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  • 1. A. Marques, Ana F.
    et al.
    Roerdink, Desiree L.
    Baumberger, Tamara
    de Ronde, Cornel E. J.
    Ditchburn, Robert G.
    Denny, Alden
    Thorseth, Ingunn H.
    Okland, Ingeborg
    Lilley, Marvin D.
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Pedersen, Rolf B.
    The Seven Sisters Hydrothermal System: First Record of Shallow Hybrid Mineralization Hosted in Mafic Volcaniclasts on the Arctic Mid-Ocean Ridge2020Annet (Annet vitenskapelig)
    Abstract [en]

    We document the discovery of an active, shallow, seafloor hydrothermal system (known as the Seven Sisters Vent Field) hosted in mafic volcaniclasts at a mid-ocean ridge setting. The vent field is located at the southern part of the Arctic mid-ocean ridge where it lies on top of a flat-topped volcano at ~130 m depth. Up to 200 deg C phase-separating fluids vent from summit depressions in the volcano, and from pinnacle-like edifices on top of large hydrothermal mounds. The hydrothermal mineralization at Seven Sisters manifests as a replacement of mafic volcaniclasts, as direct intraclast precipitation from the hydrothermal fluid, and as elemental sulfur deposition within orifices. Barite is ubiquitous, and is sequentially replaced by pyrite, which is the first sulfide to form, followed by Zn-Cu-Pb-Ag bearing sulfides, sulfosalts, and silica. The mineralized rocks at Seven Sisters contain highly anomalous concentrations of ‘epithermal suite’ elements such as Tl, As, Sb and Hg, with secondary alteration assemblages including silica and dickite. Vent fluids have a pH of ~5 and are Ba and metal depleted. Relatively high dissolved Si (~7.6 mmol/L Si) combined with low (0.2–0.4) Fe/Mn suggest high-temperature reactions at ~150 bar. A delta-13C value of -5.4 permil in CO2 dominated fluids denotes magmatic degassing from a relatively undegassed reservoir. Furthermore, low CH4 and H2 (<0.026 mmol/kg and <0.009 mmol/kg, respectively) and 3He/4He of ~8.3 R/Racorr support a MORB-like, sediment-free fluid signature from an upper mantle source. Sulfide and secondary alteration mineralogy, fluid and gas chemistry, as well as delta-34S and 87Sr/86Sr values in barite and pyrite indicate that mineralization at Seven Sisters is sustained by the input of magmatic fluids with minimal seawater contribution. 226Ra/Ba radiometric dating of the barite suggests that this hydrothermal system has been active for at least 4670 +/- 60 yr.

  • 2. Abu El-Enen, M.M.
    et al.
    Abu-Alam, T.S.
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Ali, K.A.
    Okrusch, M.
    P–T path and timing of crustal thickening during amalgamation of East and West Gondwana: A case study from the Hafafit Metamorphic Complex, Eastern Desert of Egypt.2016Inngår i: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 263, s. 213-238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The southeastern sector of the Hafafit Metamorphic Complex, southern Eastern Desert of Egypt comprises infrastructural orthogneisses of tonalite and syenogranite parentage, amphibolites, and a volcano-sedimentary association. These are overthrust by an obducted suprastructural ophiolite nappes via the Nugrus thrust. The protolith of the biotite–hornblende-gneisses was formed during island-arc accretion, while that of the garnet–biotite gneisses were formed in a within-plate regime, consistent with a transition to a post-collisional setting. The volcano-sedimentary association comprises interbedded and intercalated highly foliated metapelitic schists, metabasites, and leucocratic gneisses, deposited in a back-arc basin. The metapelites and the leucocratic gneisses originated from immature Fe-shales and arkoses derived from intermediate-mafic and acidic igneous rocks, respectively, via weak chemical weathering in a tectonically active island arc terrane. The intercalated amphibolites were derived from tholeiitic basalts generated in a back-arc setting.

    The volcano-sedimentary association was metamorphosed under upper-amphibolite facies conditions with pressures of 9–13 kbar and temperatures of 570–675 °C, as derived from conventional geothermobarometry and pseudosection calculation. A steep, tight clockwise P–T path is constrained and a geothermal gradient around 20 °C/km is estimated for the peak metamorphism. We assume that deformation and metamorphism are due to crustal thickening during the collision of East and West Gondwana, where peak metamorphism took place in the middle to lower crust at 33 km average crustal depth. This was followed by a subsequent quasi-isothermal decompression due to rapid exhumation during wrench tectonics. Sinistral transcurrent shearing with extensional denudation resulted in vertical ductile thinning that was accompanied by heat input from magmatism, as indicated by a higher geothermal gradient during retrograde metamorphism and exhumation of the complex.

    U–Pb data from magmatic zircons yields protolith ages of 731 ± 3 Ma for the biotite–hornblende gneisses and 646 ± 12 Ma for the garnet–biotite gneisses. Conforming to field evidence, our geochronology data point to a depositional age of the volcano-sedimentary cover at around 650 Ma. The age of metamorphism is constrained by a low Th/U ratio of a zircon grain crystallized at an age of 597 ± 6 Ma.

  • 3. Adam, B.
    et al.
    Klawonn, I.
    Svedén, J.
    Bergkvist, J.
    Nahar, N.
    Walve, J.
    Littmann, S.
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Lavik, G.
    Kuypers, M.M.M.
    Ploug, H.
    N2-fixation, ammonium release, and N-transfer to the microbial and classical food web within a plankton community.2016Inngår i: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 19, s. 450-459Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigated the role of N2-fixation by the colony-forming cyanobacterium, Aphanizomenon spp., for the plankton community and N-budget of the N-limited Baltic Sea during summer by using stable isotope tracers combined with novel secondary ion mass spectrometry, conventional mass spectrometry and nutrient analysis. When incubated with 15N2, Aphanizomenon spp. showed a strong 15N-enrichment implying substantial 15N2-fixation. Intriguingly, Aphanizomenon did not assimilate tracers of 15NH4+ from the surrounding water. These findings are in line with model calculations that confirmed a negligible N-source by diffusion-limited NH4+ fluxes to Aphanizomenon colonies at low bulk concentrations (<250 nm) as compared with N2-fixation within colonies. No N2-fixation was detected in autotrophic microorganisms <5 μm, which relied on NH4+ uptake from the surrounding water. Aphanizomenon released about 50% of its newly fixed N2 as NH4+. However, NH4+ did not accumulate in the water but was transferred to heterotrophic and autotrophic microorganisms as well as to diatoms (Chaetoceros sp.) and copepods with a turnover time of ~5 h. We provide direct quantitative evidence that colony-forming Aphanizomenon releases about half of its recently fixed N2 as NH4+, which is transferred to the prokaryotic and eukaryotic plankton forming the basis of the food web in the plankton community. Transfer of newly fixed nitrogen to diatoms and copepods furthermore implies a fast export to shallow sediments via fast-sinking fecal pellets and aggregates. Hence, N2-fixing colony-forming cyanobacteria can have profound impact on ecosystem productivity and biogeochemical processes at shorter time scales (hours to days) than previously thought.

  • 4.
    Adediran, Gbotemi A.
    et al.
    Department of Soil and Environment Swedish University of Agricultural Sciences Uppsala Sweden;UK Centre for Ecology and Hydrology Wallingford United Kingdom.
    Kielman-Schmitt, Melanie
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Kooijman, Ellen
    Naturhistoriska riksmuseet, Enheten för geovetenskap. Department of Geosciences Swedish Museum of Natural History Stockholm Sweden.
    Gustafsson, Jon‐Petter
    Department of Soil and Environment Swedish University of Agricultural Sciences Uppsala Sweden.
    Significance of phosphorus inclusions and discrete micron‐sized grains of apatite in postglacial forest soils2022Inngår i: European Journal of Soil Science, ISSN 1351-0754, E-ISSN 1365-2389, Vol. 73, nr 5, artikkel-id e13310Artikkel i tidsskrift (Fagfellevurdert)
  • 5. 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)
  • 6.
    Alexander, Louise
    et al.
    Birkbeck College, University of London, United Kingdom.
    Snape, Joshua
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Joy, Katherine
    University of Manchester, United Kingdom.
    Downes, Hilary
    Birkbeck College, University of London, United Kingdom.
    Crawford, Ian
    Birkbeck College, University of London, United Kingdom.
    An analysis of Apollo lunar soil samples 12070,889, 12030,187, and 12070,891: Basaltic diversity at the Apollo 12 landing site and implications for classification of small-sized lunar samples2016Inngår i: Meteoritics and Planetary Science, ISSN 1086-9379, E-ISSN 1945-5100, Vol. 51, s. 1654-1677Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lunar mare basalts provide insights into the compositional diversity of the Moon's interior. Basalt fragments from the lunar regolith can potentially sample lava flows from regions of the Moon not previously visited, thus, increasing our understanding of lunar geological evolution. As part of a study of basaltic diversity at the Apollo 12 landing site, detailed petrological and geochemical data are provided here for 13 basaltic chips. In addition to bulk chemistry, we have analyzed the major, minor, and trace element chemistry of mineral phases which highlight differences between basalt groups. Where samples contain olivine, the equilibrium parent melt magnesium number (Mg#; atomic Mg/[Mg + Fe]) can be calculated to estimate parent melt composition. Ilmenite and plagioclase chemistry can also determine differences between basalt groups. We conclude that samples of approximately 1–2 mm in size can be categorized provided that appropriate mineral phases (olivine, plagioclase, and ilmenite) are present. Where samples are fine-grained (grain size <0.3 mm), a “paired samples t-test” can provide a statistical comparison between a particular sample and known lunar basalts. Of the fragments analyzed here, three are found to belong to each of the previously identified olivine and ilmenite basalt suites, four to the pigeonite basalt suite, one is an olivine cumulate, and two could not be categorized because of their coarse grain sizes and lack of appropriate mineral phases. Our approach introduces methods that can be used to investigate small sample sizes (i.e., fines) from future sample return missions to investigate lava flow diversity and petrological significance.

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  • 7.
    Ali, Imran
    et al.
    Stockholms universitet.
    Kremer, Reinhard K.
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Johnsson, Mats
    Synthesis and Magnetic Properties of the Ternary OxofluorideFe3Sb4O6F62020Inngår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, s. 3746-3752Artikkel i tidsskrift (Fagfellevurdert)
  • 8. Ali, K.A.
    et al.
    Surour, A.A:
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Andresen, A.
    Single zircon Hf-O isotope constraints on the origin of A-type granites from the Jabal Al-Hassir ring complex, Saudi Arabia.2015Inngår i: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 256, s. 131-147Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Jabal Al-Hassir ring complex in the southern Arabian Shield is an alkaline granite complex comprising an inner core of biotite granite that outwardly becomes a porphyritic sodic-calcic amphibole (ferrobarroisite–katophorite) granite. A combined study of mineral chemistry and single zircon Hf–O zircon isotope analyses was carried out to infer the magma sources of the Neoproterozoic post-collisional A-type granitoids in Saudi Arabia. The granitic rocks show high positive initial ɛHf(t) values of +7.0 to +10.3 and δ18O values of +5.8‰ to +7.4‰ that are consistent with melting of a juvenile crustal protolith that was formed during the Neoproterozoic assembly of the Arabian-Nubian Shield (ANS). Crustal-model ages (Hf-tNC) of 0.71–0.94 Ga indicate minor contribution from an older continental crust in the formation of the Jabal Al-Hassir granitic rocks (crystallization age = 620 ±3 Ma), but any such component is likely to be Neoproterozoic in age. Temperature and oxygen fugacity (ƒO2) estimates suggested that the Jabal Al-Hassir A-type granite magma was generated at high temperature (820–1050 °C) and low ƒO2. Geochemical characteristics (e.g., low ƒO2), geochronological data, and Hf and O isotope compositions, indicate that the magmas of the Neoproterozoic A-type granites of the Jabal Al-Hassir ring complex were likely generated by crustal partial melting of a juvenile Neoproterozoic lower crustal tholeiitic rocks, following collision between East and West Gondwana in the final stages of the evolution of the Arabian Shield.

  • 9. 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)
  • 10. Al-Khirbash, Salah
    et al.
    Heikal, Mohamed Th. S.
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Windley, Brian F.
    Al Selwi, Khaled
    Evolution and Mineralization of the Precambrian Basement of Yemen2021Inngår i: The Geology of the Arabian-Nubian Shield, Regional Geology Reviews / [ed] Z. Hamimi et al. (eds.), Springer, 2021Kapittel i bok, del av antologi (Fagfellevurdert)
  • 11.
    Allard, Bert
    et al.
    Man-Technology-Environment Research Centre (MTM), Örebro University, SE-701 82 Örebro, Sweden.
    Sjöberg, Susanne
    Department of Geological Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
    Sjöberg, Viktor
    Man-Technology-Environment Research Centre (MTM), Örebro University, SE-701 82 Örebro, Sweden.
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap. Department of Geosciences, Swedish Museum of Natural History, SE-114 18 Stockholm, Sweden.
    Karlsson, Stefan
    Man-Technology-Environment Research Centre (MTM), Örebro University, SE-701 82 Örebro, Sweden.
    Metal Exchangeability in the REE-Enriched Biogenic Mn Oxide Birnessite from Ytterby, Sweden2023Inngår i: Minerals, E-ISSN 2075-163X, Vol. 13, s. 1-14, artikkel-id 1023Artikkel i tidsskrift (Fagfellevurdert)
  • 12.
    Altieri, Alessandra
    et al.
    Sapienza University, Rome, Italy.
    Luppi, Riccardo
    Sapienza University, Rome, Italy.
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Hålenius, Ulf
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Tempesta, Gioacchino
    Università degli Studi di Bari Aldo Moro, Bari, Italy.
    Pezzotta, Federico
    MUM–Mineralogical Museum “Luigi Celleri”,Campo nell’Elba, Leghorn, Italy.
    Bosi, Ferdinando
    Sapienza University, Rome, Italy.
    Thermal treatment of the tourmaline Fe-rich princivalleite Na(Mn2Al)Al6(Si6O18)(BO3)3(OH)3O2023Inngår i: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 50, nr 4, s. 1-12, artikkel-id 27Artikkel i tidsskrift (Fagfellevurdert)
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  • 13. Altieri, Alessandra
    et al.
    Pezzotta, Federico
    Andreozzi, Giovanni B.
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Bosi, Ferdinando
    Genetic model for the color anomalies at the termination of pegmatitic gem tourmaline crystals from the island of Elba, Italy2023Inngår i: European journal of mineralogy, ISSN 0935-1221, E-ISSN 1617-4011, Vol. 35, nr 5, s. 755-771Artikkel i tidsskrift (Fagfellevurdert)
  • 14. Altieri, Alessandra
    et al.
    Pezzotta, Federico
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Hålenius, Ulf
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Bosi, Ferdinando
    Blue growth zones caused by Fe2+ in tourmaline crystals from the San Piero in Campo gem-bearing pegmatites, Elba Island, Italy2022Inngår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 86, nr 6, s. 910-919Artikkel i tidsskrift (Fagfellevurdert)
  • 15. Altieri, Alessandra
    et al.
    Pezzotta, Federico
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Hålenius, Ulf
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Bosi, Ferdinando
    Dark-coloured Mn-rich overgrowths in an elbaitic tourmaline crystal from the Rosina pegmatite, San Piero in Campo, Elba Island, Italy: witness of late-stage opening of the geochemical system2023Inngår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 87, nr 1, s. 130-142Artikkel i tidsskrift (Fagfellevurdert)
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  • 16. 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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  • 17. Anand, Rajagopal
    et al.
    Balakrishnan, Srinivasan
    Kooijman, Ellen
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Mezger, Klaus
    Neoarchean crustal growth by accretionary processes: Evidence from combined zircon–titanite U–Pb isotope studies on granitoid rocks around the Hutti greenstone belt, eastern Dharwar Craton, India2014Inngår i: Journal of Asian Earth Sciences, ISSN 1367-9120, E-ISSN 1878-5786, Vol. 79, s. 72-85Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Neoarchean Hutti greenstone belt hosts mesothermal gold deposits and is surrounded by granitoid rocks on all sides. Combined U–Pb dating of zircon and titanite from the granitoid rocks constrains their emplacement history and subsequent geologic evolution. The Golapalli and Yelagatti granodiorites occurring to the north of the Hutti greenstone belt were emplaced at 2569 ± 17 Ma. The Yelagatti granodiorite yielded a younger titanite age of 2530 ± 6 Ma which indicates that it was affected by a post-crystallization thermal event that exceeded the titanite closure temperature. The western granodiorites from Kardikal have identical titanite and zircon ages of 2557 ± 6 Ma and 2559 ± 19 Ma, respectively. The eastern Kavital granodiorites yielded titanite ages of 2547 ± 6 Ma and 2544 ± 24 Ma which are identical to the published U–Pb zircon SHRIMP ages. These ages imply that the granitoid rocks surrounding the Hutti greenstone belt were formed as discrete batholiths within a short span of ca. 40 Ma between 2570 Ma and 2530 Ma ago. They were juxtaposed by horizontal tectonic forces against the supracrustal rocks that had formed in oceanic settings at the end of the Archean. The first phase of gold mineralization coincided with the last phase of granodiorite intrusion in the Hutti area. A metamorphic overprint occurred at ca. 2300 Ma ago that reset the Rb–Sr isotope system in biotites and possibly caused hydrothermal activity and enrichment of Au in the ore lodes. The eastern Dharwar Craton consists of quartz monzodiorite–granodiorite–granite suites of rocks that are younger than the greenstone belts that are older than ~2650 Ma reported from earlier studies. The granitoid magmatism took place between 2650 and 2510 Ma ago indicating accretionary growth of the eastern Dharwar Craton.

  • 18.
    Anders, Bebhinn
    et al.
    Earth and Ocean Sciences, School of Natural Sciences, NUI Galway, University Road, Galway, Ireland;Sediment Origins Research Team (SORT), NUI Galway, Ireland.
    Tyrrell, S.
    Earth and Ocean Sciences, School of Natural Sciences, NUI Galway, University Road, Galway, Ireland;Sediment Origins Research Team (SORT), NUI Galway, Ireland;Irish Centre for Research in Applied Geosciences (iCRAG), Ireland.
    Chew, D.
    Department of Geology, Trinity College Dublin, College Green, Dublin 2, Ireland;Irish Centre for Research in Applied Geosciences (iCRAG), Ireland.
    Mark, C.
    Naturhistoriska riksmuseet, Enheten för geovetenskap. UCD School of Earth Sciences, University College Dublin, Belfield, Dublin 4, Ireland.
    O'Sullivan, G.
    UCD School of Earth Sciences, University College Dublin, Belfield, Dublin 4, Ireland.
    Murray, J.
    Earth and Ocean Sciences, School of Natural Sciences, NUI Galway, University Road, Galway, Ireland;Irish Centre for Research in Applied Geosciences (iCRAG), Ireland.
    Graham, J.R.
    Department of Geology, Trinity College Dublin, College Green, Dublin 2, Ireland.
    Badenszki, E.
    Irish Centre for Research in Applied Geosciences (iCRAG), Ireland;UCD School of Earth Sciences, University College Dublin, Belfield, Dublin 4, Ireland.
    Spatial variation in provenance signal: identifying complex sand sourcing within a Carboniferous basin using multiproxy provenance analysis2022Inngår i: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 179, nr 1, artikkel-id jgs2021-045Artikkel i tidsskrift (Fagfellevurdert)
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  • 19. Anders, Bébhinn
    et al.
    Tyrrell, Shane
    Chew, David
    O’Sullivan, Gary
    Mark, Chris
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Graham, John
    Badenszki, Eszter
    Murray, John
    Wildfires and Monsoons: Cryptic Drivers for Highly Variable Provenance Signals within a Carboniferous Fluvial System2022Inngår i: Geosciences, E-ISSN 2076-3263, Vol. 12, nr 1, s. 20-20Artikkel i tidsskrift (Fagfellevurdert)
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  • 20. Andersson, Joel B.H.
    et al.
    Logan, Leslie
    Martinsson, Olof
    Chew, David
    Kooijman, Ellen
    Naturhistoriska riksmuseet, Enheten för geovetenskap. Department of Geosciences Swedish Museum of Natural History Stockholm Sweden.
    Kielman-Schmitt, Melanie
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Kampmann, Tobias C.
    Bauer, Tobias E.
    U-Pb zircon-titanite-apatite age constraints on basin development and basin inversion in the Kiruna mining district, Sweden2022Inngår i: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 372, s. 106613-106613, artikkel-id 106613Artikkel i tidsskrift (Fagfellevurdert)
  • 21. Andersson, Stefan S.
    et al.
    Wagner, Thomas
    Jonsson, Erik
    Fusswinkel, Tobias
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Apatite as a tracer of the source, chemistry and evolution of ore-forming fluids: The case of the Olserum-Djupedal REE-phosphate mineralisation, SE Sweden2019Inngår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 255, s. 163-187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study explores the suitability of apatite as a tracer of the source(s), chemistry, and evolution of ore-forming hydrothermal fluids. This is tested by analysing the halogen (F, Cl, Br, and I), stable Cl isotopic, and trace element compositions of fluorapatite from the regional-scale Olserum-Djupedal rare earth element (REE) phosphate mineralisation in SE Sweden, which is dominated by monazite-(Ce), xenotime-(Y), and fluorapatite. The primary hydrothermal fluid flow system is recorded in a sequence from proximal granite-hosted to distal metasediment-hosted fluorapatite. Along this sequence, primary fluorapatite shows a gradual increase of Cl and Br concentrations and in (Gd/Yb)N, a decrease of F and I concentrations, a decrease in δ37Cl values, in (La/Sm)N, and partly in (La/Yb)N and (Y/Ho)N. Local compositional differences of halogen and trace element concentrations have developed along rims and in domains adjacent to fractures of fluorapatite due to late-stage partial reaction with fracture fluids. These differences are insignificant compared to the larger deposit-scale zoning. This suggests that apatite can retain the primary record of the original ore-forming fluid despite later overprinting fluid events. The agreement between Br/Cl and I/Cl ratios of apatite and those of co-existing fluid inclusions at lower temperatures indicates that only a minor fractionation of Br from I occurs during apatite precipitation. The halogen ratios of apatite can thus be used as a first-order estimate for the composition of the ore-forming fluid. Taking the small fractionation factors for Cl isotopes between apatite and co-existing fluid at high temperatures into account, we propose that the Cl isotopic composition of apatite and the halogen ratios derived from the apatite composition can be used jointly to trace the source(s) of ore-forming fluids. By contrast, most trace elements incorporated in apatite are affected by the host rock environment and by fluid-mineral partitioning due to growth competition between co-crystallising minerals. Collectively, apatite is sensitive to changing fluid compositions, yet it is also able to record the character of primary ore-forming fluids. Thus, apatite is suitable for tracing the origin, chemistry, and evolution of fluids in hydrothermal ore-forming settings.

  • 22.
    Andreozzi, Giovanni
    et al.
    Sapienza Università di Roma, Italy.
    D'Ippolito, Veronica
    Sapienza Università di Roma, Italy.
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Hålenius, Ulf
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Bosi, Ferdinando
    Sapienza Università di Roma, Italy.
    Color mechanisms in spinel: a multi-analytical investigation of natural crystals with a wide range of coloration.2019Inngår i: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 46, nr 4, s. 343-360Artikkel i tidsskrift (Fagfellevurdert)
  • 23.
    Ardit, Matteo
    et al.
    University of Ferrara, Italy.
    Cámara, Fernando
    University of Milano, Italy.
    Hålenius, Ulf
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Vanadium-induced coloration in grossite (CaAl4O7) and hibonite (CaAl12O19)2021Inngår i: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 106, nr 4, s. 599-608Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High concentrations of vanadium cause very unusual coloration in hibonite (purple) and grossite (light violet) crystals in an exotic mineral assemblage from Sierra de Comechingones (Argentina). In the hibonite (CaAl12O19) structure vanadium ions, in various valence states (divalent, trivalent, and tetravalent), may be distributed over five crystallographic sites with coordinations corresponding to different polyhedra, namely, three unequal octahedra [M1 (D3d), M4 (C3ν), and M5 (Cs)], one M3 tetrahedron (C3ν), and one unusual fivefold-coordinated trigonal bipyramid M2 (D3h). Possible locations of vanadium ions in grossite (CaAl4O7) are limited to two crystallographically distinct sites (T1 and T2, both C1) in tetrahedral coordination.

    The combination of single-crystal X-ray diffraction and absorption spectroscopy techniques aided by chemical analyses has yielded details on the nature of the vanadium-induced color in both hibonite and grossite crystals. In hibonite, both M4 face-sharing octahedral and M2 trigonal bipyramid sites of the R-block are partially occupied by V3+. Strongly polarized bands recorded at relatively low energies in optical absorption spectra indicate that V2+ is located at the M4 octahedral site of the hibonite R-block. Chemical analyses coupled with an accurate determination of the electron densities at structural sites in hibonite suggest that the vanadium ions occupy about 10 and 5% of the M4 and M2 sites, respectively. For grossite, polarized optical absorption spectra reveal no indications of V2+; all observed absorption bands can be assigned to V3+ in tetrahedral coordination. Although not evident by the observed electron densities at the T sites of grossite (due to the low-V content), longer bond distances, and a higher degree of polyhedral distortion suggest that V3+ is located at the T2 site.

  • 24. Armands, Gösta
    et al.
    Claesson, Stefan
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Johansson, Åke
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Lundqvist, Thomas
    En pionjär inom svensk isotopgeologi. In memoriam, Eric Welin, 1923-20142015Inngår i: Geologiskt forum, Vol. 22, nr 85, s. 26-27Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 25.
    Augustsson, Anna
    et al.
    Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden.
    Uddh-Söderberg, Terese
    Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden.
    Filipsson, Monika
    Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden.
    Helmfrid, Ingela
    Occupational and Environmental Medicine Centre, Department of Clinical and Experimental Medicine Linköping University, Linköping, Sweden.
    Berglund, Marika
    Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
    Karlsson, Helen
    Occupational and Environmental Medicine Centre, Department of Clinical and Experimental Medicine Linköping University, Linköping, Sweden.
    Hogmalm, Johan
    Department of Earth Sciences, University of Gothenburg, Gothenburg, Sweden.
    Karlsson, Andreas
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Alriksson, Stina
    Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden.
    Challenges in assessing the health risks of consuming vegetables in metal-contaminated environments2018Inngår i: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 113, s. 269-280Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 26. 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.

  • 27.
    Babechuk, Michael
    et al.
    Isotope Geochemistry Group, Department of Geosciences, Eberhard Karls University of Tübingen, Tübingen, Germany.
    Weimar, Nadine
    Isotope Geochemistry Group, Department of Geosciences, Eberhard Karls University of Tübingen, Tübingen, Germany.
    Kleinhanns, Ilka
    Isotope Geochemistry Group, Department of Geosciences, Eberhard Karls University of Tübingen, Tübingen, Germany.
    Eroglu, Suemeyya
    Isotope Geochemistry Group, Department of Geosciences, Eberhard Karls University of Tübingen, Tübingen, Germany.
    Swanner, Elizabeth
    Department of Geological & Atmospheric Sciences, Iowa State University, Ames, USA.
    Kenny, Gavin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Kamber, Balz
    Department of Geology, Trinity College Dublin, Dublin, Ireland.
    Schoenberg, Ronny
    Isotope Geochemistry Group, Department of Geosciences, Eberhard Karls University of Tübingen, Tübingen, Germany.
    Pervasively anoxic surface conditions at the onset of the Great Oxidation Event: New multi-proxy constraints from the Cooper Lake paleosol2019Inngår i: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 323, s. 126-163Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oceanic element inventories derived from marine sedimentary rocks place important constraints on oxidativecontinental weathering in deep time, but there remains a scarcity in complementary observations directly fromcontinental sedimentary reservoirs. This study focuses on better defining continental weathering conditions nearthe Archean-Proterozoic boundary through the multi-proxy (major and ultra-trace element, Fe and Cr stableisotopes, μ-XRF elemental mapping, and detrital zircon U-Pb geochronology) investigation of the ca. 2.45 billionyear old (giga annum, Ga) Cooper Lake paleosol (saprolith) developed on a sediment-hosted mafic dike withinthe Huronian Supergroup (Ontario, Canada).Throughout the variably altered Cooper Lake saprolith, ratios of immobile elements (Nb, Ta, Zr, Hf, Th, Al, Ti)are constant, indicating a uniform pre-alteration dike composition, lack of extreme pH weathering conditions,and no major influence from ligand-rich fluids during weathering or burial metasomatism/metamorphism. Theloss of Mg, Fe, Na, Sr, and Li, a signature of albite and ferromagnesian silicate weathering, increases towards thetop of the preserved profile (unconformity) and dike margins. Coupled bulk rock behaviour of Fe-Mg-Mn and colocalizationof Fe-Mn in clay minerals (predominantly chlorite) indicates these elements were solubilized primarilyin their divalent state without Fe/Mn-oxide formation. A lack of a Ce anomaly and immobility of Mo, V, and Cr further support pervasively anoxic weathering conditions. Subtle U enrichment, if primary, is the onlygeochemical evidence that could be consistent with oxidative element mobilization. The leaching of ferromagnesiansilicates was accompanied by variable mobility and depletion of transition metals with a relativedepletion order of Fe≈Mg≈Zn > Ni > Co > Cu (Cu being significantly influenced by secondary sulfideformation). Mild enrichment of heavy Fe isotopes (δ56/54Fe from 0.169 to 0.492‰) correlating with Fe depletionin the saprolith indicates open-system loss of isotopically light aqueous Fe(II). Minor REE+Y fractionation withincreasing alteration intensity, including a decreasing Eu anomaly and Y/Ho ratio, is attributed to albitebreakdown and preferential scavenging of HREE > Y by clay minerals, respectively. Younger metasomatismresulted in the addition of several elements (K, Rb, Cs, Be, Tl, Ba, Sn, In, W), partly or wholly obscuring theirearlier paleo-weathering trends.The behavior of Cr at Cooper Lake can help test previous hypotheses of an enhanced, low pH-driven continentalweathering flux of Cr(III) to marine reservoirs between ca. 2.48–2.32 Ga and the utility of the stable Crisotope proxy of Mn-oxide induced Cr(III) oxidation. Synchrotron μ-XRF maps and invariant Cr/Nb ratios revealcomplete immobility of Cr despite its distribution amongst both clay-rich groundmass and Fe-Ti oxides.Assuming a pH-dependent, continental source of Cr(III) to marine basins, the Cr immobility at Cooper Lakeindicates either that signatures of acidic surface waters were localized to uppermost and typically unpreservedregolith horizons or were geographically restricted to acid-generating point sources. However, given detritalpyrite preservation in overlying fluvial sequences, it is probable that the oxidative sulfide corrosion required todrive surface pH < 4 lagged behind in this region relative to other early Proterozoic sequences. The entiresaprolith exhibits a consistently light stable Cr isotope composition (δ53/52Cr: −0.321 ± 0.038‰, 2sd, n=34)that cannot be linked to Cr(III) oxidation and is instead interpreted to have a magmatic origin.

  • 28. Badenszki, Eszter
    et al.
    Daly, J Stephen
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Kronz, Andreas
    Upton, Brian G J
    Horstwood, Matthew S A
    Age and Origin of Deep Crustal Meta-igneous Xenoliths from the Scottish Midland Valley: Vestiges of an Early Palaeozoic Arc and ‘Newer Granite’ Magmatism2019Inngår i: Journal of Petrology, ISSN 0022-3530, E-ISSN 1460-2415, Vol. 60, nr 8, s. 1543-1574Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Deep crustal felsic xenoliths from classic Scottish Midland Valley localities, carried to the surface by Permo-Carboniferous magmatism, are shown for the first time to include metaigneous varieties with dioritic and tonalitic protoliths. Four hypotheses regarding their origin have been evaluated: (1) Precambrian basement; (2) Permo-Carboniferous underplating; (3) ‘Newer Granite’ magmatism; (4) Ordovician arc magmatism. U–Pb zircon dating results rule out the Precambrian basement and Permo-Carboniferous underplating hypotheses, but establish that the meta-igneous xenoliths represent both ‘Newer Granite’ and Ordovician (to possibly Silurian) arc magmatism. The metadiorite xenoliths are shown to have protolith ages of c. 415 Ma with εHft zircon values ranging from +0·1 to +11·1. These are interpreted to represent unexposed ‘Newer Granite’ plutons, based on age, mineralogical, isotopic and geochemical data. This shows that Devonian ‘Newer Granite’ magmatism had a greater impact on the Midland Valley and Southern Uplands crust than previously realized. Clinopyroxene–plagioclase–quartz barometry on the metadiorites from the east and west of the Midland Valley yielded a similar pressure range of c. 5–10 kbar, and a metadiorite from the east yielded a minimum two-feldspar temperature estimate of c. 793–816°C. These results indicate that the metadiorites once resided in the middle–lower crust. In contrast, two metatonalite xenoliths have a Late Ordovician protolith age (c. 453 Ma), with zircon εHft values of +7·8 to +9·0. These are interpreted as samples of a buried Late Ordovician magmatic arc situated within the Midland Valley. Inherited zircons with similar Late Ordovician ages and εHft=453 values (+1·6 to +10·8) are present in the metadiorites, suggesting that the Devonian ‘Newer Granites’ intruded within or through this Late Ordovician Midland Valley arc. A younger protolith age of c. 430 Ma from one of the metatonalites suggests that arc activity continued until Silurian times. This validates the long-standing ‘arc collision’ hypothesis for the development of the Caledonian Orogen. Based on U–Pb zircon dating, the metatonalite and metadiorite xenoliths have both experienced metamorphism between c. 400 and c. 391 Ma, probably linked to the Acadian Orogeny. An older phase of metamorphism at c. 411 Ma was possibly triggered by the combined effects of heating owing to the emplacement of the ‘Newer Granite’ plutons and the overthrusting of the Southern Uplands terrane onto the southern margin of the Midland Valley terrane.

  • 29.
    Bailey, Lydia R.
    et al.
    Department of Geosciences University of Arizona Tucson AZ USA.
    Drake, Henrik
    Department of Biology and Environmental Science Linnæus University Kalmar Sweden.
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Reiners, Peter W.
    Department of Geosciences University of Arizona Tucson AZ USA;Faculty of Environment University of Northern British Columbia Prince George BC Canada.
    Characteristics and Consequences of Red Bed Bleaching by Hydrocarbon Migration: A Natural Example From the Entrada Sandstone, Southern Utah2022Inngår i: Geochemistry Geophysics Geosystems, E-ISSN 1525-2027, Vol. 23, nr 8, artikkel-id e2022GC010465Artikkel i tidsskrift (Fagfellevurdert)
  • 30.
    Baker, Don R.
    et al.
    Department of Earth and Planetary Sciences, McGill University, Montreal, Quebec H3A 0E8, Canada;‡ Special collection papers can be found online at http://www.minsocam.org/MSA/AmMin/special-collections.html..
    Callegaro, Sara
    Centre for Earth Evolution and Dynamics (CEED), University of Oslo, PO Box 1028, Blindern N-0316 Oslo, Norway.
    De Min, Angelo
    Department of Mathematics and Geoscience, University of Trieste, via Weiss 2, 34128 Trieste, Italy.
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Marzoli, Andrea
    Department of Land, Environment, Agriculture and Forestry, University of Padova, 16-35020 Legnaro, Padova, Italy.
    Fluorine partitioning between quadrilateral clinopyroxenes and melt2022Inngår i: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 107, nr 2, s. 167-177Artikkel i tidsskrift (Fagfellevurdert)
  • 31. Baker, Don R.
    et al.
    Callegaro, Sara
    Marzoli, Andrea
    De Min, Angelo
    Geraki, Kalotina
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Krzesinska, Agata M.
    Fioretti, Anna Maria
    Sulfur and chlorine in nakhlite clinopyroxenes: Source region concentrations and magmatic evolution2023Inngår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 359, s. 1-19Artikkel i tidsskrift (Fagfellevurdert)
  • 32. Ballirano, Paolo
    et al.
    Celata, Beatrice
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Andreozzi, Giovanni
    Bosi, Ferdinando
    HT breakdown of Mn-bearing elbaite from the Anjanabonoina pegmatite, Madagascar2022Inngår i: Journal of Geosciences, ISSN 1802-6222, E-ISSN 1803-1943, Vol. 67, s. 151-161Artikkel i tidsskrift (Fagfellevurdert)
  • 33. Ballirano, Paolo
    et al.
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Gianchiglia, Flaminia
    Di Carlo, Maria Cristina
    Campopiano, Antonella
    Cannizzaro, Annapaola
    Olori, Angelo
    Pacella, Alessandro
    Chemical and structural characterization of UICC amosite fibres from Penge mine (South Africa)2022Inngår i: Periodico di Mineralogia, ISSN 0369-8963, E-ISSN 2239-1002, Vol. 91, s. 143-154Artikkel i tidsskrift (Fagfellevurdert)
  • 34. Barnes, Christopher J.
    et al.
    Bukała, Michał
    Callegari, Riccardo
    Walczak, Katarzyna
    Kooijman, Ellen
    Naturhistoriska riksmuseet, Enheten för geovetenskap. Department of Geosciences Swedish Museum of Natural History Stockholm Sweden.
    Kielman-Schmitt, Melanie
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Majka, Jarosław
    Zircon and monazite reveal late Cambrian/early Ordovician partial melting of the Central Seve Nappe Complex, Scandinavian Caledonides2022Inngår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 177, nr 9, artikkel-id 92Artikkel i tidsskrift (Fagfellevurdert)
  • 35. Barnes, Christopher J..
    et al.
    Majka, Jarek
    Jeanneret, Pauline
    Ziemniak, Grzegorz
    Kooijman, Ellen
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Kośmińska, Karolina
    Kielman-Schmitt, Melanie
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Schneider, D.A.
    Using Th-U-Pb geochronology to extract crystallization ages of Paleozoic metamorphic monazite contaminated by initial Pb2021Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 582, s. 120450-120450, artikkel-id 120450Artikkel i tidsskrift (Fagfellevurdert)
  • 36.
    Barnes, Christopher
    et al.
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Jarosław, Majka
    Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Schneider, David
    Department of Earth and Environmental Sciences, University of Ottawa, Ottawa, Canada.
    Walczak, Katarzyna
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Bukała, Michał
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Kośmińska, Karolina
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Tokarski, Tomasz
    Academic Center for Materials and NanotechnologyAGH University of Science and TechnologyKrakówPoland.
    Karlsson, Andreas
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    High-spatial resolution dating of monazite and zircon reveals the timing of subduction–exhumation of the Vaimok Lens in the SeveNappe Complex (Scandinavian Caledonides)2019Inngår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 174, nr 1, artikkel-id 5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

    Fulltekst (pdf)
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  • 37. Barão, Lúcia
    et al.
    Vandevenne, Floor
    Clymans, Wim
    Frings, Patrick J
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Ragueneau, Olivier
    Meire, Patrick
    Conley, Daniel J.
    Struyf, Eric
    Alkaline-extractable silicon from land to ocean: A challenge for biogenic silicon determination2015Inngår i: Limnology and Oceanography: Methods, E-ISSN 1541-5856, s. n/a-n/aArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The biogeochemical cycling of silicon (Si) along the land-to-ocean continuum is studied by a variety of research fields and for a variety of scientific reasons. However, there is an increasing need to refine the methodology and the underlying assumptions used to determine biogenic silica (BSi) concentrations. Recent evidence suggests that contributions of nonbiogenic sources of Si dissolving during alkaline extractions, not corrected by standard silicate mineral dissolution correction protocols, can be substantial. The ratio between dissolved Si and aluminum (Al) monitored continuously during the alkaline extraction can be used to infer the origin of the Si fractions present. In this study, we applied both a continuous analysis method (0.5 M NaOH) and a traditional 0.1 M Na2CO3 extraction to a wide array of samples: (1) terrestrial vegetation, (2) soils from forest, cropland and pasture, (3) lake sediments, (4) suspended particulate matter and sediments from rivers, (5) sediments from estuaries and salt marshes and (6) ocean sediments. Our results indicate that the 0.1 M Na2CO3 extraction protocol can overestimate the BSi content, by simultaneously dissolving Si fractions of nonbiogenic origin that may represent up to 100% of the Si traditionally considered as biogenic, hampering interpretation especially in some deeper soil horizons, rivers and coastal oceanic sediments. Moreover, although the term amorphous Si was coined to reflect a growing awareness of nonbiogenic phases we show it is actually inappropriate in samples where silicate minerals may account for a large part of the extracted Si even after linear mineral correction.

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  • 38. Baumgartner, Raphael J
    et al.
    Caruso, Stefano
    Fiorentini, Marco L
    Van Kranendonk, Martin J
    Martin, Laure
    Jeon, Heejin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Pagès, Anais
    Wacey, David
    Sulfidization of 3.48 billion-year-old stromatolites of the Dresser Formation, Pilbara Craton: Constraints from in-situ sulfur isotope analysis of pyrite2020Inngår i: Chemical Geology, Vol. 538Artikkel i tidsskrift (Fagfellevurdert)
  • 39.
    Belkin, Igor
    et al.
    Zhejiang Ocean University, Zhoushan, China.
    Andersson, Per
    Naturhistoriska riksmuseet, Forskningsavdelningen centralt. Naturhistoriska riksmuseet.
    Langhof, Jörgen
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    On the discovery of ferromanganese nodules in the world ocean2021Inngår i: Deep Sea Research Part I: Oceanographic Research Papers, ISSN 0967-0637, E-ISSN 1879-0119, Vol. 175Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For a century, the discovery of ferromanganese (Fe–Mn) nodules in the World Ocean was universally and indisputably credited to the Challenger circum-global oceanographic expedition of 1872–1876, during which the first manganese nodules and crusts were dredged up from the sea floor in February–March 1873. A century later, a counterclaim appeared in the literature, crediting Nordenskiöld’s expedition on Sofia in 1868, five years before the Challenger findings, for the discovery of Fe–Mn nodules in the ocean. This counterclaim, widely accepted without scrutiny, was based on the Gustaf Lindström (1884) chemical analysis of a single bottom sediment sample among 14 samples from two Arctic expeditions led by Nordenskiöld:Sofia 1868 and Vega 1878–1880. The Lindström (1884) report published as an eight-page brochure in Swedish remained almost unknown to the research community until now. A close examination of this report and other historical evidence revealed that the counterclaim of discovery by the Sofia 1868 expedition to the Kara Sea is invalid based on three notable facts: (1) Sofia never sailed in the Kara Sea; (2) the single bottom sediment sample with an extremely high content of Mn (24%), was collected in the Kara Sea during the Vega Expedition across the Northeast Passage; (3) the Vega sampling was in 1878, not in 1868. Meanwhile, five and a half years prior to the Vega sampling, the first Fe–Mn nodules and crusts were dredged up from the sea floor on 18 February and March 7, 1873 during the Challenger expedition. These findings have been promptly reported and published in May 1873. Thus, the credit for the discovery of ferromanganese nodules in the World Ocean firmly belongs to the Challenger expedition.

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  • 40. Bellucci, J. J.
    et al.
    Herd, C. D. K.
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Nemchin, A. A.
    Kenny, G. G.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Merle, Renaud E.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Insights into the chemical diversity of the martian mantle from the Pb isotope systematics of shergottite Northwest Africa 81592020Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 545, artikkel-id 119638Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Shergottite Northwest Africa (NWA) 8159 is a basaltic rock derived from a mantle source with chemical characteristics that are unique in the martian meteorite suite. To further investigate this source reservoir, the Pb isotope compositions of plagioclase/maskelynite, pyroxene, phosphates, and shock melt-glass in NWA 8159 have been measured in situ by Secondary Ion Mass Spectrometry (SIMS). Due to the limited spread in Pb isotope data, these Pb isotope compositions have been used to calculate an imprecise PbPb isochron age of 3.4 ± 2.1 Ga (2σ), which is broadly consistent with the crystallization age of 2.37 ± 0.25 Ga determined previously by 147Sm143Nd. The lack of radiogenic in-growth within individual minerals since 2.4 Ga means that this sample is depleted in U, which is in agreement with NWA 8159's positive initial ε143Nd. An initial Pb composition was calculated using an x-y weighted average of the least radiogenic Pb isotope population measured in the sample. This initial Pb composition is not consistent with the model for Pb growth in the shergottite mantle at 2.4 Ga. This composition is, however, consistent with the model for the Nakhla-Chassigny mantle. Using the latter model, a source μ (238U/204Pb) of 2.6 ± 0.6 has been calculated. This μ-value is in contrast with the other depleted shergottites (1.4-1.5) and falls significantly off the array of source ε143Nd vs. μ defined by the rest of the martian meteorite suite and thus, necessitates a differentiation history distinct from the other martian meteorites. Sequestering Pb in sulphides during differentiation is the only mechanism to fractionate U from Pb and create a low-μ reservoir. Consequently, the relatively high μ-value of the source of NWA 8159 is in contrast with the positive initial ε143Nd and indicates that its mantle source region likely lacked significant sulphur. This is consistent with the lack of sulphides in the sample itself and could have played a role in its complicated oxidation history.

  • 41. Bellucci, J. J.
    et al.
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Nemchin, A. A.
    Snape, J. F.
    Kenny, G. G.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Merle, Renaud E.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Bland, P. A.
    Benedix, G. K.
    Tracing martian surface interactions with the triple O isotope compositions of meteoritic phosphates2020Inngår i: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 531, artikkel-id 115977Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The triple oxygen isotope compositions of phosphate grains in six martian meteorites have been measured by Secondary Ion Mass Spectrometry (SIMS) and combined together with their chlorine isotope and halogen concentrations have been used to constrain hydrosphere-lithosphere interactions on Mars. These samples include three enriched shergottites (Zagami, Roberts Massif 04262 and Larkman Nunatak 12011), one depleted shergottite (Tissint), an orthopyroxenite (Allan Hills 84001), and a regolith breccia (Northwest Africa 7533). The phosphates measured here have a range in δ18O [(18O/16O)sample/(18O/16O)Standard-1] × 103] from +1.0 to +6.8‰ and could be a result of indigenous mantle values, mixing with martian water, or replacement reactions taking place on the surface of Mars. Three samples have a Δ17O [δ17O-1000(1 + δ18O /1000)0.528-1] in equilibrium with the martian mantle (ALH 84001, Tissint, and Zagami), while three samples (LAR 12011, RBT 04262, and NWA 7533) have an elevated positive Δ17O outside of analytical uncertainty of the martian fractionation line (MFL). The phosphates in the latter group also have positive and negative δ37Cl [(37Cl/35Cl)sample/(37Cl/35Cl)standard – 1] × 103] and enrichments in halogens not seen in the rest of the sample suite. Perchlorate formation on Earth fractionates Cl in both positive and negative directions and generates a correlated positive Δ17O. Further, perchlorate has been detected in wt% amounts on the martian surface. Thus, these results strongly suggest the presence of multiple Cl isotope reservoirs on the martian surface that have interacted with the samples studied here over the last ca. 2 Ga of geologic time. The weighted average of Δ17O measurements from phosphate grains (n = 13) in NWA 7533, which are the explicit result of exchange reactions on the martian surface, yields a statistically robust mean value of 1.39 ± 0.19‰ (2σ, MSWD = 1.5, p = 0.13). This value likely represents an accurate estimate for an oxidized surface reservoir on Mars.

  • 42.
    Bellucci, Jeremy
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Pb Isotopic Composition of Panamanian Colonial Majolica by LA-ICP-MS2016Inngår i: Recent Advances in Laser Ablation ICP-MS for Archaeology / [ed] L. Dussubieux, Springer Berlin/Heidelberg, 2016Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Panama ́ Viejo, founded in 1519 by the Spanish explorer Pedrarias Da ́vila, was the first permanent European settlement on the Pacific Ocean, and became a city, by royal decree, in 1521. Shortly after its creation, the city became an important base for trade with Spain. In 1671, the English pirate Henry Morgan waged an attack on Panama ́ Viejo, which resulted in a fire that destroyed the entire city. A new settlement built a few miles west, called Casco Antiguo or San Felipe, is now the historic district of modern Panama City. The Pb isotopic compositions of the glazes on the surface of sixteenth to seventeenth century majolica pottery sherds from Panama Viejo and Casco Antiguo (both in Panama), and Lima (Peru) were determined via non-destructive laser ablation multi-collector ICP-MS (LA-MC-ICP-MS). The contrast in Pb isotopic compositions in the glazes on ceramics recovered in different locations demonstrate that early majolica pottery production during this period used Pb obtained from the Andes. However, the Pb used in later majolica production in Panama is of Spanish origin. After Panama ́ Viejo was burned to the ground, Panamanian majolica production ended.

    Fulltekst (pdf)
    fulltext
  • 43.
    Bellucci, Jeremy
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Joshua, Snape
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Whitehouse, Martin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Nemchin, Alexander
    Direct Pb Isotopic Analysis of a Nuclear Fallout Debris Particle from the Trinity Nuclear Test2017Inngår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 89, s. 1887-1891Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Pb isotope composition of a nuclear fallout debris particle has been directly measured in post-detonation materials produced during the Trinity nuclear test by a secondary ion mass spectrometry (SIMS) scanning ion image technique (SII). This technique permits the visual assessment of the spatial distribution of Pb and can be used to obtain full Pb isotope compositions in user-defined regions in a 70 μm × 70 μm analytical window. In conjunction with backscattered electron (BSE) and energy-dispersive spectroscopy (EDS) mapping of the same particle, the Pb measured in this fallout particle cannot be from a major phase in the precursor arkosic sand. Similarly, the Pb isotope composition of the particle is resolvable from the surrounding glass at the 2σ uncertainty level (where σ represents the standard deviation). The Pb isotope composition measured in the particle here is in excellent agreement with that inferred from measurements of green and red trinitite, suggesting that these types of particles are responsible for the Pb isotope compositions measured in both trinitite glasses. 

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    fulltext
  • 44.
    Bellucci, Jeremy
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Nemchin, Alexander
    Grange, Marion
    Collins, Gareth
    Whitehouse, Martin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Snape, Joshua
    Norman, Marc
    Kring, David
    Terrestrial-like zircon in an Apollo 14 breccia.2019Inngår i: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 510, s. 173-185Artikkel i tidsskrift (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 45.
    Bellucci, Jeremy
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Nemchin, Alexander
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Whitehouse, Martin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Ross, Kielman
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Snape, Joshua
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Pidgeon, Robert
    Geochronology of Hadean zircon grains from the Jack Hills, Western Australia constrained by quantitative scanning ion imaging2018Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 476, s. 469-480Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Five Hadean (> 4 Ga) aged zircon grains from the Jack Hills metasedimentary belt have been investigated by a secondary ion mass spectrometry scanning ion image technique. This technique has the ability to obtain accurate and precise full U-Pb systematics on a scale < 5 μm, as well as document the spatial distribution of U, Th and Pb. All five of the grains investigated here have complex cathodoluminescence patterns that correlate to different U, Th, and Pb concentration domains. The age determinations for these different chemical zones indicate multiple reworking events that are preserved in each grain and have affected the primary crystalized zircon on the scale of < 10 μm, smaller than conventional ion microprobe spot analyses. In comparison to the spot analyses performed on these grains, these new scanning ion images and age determinations indicate that almost half of the spot analyses have intersected several age and chemical domains in both fractured and unfractured parts of the individual crystals. Some of these unfractured, mixed domain spot analyses have concordant ages that are inaccurate. Thus, if the frequency of spot analyses intersecting mixed domains here is even close to representative of all other studies of the Jack Hills zircon population, it makes the interpretation of any trace element, Hf, or O isotopic data present in the literature tenuous. Lastly, all of the grains analysed here preserve at least two distinguishable 207Pb/206Pb ages. These ages are preserved in core-rim and/or complex internal textural relationships in unfractured domains. These secondary events took place at ca. 4.3, 4.2, 4.1, 4.0, 3.7, and 2.9 Ga, which are coincident with previously determined statistically robust age peaks present in this zircon population.

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    fulltext
  • 46.
    Bellucci, Jeremy
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Nemchin, Alexander
    Whitehouse, Martin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Snape, Joshua
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Bland, Phil
    Benedix, Gretchen
    Roszjar, Julia
    Pb evolution in the Martian mantle2018Inngår i: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 485, s. 79-87Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The initial Pb compositions of one enriched shergottite, one intermediate shergottite, two depleted shergottites, and Nakhla have been measured by Secondary Ion Mass Spectrometry (SIMS). These values, in addition to data from previous studies using an identical analytical method performed on three enriched shergottites, ALH 84001, and Chassigny, are used to construct a unified and internally consistent model for the differentiation history of the Martian mantle and crystallization ages for Martian meteorites. The differentiation history of the shergottites and Nakhla/Chassigny are fundamentally different, which is in agreement with short-lived radiogenic isotope systematics. The initial Pb compositions of Nakhla/Chassigny are best explained by the late addition of a Pb-enriched component with a primitive, non-radiogenic composition. In contrast, the Pb isotopic compositions of the shergottite group indicate a relatively simple evolutionary history of the Martian mantle that can be modeled based on recent results from the Sm–Nd system. The shergottites have been linked to a single mantle differentiation event at 4504 Ma. Thus, the shergottite Pb isotopic model here reflects a two-stage history 1) pre-silicate differentiation (4504 Ma) and 2) post-silicate differentiation to the age of eruption (as determined by concordant radiogenic isochron ages). The μ-values (238U/204Pb) obtained for these two different stages of Pb growth are μ1 of 1.8 and a range of μ2 from 1.4–4.7, respectively. The μ1-value of 1.8 is in broad agreement with enstatite and ordinary chondrites and that proposed for proto Earth, suggesting this is the initial μ-value for inner Solar System bodies. When plotted against other source radiogenic isotopic variables (Sri, γ187Os, ε143Nd, and ε176Hf), the second stage mantle evolution range in observed mantle μ-values display excellent linear correlations (r2 > 0.85) and represent a spectrum of Martian mantle mixing-end members (depleted, intermediate, enriched).

    Fulltekst (pdf)
    fulltext
  • 47.
    Bellucci, Jeremy
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Whitehouse, Martin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Aleshin, Matvej
    Eriksson, Mats
    Simultaneous Pu and U isotope nuclear forensics on an environmentally recovered hot particle2019Inngår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, s. 5599-5604Artikkel i tidsskrift (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 48.
    Bellucci, Jeremy
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Nemchin, Alexander
    Pidgeon, Robert
    Grange, Marion
    Reddy, Steven
    Timms, Nick
    A scanning ion imaging investigation into the micron-scale U-Pb systematics in a complex lunar zircon2016Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 438, s. 112-122Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The full U-Pb isotopic systematics in a complex lunar zircon ‘Pomegranate’ from lunar impact breccia 73235 have been investigated by the development of a novel Secondary Ion Mass Spectrometry (SIMS) scanning ion imaging (SII) technique. This technique offers at least a four-fold increase in analytical spatial resolution over traditional SIMS analyses in zircon. Results from this study confirm the hypothesis that the Pomegranate zircon crystallized at 4.302 ± 0.013 Ga and experienced an impact that formed, U-enriched zircon around primary zircon cores at 4.184 ± 0.007 Ga (2σ, all uncertainties). The increase in spatial resolution offered by this technique has facilitated targeting of primary zircon that was previously inaccessible to conventional spot analyses. This approach has yielded results indicating that individual grains with a diffusive distance of less than ~4 μm have been reset to the young impact age, while individual grains with a diffusive distance larger than ~6 μm have retained the old crystallization age. Assuming a broad range in cooling rate of 0.5–50 °C/year, which has been observed in a suite of similar lunar breccias, a maximum localized temperature generated by the impact that reset small prima- ry zircon and created new, high-U zircon is estimated to be between 1100 and 1280 °C.

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    fulltext
  • 49.
    Bellucci, Jeremy
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Whitehouse, Martin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Snape, Joshua
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Halogen and Cl isotopic systematics in Martian phosphates: Implications for the Cl cycle and surface halogen reservoirs on Mars2017Inngår i: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 458, s. 192-202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Cl isotopic compositions and halogen (Cl, F, Br, and I) abundances in phosphates from eight Martian meteorites, spanning most rock types and ages currently available, have been measured in situ by Secondary Ion Mass Spectrometry (SIMS). Likewise, the distribution of halogens has been documented by x-ray mapping. Halogen concentrations range over several orders of magnitude up to some of the largest concentrations yet measured in Martian samples or on the Martian surface, and the inter-element ratios are highly variable. Similarly, Cl isotope compositions exhibit a larger range than all pristine terrestrial igneous rocks. Phosphates in ancient (>4 Ga) meteorites (orthopyroxenite ALH 84001 and breccia NWA 7533) have positive d37Cl anomalies (+1.1 to +2.5 ‰).  These samples also exhibit explicit whole rock and grain scale evidence for hydrothermal or aqueous activity. In contrast, the phosphates in the younger basaltic Shergottite meteorites (<600 Ma) have negative d37Cl anomalies (-0.2 to -5.6 ‰).  Phosphates with the largest negative d37Cl anomalies display zonation where the rims of the grains are enriched in all halogens and have significantly more negative d37Cl anomalies indicating interaction with the surface of Mars during the latest stages of basalt crystallization. The phosphates with no textural, major element, or halogen enrichment evidence for mixing with this surface reservoir have an average d37Cl of -0.6 ‰, which suggests a similar Cl isotope composition between Mars, the Earth, and the Moon. The only process known to fractionate Cl isotopes, both positively and negatively, is formation of perchlorate, which has been detected in weight percent concentrations on the Martian surface. The age range and obvious mixing history of the phosphates studied here suggest perchlorate formation and halogen cycling via brines, which have also been observed on the Martian surface, has been active throughout Martian history. 

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  • 50.
    Bellucci, Jeremy
    et al.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Whitehouse, Martin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Snape, Joshua
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Nemchin, Alexander
    A Pb isotopic resolution to the Martian meteorite age paradox2016Inngår i: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 433, s. 241-248Artikkel i tidsskrift (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
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