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  • 1. Agangi, Andrea
    et al.
    Reddy, S M
    Plavsa, D
    Vieru, C
    Selvaraja, V
    LaFlamme, C
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Martin, L
    Nozaki, T
    Takaya, Y
    Suzuki, K
    Subsurface deposition of Cu-rich massive sulphide underneath a Palaeoproterozoic seafloor hydrothermal system—the Red Bore prospect, Western Australia2018Inngår i: Mineralium Deposita, s. 1-18Artikkel i tidsskrift (Fagfellevurdert)
  • 2. Ali, Kamal A
    et al.
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Andresen, Arild
    Li, Shuang-Qing
    Harbi, Hesham M
    Hegner, Ernst
    U–Pb zircon geochronology and Nd–Hf–O isotopic systematics of the Neoproterozoic Hadb adh Dayheen ring complex, Central Arabian Shield, Saudi Arabia2014Inngår i: Lithos, Vol. 206, s. 348-360Artikkel i tidsskrift (Fagfellevurdert)
  • 3. Alvarez, Belinda
    et al.
    Frings, Patrick J
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Clymans, Wim
    Fontorbe, Guillaume
    Conley, Daniel
    Assessing the Potential of Sponges (Porifera) as Indicators of Ocean Dissolved Si Concentrations2017Inngår i: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 4, nr 373Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We explore the distribution of sponges along dissolved silica (dSi) concentration gradients to test whether sponge assemblages are related to dSi and to assess the validity of fossil sponges as a palaeoecological tool for inferring dSi concentrations of the past oceans. We extracted sponge records from the publically available Global Biodiversity Information Facility (GBIF) database and linked these records with ocean physiochemical data to evaluate if there is any correspondence between dSi concentrations of the waters sponges inhabit and their distribution. Over 320,000 records of Porifera were available, of which 62,360 met strict quality control criteria. Our analyses was limited to the taxonomic levels of family, order and class. Because dSi concentration is correlated with depth in the modern ocean, we also explored sponge taxa distributions as a function of depth. We observe that while some sponge taxa appear to have dSi preferences (e.g., class Hexactinellida occurs mostly at high dSi), the overall distribution of sponge orders and families along dSi gradients is not sufficiently differentiated to unambiguously relate dSi concentrations to sponge taxa assemblages. We also observe that sponge taxa tend to be similarly distributed along a depth gradient. In other words, both dSi and/or another variable that depth is a surrogate for, may play a role in controlling sponge spatial distribution and the challenge is to distinguish between the two. We conclude that inferences about palaeo-dSi concentrations drawn from the abundance of sponges in the stratigraphic records must be treated cautiously as these animals are adapted to a great range of dSi conditions and likely other underlying variables that are related to depth. Our analysis provides a quantification of the dSi ranges of common sponge taxa, expands on previous knowledge related to their bathymetry preferences and suggest that sponge taxa assemblages are not related to particular dSi conditions. 

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  • 4. Augustsson, Carita
    et al.
    Rüsing, Tobias
    Niemeyer, Hans
    Kooijman, Ellen
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Berndt, Jasper
    Bahlburg, Heinrich
    Zimmermann, Udo
    0.3 byr of drainage stability along the Palaeozoic palaeo-Pacific Gondwana margin; a detrital zircon study2015Inngår i: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 172, s. 186-200Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The palaeo-Pacific margin of Gondwana in the present-day south–central Andes is marked by tectonic activity related to subduction and terrane accretion. We present detrital zircon U–Pb data encompassing the Palaeozoic era in northern Chile and northwestern Argentina. Cathodoluminescence images reveal dominantly magmatic zircon barely affected by abrasion and displaying only one growth phase. The main age clusters for these zircon grains are Ediacaran to Palaeozoic with an additional peak at 1.3–0.9 Ga and they can be correlated with ‘Grenvillian’ age, and the Brasiliano, Pampean, and Famatinian orogenies. The zircon data reveal main transport from the nearby Ordovician Famatinian arc and related rocks. The Silurian sandstone units are more comparable with Cambrian units, with Brasiliano and Transamazonian ages (2.2–1.9 Ga) being more common, because the Silurian deposits were situated within or east of the (extinct) Famatinian arc. Hence, the arc acted as a transport barrier throughout Palaeozoic time. The complete suite of zircon ages does not record the accretions of exotic terranes or the Palaeozoic glacial periods. We conclude that the transport system along the palaeo-Pacific margin of Gondwana remained stable for c. 0.3 byr and that provenance data do not necessarily reflect the interior of a continent. Hence, inherited geomorphological features must be taken into account when detrital mineral ages are interpreted.

  • 5.
    Bagriy, Ihor Dmytrovych
    et al.
    Institute of Geological Sciences of the National Academy of Sciences of Ukraine.
    Riepkin, Oleksandr Oleksandrovуch
    Ukrainian Hydrogen Council.
    Zabulonov, Yuriy Leonidovych
    Institute of Environmental Geochemistry of the NAS of Ukraine.
    Vyzhva, Sergiy Andriyovych
    Institute of Geology of Taras Shevchenko Kyiv National University.
    Khrushchev, Dmytro Pavlovуch
    National Academy of Sciences of Ukraine.
    Rusakov, Oleg Maksimovich
    Institute of Geophysics of NAS of Ukraine.
    Popov, Oleksandr Oleksandrovych
    Institute of Geochemistry of the Environment, NAS of Ukraine.
    Maslun, Ninel Volodymyrivna
    Institute of Geological Sciences of the NAS of Ukraine.
    Ivanik, Olena Mykhailivna
    Department of General and Historical Geology, Institute of Geology, Taras Shevchenko National University of Kyiv, Ukraine.
    Kovach, Valeriya Omelanivna
    Institute of Environmental Geochemistry of the NAS of Ukraine.
    Shevchuk, Olena
    Naturhistoriska riksmuseet, Enheten för paleobiologi. Ukrainian Academy of Sciences; Stockholm University.
    Kryl, Iaroslav Mykolayovych
    Voden Ukrainy.
    Payuk, Serhii Oleksiyovych
    State Commission of Ukraine on Mineral Reserves.
    Shchurov, Ihor Vyacheslavovуch
    DTEK Naftogaz.
    Hafуch, Ivan Petrovych
    DTEK Naftogaz.
    Leskiv, Ihor Volodymyrovych
    UNGA.
    Rudenko, Yury Fedorovych
    Scientific and Engineering Center of Radio-Hydrogeoecological Polygon Research of the National Academy of Sciences of Ukraine.
    Semenyuk, Volodymyr Grуgorovуch
    Smart Energy.
    Sira, Nataliia Vasilivna
    Ukrainian Geological Research and Production Center.
    Grishanenko, Volodymyr Petrovych
    Center of Oil and Gas Resources.
    Solodkyy, Evgeniy Valeriyovych
    Naftogaz LLC.
    Dubosarsky, Viktor Rudolfovich
    Institute of Geological Sciences of the National Academy of Sciences of Ukraine.
    Dovbysh, Nina Serhiivna
    Institute of Geological Sciences of the NAS of Ukraine.
    Mamyshev, Ihor Evgeniyovych
    Institute of Geological Sciences of the NAS of Ukraine.
    Lihvan, Vadim Maksymovich
    Plativske LLC.
    Kuzmenko, Svyatoslav Oleksandrovich
    Institute of Geological Sciences of the NAS of Ukraine.
    Koval, Anatoly Mykhailovych
    Naftogaz of Ukraine.
    Starodubets, Kyrylо Mykolayovych
    Institute of Geological Sciences of National Academy of Sciences of Ukraine.
    Development and implementation of monitoring of corrosion processes of hydrogen degasation in embrillation zones during the operation of gas pipeline2023Inngår i: Environmental and Energy Challenges of the XXI Century. Global Projects. Ways of Implementation / [ed] I.D. Bagriy, Kyiv: Institute of Geological Sciences of the National Academy of Sciences of Ukraine , 2023, s. 254-286Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Pipelines for oil and gas create significant risks of destruction in the systems of industrial and main transportation of hydrocarbons in the presence of corrosion-embrittlement of metal. According to many researchers one of the main reasons for this process is in the area of hydrogen anomalies. It occurs under insulating coating. Insulating coating on the pipeline is peeled off from the metal in such places. Microcracks and pores appear; then moisture spreads to outer surface of the pipe and causes corrosion processes — embrittlement. In addition, it is not excluded that corrosion is intensified due to electrochemical processes and due to undercurrents of gaseous diffusion of hydrogen gas from the mantle strata formed in the areas of the pipeline location. Hydrogen is extremely permeable gas. It leads to swelling, insulation peeling off and defects expanding. The situation creates possibility for moisture penetration to the pipes surface. It also directly affects strength of the metal causing corrosion, cracking and embrittlement. Results of the studies show that embrittlement processes take place mostly in the areas where pipelines pass through oil and gas-bearing structures. In such places hydrogen exits are recorded.

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  • 6.
    Bagriy, Ihor Dmytrovych
    et al.
    Institute of Geological Sciences of the National Academy of Sciences of Ukraine.
    Riepkin, Oleksandr Oleksandrovуch
    Ukrainian Hydrogen Council.
    Zabulonov, Yuriy Leonidovych
    Institute of Environmental Geochemistry of the NAS of Ukraine.
    Vyzhva, Sergiy Andriyovych
    Institute of Geology of Taras Shevchenko Kyiv National University.
    Khrushchev, Dmytro Pavlovуch
    National Academy of Sciences of Ukraine.
    Rusakov, Oleg Maksimovich
    Institute of Geophysics of NAS of Ukraine.
    Popov, Oleksandr Oleksandrovych
    Institute of Geochemistry of the Environment, NAS of Ukraine.
    Maslun, Ninel Volodymyrivna
    Institute of Geological Sciences of the NAS of Ukraine.
    Ivanik, Olena Mykhailivna
    Department of General and Historical Geology, Institute of Geology, Taras Shevchenko National University of Kyiv, Ukraine.
    Kovach, Valeriya Omelanivna
    Institute of Environmental Geochemistry of the NAS of Ukraine.
    Shevchuk, Olena
    Naturhistoriska riksmuseet, Enheten för paleobiologi. Ukrainian Academy of Sciences; Stockholm University.
    Kryl, Iaroslav Mykolayovych
    Voden Ukrainy.
    Payuk, Serhii Oleksiyovych
    State Commission of Ukraine on Mineral Reserves.
    Shchurov, Ihor Vyacheslavovуch
    DTEK Naftogaz.
    Hafуch, Ivan Petrovych
    DTEK Naftogaz.
    Leskiv, Ihor Volodymyrovych
    UNGA.
    Rudenko, Yury Fedorovych
    Scientific and Engineering Center of Radio-Hydrogeoecological Polygon Research of the National Academy of Sciences of Ukraine.
    Semenyuk, Volodymyr Grуgorovуch
    Smart Energy.
    Sira, Nataliia Vasilivna
    Ukrainian Geological Research and Production Center.
    Grishanenko, Volodymyr Petrovych
    Center of Oil and Gas Resources.
    Solodkyy, Evgeniy Valeriyovych
    Naftogaz LLC.
    Dubosarsky, Viktor Rudolfovich
    Institute of Geological Sciences of the National Academy of Sciences of Ukraine.
    Dovbysh, Nina Serhiivna
    Institute of Geological Sciences of the NAS of Ukraine.
    Mamyshev, Ihor Evgeniyovych
    Institute of Geological Sciences of the NAS of Ukraine.
    Lihvan, Vadim Maksymovich
    Plativske LLC.
    Kuzmenko, Svyatoslav Oleksandrovich
    Institute of Geological Sciences of the NAS of Ukraine.
    Koval, Anatoly Mykhailovych
    Naftogaz of Ukraine.
    Starodubets, Kyrylо Mykolayovych
    Institute of Geological Sciences of National Academy of Sciences of Ukraine.
    Gas dynamic phenomena (gdf) and causes of accidents at mines2023Inngår i: Environmental and Energy Challenges of the XXI Century. Global Projects. Ways of Implementation / [ed] I.D. Bagriy, Kyiv: Institute of Geological Sciences of the National Academy of Sciences of Ukraine , 2023, s. 238-253Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    There is a problem of development and implementation of prospecting technology to ensure protection of mining products and prevent disasters during the of coal deposits. It is especially relevant now when issue of environmental protection and improving labor safety in coal mines is very acute. Development of safe search technology for coal deposits is proposed by the authors. It will allow early monitoring to identify places of possible manifestations of gas-dynamic phenomena and make operational decisions for their elimination. The technology is based on application of exploratory gas-geochemical methods for mapping places of accumulation of gas-hydrogen accumulations and their areas. It together with a complex of geological-geophysical method allows to identify areas of possible emergency processes in development zones of mine fields. Feasibility of using search technology to justify use of laying anticipatory degassing wells to prevent uncontrolled explosive processes and technical disasters was proved on large array of conducted field work of planar and profile surveys. The proposed technology was tested on numerous mining sites in the process of exploratory and ecological research in development zones of active and exhausted mine fields.

    Fulltekst (pdf)
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  • 7.
    Bagriy, Ihor Dmytrovych
    et al.
    Institute of Geological Sciences of the National Academy of Sciences of Ukraine.
    Riepkin, Oleksandr Oleksandrovуch
    Ukrainian Hydrogen Council.
    Zabulonov, Yuriy Leonidovych
    Institute of Environmental Geochemistry of the NAS of Ukraine.
    Vyzhva, Sergiy Andriyovych
    Institute of Geology of Taras Shevchenko Kyiv National University.
    Khrushchev, Dmytro Pavlovуch
    National Academy of Sciences of Ukraine.
    Rusakov, Oleg Maksimovich
    Institute of Geophysics of NAS of Ukraine.
    Popov, Oleksandr Oleksandrovych
    Institute of Geochemistry of the Environment, NAS of Ukraine.
    Maslun, Ninel Volodymyrivna
    Institute of Geological Sciences of the NAS of Ukraine.
    Ivanik, Olena Mykhailivna
    Department of General and Historical Geology, Institute of Geology, Taras Shevchenko National University of Kyiv, Ukraine.
    Kovach, Valeriya Omelanivna
    Institute of Environmental Geochemistry of the NAS of Ukraine.
    Shevchuk, Olena
    Naturhistoriska riksmuseet, Enheten för paleobiologi. Ukrainian Academy of Sciences; Stockholm University.
    Kryl, Iaroslav Mykolayovych
    Voden Ukrainy.
    Payuk, Serhii Oleksiyovych
    State Commission of Ukraine on Mineral Reserves.
    Shchurov, Ihor Vyacheslavovуch
    DTEK Naftogaz.
    Hafуch, Ivan Petrovych
    DTEK Naftogaz.
    Leskiv, Ihor Volodymyrovych
    UNGA.
    Rudenko, Yury Fedorovych
    Scientific and Engineering Center of Radio-Hydrogeoecological Polygon Research of the National Academy of Sciences of Ukraine.
    Semenyuk, Volodymyr Grуgorovуch
    Smart Energy.
    Sira, Nataliia Vasilivna
    Ukrainian Geological Research and Production Center.
    Grishanenko, Volodymyr Petrovych
    Center of Oil and Gas Resources.
    Solodkyy, Evgeniy Valeriyovych
    Naftogaz LLC.
    Dubosarsky, Viktor Rudolfovich
    Institute of Geological Sciences of the National Academy of Sciences of Ukraine.
    Dovbysh, Nina Serhiivna
    Institute of Geological Sciences of the NAS of Ukraine.
    Mamyshev, Ihor Evgeniyovych
    Institute of Geological Sciences of the NAS of Ukraine.
    Lihvan, Vadim Maksymovich
    Plativske LLC.
    Kuzmenko, Svyatoslav Oleksandrovich
    Institute of Geological Sciences of the NAS of Ukraine.
    Koval, Anatoly Mykhailovych
    Naftogaz of Ukraine.
    Starodubets, Kyrylо Mykolayovych
    Institute of Geological Sciences of National Academy of Sciences of Ukraine.
    Justification of global natural, environmental and hydrological conditions of green hydrogen generation, accumulation and logistics ways2023Inngår i: Environmental and Energy Challenges of the XXI Century. Global Projects. Ways of Implementation / [ed] I. D. Bagriy, Kyiv: Institute of Geological Sciences of the National Academy of Sciences of Ukraine , 2023, s. 26-95Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The implementation of global energy projectsfor comprehensive solutions to the developmentof energy from renewable sources has all thenecessary conditions for the production, accumulationand transportation of green hydrogenin the south-west of the Odesa region, within theboundaries of the Izmail administrative districtand is timed to the floodplain of the Danube River.

    Fulltekst (pdf)
    fulltext
  • 8.
    Bagriy, Ihor Dmytrovych
    et al.
    Institute of Geological Sciences of the National Academy of Sciences of Ukraine.
    Riepkin, Oleksandr Oleksandrovуch
    Ukrainian Hydrogen Council.
    Zabulonov, Yuriy Leonidovych
    Institute of Environmental Geochemistry of the NAS of Ukraine.
    Vyzhva, Sergiy Andriyovych
    Institute of Geology of Taras Shevchenko Kyiv National University.
    Khrushchev, Dmytro Pavlovуch
    National Academy of Sciences of Ukraine.
    Rusakov, Oleg Maksimovich
    Institute of Geophysics of NAS of Ukraine.
    Popov, Oleksandr Oleksandrovych
    Institute of Geochemistry of the Environment, NAS of Ukraine.
    Maslun, Ninel Volodymyrivna
    Institute of Geological Sciences of the NAS of Ukraine.
    Ivanik, Olena Mykhailivna
    Department of General and Historical Geology, Institute of Geology, Taras Shevchenko National University of Kyiv, Ukraine.
    Kovach, Valeriya Omelanivna
    Institute of Environmental Geochemistry of the NAS of Ukraine.
    Shevchuk, Olena
    Naturhistoriska riksmuseet, Enheten för paleobiologi. Ukrainian Academy of Sciences; Stockholm University.
    Kryl, Iaroslav Mykolayovych
    Voden Ukrainy.
    Payuk, Serhii Oleksiyovych
    State Commission of Ukraine on Mineral Reserves.
    Shchurov, Ihor Vyacheslavovуch
    DTEK Naftogaz.
    Hafуch, Ivan Petrovych
    DTEK Naftogaz.
    Leskiv, Ihor Volodymyrovych
    UNGA.
    Rudenko, Yury Fedorovych
    Scientific and Engineering Center of Radio-Hydrogeoecological Polygon Research of the National Academy of Sciences of Ukraine.
    Semenyuk, Volodymyr Grуgorovуch
    Smart Energy.
    Sira, Nataliia Vasilivna
    Ukrainian Geological Research and Production Center.
    Grishanenko, Volodymyr Petrovych
    Center of Oil and Gas Resources.
    Solodkyy, Evgeniy Valeriyovych
    Naftogaz LLC.
    Dubosarsky, Viktor Rudolfovich
    Institute of Geological Sciences of the National Academy of Sciences of Ukraine.
    Dovbysh, Nina Serhiivna
    Institute of Geological Sciences of the NAS of Ukraine.
    Mamyshev, Ihor Evgeniyovych
    Institute of Geological Sciences of the NAS of Ukraine.
    Lihvan, Vadim Maksymovich
    Plativske LLC.
    Kuzmenko, Svyatoslav Oleksandrovich
    Institute of Geological Sciences of the NAS of Ukraine.
    Koval, Anatoly Mykhailovych
    Naftogaz of Ukraine.
    Starodubets, Kyrylо Mykolayovych
    Institute of Geological Sciences of National Academy of Sciences of Ukraine.
    Scientific justification of spatial distribution of hydrogen anomalies in the nearsurface layer of traditional and untraditional oil and gas-bearing structures and implementation of hydrogen search technology2023Inngår i: Environmental and Energy Challenges of the XXI Century. Global Projects. Ways of Implementation / [ed] I.D. Bagriy, Kyiv: Institute of Geological Sciences of the National Academy of Sciences of Ukraine , 2023, s. 96-237Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Long-term results of research on mapping of oil and gas-bearing areas on traditional and non-traditional objects (mine fields, shelf areas, astroblems) made it possible to create a database of system criteria for search technology of structural-thermo-atmospheric-hydrologic geochemical research (STAHGR). It is an integral part of methodological solutions complex.There hydrogen was used as the main constituent element of explosives for the first time insearch practice. There are of hydrogen concentrations obtained in the process of research into the mapping features of the oil and gas capacity of traditional and non-traditional HC (hydrocarbons). Their spectrum of research includes H2-hydrogen. Analysis of data results made it possible to single out anomalous single values in areas and in productive areas (in the absence of background) and to conduct detailed, multi-scale studies for the purpose of planar mapping on prospecting works and environmental impacts of gas dynamic phenomena (GDF) during the development of coal massifs.

    Fulltekst (pdf)
    fulltext
  • 9.
    Bauer, Harald
    et al.
    Landesverein für Höhlenkunde in Wien und Niederösterreich.
    Exel, Thomas
    Landesverein für Höhlenkunde in Wien und Niederösterreich.
    Oberender, Pauline
    Naturhistorisches Museum Karst und Höhlenkundliche Arbeitsgemeinschaft.
    Sjöberg, Rabbe
    P&G Group.
    Lundberg, Johannes
    Naturhistoriska riksmuseet, Enheten för botanik.
    Scheuerer, Manuela
    Die Gobholo-Höhle in Swasiland: Expedition in eine der längsten Granithöhlen der Welt2015Inngår i: Die Höhlen, ISSN 0018-3091, Vol. 66, nr 1-4, s. 27-42Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    A small part of the Gobholo cave in westernSwaziland (southern Africa) has been usedfor touristic adventure tours for a few years,but the cave has never been surveyed norinvestigated scientifically. An internationalteam of speleologists started exploring, surveyingand documenting the cave in early2014. So far, more than 1 km has been surveyed,making Gobholo cave one of theworld’s longest granite caves and severalcontinuations are still unexplored. The upperparts of the cave are located in a rockfalldeposit overlying the Gobholo river, whereasthe lower parts originated from in-situweathering of the archaic alkali feldspargranite. The river floods large parts of thecave during heavy rainfalls and is responsiblefor the partial removal of the weatheringmaterial out of the cave. Manifold and numerousflowstones (composed of opal-Aand pigotite) probably formed via microbialprocesses. The cave is also a habitat for variousanimal species, including bats, spidersand cave crickets. Archaeologic artefactsprobably dating back to the local Stone Ageand Iron Age bear evidence of a former culturaluse of the cave. A thermal spring wasfound and temperature, CO2 and radonmeasurements provide data about the caveclimate which is characterised by fairly goodventilation. The age of the cave is uncertainbut the only approximately dated archaeologicalartefacts suggest a minimum age of40,000 years.

  • 10. Bellucci, Jeremy
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Humayan, M
    Hewins, R
    Zanda, B
    Pb-isotopic evidence for an early, enriched crust on Mars2015Inngår i: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 410, s. 34-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Martian meteorite NWA 7533 is a regolith breccia that compositionally resembles the Martian surface measured by orbiters and landers. NWA 7533 contains monzonitic clasts that have zircon with U–Pb ages of 4.428 Ga. The Pb isotopic compositions of plagioclase and alkali feldspars, as well as U–Pb isotopic compositions of chlorapatitein the monzonitic clasts of NWA 7533 have been measured by Secondary Ion Mass Spectrometry (SIMS). The U–Pb isotopic compositions measured from the chlorapatitein NWA 7533 yield an age of 1.357 ±81Ga(2σ). The least radiogenic Pb isotopic compositions measured in plagioclase and K-feldspar lie within error of the 4.428 Ga Geochron. These data indicate that the monzonitic clasts in NWA 7533 are a product of a differentiation history that includes residence in areservoir that formed prior to 4.428 Ga with a μ-value (238U/204Pb) of at least 13.4 ±1.7 (2σ)and aκ-value (232Th/238U) of ∼4.3. This μ-value is more than three times higher than any other documented Martian reservoir. These results indicate either the Martian mantle is significantly more heterogeneous than previously thought (μ-value of 1–14 vs. 1–5) and/or the monzonitic clasts formed by the melting of Martian crust with a μ-value of at least 13.4. Therefore, NWA 7533 may contain the first isotopic evidence for an enriched, differentiated crust on Mars.

  • 11. Bennike, Ole
    et al.
    Hedenäs, Lars
    Naturhistoriska riksmuseet, Enheten för botanik.
    Lemdahl, Geoffrey
    Wiberg-Larsen, Peter
    A multiproxy macrofossil record of Eemian palaeoenvironments from Klaksvík, the Faroe Islands2018Inngår i: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 47, s. 106-113Artikkel i tidsskrift (Fagfellevurdert)
  • 12.
    Billström, K
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Evins, P
    Martinsson, O
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Weihed, P
    Conflicting zircon vs. titanite U-Pb age systematics and the deposition of the host volcanic sequence to Kiruna-type and IOCG deposits in northern Sweden, Fennoscandian shield2018Inngår i: Precambrian ResearchArtikkel i tidsskrift (Fagfellevurdert)
  • 13. Bosi, Ferdinando
    et al.
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Hovis, Guy L.
    Crystal chemistry of povondraite by single-crystal XRD, EMPA, Mössbauer spectroscopy and FTIR2023Inngår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 87, nr 2, s. 178-185Artikkel i tidsskrift (Fagfellevurdert)
  • 14.
    Bouchal, Johannes M.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Zetter, Reinhard ()
    Pollen and spores of the uppermost Eocene Florissant Formation, Colorado: A combined light and scanning electron microscopy study2016Inngår i: Grana, Vol. 55, nr 3, s. 179-245Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The uppermost Eocene Florissant Formation, Rocky Mountains, Colorado, has yielded numerous insect, vertebrate, and plant fossils. Three previous comprehensive palynological studies investigated sections of lacustrine deposits of the Florissant Formation and documented the response of plant communities to volcanic eruptive phases but overall found little change in plant composition throughout the investigated sections. These studies reported up to 150 pollen and spore phenotypes. In the present paper we used a taxonomic approach to the investigation of dispersed pollen and spores of the Florissant Formation. Sediment samples from the shale units containing macrofossils were investigated using light microscopy (LM) and scanning electron microscopy (SEM). The general picture of the palynoflora is in agreement with previous studies. However, the combined LM and SEM investigation provides important complementary information to previous LM studies. While a fairly large amount of previous pollen determinations could be confirmed, the purported taxonomic affinities of several pollen phenotypes need to be revised. For example, pollen referred to as Podocarpus or Podocarpidites sp. belongs to the Pinaceae Cathaya, Malus/Pyrus actually belongs to Dryadoideae, pollen of the form genus Boehlensipollis referred to as Proteaceae/Sapindaceae/Elaeagnaceae or Cardiospermum belongs to Sapindaceae but not to Cardiospermum, and pollen of Persicarioipollis sp. B with previously assumed affinities to Polygonaceae actually belongs to Thymelaeaceae. Pandaniidites and one type of Malvacipollis cannot be linked with Pandanaceae and Malvaceae. A few taxa are new records for Florissant (Ebenaceae: Diospyros; Mernispermaceae; Trochodendraceae: Tetracentron). In general, SEM investigations complement the LM palynological studies and improve the identification of dispersed pollen and spores and enable integration of data from dispersed fossil pollen into a wide range of comparative morphological, taxonomic, evolutionary, biogeographic, and phylogenetic studies.

    Fulltekst (pdf)
    fulltext
  • 15.
    Bouchal, Johannes M.
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Denk, Thomas
    An overview of the palynoflora of the Miocene Yatağan basin, Turkey2014Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The palynoflora of the lignite strip mines of the Yatağan basin, located in the Muğla province of western Turkey, is the focus of this study. Samples were taken from the Eskihisar, Salihpasalar and Tinaz mines. In the Yatağan basin two Miocene formations, formed from river and lake deposits, Eskihisar Formation (middle Miocene) and Yatağan Formation (late Miocene) have been designated. Both show a general lithology consisting of conglomerate, sandstone, claystone, limestone and tuffite, the mined/excavated lignite bearing strata are restricted to the Eskihisar Formation.

    Until now, pollen from the Yatağan basin has mostly been described according to conventional morphological nomenclature, using light microscopy (LM) only. In this study, the same individual pollen grains are investigated by using both, LM and scanning electron microscopy (SEM). The  high resolution pictographs allow a higher taxonomic resolution.

    The rich palynoflora (Table 1) is comprised of diverse spores (at least nine morphotypes), gymnosperm pollen from Cupressaceae, Gnetales, Pinaceae, and angiosperm pollen from Poaceae, Typhaceae, Altingiaceae,  Amaranthaceae (Chenopodieae), Anacardiaceae, Apiaceae, Betulaceae, Buxaceae, Caprifoliaceae (Dipsacoideae, Lonicera) Caryophyllaceae, Compositae (Asteroideae, Cichoriodeae), Cornaceae, Eucommiaceae, Fabaceae, Fagaceae (Fagus, Quercus, Trigonobalanopsis) Geraniaceae, Juglandaceae, Malvaceae, Myricaceae, Nymphaeaceae, Oleaceae, Palmae, Plumbaginaceae (Armeria, Plumbago), Polygonaceae (Rumex), Salicaceae, Sapindaceae (Acer), Smilacaceae, and Ulmaceae (Cedrelospermum, Ulmus, Zelkova).

    Fulltekst (pdf)
    YataganBasinPollen
  • 16.
    Bouchal, Johannes M.
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Güner, Tuncay H.
    Denk, Thomas
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Palynological and palaeobotanical investigations in the Miocene Yatağan basin, Turkey: High-resoluton taxonomy and biostratigraphy2015Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The subject of this study is the palynology (biostratigraphic and taxonomic) and the plant remains of the lignite strip mines of Eskihisar, Salihpasalar, and Tinaz (Muğla province, western Turkey). In the Yatağan basin two Miocene to Pliocene formations are present, the Eskihisar Formation (early to middle Miocene) and the Yatağan Formation (late Miocene to early Pliocene). Both formations represent river and lake deposits consisting mainly of conglomerate, sandstone, claystone, limestone, tuffite, and intercalated lignite; the thickest, actively mined lignite seams occur in the Sekköy member of the Eskihisar Formation.

    Previous palynological studies of the palynoflora of the Yatağan basin mainly focussed on its biostratigraphic and palaeoclimatic significance, using conventional morphological nomenclature and light microscopy (LM).

    In this study the „single grain method“ is applied. Using this method, the same individual pollen grains are investigated by using both LM and scanning electron microscopy (SEM). The resulting high-resolution pictographs enable a much higher taxonomic resolution.

     

    The studied palynoflora is very rich and taxonomically diverse. Cryptogams are represented by more than ten spore morphotypes of at least three families (Osmundaceae, Pteridaceae, Polypodiaceae). Gymnosperm pollen is dominated by Cupressaceae, Gnetales (Ephedra), and Pinaceae (Cathaya, Keteleeria, Pinus). Angiosperm pollen can be assigned to 57 different genera belonging to Poaceae, Typhaceae, Altingiaceae, Amaranthaceae (Chenopodieae), Anacardiaceae, Apiaceae (three types), Asteraceae (Asteroideae, Cichoriodeae), Betulaceae (Alnus, Betula, Carpinus, Ostrya) Buxaceae, Campanulaceae, Caprifoliaceae (Lonicera), Caryophyllaceae, Dipsacaceae, Eucommiaceae, Euphorbiaceae, Fabaceae, Fagaceae (Fagus, Quercus, Trigonobalanopsis) Geraniaceae, Juglandaceae, Linnaceae (Linnum), Malvaceae, Myricaceae, Nymphaeaceae, Oleaceae (four different types), Plumbaginaceae (Armeria,), Polygonaceae (Rumex), Rosaceae, Sapindaceae (Acer), Ulmaceae (Cedrelospermum, Ulmus, Zelkova), and Zingiberales (Spirematospermum).

     

    In addition, more than two thousand plant macrofossils were collected in the course of repeated field trips, including remains of Pinaceae, Berberidiaceae (Mahonia), Betulaceae (Alnus, Carpinus), Buxaceae (Buxus), Fagaceae (Fagus, Quercus), Lauraceae, Malvaceae (Tilia), Myricaceae (Myrica), Rosaceae, Salicaceae (Populus, Salix), Sapindaceae (Acer), Smilacaceae (Smilax), Typhaceae (Typha), Ulmaceae (Zelkova).

     

    A combined analysis integrating these rich and diverse plant macro- and microfossil records will lead to a better understanding and refined reconstruction of the vegetation in the Yatağan basin during the middle to late Miocene.

    Fulltekst (pdf)
    EGU2015Poster
  • 17. Chi Fru, E.
    et al.
    Ivarsson, M.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Kilias, S. P.
    Frings, Patrick J
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Hemmingsson, C.
    Broman, C.
    Bengtson, S.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Chatzitheodoridis, E.
    Biogenicity of an Early Quaternary iron formation, Milos Island, Greece2015Inngår i: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 13, nr 3, s. 225-244Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 18.
    Chris, Mays
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi. Monash University.
    Bevitt, Joseph
    Australian Nuclear Science and Technology Organisation, Research Office, Lucas Heights, Australia.
    Stilwell, Jeffrey
    School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria, Australia.
    Pushing the limits of neutron tomography in palaeontology: Three-dimensional modelling of in situ resin within fossil plants2017Inngår i: Palaeontologia Electronica, ISSN 1935-3952, E-ISSN 1094-8074, Vol. 20, nr 3, s. 1-12, artikkel-id 20.3.57AArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Computed tomography is an increasingly popular technique for the non-destructivestudy of fossils. Whilst the science of X-ray computed tomography (CT) has greatlymatured since its first fossil applications in the early 1980s, the applications and limitationsof neutron tomography (NT) remain relatively unexplored in palaeontology. Thesehighest resolution neutron tomographic scans in palaeontology to date were conductedon a specimen of Austrosequoia novae-zeelandiae (Ettingshausen) Mays and Cantrillrecovered from mid-Cretaceous (Cenomanian; ~100–94 Ma) strata of the ChathamIslands, eastern Zealandia. Previously, the species has been identified with in situ fossilresin (amber); the new neutron tomographic analyses demonstrated an anomalouslyhigh neutron attenuation signal for fossil resin. The resulting data provided astrong contrast between, and distinct three-dimensional representations of the: 1) fossilresin; 2) coalified plant matter; and 3) sedimentary matrix. These data facilitated ananatomical model of endogenous resin bodies within the cone axis and bract-scalecomplexes. The types and distributions of resin bodies support a close alliance withSequoia Endlicher (Cupressaceae), a group of conifers whose extant members areonly found in the Northern Hemisphere. This study demonstrates the feasibility of NTas a means to differentiate chemically distinct organic compounds within fossils.Herein, we make specific recommendations regarding: 1) the suitability of fossil preservationstyles for NT; 2) the conservation of organic specimens with hydrogenous consolidantsand adhesives; and 3) the application of emerging methods (e.g., neutronphase contrast) for further improvements when imaging fine-detailed anatomical structures.These findings demonstrate that we are still far from reaching the conceptuallimits of NT as a means of virtually extracting fossils, or imaging their internal anatomyeven when embedded within a rock matrix.

    Fulltekst (pdf)
    Mays et al (2017) - Neutron tomography - methods - in situ resin
  • 19. Conley, Daniel
    et al.
    Frings, Patrick J
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    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 time2017Inngår i: Frontiers in Marine Science, E-ISSN 2296-7745Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 20. Crossley, R J
    et al.
    Evans, K A
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Kilburn, M R
    Insights into sulfur cycling at subduction zones from in-situ isotopic analysis of sulfides in high-pressure serpentinites and ‘hybrid’ samples from Alpine Corsica2018Inngår i: Chemical GeologyArtikkel i tidsskrift (Fagfellevurdert)
  • 21.
    Dalsätt, Johan
    et al.
    Naturhistoriska riksmuseet, Enheten för zoologi.
    Ericson, Per G P
    Naturhistoriska riksmuseet, Enheten för bioinformatik och genetik.
    ZHOU, Zhonge
    Institute of Vertebrate Paleontology and Paleoanthropology; Chinese Academy of Sciences; Beijing 100044 China.
    A New Enantiornithes (Aves) from the Early Cretaceous of China2014Inngår i: Acta Geologica Sinica, ISSN 1000-9515, E-ISSN 1755-6724, Vol. 88, nr 4, s. 1034-1040Artikkel i tidsskrift (Fagfellevurdert)
  • 22.
    Dalton, April S.
    et al.
    Department of Physical Geography and Geoecology, Charles University, Prague, Czech Republic.
    Pico, Tamara
    Caltech, Pasadena, CA, United States.
    Gowan, Evan J.
    Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany; MARUM, University of Bremen, Bremen, Germany ; Department of Earth and Environmental Sciences, Kumamoto University, Kumamoto, Japan.
    Clague, John J.
    Department of Earth Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
    Forman, Steven L.
    Department of Geosciences, Baylor University, Waco, TX, United States.
    McMartin, Isabelle
    Geological Survey of Canada, Natural Resources Canada, Ottawa, Ontario, Canada.
    Sarala, Pertti
    Oulu Mining School, P.O. Box 3000, FI-90014, University of Oulu, Finland; Geological Survey of Finland, P.O. Box 77, FI-96101 Rovaniemi, Finland.
    Helmens, Karin
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    The marine δ18O record overestimates continental ice volume during Marine Isotope Stage 32022Inngår i: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 212, s. 103814-103814, artikkel-id 103814Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is disagreement in the Quaternary research community in how much of the marine δ18O signal is driven by change in ice volume. Here, we examine this topic by bringing together empirical and modelling work for Marine Isotope Stage 3 (MIS 3; 57 ka to 29 ka), a time when the marine δ18O record indicates moderate continental glaciation and a global mean sea level between −60 m and −90 m. We compile and interpret geological data dating to MIS 3 to constrain the extent of major Northern Hemisphere ice sheets (Eurasian, Laurentide, Cordilleran). Many key data, especially published in the past ~15 years, argue for an ice-free core of the formerly glaciated regions that is inconsistent with inferences from the marine δ18O record. We compile results from prior studies of glacial isostatic adjustment to show the volume of ice inferred from the marine δ18O record is unable to fit within the plausible footprint of Northern Hemisphere ice sheets during MIS 3. Instead, a global mean sea level between −30 m and − 50 m is inferred from geological constraints and glacial isostatic modelling. Furthermore, limited North American ice volumes during MIS 3 are consistent with most sea-level bounds through that interval. We can find no concrete evidence of large-scale glaciation during MIS 3 that could account for the missing ~30 m of sea-level equivalent during that time, which suggests that changes in the marine δ18O record are driven by other variables, including water temperature. This work urges caution regarding the reliance of the marine δ18O record as a de facto indicator of continental ice when few geological constraints are available, which underpins many Quaternary studies.

    Fulltekst (pdf)
    fulltext
  • 23.
    Deegan, Frances M
    et al.
    Uppsala University.
    Whitehouse, Martin J
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Troll, Valentin R
    Uppsala University.
    Geiger, Harri
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    le Roux, Petrus
    Harris, Chris
    van Helden, Marcel
    González-Maurel, Osvaldo
    Sunda arc mantle source δ18O value revealed by intracrystal isotope analysis2021Inngår i: Nature Communications, Vol. 12, nr 1, s. 1-10, artikkel-id 3930Artikkel i tidsskrift (Fagfellevurdert)
  • 24. Deng, Jun
    et al.
    Wang, Changming
    Bagas, Leon
    Selvaraja, Vikraman
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Wu, Bin
    Yang, Lifei
    Insights into ore genesis of the Jinding Zn–Pb deposit, Yunnan Province, China: Evidence from Zn and in-situ S isotopes2017Inngår i: Ore Geology Reviews, Vol. 90, s. 943-957Artikkel i tidsskrift (Fagfellevurdert)
  • 25. Denk, Thomas
    Zohner, Constantin M. ()
    Renner, Susanne S.
    Plant fossils reveal major biomes occupied by the late Miocene Old-World Pikermian fauna2018Inngår i: Nature Ecology & Evolution, E-ISSN 2397-334X, Vol. 2, s. 1864-1870Artikkel i tidsskrift (Fagfellevurdert)
  • 26.
    Denk, Thomas
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Güner, Tuncay H.
    , Istanbul University, Istanbul, Turkey.
    Kvaček, Zlatko
    Charles University, Prague, Czech Republic.
    Bouchal, Johannes M.
    Naturhistoriska riksmuseet, Enheten för paleobiologi. johannes.bouchal@nrm.se.
    The early Miocene flora of Güvem (Central Anatolia, Turkey): a window into early Neogene vegetation and environments in the Eastern Mediterranean2017Inngår i: Acta Palaeobotanica, ISSN 0001-6594, E-ISSN 1427-6402, Vol. 57, nr 2, s. 237-338Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The early Burdigalian (MN3) plant assemblage of the Güvem area (northwestern Central Anatolia) is preserved in lacustrine sediments of the Dereköy pyroclastics. Its age is well constrained by radiometric dates of basaltic rocks bracketing the pyroclastics, making the Güvem flora one of the extremely few precisely dated early Miocene floras in the Mediterranean region. The rich assemblage of impression fossils comprises ferns and fern allies (2 species), gymnosperms (12 spp.) and angiosperms (129 spp.). Ilex miodipyrena sp. nov. is described as a new fossil-species. The most diverse families in the assemblage are the Fagaceae with 12 taxa and the Fabaceae with 12 leaf morphotypes and one fruit taxon. Aquatic plants are represented by seven taxa, riparian (including palms) and swamp forest elements by >35 taxa, and lianas by three taxa (Smilax spp., Chaneya). The relatively large number of aquatic and riparian/swamp elements is congruent with the rich fish, amphibian and reptile record of the Güvem area. Another characteristic feature of the plant assemblage is the presence of various lobed leaves which show similarities with modern species of different families (e.g. Alangium, various Malvales). Trees and shrubs growing on well-drained soils and forming closed-canopy and open-canopy forests are the most diversified group (>70 taxa). In terms of number of specimens in the collection and based on field observations, by far the most abundant leaf fossils belong to evergreen oaks of Quercus drymeja and Q. mediterranea and to various types of foliage that cannot be assigned to a particular extant or extinct genus of Fagaceae. These sclerophyllous trees must have covered vast areas surrounding the wetlands that developed during the early Miocene in the Güvem Basin. Based on a recent reassessment of the ecology and taxonomic affinity of these trees, they are considered to reflect humid temperate climatic conditions but with a brief drier season during the winter months. These forests are more similar to the laurel forests of the southeastern United States and those stretching in a narrow belt south of the Himalayas to eastern central China. The large number of Fabaceae may indicate the presence of warm subtropical environments but this is difficult to assess, as they are known for having wide ecological ranges today and in the past. All in all, a larger part of the plant taxa point to forested vegetation. This is in agreement with previous palynological studies which detected only small amounts of herbaceous and grass pollen. Open patches of vegetation may have been restricted to river banks and to rocky areas in a volcanic landscape. The biogeographic patterns detected for the early Miocene of the Güvem assemblage are manifold; most taxa are widespread Northern Hemispheric elements. A substantial part of the species migrated from Asia into Europe during the (late) Paleogene and reached Anatolia during the early Miocene (Fagus, Paliurus, Chaneya, Ailanthus, Quercus kubinyii, Davallia haidingeri, Acer angustilobum, A. palaeosaccharinum). Fewer taxa may have been in Anatolia before they migrated to Europe (e.g. Nerium, Smilax miohavanensis, Quercus sosnowskyi). Finally, very few taxa are Anatolian endemics (e.g. Ilex miodipyrena).

    Fulltekst (pdf)
    fulltext
  • 27.
    Ericson, Per G P
    Naturhistoriska riksmuseet, Enheten för bioinformatik och genetik.
    Systematics, anatomy and paleoecology of the Paleogene family Presbyornithidae (Aves: Anseriformes)2000Inngår i: PaleoBios, ISSN 0031-0298, Vol. 20, s. 1-23Artikkel i tidsskrift (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 28. Fontorbe, G.
    et al.
    Frings, Patrick J
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    De La Rocha, C. L.
    Hendry, K. R.
    Conley, D. J.
    A silicon depleted North Atlantic since the Palaeogene: Evidence from sponge and radiolarian silicon isotopes2016Inngår i: Earth and Planetary Science Letters, Vol. 453, s. 67-77Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite being one of Earth's major geochemical cycles, the evolution of the silicon cycle has received little attention and changes in oceanic dissolved silica (DSi) concentration through geologic time remain poorly constrained. Silicon isotope ratios (expressed as delta Si-30) in marine microfossils are becoming increasingly recognised for their ability to provide insight into silicon cycling. In particular, the delta Si-30 of siliceous sponge spicules has been demonstrated to be a useful proxy for past DSi concentrations. We analysed delta Si-30 in radiolarian tests and sponge spicules from the Blake Nose Palaeoceanographic Transect (ODP Leg 171B) spanning the Palaeocene-Eocene (ca. 60-30 Ma). Our delta Si-30 results range from +0.32 to +1.67 parts per thousand and -0.48 to +0.63 parts per thousand for the radiolarian and sponge records, respectively. Using an established relationship between ambient dissolved Si (DSi) concentrations and the magnitude of silicon isotope fractionation in siliceous sponges, we demonstrate that the Western North Atlantic was DSi deplete during the Palaeocene-Eocene throughout the water column, a conclusion that is robust to a range of assumptions and uncertainties. These data can constitute constraints on reconstructions of past-ocean circulation. Previous work has suggested ocean DSi concentrations were higher than modern ocean concentrations prior to the Cenozoic and has posited a drawdown during the Early Palaeogene due to the evolutionary expansion of diatoms. Our results challenge such an interpretation. We suggest here that if such a global decrease in oceanic DSi concentrations occurred, it must predate 60 Ma. (C) 2016 The Authors. Published by Elsevier B.V.

    Fulltekst (pdf)
    fulltext
  • 29. Fontorbe, Guillaume
    et al.
    Frings, Patrick J
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    De La Rocha, Christina
    Hendry, Kate
    Carstensen, Jacob
    Conley, Daniel
    Enrichment of dissolved silica in the deep equatorial Pacific during the Eocene-Oligocene2017Inngår i: Paleoceanography, ISSN 0883-8305, E-ISSN 1944-9186, Vol. 32, s. 848-863Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Silicon isotope ratios (expressed as δ30Si) in marine microfossils can provide insights into silica cycling over geologic time. Here we used δ30Si of sponge spicules and radiolarian tests from the Paleogene Equatorial Transect (Ocean Drilling Program Leg 199) spanning the Eocene and Oligocene (~50–23 Ma) to reconstruct dissolved silica (DSi) concentrations in deep waters and to examine upper ocean δ30Si. The δ30Si values range from 3.16 to +0.18‰ and from 0.07 to +1.42‰ for the sponge and radiolarian records, respectively. Both records show a transition toward lower δ30Si values around 37 Ma. The shift in radiolarian δ30Si is interpreted as a consequence of changes in the δ30Si of source DSi to the region. The decrease in sponge δ30Si is interpreted as a transition from low DSi concentrations to higher DSi concentrations, most likely related to the shift toward a solely Southern Ocean source of deep water in the Pacific during the Paleogene that has been suggested by results from paleoceanographic tracers such as neodymium and carbon isotopes. Sponge δ30Si provides relatively direct information about the nutrient content of deep water and is a useful complement to other tracers of deep water circulation in the oceans of the past. 

    Fulltekst (pdf)
    fulltext
  • 30.
    Forsström, Anna
    Naturhistoriska riksmuseet, Enheten för geovetenskap. Linköping University.
    Extraction and determination of Hf in water using a chelating resin and ICP-AES2014Student paper other, 10 hpOppgave
    Fulltekst (pdf)
    Projektrapport 2.0
  • 31.
    Frank, T.D.
    et al.
    Department of Earth and Atmospheric Sciences, University of Nebraska–Lincoln, 126 Bessey Hall, Lincoln, Nebraska 68588-0340, USA.
    Fielding, C.R.
    Department of Earth and Atmospheric Sciences, University of Nebraska–Lincoln, 126 Bessey Hall, Lincoln, Nebraska 68588-0340, USA.
    Winguth, A.M.E.
    Department of Earth and Environmental Sciences, University of Texas Arlington, 107 Geoscience Building, 500 Yates Street, Arlington, Texas 76019, USA.
    Savatic, K.
    Department of Earth and Atmospheric Sciences, University of Nebraska–Lincoln, 126 Bessey Hall, Lincoln, Nebraska 68588-0340, USA.
    Tevyaw, A.
    Department of Earth and Atmospheric Sciences, University of Nebraska–Lincoln, 126 Bessey Hall, Lincoln, Nebraska 68588-0340, USA.
    Winguth, C.
    Department of Earth and Environmental Sciences, University of Texas Arlington, 107 Geoscience Building, 500 Yates Street, Arlington, Texas 76019, USA.
    McLoughlin, Stephen
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Vajda, Vivi
    Naturhistoriska riksmuseet, Enheten för paleobiologi. Department of Geology, Lund University, Sweden.
    Mays, Chris
    Naturhistoriska riksmuseet, Enheten för paleobiologi. Department of Palaeobiology, Swedish Museum of Natural History, Box 50007, S-104 05 Stockholm, Sweden.
    Nicoll, R.
    72 Ellendon Street, Bungendore, NSW 2621, Australia.
    Bocking, M.
    Bocking Associates, 8 Tahlee Close, Castle Hill, NSW 2154, Australia.
    Crowley, J.L.
    Isotope Geology Laboratory, Boise State University, 1910 University Drive, Boise, Idaho 83725-1535, USA.
    Pace, magnitude, and nature of terrestrial climate change through the end-Permian extinction in southeastern Gondwana2021Inngår i: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 49, nr 9, s. 1089-1095Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rapid climate change was a major contributor to the end-Permian extinction (EPE). Although well constrained for the marine realm, relatively few records document the pace, nature, and magnitude of climate change across the EPE in terrestrial environments. We generated proxy records for chemical weathering and land surface temperature from continental margin deposits of the high-latitude southeastern margin of Gondwana. Regional climate simulations provide additional context. Results show that Glossopteris forest-mire ecosystems collapsed during a pulse of intense chemical weathering and peak warmth, which capped ∼1 m.y. of gradual warming and intensification of seasonality. Erosion resulting from loss of vegetation was short lived in the low-relief landscape. Earliest Triassic climate was∼10–14 °C warmer than the late Lopingian and landscapes were no longer persistently wet. Aridification, commonly linked to the EPE, developed gradually, facilitating the persistence of refugia for moisture-loving terrestrial groups.

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  • 32.
    Frings, Patrick J
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Revisiting the dissolution of biogenic Si in marine sediments: a key term in the ocean Si budget2017Inngår i: Acta Geochimica, ISSN 2096-0956, Vol. 36, nr 3, s. 429-432Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Of the ~240 × 1012 mol year−1 of biogenic silica (bSi) produced by diatoms and other silicifying organisms, only roughly 3%–4% escapes dissolution to be permanently buried. At the global scale, how, where and why bSi is preserved in sediment is not well understood. To help address this, I compile 6245 porewater dissolved Si concentrations from 453 sediment cores, to derive the concentration gradient at the sediment–water interface and thus diffusive fluxes out of the sediment. These range from <0.002 to 3.4 mol m−2 year−1, and are independent of temperature, depth and latitude. When classified by sediment lithology, predominantly siliceous sediments unsurprisingly have higher mean diffusive fluxes than predominantly calcareous or clay-rich sediment. Combined with the areal extent of these lithologies, the ‘best-guess’ global sedimentary bSi recycling flux is 69 × 1012 mol year−1.

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  • 33.
    Frings, Patrick J
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Clymans, Wim
    Conley, Daniel J.
    Amorphous Silica Transport in the Ganges Basin: Implications for Si Delivery to the Oceans2014Inngår i: Procedia Earth and Planetary Science, E-ISSN 1878-5220, Vol. 10, nr 0, s. 271-274Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rivers transport ∽6 x1012 mol yr-1 of dissolved Si (DSi) from the continents to the oceans. They also carry amorphous silica (ASi), solid phases likely to dissolve in seawater. Unfortunately, the magnitude of this flux is poorly constrained at a global scale. We present 92 new ASi values from suspended particulate matter (SPM) from the Ganges basin. Bulk SPM is ∽1.2% ASi, and mean ASi concentrations are ∽65 μM, of comparable magnitude to DSi concentrations. Our results also indicate a) ASi is not evenly distributed in the water column of large rivers, b) the ASi is not a wholly biogenic Si endmember and c) the ASi flux is, to a first order, a function of the SPM load. Our results suggest that the ASi particulate load is much greater than previously believed, rivaling that of the DSi load with important implications for the global Si cycle and oceanic Si isotopic budget.

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  • 34.
    Frings, Patrick J
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Clymans, Wim
    Jeppesen, Erik
    Lauridsen, Torben L
    Struyf, Eric
    Conley, Daniel J
    Lack of steady-state in the global biogeochemical Si cycle: emerging evidence from lake Si sequestration2014Inngår i: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 117, nr 2-3, s. 255-277Artikkel i tidsskrift (Fagfellevurdert)
    Fulltekst (pdf)
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  • 35.
    Frings, Patrick J
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    De La Rocha, Christina
    Struyf, Eric
    van Pelt, Dimitri
    Schoelynck, Jonas
    Hudson, Mike Murray
    Gondwe, Mangaliso J.
    Wolski, Piotr
    Mosimane, Keotsheple
    Gray, William
    Schaller, Jörg
    Conley, Daniel J.
    Tracing silicon cycling in the Okavango Delta, a sub-tropical flood-pulse wetland using silicon isotopes2014Inngår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 142, nr 0, s. 132-148Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Chemical weathering of silicate minerals releases elements into solution whereas the neoformation of secondary minerals works in the opposite direction, potentially confounding estimates of silicate weathering rates. Silicon isotopes (δ30Si) may be a useful tool to investigate these processes. Here, we present 82 δ30Si measurements from surface waters, pore waters, biogenic silica (BSi), clays, sand and vegetation from the Okavango Delta, Botswana, a freshwater sub-tropical, flood-pulse wetland. Hydrologically, the Okavango is dominated by evapotranspiration water losses to the atmosphere. It receives an annual pulse of water that inundates seasonal floodplains, while river baseflow is sufficient to maintain a permanent floodplain. δ30Si in dissolved silica (DSi) in surface waters along a 300 km transect at near-peak flood show a limited range (0.36–1.19‰), implying the Delta is well buffered by a balance of processes adding and removing DSi from the surface water. A key control on DSi concentrations is the uptake, production of BSi and recycling of Si by aquatic vegetation, although the net isotopic effect is necessarily small since all BSi re-dissolves on short timescales. In the sediments, BSi δ30Si (n = 30) ranges from −1.49‰ to +0.31‰ and during dissolution, residual BSi tends towards higher δ30Si. The data permit a field-based estimate of the fractionation associated with BSi dissolution, ε30BSi-DSi = −0.26‰, though it is unclear if this is an artefact of the process of dissolution. Clay δ30Si ranges from −0.97‰ to +0.10‰, (n = 15, mean = −0.31‰) and include the highest values yet published, which we speculate may be due to an equilibrium isotope effect during diagenetic transformation of BSi. Two key trends in surface water DSi δ30Si merit further examination: declining δ30Si in an area roughly corresponding to the permanent floodplains despite net DSi removal, and increasing δ30Si in the area corresponding to the seasonal floodplains. We infer that evaporative enrichment of surface waters creates two contrasting regimes. Chemical weathering of low δ30Si phases releases low δ30Si DSi in the relatively dilute waters of the permanent floodplains, whereas silicon removal via clay formation or vegetation uptake is the dominant process in the more enriched, seasonal floodplains.

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  • 36.
    Frings, Patrick J
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Fontorbe, G.
    Clymans, W.
    De La Rocha, C. L.
    Conley, D.J.
    The continental Si cycle and its impact on the ocean Si isotope budget2016Inngår i: Chemical Geology, Vol. 425, s. 12-36Artikkel i tidsskrift (Fagfellevurdert)
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  • 37. Gardiner, N J
    et al.
    Maidment, D W
    Kirkland, C L
    Bodorkos, S
    Smithies, R H
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Isotopic insight into the Proterozoic crustal evolution of the Rudall Province, Western Australia2018Inngår i: Precambrian Research, Vol. 313, s. 31-50Artikkel i tidsskrift (Fagfellevurdert)
  • 38. Gardiner, Nicholas J
    et al.
    Wacey, David
    Kirkland, Christopher L
    Johnson, Tim
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Zircon U–Pb, Lu–Hf and O isotopes from the 3414 Ma Strelley Pool Formation, East Pilbara Terrane, and the Palaeoarchaean emergence of a cryptic cratonic core2018Inngår i: Precambrian ResearchArtikkel i tidsskrift (Fagfellevurdert)
  • 39. Gillespie, Jack
    et al.
    Nemchin, Alexander A
    Kinny, Peter D
    Martin, Laure
    Aleshin, Matvei
    Roberts, Malcolm P
    Ireland, Trevor R
    Whitehouse, Martin J
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Cavosie, Aaron J
    Kirkland, Christopher L
    Strontium isotope analysis of apatite via SIMS2021Inngår i: Chemical Geology, Vol. 559, artikkel-id 119979Artikkel i tidsskrift (Fagfellevurdert)
  • 40. Grimm, Guido
    et al.
    Bouchal, Johannes M.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Denk, Thomas
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Potts, Alastair
    Fables and foibles: A critical analysis of the Palaeoflora database and the Coexistence Approach for palaeoclimate reconstruction2016Inngår i: Review of Palaeobotany and Palynology, ISSN 0034-6667, E-ISSN 1879-0615, Vol. 233, s. 216-235Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ‘Coexistence Approach’ is amutual climate range (MCR) technique combinedwith the nearest-living relative (NLR) concept. It has been widely used for palaeoclimate reconstructions based on Eurasian plant fossil assemblages; most of them palynofloras (studied using light microscopy). The results have been surprisingly uniform, typically converging to subtropical, per-humid or monsoonal conditions. Studies based on the Coexistence Approach have had a marked impact in literature, generating over 10,000 citations thus far. However, recent studies have pointed out inherent theoretical and practical problems entangled in the application of this widely used method. But so far little is known how results generated by the Coexistence Approach are affected by subjective errors, data errors, and violations of the basic assumptions. The majority of Coexistence Approach studies make use of the Palaeoflora database (the combination of which will be abbreviated to CA + PF). Testing results produced by CA + PF studies has been hindered by the general unavailability of the contents in the underlying Palaeoflora database; two exceptions are the mean-annual temperature tolerances and lists of assigned associations between fossils and nearest-living relatives. Using a recently published study on the Eocene of China,which provides the first and only insight into the data structure of the Palaeoflora database,we compare the theory and practice of Coexistence Approach using the Palaeoflora database (CA+PF).We show that CA+PF is riddled by association and climate data error.We reveal flaws in the application of the Coexistence Approach,which is often in stark contrast to the theory of the method. We show that CA + PF is highly vulnerable against numerous sources of errors, mainly because it lacks safeguards that could identify unreliable data. We demonstrate that the CA+PF produces coherent, pseudo-precise results even for artificially generated, randomplant assemblages. AlternativeMCR-NLR methods can surpass the most imminent deficits of the Coexistence Approach, and may be used as a stop-gap until more accurate bioclimatic and distribution data on potential Eurasian NLRs, and theoretically and statistically robust methods will become available. Finally, general guidelines are provided for the future application of methods using the mutual climatic range with nearest living relatives approach when reconstructing climate from plant fossil assemblages.

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  • 41. Grímsson, F.
    Meller, Barbara ()
    Bouchal, Johannes M. ()
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Grimm, Guido ()
    Combined LM and SEM study of the middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin, Austria: Part III. Magnoliophyta 1 – Magnoliales to Fabales2015Inngår i: Grana, ISSN 0017-3134, E-ISSN 1651-2049, Vol. 54, s. 85-128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Previous studies on the palynoflora from the Lavanttal Basin show that it contains a rich

    assemblage of spores and gymnosperm pollen. Present and ongoing investigations of

    dispersed angiosperm pollen suggest a high diversity within this group, and due to the

    excellent preservation of the material some rare pollen types are recognized. The Magnoliales

    to Fabales pollen record documented here contains 30 different taxa. Only a few pollen types

    are assigned to Magnoliids (four taxa); these are rare in the pollen record. Similarly, the

    Commelinids comprise five taxa and are also rare. Most of the angiosperm pollen originate

    from Eudicots, 21 taxa. Of the angiosperm taxa documented here, Magnolia , Carex ,

    Ranunculaceae, Platanus , Trochodendron , Buxus , Cercidiphyllum , Daphniphyllum ,

    Distylium , Fortunearia , Parrotia , Parthenocissus , Vitis , Euphorbia , Salix , and

    Papilionoideae are recorded for the first time from the Lavanttal Basin. This also includes the

    first fossil pollen record of Trochodendron  worldwide and the first reliable pollen record of

    Daphniphyllum . Several of the taxa described here had a wide Northern Hemispheric

    distribution from Eocene until the end of the Miocene. Also, key relatives of the fossil taxa

    are presently confined to humid warm-temperate environments, suggesting a very mild

    climate during the middle Miocene (Sarmatian) of the Lavanttal area. Some of the taxa

    encountered also support previous observations that the sediments of the Lavanttal Basin

    accumulated in a lowland wetland environment. This is based on pollen from aquatic taxa

    thriving in lakes, streams and swamps, and pollen of terrestrial plant taxa occupying margins

    of lakes and streams, backswamps, floodplains, river plains, and hummocks. Other 

     angiosperm pollen clearly originate from plants thriving on drier substrates, reflecting various

    vegetation units of the mixed evergreen/deciduous broad-leaved/conifer forests surrounding

    the wetland basin.

  • 42. Grímsson, F.
    Bouchal, Johannes M. ()
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Meller, Barbara ()
    Zetter, Reinhard ()
    Combined LM and SEM study of the middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin, Austria: part IV. Magnoliophyta 2 – Fagales to RosalesInngår i: Grana, ISSN 0017-3134, E-ISSN 1651-2049Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An ongoing investigation of the middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin continues to show that it contains an extremely rich assemblage of angiosperm taxa. The Fagales to Rosales pollen record documented here contains 34 different taxa belonging to the Betulaceae (Alnus, Betula, Carpinus, Corylus, Ostrya), Fagaceae (Castanea, Fagus, Quercus Groups Cerris, Ilex, Cyclobalanopsis, Quercus/Lobatae), Juglandaceae (Engelhardioideae, Carya, Juglans, Pterocarya), Myricaceae (Morrella vel Myrica), Cannabaceae (Celtis), Elaeagnaceae (Elaeagnus), Rhamnaceae, Rosaceae (Prunus) and Ulmaceae (Cedrelospermum, Ulmus, Zelkova). Two of the pollen types represent extinct genera, Trigonobalanopsis and Cedrelospermum, and are also reported for the first time from the Lavanttal Basin along with pollen of Rhamnaceae and Prunus. The different types of Quercus pollen are now affiliated with Groups Cerris, Cyclobalanopsis, Ilex and Quercus/Lobatae based on sculpturing elements observed using scanning electron microscopy (SEM). Köppen signatures of potential modern analogues of the fossil Fagales and Rosales suggest a subtropical (Cfa, Cwa) climate at lower elevation and subsequent subtropical to temperate climate with altitudinal succession (Cfa→Cfb/Dfa→Dfb; Cwa→Cwb→Dwb) in the Lavanttal area during accumulation of the palynoflora. Most of the fossil taxa have potential modern analogues that can be grouped as nemoral and/or merido-nemoral vegetation elements, and the diversity of Fagales indicates a varying landscape with a high variety of niches.

  • 43. Grímsson, F.
    et al.
    Bouchal, Johannes M.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Grimm, Guido
    Zetter, Reinhard
    Evaluating the mid Miocene paleoclimate of Lower Carinthia (Austria) based on high resolution palynological studies from the Lavanttal Basin2016Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Köppen signatures (Denk et al. 2013, Grímsson et al. 2015) can be used to generalize the climatic niche occupied by potential modern analogues (PMA) of fossil plants (here: palynological) assemblages. The Köppen climate system distinguishes climate zones by certain abiotic parameters or combinations thereof and represents them in a three letter code referring to the general climate types (first letter), the seasonal distribution of precipitation (second letter) and the seasonal distribution or general level of warmth (third letter). Based on their Köppen signatures PMAs can be categorized as arctic-alpine, boreal, nemoral, meridio-nemoral, tropical-meridional, tropical, eurytropical, and/or semihumid meridional vegetation elements (see also Denk et al. 2013, Velitzelos et al. 2014, Grímsson et al. 2015). Based on the climatic preferences of their PMAs, the Fagales and Rosales lineages present at the Lavanttal site rule out tropical (A-)climates and climates with pronounced (summer) draught (B-, Cs-, Ds-climates). The same holds for boreal/subarctic climates with short but humid summers (Cfc, Dfc, Dfd, Dwc). The Fagales are represented by 23 lineages at the Lavanttal site including genera that are today composed (predominately or exclusively) of nemoral and meridio-nemoral elements. This points to climate conditions not unlike those found today in the lowlands and adjacent mountain regions of the (south-)eastern United States, the humid-meridional region of western Eurasia (e.g. northern Italy, Black Sea region, western Caucasus), central and southern China, or Honshu (Japan). These regions are characterised by subtropical conditions at lower elevations (Cfa-, Cwa-climates) and subsequent altitudinal successions: Cfa! Cfb/Dfa! Dfb in eastern United States, western Eurasia, central China and Japan, or Cwa! Cwb! Dwb in southern China. The climax vegetation in these areas are mixed mesophytic forests and various mixed evergreen/deciduous broad-leaved forests, characteristic for the humid and semi-humid, summer-rain areas of the meridional and nemoral zone. (Co-)Dominant genera in these forests are the various members of the northern hemispheric Fagales. Important indicator taxa include Fagus , one of the most common and widespread genera in temperate, mixed mesophytic forests of North America, China and Japan, and Quercus Group Ilex, a co-dominant group in the East Asian monsoon influenced, winter-dry or fully humid southern foothills of the Himalayas and montane regions of south-western and central China. Equally informative is Corylus, and the co-occurrence of Carya , Juglans , Pterocarya  and Engelhardioideae, pinpointing towards forests as today found in south-western China and the warm subtropical parts of the southeastern United States.

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  • 44.
    Güner, Tuncay H.
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi. Faculty of Forestry, Department of Forest Botany, Istanbul University Cerrahpa¸sa, 34473 Bahçeköy, Istanbul, Turkey.
    Bouchal, Johannes M.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Köse, Nesibe
    University of Istanbul, Faculty of Forestry, Department of Forest Botany, Istanbul, Turkey.
    Göktaş, Fikret
    Mayda, Serdar
    Denk, Thomas
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Landscape heterogeneity in the Yatağan Basin (southwestern Turkey) during the middle Miocene inferred from plant macro fossils2017Inngår i: Palaeontographica. Abteilung B, Palaophytologie, ISSN 0375-0299, Vol. 296, s. 113-171Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Plant macro fossils from the lignite mines of Eskihisar, Tınaz, and Salihpaşalar (Yatağan Basin, southwestern Anatolia) were investigated. The fossils were collected from marls overlying the exploited lignite seams and represent three subbasins within the main Yatağan Basin. The age of the Eskihisar lignite seam is well constrained by vertebrate fossils (MN 6, middle Miocene). Further, lithological and palynological correlation suggests that the lignite seams and overlying marls in the three lignite mines were formed at the same time. Three distinct zonal vegetation types are reflected in the local plant assemblages: (i) In Eskihisar, Fagus and evergreen Quercus mediterranea-Q. sosnowskyi communities formed important parts of the zonal vegetation along with the deciduous Quercus kubinyii; (ii) in Tınaz, Quercus sosnowskyi-Q. mediterranea-Q. drymeja communities occurred, while Fagus is rarely encountered in the macrofossil record. (iii) In Salihpaşalar, Quercus mediterranea and Q. drymeja are the most abundant elements, while Fagus and Q. sosnowskyi are absent or nearly so. This demonstrates that local environmental conditions within a geographically restricted region varied and probably were controlled by slope aspects, edaphic conditions, and river drainage. Overall, the zonal vegetation is characterized by a high diversity of evergreen and deciduous oaks belonging to Quercus subgen. Cerris sect. Ilex and sect, Cerris and the local dominance of Fagus. The riparian vegetation was dominated by Populus, Salix and Acer, whereas Alnus and taxodiaceous Cupressaceae and ferns were very rare or absent. The mass occurrence of Quercus sosnowskyi in the Yatağan Basin floras is biogeographically interesting, as this distinct sclerophyllous oak has previously been known to occur only in late Miocene sediments of northern Greece and Abkhasia (Georgia). 

  • 45. Hammerli, Johannes
    et al.
    Kemp, Anthony IS
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    An Archean Yellowstone?: Evidence from extremely low δ18O in zircons preserved in granulites of the Yilgarn Craton, Western Australia2018Inngår i: Geology, Vol. 46, nr 5, s. 411-414Artikkel i tidsskrift (Fagfellevurdert)
  • 46. Harrison, John A.
    et al.
    Frings, Patrick J
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Beusen, Arthur H. W.
    Conley, Daniel J.
    McCrackin, Michelle L.
    Global importance, patterns, and controls of dissolved silica retention in lakes and reservoirs2012Inngår i: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 26, nr 2, s. n/a-n/aArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lentic water bodies (lakes and reservoirs) offer favorable conditions for silica (SiO2) burial in sediments. Recent global estimates suggest that (1) lentic SiO2 trapping is a globally important SiO2 flux, and (2) through reservoir construction, humans have dramatically altered river dissolved SiO2 (DSi) transport and coastal DSi delivery. However, regional to global scale patterns and controls of DSi removal in lentic systems are poorly constrained. Here we use 27 published lake and reservoir DSi budgets to develop insights into patterns and controls of lentic DSi retention and to develop a new, spatially explicit, global model of lentic DSi removal called SiRReLa (Silica Retention in Reservoirs and Lakes). In our analysis, lentic DSi removal (kg SiO2 yr−1) was significantly and positively related to DSi loading (P < 0.0001; r2 = 0.98), and DSi removal efficiency was significantly and positively related to water residence time (P < 0.0001; r2 = 0.68). In addition, DSi settling rates were, on average, 6.5-fold higher in eutrophic systems than in non-eutrophic systems (median settling velocities: 11.1 and 1.7 m yr−1 for eutrophic and non-eutrophic systems, respectively; P < 0.01). SiRReLa, which incorporates these insights, performed quite well in predicting both total DSi removal (kg SiO2 yr−1; Nash Sutcliffe Efficiency (N.S.E) = 0.88) and DSi removal efficiency (% Si removed; N.S.E. = 0.75), with no detectable bias in the model. Global application of SiRReLa confirms that lentic systems are important sinks for DSi, removing 89.1 Tg DSi yr−1 from watersheds globally, roughly 19–38% of all DSi inputs to surface waters. Small lakes and reservoirs (<50 km2) were critical in the analysis, retaining 81% (72 Tg DSi yr−1) of the globally retained total. Furthermore, although reservoirs occupy just 6% of the global lentic surface area, they retained approximately 35% of the total DSi removed by lentic systems. Regional hot spots for lentic DSi removal were identified and imply that lentic systems can remove the vast majority of DSi across a large fraction of Earth's land surface. Finally, a sensitivity analysis indicates that future improvements in DSi trapping and transport models should focus on improving estimates of DSi input to surface waters.

  • 47. He, Wenyan
    et al.
    Yang, Liqiang
    Lu, Yongjun
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Xie, Shixiong
    Gao, Xue
    Zircon U–Pb dating, geochemistry and Sr–Nd–Hf–O isotopes for the Baimaxueshan granodiorites and mafic microgranulars enclaves in the Sanjiang Orogen: Evidence for westward subduction of Paleo-Tethys2018Inngår i: Gondwana ResearchArtikkel i tidsskrift (Fagfellevurdert)
  • 48. Hirst, Catherine
    et al.
    Andersson, Per S.
    Mörth, Carl-Magnus
    Murphy, Melissa J.
    Schmitt, Melanie
    Kooijman, Ellen
    Naturhistoriska riksmuseet, Enheten för geovetenskap. Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden.
    Kutscher, Liselott
    Petrov, Roman
    Maximov, Trofim
    Porcelli, Don
    Iron isotopes reveal seasonal variations in the mechanisms for iron-bearing particle and colloid formation in the Lena River catchment, NE Siberia2023Inngår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 363, s. 77-93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Large Arctic rivers are an important source of iron (Fe) to the Arctic Ocean, though seasonal variations in the terrestrial source and supply of Fe to the ocean are unknown. To constrain the seasonal variability, we present Fe concentrations and isotopic compositions (δ56Fe) for particulate (>0.22 µm) and colloidal (<0.22 µm–1 kDa) Fe from the Lena River, NE Russia. Samples were collected every month during winter baseflow (September 2012–March 2013) and every 2–3 days before, during and after river ice break-up (May 2015).

    Iron in particles have isotope ratios lower than crustal values during winter (e.g., δ56FePart = −0.37 ± 0.16‰), and crustal-like values during river ice break-up and spring flood (e.g., δ56FePart = 0.07 ± 0.08‰), indicating a change in the source of particulate Fe between winter and spring flood. Low isotope values are indicative of mineral dissolution, transport of reduced Fe in sub-oxic, ice-covered sub-permafrost groundwaters and near-quantitative precipitation of Fe as particles. Crustal-like isotopic compositions result from the increased supply of detrital particles from riverbank and soil erosion during river ice break-up and flooding. Iron colloids (<0.22 μm) have δ56Fe values that are comparable to or lower than crustal values during winter (e.g., δ56FeCol = −0.08 ± 0.05‰) but similar to or higher than crustal values during spring flood (e.g., δ56FeCol = +0.24 ± 0.11‰). Low δ56Fe ratios for colloidal Fe during winter are consistent with precipitation from isotopically light Fe(II)aq transported in sub-permafrost groundwaters. Higher colloidal δ56Fe ratios during the spring flood indicate that these colloids are supplied from surface soils, where Fe is fractionated via oxidation or organic carbon complexation, similar to during summer. Approximately half of the annual colloidal Fe flux occurs during spring flood while most of the remaining colloidal Fe is supplied during summer months. The total amount of colloidal Fe transported during winter was relatively low. The seasonal variation in colloidal Fe isotope values may be a useful tool to trace the source of colloidal Fe to the Arctic Ocean and monitor future changes in the sources and supply of Fe from the permafrost landscape to the Lena River basin.

  • 49.
    Holtstam, Dan
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Söderhielm, Johan
    Sveriges Geologiska Undersökning.
    An 18th century find of an erratic lazulite-andalusite-quartz boulder in Södermanland, Sweden, and its implications2019Inngår i: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 141, nr 3, s. 216-221Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    At some point in the 1750s, a jeweller-apprentice by the name Jacob Hässelgren found an erratic bouldernext to the Eskilstuna country road in the neighbourhood of Ärla in Södermanland. It contained a deep bluemass of lazulite, at the time an unknown mineral. Pieces of the find eventually reached Daniel Tilas, TorbernBergman and Axel Fredrik Cronstedt ˗ renowned natural scientists in Sweden ˗ but no detailed studies of thematerial seem to have been carried out by them. Two fragments of the original boulder are still preserved,and a recent examination shows them to consist of mainly lazulite, andalusite, quartz, pyrophyllite, augeliteand svanbergite. The average composition of lazulite is Mg0.700Fe2+0.261Mn0.003Al1.954Fe3+0.017 P2.031O8(OH)2.The mineral assemblage is characteristic of known occurrences of phosphate-Al silicate-quartz appearingalong the Protogine Zone in southern Sweden. Transportation of the boulder from its source rock, likely tobe located somewhere along the Protogine Zone, ought to have occurred in connection with the developmentof the Fennoscandian ice sheet during the final Weichselian deglaciation, and the material waspossibly discharged from floating ice on the Yoldia Sea.

  • 50.
    Hutchinson, David K.
    et al.
    Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University.
    Coxall, Helen K.
    Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University.
    Lunt, Daniel J.
    School of Geographical Sciences, University of Bristol.
    Steinthorsdottir, Margret
    Naturhistoriska riksmuseet, Enheten för paleobiologi. Bolin Centre for Climate Research, Stockholm University.
    de Boer, Agatha M.
    Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University.
    Baatsen, Michiel
    Institute for Marine and Atmospheric Research, Department of Physics, Utrecht University.
    von der Heydt, Anna
    Institute for Marine and Atmospheric Research, Department of Physics, Utrecht University.
    Huber, Matthew
    Department of Earth, Atmospheric, and Planetary Sciences, Purdue University.
    Kennedy-Asser, Alan T.
    School of Geographical Sciences, University of Bristol.
    Kunzmann, Lutz
    Senckenberg Natural History Collections Dresden.
    Ladant, Jean-Baptiste
    Department of Earth and Environmental Sciences, University of Michigan.
    Lear, Caroline H.
    School of Earth and Ocean Sciences, Cardiff University.
    Moraweck, Karolin
    Senckenberg Natural History Collections Dresden.
    Pearson, Paul N.
    School of Earth and Ocean Sciences, Cardiff University.
    Piga, Emanuela
    School of Earth and Ocean Sciences, Cardiff University.
    Pound, Matthew J.
    Department of Geography and Environmental Sciences, Northumbria University.
    Salzmann, Ulrich
    Department of Geography and Environmental Sciences, Northumbria University.
    Scher, Howie D.
    School of the Earth, Ocean and Environment, University of South Carolina.
    Sijp, Willem P.
    Climate Change Research Centre, University of New South Wales.
    Śliwińska, Kasia K.
    Department of Stratigraphy, Geological Survey of Denmark and Greenland.
    Wilson, Paul A.
    University of Southampton, National Oceanography Centre Southampton.
    Zhang, Zhongshi
    Department of Atmospheric Science, China University of Geoscience, Wuhan.
    The Eocene-Oligocene transition: a review of marine and terrestrial proxy data, models and model-data comparisons2021Inngår i: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 17, nr 1, s. 269-315Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Eocene–Oligocene transition (EOT) was a climate shift from a largely ice-free greenhouse world to an icehouse climate, involving the first major glaciation of Antarctica and global cooling occurring ∼ 34 million years ago (Ma) and lasting ∼ 790 kyr. The change is marked by a global shift in deep-sea δ18O representing a combination of deep-ocean cooling and growth in land ice volume. At the same time, multiple independent proxies for ocean tempera- ture indicate sea surface cooling, and major changes in global fauna and flora record a shift toward more cold-climate- adapted species. The two principal suggested explanations of this transition are a decline in atmospheric CO2 and changes to ocean gateways, while orbital forcing likely influenced the precise timing of the glaciation. Here we review and synthesise proxy evidence of palaeogeography, temperature, ice sheets, ocean circulation and CO2 change from the marine and terrestrial realms. Furthermore, we quantitatively com- pare proxy records of change to an ensemble of climate model simulations of temperature change across the EOT. The simulations compare three forcing mechanisms across the EOT: CO2 decrease, palaeogeographic changes and ice sheet growth. Our model ensemble results demonstrate the need for a global cooling mechanism beyond the imposition of an ice sheet or palaeogeographic changes. We find that CO2 forcing involving a large decrease in CO2 of ca. 40 % (∼ 325 ppm drop) provides the best fit to the available proxy evidence, with ice sheet and palaeogeographic changes play- ing a secondary role. While this large decrease is consistent with some CO2 proxy records (the extreme endmember of decrease), the positive feedback mechanisms on ice growth are so strong that a modest CO2 decrease beyond a critical threshold for ice sheet initiation is well capable of triggering rapid ice sheet growth. Thus, the amplitude of CO2 decrease signalled by our data–model comparison should be consid- ered an upper estimate and perhaps artificially large, not least because the current generation of climate models do not in- clude dynamic ice sheets and in some cases may be under- sensitive to CO2 forcing. The model ensemble also cannot exclude the possibility that palaeogeographic changes could have triggered a reduction in CO2.

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