complex (Mid-Atlantic Ridge): a new ultramafic-hosted seafloor hydrothermal deposit?2011In: Marine Geology, ISSN 0025-3227, E-ISSN 1872-6151, Vol. 288, p. 90-102Article in journal (Refereed)
  • 80.
    Dekov, Vesselin
    et al.
    University of Sofia.
    Boycheva, Tanya
    University of Sofia.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Petersen, Sven
    Leibiz-Institut für Meeresforschung, IFM-GEOMAR.
    Billström, Kjell
    Swedish Museum of Natural History, Department of Geology.
    Stummeyer, Jens
    Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover.
    Kamenov, George
    University of Florida.
    Shanks, Wayne
    U.S. Geological Survey, Denver.
    Atacamite and paratacamite from the ultramafic-hosted Logatchev seafloor vent field (14°45´ N, Mid-Atlantic Ridge)2011In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 286, p. 169-184Article in journal (Refereed)
  • 81.
    Dekov, Vesselin M.
    et al.
    University of Sofia.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Billström, Kjell
    Swedish Museum of Natural History, Department of Geology.
    Kamenov, George D.
    University of Florida.
    Munnik, Frans
    Forschungszentrum Dresden-Rossendorf.
    Eriksson, Lars
    Stockholms universitet.
    Dyer, Alan
    University of Salford.
    Schmidt, Mark
    Leibniz-Institut für Meeresforschung, IFM-GEOMAR.
    Botz, Reiner
    Universität Kiel.
    Native Sn-Pb droplets in a zeolitic amygdale (Isle of Mull, Inner Hebrides)2009In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 73, p. 2907-2919Article in journal (Refereed)
  • 82.
    Dekov, Vesselin M.
    et al.
    IFREMER.
    Rouxel, Olivier
    Woods Hole Oceanographic Institution.
    Asael, Dan
    IFREMER.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Munnik, Frans
    Helmoholz-Zentrum Dresden-Rossendorf.
    Native Cu from the oceanic crust: Isotopic insights into native metal origin2013In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 359, p. 136-149Article in journal (Refereed)
  • 83. Dekov, Vesselin
    et al.
    Vanlierde, E.
    Billström, Kjell
    Swedish Museum of Natural History, Department of Geology.
    Garbe-Schönberg, C-D.
    Weiss, D.J.
    Gatto Rotondo, G.
    Van Mee, K.
    Kuzmann, E.
    Fortin, D.
    Darchuk, L.
    Van Grieken, R.
    Ferrihydrite precipitation in goundwater-fed river systems (Nete and Demer river basins, Belgium): Insights from a combined Fe-Zn-Sr-Nd-Pb-isotope study.2014In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 386, p. 1-15Article in journal (Refereed)
    Abstract [en]

    Two groundwater-fed river systems (Nete and Demer, Belgium) carry red suspended material that settles on the river bed forming red sediments. The local aquifer that feeds these river systems is a glauconite-rich sand, which provides most of the dissolved Fe to the rivers. The solid component of these systems, i.e., the red suspended material and sediments, has a simple mineralogy (predominantly ferrihydrite), but shows a complex geochemistry pointing out the different processes contributing to the river chemistry: (1) the red sediments have higher transition metal (excluding Cu) and detrital element (e.g., Si, Al, K, Rb, etc.) concentrations than the red suspended matter because of their longer residence time in the river and higher contribution of the background (aquifer) component, respectively; (2) the red suspended material and sediments have inherited their rare earth element (REE) patterns from the aquifer; (3) the origin of Sr present in the red suspended matter and red sediments is predominantly marine (i.e., Quaternary calcareous rocks), but a small amount is geogenic (i.e., from detrital rocks); (4) Pb in both solids originates mostly from anthropogenic and geogenic sources; (5) all of the anthropogenic Pb in the red suspended material and sediments is hosted by the ferrihydrite; (6) Nd budget of the red riverine samples is controlled by the geogenic source and shows little anthropogenic component; (7) the signi- ficant Fe- and Zn-isotope fractionations are in line with the previous studies. Their fractionation patterns do not correlate, suggesting that the processes controlling the isotope geochemistry of Fe and Zn are different: oxidation/reduction most likely governs the Fe-isotope fractionation, whereas adsorption/desorption or admixing of anthropogenic sources controls the isotope fractionation of Zn.

  • 84.
    Delmonte, B
    et al.
    University Milano-Bicocca, Milano, Italy.
    Paleari, C. I.
    University Milano-Bicocca, Milano, Italy.
    Andò, S
    University Milano-Bicocca, Milano, Italy.
    Garzantini, E
    University Milano-Bicocca, Milano, Italy.
    Andersson, Per Sune
    Swedish Museum of Natural History, Department of Geology.
    Petit, J.R.
    University of Grenobles, Grenoble, France.
    Crosta, X
    Unversity of Bordeaux, St Hilaire, France.
    Narcisi, B
    ENEA, Rome, Italy.
    Baroni, C
    University of Pisa, Pisa, Italy.
    Salvatore, M.C.
    University of Pisa, Pisa, Italy.
    Baccolo, G.
    University Milano-Bicocca, Milano, Italy.
    Maggi, Valter
    University Milano-Bicocca, Milano, Italy.
    Causes of dust size variability in central East Antarctica (Dome B):Atmospheric transport from expanded South American sources during Marine Isotope Stage 22017In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 168, p. 55-68Article in journal (Refereed)
    Abstract [en]

    We here investigate the spatial and temporal variability of eolian dust particle sorting recorded in the Dome B (77 05 S, 94 55 E) ice core, central East Antarctica, during Marine Isotope Stage (MIS) 2. We address the question whether such changes reflect variable transport pathways from a unique source area or rather a variable apportionment from diverse Southern Hemisphere sources transported at different elevation in the troposphere. The Sr-Nd radiogenic isotope composition of glacial dust samples as well as single-particle Raman mineralogy support the hypothesis of a single dust provenance both for coarse and fine mode dust events at Dome B. The southern South American provenance of glacial dust in Antarctica deduced from these results indicate a dust composition coherent with a mixture of volcanic material and minerals derived from metamorphic and plutonic rocks. Additionally, Dome B glacial samples contain aragonite particles along with diatom valves of marine benthic/epiphytic species and freshwater species living today in the northern Antarctic Peninsula and southern South America. These data suggest contribution from the exposed Patagonian continental shelf and glacial outwash plains of southern Patagonia at the time when sea level reached its minimum. Our results confirm that dust sorting is controlled by the relative intensity of the two main patterns of tropospheric dust transport onto the inner Plateau, i.e. fast low-level advection and long-range high-altitude transport including air subsidence over Antarctica.

  • 85. Deng, Kai
    et al.
    Yang, Shouye
    Lei, Bi
    Chang, Yuan-Pin
    Su, Ni
    Frings, Patrick J
    Swedish Museum of Natural History, Department of Geology.
    Xie, Xiaolei
    Small dynamic mountainous rivers in Taiwan exhibit large sedimentary geochemical and provenance heterogeneity over multi-spatial scales2019In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 505, p. 96-109Article in journal (Refereed)
    Abstract [en]

    Taiwan rivers are characterized by extremely rapid mass wasting and sediment transfer due to active tectonics and frequent typhoons. Various methods have been applied to constrain processes affecting their sediment source-to-sink routing. In most cases, the sediment at the outlet is considered to be a representative average of the whole upstream basin due to the short sediment routes (<200 km). However, this assumption may be inappropriate because huge compositional heterogeneity can exist even within such small dynamic river systems. To reveal their intra-station and basin-wide geochemical heterogeneity, we collected sediment samples along the Zhuoshui and Liwu Rivers in Taiwan. Multiple samples deposited in different locations or with different grain-sizes were collected at each station, and the <63 μm fractions were measured for their elemental and Sr–Nd isotopic compositions. Elemental ratios and dimension-reducing technique were firstly applied to discriminate the sediment provenances. They show that the large elemental heterogeneity exists between samples at the same station and also between stations along each river, explainable by variable sediment mixing and local lithological heterogeneity. When combining our Sr–Nd isotopic data with literature data from Taiwan rivers, five discrete clusters of river sediments can be distinguished, reflecting the inter-catchment heterogeneity of sediment provenance in Taiwan Island. We also applied a Sr–Nd isotopic mixing model coupled with Monte-Carlo simulations to quantify the provenance heterogeneity in both rivers. The sediment contribution of the Western Foothills/Tailuko Belt to the Zhuoshui/Liwu downstream can vary by a factor of ∼2 between sediment samples that were considered as spatial or temporal replicates. Combined with field in-situ observations, we propose that fast-changing sediment transport modes cause the provenance heterogeneity in small dynamic mountainous rivers attacked by frequent heavy storms or typhoons. Sediments transported during different events and with different provenances can be preserved at each station, which leads to the intra-station and basin-wide geochemical heterogeneity. This study shows that “small” dynamic mountainous rivers can exhibit “large” geochemical and provenance heterogeneity over multi-spatial scales, and thus the common assumption that “let nature do the averaging” should be treated cautiously in this kind of river. Therefore, we propose several effective sediment sampling approaches on small mountainous rivers for reference. Future studies relying on detrital sediments, e.g. applying cosmogenic nuclides or Li isotopes, should also be aware of the heterogeneous nature in small mountainous rivers, because fast-changing provenances can simultaneously bias the weathering and erosion signals and lead to unrepresentative results.

  • 86.
    D'Ippolito, Veronica
    et al.
    Sapienza Università di Roma.
    Andreozzi, Giovanni B.
    Sapienza Università di Roma.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Blue spinel crystals in the MgAl2O4-CoAl2O4 series: I. Flux growth and chemical characterisation2012In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 97, p. 1828-1833Article in journal (Refereed)
  • 87.
    D'Ippolito, Veronica
    et al.
    Sapienza Università di Roma.
    Andreozzi, Giovanni B.
    Sapienza Università di Roma.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Mantovani, L.
    Università di Parma.
    Bersani, D.
    Università di Parma.
    Fregola, Rosa Anna
    Università di Bari.
    Crystallographic and spectroscopic characterisation of a natural Zn-rich spinel approaching the endmember gahnite (ZnAl2O4) composition2013In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, p. 2941-2953Article in journal (Refereed)
  • 88.
    D'Ippolito, Veronica
    et al.
    Sapienza University, Rome, Italy.
    Andreozzi, Giovanni
    Sapienza University, Rome, Italy.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hametner, Kathrin
    ETH, Zürich, Switzerland.
    Günther, Detlef
    ETH, Zürich, Swizerland.
    Color mechanisms in spinel: cobalt and iron interplay for the blue color2015In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 42, no 6, p. 431-439Article in journal (Refereed)
    Abstract [en]

    Six natural, blue colored spinel crystals were studied chemically by electron microprobe and laser ablation inductively coupled plasma mass spectrometry (LAICP-MS) techniques and optically by UV–VIS–NIR–MIR spectroscopy in the range 30,000–2,000 cm1  to investigate the causes of their blue color hues. The positions of the absorption bands vary only marginally with the principal composition of the samples (gahnite vs. spinel s.s .). Although blue colors in spinels are frequently the result of various electronic processes in Fe cations, we demonstrate by comparison with synthetic Co-bearing samplesthat Co acts as an important chromophore also in natural spinels. Already at concentration levels of a few ppm (e.g.,>10 ppm), cobalt gives rise to absorption bands at ~18,000, 17,000 and 16,000 cm1  that result in distinct blue coloration. In spinels with insignificant Co contents, different shades of paler blue (from purplish to greenish blue) colors are caused by electronic transitions in TFe2+, MFe2+, MFe3and Fe2+–Fe3 cation pairs.

  • 89.
    Donadini, Fabio
    et al.
    ETH Zürich.
    Elming, Sten-Åke
    Luleå Tekniska Universitet.
    Tauxe, Lisa
    University of California, La Jolla.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Paleointensity determination on a 1.786 Ga old gabbro from Hoting, Central Sweden2011In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 309, p. 234-248Article in journal (Refereed)
  • 90. Drake, H.
    et al.
    Tullborg, E.L.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Sandberg, B.
    Blomfeldt, T.
    Åström, M.E.
    Extreme fractionation and micro-scale variation of sulphur isotopes during bacterial sulphate reduction in deep groundwater systems.2015In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 161, p. 1-18Article in journal (Refereed)
    Abstract [en]

    This study conducted at the Äspö Hard Rock Laboratory, SE Sweden, determines the extent and mechanisms of sulphur-isotope fractionation in permanently reducing groundwater in fractured crystalline rock. Two boreholes >400 m below the ground surface were investigated. In the 17-year-old boreholes, the Al instrumentation pipes had corroded locally (i.e., Al-[oxy]hydroxides had formed) and minerals (i.e., pyrite, iron monosulphide, and calcite) had precipitated on various parts on the equipment. By chemically and isotopically comparing the precipitates on the withdrawn instrumentation and the borehole waters, we gained new insight into the dynamics of sulphate reduction, sulphide precipitation, and sulphur-isotope fractionation in deep-seated crystalline-rock settings. An astonishing feature of the pyrite is its huge variability in δ34S, which can exceed 100‰ in total (i.e., −47.2 to +53.3‰) and 60‰ over 50 μm of growth in a single crystal. The values at the low end of the range are up to 71‰ lower than measured in the dissolved sulphate in the water (20–30‰), which is larger than the maximum difference reported between sulphate and sulphide in pure-culture experiments (66‰) but within the range reported from natural sedimentary settings. Although single-step reduction seems likely, further studies are needed to rule out the effects of possible S disproportionation. The values at the high end of the range (i.e., high δ34Spy) are much higher than could be produced from the measured sulphate under any biogeochemical conditions. This strongly suggests the development of closed-system conditions near the growing pyrite, i.e., the rate of sulphate reduction exceeds the rate of sulphate diffusion in the local fluid near the pyrite, causing the local aqueous phase (and thus the forming pyrite) to become successively enriched in heavy S (34S). Consequently, the δ34S values of the forming pyrite become exceptionally high and strongly decoupled from the δ34S values of the sulphate in the bulk fluid. The Al-(oxy)hydroxide and calcite precipitates are explained by a combination of deposit and galvanic corrosion initiated by Al corrosion by H2S produced by sulphate-reducing microorganisms.

  • 91. Drake, Henrik
    et al.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Heim, Christine
    Siljeström, Sandra
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Broman, Curt
    Belivanova, Veneta
    Swedish Museum of Natural History, Department of Paleobiology.
    Åström, Mats E.
    Anaerobic consortia of fungi and sulfate reducing bacteria in deep granite fractures2017In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, no 55, p. 1-9Article in journal (Refereed)
    Abstract [en]

    The deep biosphere is one of the least understood ecosystems on Earth. Although most microbiological studies in this system have focused on prokaryotes and neglected microeukaryotes, recent discoveries have revealed existence of fossil and active fungi in marine sediments and sub-seafloor basalts, with proposed importance for the subsurface energy cycle. However, studies of fungi in deep continental crystalline rocks are surprisingly few. Consequently, the characteristics and processes of fungi and fungus-prokaryote interactions in this vast environment remain enigmatic. Here we report the first findings of partly organically preserved and partly mineralized fungi at great depth in fractured crystalline rock (-740 m). Based on environmental parameters and mineralogy the fungi are interpreted as anaerobic. Synchrotron-based techniques and stable isotope microanalysis confirm a coupling between the fungi and sulfate reducing bacteria. The cryptoendolithic fungi have significantly weathered neighboring zeolite crystals and thus have implications for storage of toxic wastes using zeolite barriers.

  • 92.
    Drake, Henrik
    et al.
    Linnæus University, Department of Biology and Environmental Science, 39182 Kalmar, Sweden.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology. University of Southern Denmark, Department of Biology and Nordic Center for Earth Evolution, Campusvej 55, Odense M, DK-5230, Denmark.
    Tillberg, Mikael
    Department of Biology and Environmental Science, Linnaeus University, 392 31 Kalmar, Sweden.
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Ancient microbial activity in deep hydraulically conductive fracture zones within the Forsmark target area for deep geological nuclear waste disposal, Sweden2018In: Geosciences, Vol. 8, article id 211Article in journal (Refereed)
    Abstract [en]

    Recent studies reveal that organisms from all three domains of life—Archaea, Bacteria, and even Eukarya—can thrive under energy-poor, dark, and anoxic conditions at large depths in the fractured crystalline continental crust. There is a need for an increased understanding of the processes and lifeforms in this vast realm, for example, regarding the spatiotemporal extent and variability of the different processes in the crust. Here, we present a study that set out to detect signs of ancient microbial life in the Forsmark area—the target area for deep geological nuclear waste disposal in Sweden. Stable isotope compositions were determined with high spatial resolution analyses within mineral coatings, and mineralized remains of putative microorganisms were studied in several deep water-conducting fracture zones (down to 663 m depth), from which hydrochemical and gas data exist. Large isotopic variabilities of 13Ccalcite (􀀀36.2 to +20.2‰V-PDB) and 34Spyrite (􀀀11.7 to +37.8‰V-CDT) disclose discrete periods of methanogenesis, and potentially, anaerobic oxidation of methane and related microbial sulfate reduction at several depth intervals. Dominant calcite–water disequilibrium of 18O and 87Sr/86Sr precludes abundant recent precipitation. Instead, the mineral coatings largely reflect an ancient archive of episodic microbial processes in the fracture system, which, according to our microscale Rb–Sr dating of co-genetic adularia and calcite, date back to the mid-Paleozoic. Potential Quaternary precipitation exists mainly at ~400 m depth in one of the boreholes, where mineral–water compositions corresponded.

  • 93. Drake, Henrik
    et al.
    Ivarsson, Magnus
    Tillberg, Mikael
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Ancient Microbial Activity in Deep Hydraulically Conductive Fracture Zones within the Forsmark Target Area for Geological Nuclear Waste Disposal, Sweden2018In: Geosciences, Vol. 8, no 211Article in journal (Refereed)
    Abstract [en]

    Recent studies reveal that organisms from all three domains of life—Archaea, Bacteria, and even Eukarya—can thrive under energy-poor, dark, and anoxic conditions at large depths in the fractured crystalline continental crust. There is a need for an increased understanding of the processes and lifeforms in this vast realm, for example, regarding the spatiotemporal extent and variability of the different processes in the crust. Here, we present a study that set out to detect signs of ancient microbial life in the Forsmark area—the target area for deep geological nuclear waste disposal in Sweden. Stable isotope compositions were determined with high spatial resolution analyses within mineral coatings, and mineralized remains of putative microorganisms were studied in several deep water-conducting fracture zones (down to 663 m depth), from which hydrochemical and gas data exist. Large isotopic variabilities of δ13Ccalcite (−36.2 to +20.2‰ V-PDB) and δ34Spyrite (−11.7 to +37.8‰ V-CDT) disclose discrete periods of methanogenesis, and potentially, anaerobic oxidation of methane and related microbial sulfate reduction at several depth intervals. Dominant calcite–water disequilibrium of δ18O and 87Sr/86Sr precludes abundant recent precipitation. Instead, the mineral coatings largely reflect an ancient archive of episodic microbial processes in the fracture system, which, according to our microscale Rb–Sr dating of co-genetic adularia and calcite, date back to the mid-Paleozoic. Potential Quaternary precipitation exists mainly at ~400 m depth in one of the boreholes, where mineral–water compositions corresponded.

  • 94.
    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.

  • 95. Drake, Henrik
    et al.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Heim, Christine
    Reiners, Peter W.
    Tillberg, Mikael
    Hogmalm, K. Johan
    Dopson, Mark
    Broman, Curt
    Åström, Mats E.
    Unprecedented 34S-enrichment of pyrite formed following microbial sulfate reduction in fractured crystalline rocks2018In: Geobiology, Vol. 16, no 5, p. 556-574Article in journal (Refereed)
    Abstract [en]

    In the deep biosphere, microbial sulfate reduction (MSR) is exploited for energy. Here, we show that, in fractured continental crystalline bedrock in three areas in Sweden, this process produced sulfide that reacted with iron to form pyrite extremely enriched in 34S relative to 32S. As documented by secondary ion mass spectrometry (SIMS) microanalyses, the δ34Spyrite values are up to +132‰V-CDT and with a total range of 186‰. The lightest δ34Spyrite values (−54‰) suggest very large fractionation during MSR from an initial sulfate with δ34S values (δ34Ssulfate,0) of +14 to +28‰. Fractionation of this magnitude requires a slow MSR rate, a feature we attribute to nutrient and electron donor shortage as well as initial sulfate abundance. The superheavy δ34Spyrite values were produced by Rayleigh fractionation effects in a diminishing sulfate pool. Large volumes of pyrite with superheavy values (+120 ± 15‰) within single fracture intercepts in the boreholes, associated heavy average values up to +75‰ and heavy minimum δ34Spyrite values, suggest isolation of significant amounts of isotopically light sulfide in other parts of the fracture system. Large fracturespecific δ34Spyrite variability and overall average δ34Spyrite values (+11 to +16‰) lower than the anticipated δ34Ssulfate,0 support this hypothesis. The superheavy pyrite found locally in the borehole intercepts thus represents a late stage in a much larger fracture system undergoing Rayleigh fractionation. Microscale Rb–Sr dating and U/Th– He dating of cogenetic minerals reveal that most pyrite formed in the early Paleozoic era, but crystal overgrowths may be significantly younger. The δ13C values in cogenetic calcite suggest that the superheavy δ34Spyrite values are related to organotrophic MSR, in contrast to findings from marine sediments where superheavy pyrite has been proposed to be linked to anaerobic oxidation of methane. The findings provide new insights into MSR-related S-isotope systematics, particularly regarding formation of large fractions of 34S-rich pyrite.

  • 96. Eichner, M.J.
    et al.
    Klawonn, I.
    Wilson, S.T.
    Littmann, S.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Church, M.J.
    Kuypers, M.M.M.M.
    Karl, D.M.
    Ploug, H.
    Chemical microenvironments and single-cell carbon and nitrogen uptake in field-collected colonies of Trichodesmium under different pCO22017In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 11, p. 1305-1317Article in journal (Refereed)
    Abstract [en]

    Gradients of oxygen (O2) and pH, as well as small-scale fluxes of carbon (C), nitrogen (N) and O2 were investigated under different partial pressures of carbon dioxide (pCO2) in field-collected colonies of the marine dinitrogen (N2)-fixing cyanobacterium Trichodesmium. Microsensor measurements indicated that cells within colonies experienced large fluctuations in O2, pH and CO2concentrations over a day–night cycle. O2 concentrations varied with light intensity and time of day, yet colonies exposed to light were supersaturated with O2 (up to ~200%) throughout the light period and anoxia was not detected. Alternating between light and dark conditions caused a variation in pH levels by on average 0.5 units (equivalent to 15 nmol l−1 proton concentration). Single-cell analyses of C and N assimilation using secondary ion mass spectrometry (SIMS; large geometry SIMS and nanoscale SIMS) revealed high variability in metabolic activity of single cells and trichomes of Trichodesmium, and indicated transfer of C and N to colony-associated non-photosynthetic bacteria. Neither O2 fluxes nor C fixation by Trichodesmium were significantly influenced by short-term incubations under different pCO2 levels, whereas N2fixation increased with increasing pCO2. The large range of metabolic rates observed at the single-cell level may reflect a response by colony-forming microbial populations to highly variable microenvironments.

  • 97. El Albani, Abderrazak
    et al.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Canfield, Donald E.
    Riboulleau, Armelle
    Rollion Bard, Claire
    Macchiarelli, Roberto
    Ngombi Pemba, Lauriss
    Hammarlund, Emma
    Meunier, Alain
    Moubiya Mouele, Idalina
    Benzerara, Karim
    Bernard, Sylvain
    Boulvais, Philippe
    Chaussidon, Marc
    Cesari, Christian
    Fontaine, Claude
    Chi-Fru, Ernest
    Garcia Ruiz, Juan Manuel
    Gauthier-Lafaye, François
    Mazurier, Arnaud
    Pierson-Wickmann, Anne Catherine
    Rouxel, Olivier
    Trentesaux, Alain
    Vecoli, Marco
    Versteegh, Gerard J. M.
    White, Lee
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Bekker, Andrey
    The 2.1 Ga old Francevillian biota: biogenicity, taphonomy and biodiversity.2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 6:e99438, p. 1-18Article in journal (Refereed)
    Abstract [en]

    The Paleoproterozoic Era witnessed crucial steps in the evolution of Earth’s surface environments following the first appreciable rise of free atmospheric oxygen concentrations ~2.3 to 2.1 Ga ago, and concomitant shallow ocean oxygenation. While most sedimentary successions deposited during this time interval have experienced thermal overprinting from burial diagenesis and metamorphism, the ca. 2.1 Ga black shales of the Francevillian B Formation (FB2) cropping out in southeastern Gabon have not. The Francevillian Formation contains centimeter-sized structures interpreted as organized and spatially discrete populations of colonial organisms living in an oxygenated marine ecosystem. Here, new material from the FB2 black shales is presented and analyzed to further explore its biogenicity and taphonomy. Our extended record comprises variably sized, shaped, and structured pyritized macrofossils of lobate, elongated, and rodshaped morphologies as well as abundant non-pyritized disk-shaped macrofossils and organic-walled acritarchs. Combined microtomography, geochemistry, and sedimentary analysis suggest a biota fossilized during early diagenesis. The emergence of this biota follows a rise in atmospheric oxygen, which is consistent with the idea that surface oxygenation allowed the evolution and ecological expansion of complex megascopic life.

  • 98. Emo, Robert
    et al.
    Smit, Matthijs
    Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Scherer, Erik
    Sprung, Peter
    Bleeker, Wouter
    Mezger, Klaus
    Evidence for evolved Hadean crust from Sr isotopes in apatite within Eoarchean zircon from the Acasta Gneiss Complex2018In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 235, p. 450-462Article in journal (Refereed)
    Abstract [en]

    Current models for the properties of Hadean-Eoarchean crust encompass a full range of possibilities, involving crust that is anywhere from thick and differentiated to thin and mafic. New data are needed to test and refine these models, and, ultimately, to determine how continents were first formed. The Rb-Sr system provides a potentially powerful proxy for crustal evolution and composition. However, this system has thus far been underutilized in studies on early crustal evolution due to its susceptibility to re-equilibration. Overcoming this issue requires new analytical approaches to micro-sample ancient Sr-rich mineral relics that may retain primary Rb-Sr systematics, allowing for the precise and accurate determination of initial 87Sr/86Sr values. In this study, we used a novel application of laser-ablation multi-collector inductively coupled plasma mass spectrometry to determine the Sr isotope composition of apatite inclusions in >3.6 Ga zircon grains from Eoarchean granodiorite gneisses of the Acasta Gneiss Complex, Slave Province, Canada. The 87Rb-corrected 87Sr/86Sr values of these inclusions are largely identical and are distinctly different from values obtained from altered matrix apatite. The inclusion data provide the first direct estimate of initial 87Sr/86Sr for these ancient rocks. Combining this result with information on the protolith and source-extraction age yields estimates for the range of Rb/Sr values, and by extension composition, that the source of these rocks may have had. The data indicate that continental crust containing over 60 wt% of SiO2 was present in the ca. 4.2 Ga source of the Acasta Gneiss Complex. Thus vestiges of evolved crust must have existed within the primitive proto-continents that were present on the Hadean Earth.

  • 99.
    Esmaeilzadeh, Saeid
    et al.
    Stockholms universitet.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Valldor, Martin
    Technische Universität Braunschweig.
    Crystal growth, magnetic and optical properties of the ternary nitride MnSiN22006In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 18, p. 2713-2718Article in journal (Refereed)
  • 100. Eyal, Moshe
    et al.
    Be'eri-Shlevin, Yaron
    Eyal, Yehuda
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Litvinovsky, Boris
    Three successive Proterozoic island arcs in the Northern Arabian–Nubian Shield: Evidence from SIMS U–Pb dating of zircon2014In: Gondwana Research, ISSN 1342-937X, E-ISSN 1878-0571, Vol. 25, p. 338-357Article in journal (Refereed)
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