title: Characterization and10Be content of iron carbonate concretions for genetic aspects - Weathering, desert varnish or burning: Rim effects in iron carbonate concretions.
abstract: The research investigated three iron carbonate (siderite) sedimentary concretions from Nagykovácsi, Úri and Délegyháza, Hungary. To identify possible source rocks and effects of the glaze-like exposed surface of the concretions, we carried on comparative petrological, mineralogical, geochemical and isotopic studies. The samples were microbially mediated siderite concretions with embedded metamorphous and igneous mineral clasts, and had specific rim belts characterized by semi-concentric outer Fe-oxide layers, fluffy pyrite-rich outer belts and siderite inner parts. We investigated the cross section of the Fe-carbonate concretions by independent methodologies in order to identify their rim effects. Their surficial oxide layers showed evidence of degassing of the exposed surface caused most probably by elevated temperatures. The inner rim pyrite belt in the concretions excluded the possibility of a prolonged wet surface environment. Microtextural and mineralogical features did not support desert varnish formation.10Be nuclide values of the Nagykovácsi and Uri concretions were far above the level of terrestrial in-situ cosmogenic nuclides, but they were consistent with the lowest levels for meteorites. Though the data were not conclusive to confirm any kind of known origin, they are contradictary, and open possibilities for a scenario of terrestrial meteorite origin.
authors.affiliation: Research Center for Astronomy and Geosciences, Geobiomineralization and Astrobiological Research Group, Institute for Geology and Geochemistry, Hungarian Academy of Sciences, 1112, Budapest, Budaörsi út. 45, Hungary; Eszterházy Károly University, Dept. of Physical Geography and Geoinformatics, Leányka str. 6, 3300, Eger, Hungary. Electronic address: rodokrozit@gmail.com.
authors.forename: Márta
authors.initials: M
authors.lastname: Polgári
authors.affiliation: Eötvös University, Faculty of Science, Dept. of Materials Physics, Cosmic Materials Space Res. Group, 1117, Budapest, Pázmány P. s. 1/a, Hungary. Electronic address: bercziszani@caesar.elte.hu.
authors.forename: Szaniszló
authors.initials: S
authors.lastname: Bérczi
authors.affiliation: Graduate School of Science and Technology, Hirosaki University, 3, Bunkyo-chou, Hirosaki, Aomori, 036-8561, Japan. Electronic address: kh@cc.hirosaki-u.ac.jp.
authors.forename: Kazuho
authors.initials: K
authors.lastname: Horiuchi
authors.affiliation: Micro Analysis Laboratory, Tandem Accelerator (MALT), The University Museum, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan. Electronic address: hmatsu@um.u-tokyo.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsuzaki
authors.affiliation: Institute of Radiochemistry and Radioecology, University of Pannonia, Egyetem Str. 10, Veszprém, H-8200, Hungary. Electronic address: kt@almos.uni-pannon.hu.
authors.forename: Tibor
authors.initials: T
authors.lastname: Kovács
authors.affiliation: Eötvös University, Dept. Petrology and Geochemistry, 1117, Budapest, Pázmány P. s. 1/c, Hungary.
authors.forename: Sándor
authors.initials: S
authors.lastname: Józsa
authors.affiliation: Eötvös University, Dept. Petrology and Geochemistry, 1117, Budapest, Pázmány P. s. 1/c, Hungary.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Bendő
authors.affiliation: Szeged University, Department of Mineralogy, Geochemistry and Petrology, Egyetem str. 2-6, 6702, Szeged, Hungary. Electronic address: efkrisz@gmail.com.
authors.forename: Krisztián
authors.initials: K
authors.lastname: Fintor
authors.affiliation: Research Center for Astronomy and Geosciences, Geobiomineralization and Astrobiological Research Group, Institute for Geology and Geochemistry, Hungarian Academy of Sciences, 1112, Budapest, Budaörsi út. 45, Hungary.
authors.forename: József
authors.initials: J
authors.lastname: Fekete
authors.affiliation: Eötvös University, Inst. of Chemistry, 1117, Budapest, Pázmány P. s. 1/a, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Homonnay
authors.affiliation: Eötvös University, Inst. of Chemistry, 1117, Budapest, Pázmány P. s. 1/a, Hungary.
authors.forename: Ernő
authors.initials: E
authors.lastname: Kuzmann
authors.affiliation: University of Johannesburg, Department of Geology, 2600, Auckland Park, Johannesburg, South Africa.
authors.forename: Arnold
authors.initials: A
authors.lastname: Gucsik
authors.affiliation: Research Center for Astronomy and Geosciences, Geobiomineralization and Astrobiological Research Group, Institute for Geology and Geochemistry, Hungarian Academy of Sciences, 1112, Budapest, Budaörsi út. 45, Hungary.
authors.forename: Ildikó
authors.initials: I
authors.lastname: Gyollai
authors.affiliation: Department of Geology & Meteorology, Environmental Analytical & Geoanalytical Research Group, Szentágothai Research Centre, University of Pécs, 7624, Pécs, Ifjúság útja 6 and 20, Hungary.
authors.forename: János
authors.initials: J
authors.lastname: Kovács
authors.affiliation: Eötvös University, Dept. Mineralogy, H-1117, Budapest, Pázmány P. s. 1/c, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Dódony
mesh_terms: D001608:Beryllium / Q000032:analysis*; D002254:Carbonates / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry; D006814:Hungary; D008903:Minerals / Q000737:chemistry; D010150:Paint; D011834:Radiation Monitoring; D014887:Weather
chemical_list: D002254:Carbonates; D005290:Ferric Compounds; D008903:Minerals; C486982:siderite; D001608:Beryllium
keywords: (10)Be content; Heated rim minerals; Iron-carbonate concretions; Microbial; Siderite; Weathering vs. heating effects