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    Wyświetlanie 1-3 z 3
    Tytuł:
    Nowy chondryt zwyczajny L6, S1, W1: Northwest Africa 11779
    A new ordinary chondrite L6, S1, W1: Northwest Africa 11779
    Autorzy:
    Przylibski, Tadeusz A.
    Łuszczek, Katarzyna
    Kryza, Ryszard
    Powiązania:
    https://bibliotekanauki.pl/articles/1033133.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Towarzystwo Meteorytowe
    Tematy:
    L6 chondrite
    NWA chondrite
    bulk chemistry
    chemistry of minerals
    meteorite
    ordinary chondrite
    Opis:
    Based on petrological, mineralogical and geochemical research authors classified new meteorite Northwest Africa 11779 as the ordinary chondrite L6, S1, W1. Chemical composition of olivine crystals (Fa 24.9 mol.%) and of pyroxene crystals (Fs 19.4 mol.%) proved that this meteorite belongs to L chondrites. However, bulk chemical composition of NWA 11779 is not typical for L chondrites. Nevertheless, all analyzed elements (except Mo, Sn and Nb) are in abundances reported for L chondrites, some of elements have concentration closed to average abundances for L chondrites. The content of chosen, characteristic lithophile, siderophile and chalkophile elements in NWA 11779 chondrite is in most cases in accord with its typical abundance in L chondrites. Presence of poorly defined chondrules, secondary feldspar crystals larger than 50 µm in size, absence of glass within chondrules, coarse recrystallized matrix (with olivine crystals of 0.5 mm in diameter and pyroxene crystals of 0.3 mm in diameter) as well as carbon content below 0.2 wt% proved that studied meteorite belongs to the petrologic type 6. The only difference from characteristic features of petrologic type 6 in case of NWA 11779 chondrite is presence of ca. 10% of monoclinic Ca-poor pyroxenes. Undulatory extinction by olivine and absence of other shock features in this chondrite allow to determine the shock level as S1. Weathering grade of NWA 11779 was identified as W1 based on weathering of only FeNi alloy grains. The outer part of metallic grains as well as contact zones of FeNi and FeS are changed due to weathering. Between 10 and 20% of FeNi alloy grains are oxidized to iron oxides and hydroxides. These secondary products of weathering replace outer zone of FeNi grains and fill the small cracks, creating a few thin veins.
    Źródło:
    Acta Societatis Metheoriticae Polonorum; 2019, 10; 121-139
    2080-5497
    Pojawia się w:
    Acta Societatis Metheoriticae Polonorum
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sołtmany meteorite
    Autorzy:
    Karwowski, Ł.
    Powiązania:
    https://bibliotekanauki.pl/articles/411492.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Meteorytowe
    Tematy:
    meteorite
    ordinary chondrite
    L6 chondrite
    meteorite fall
    hammer meteorite
    Warmia-Masuria Province
    Sołtmany village
    Opis:
    This paper presents the results of a mineralogical and petrological study of the Sołtmany meteorite, which fell on April 30, 2011 in northern Poland. The meteorite was found almost immediately after it fell and has been little altered by weathering. Sołtmany is not the only observed fall of an L6 chondrite over Europe in the past few years. The preceding fall of this type, Jesenice (Slovenia), was also witnessed in April of 2009. However, it was not until several weeks after the fall that the first specimen of Jesenice was found, whereas Sołtmany was collected after a few minutes and submitted for analysis within a couple of days. The author presents mineral and petrographic features and chemical characteristics of mineral phases in Sołtmany. The mineral components are represented by metallic phases (kamacite, taenite, tetrataenite, native copper), as well as chromite, olivine, low and high-calcium pyroxene, feldspar, chlorine-bearing apatite, and merrillite. This study also describes the texture of the meteorite and takes notice of a low number of preserved chondrules and the presence of oval chondrule like areas, which exhibit a metamorphosed, recrystallized texture. Sołtmany was classified as an L6 ordinary chondrite with a weathering grade of W0. A shock stage S2 was determined on the basis of undulose extinction and lack of planar fractures in olivine crystals.
    Źródło:
    Meteorites; 2012, 2, No. 1-2; 15-30
    2299-0313
    2299-1220
    Pojawia się w:
    Meteorites
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Chondryt Sołtmany
    Sołtmany chondrite
    Autorzy:
    Przylibski, Tadeusz A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1033061.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Meteorytowe
    Tematy:
    Gefion family
    L6
    asteroid
    atomic weight
    bulk chemistry
    cosmic-ray exposure age
    cosmogenic radionuclides
    density
    fusion crust
    magnetic susceptibility
    meteorite
    meteorite age
    meteorite fall
    mössbauer spectroscopy
    noble gas
    ordinary chondrite
    organic matter
    parent body
    porosity
    primordial radionuclides
    thermophysical properties
    troilite thermometer
    Opis:
    The Sołtmany hammer meteorite is classified as an ordinary chondrite type L6, W0, S2. At present it is the most thoroughly and comprehensively examined Polish meteorite. A comprehensive petrological, mineralogical and geochemical analysis alongside the investigation of its physical and particularly thermophysical properties, and, most of all, analyses of cosmogenic radionuclides and noble gases isotopes content, as well as the use of a troilite thermometer has made it possible to draw interesting conclusions concerning the genesis and evolution of the parent body and the history of the parent meteoroid and, finally, the Sołtmany meteorite. The present report attempts at summing up the results of studies conducted at several European research centres in the last four years. The age of the the Sołtmany chondrite parent rock has been defined at 4.137 billion years. It was formed at a temperature of up to 440–450 K (about 170°C), probably at a depth of up to 3 to 7 km under the surface of the parent body, i.e. at a pressure of the order of 1–2.4 kbar. Such a low temperature during the accretion, diagenesis and metamorphism of the parent body may point to its complicated development, which may be in part due to collisions of partially melted planetesimals. Like with other type L ordinary chondrites, one can infer that the parent body could have been destroyed about 467 million years ago, at the time of a catastrophic collision which led to the formation of Gefion family of planetoids. Perhaps one of the bodies in this family was involved in another collision about 29.2 million years ago, which resulted in ejecting the parent meteoroid of the Sołtmany chondrite onto the Earth collision trajectory. Before entering the Earth’s atmosphere, this meteoroid had the mass of about 36 kg and the diameter of ca 13.5 cm. During its flight through the atmosphere, it rotated and somersaulted, which resulted in the formation of an uniform thin (0.5–0.7 mm) fusion crust, whose temperature reached 1000°C. In the last phase, the Sołtmany meteorite fell almost vertically and its mass was a mere 3% of the mass of the parent meteoroid – 1.066 kg. It hit the roof and then the concrete stairs of a farm building, which caused it to break into two bigger and many small pieces. It was found a few minutes after the fall, which occurred at 6:03 a.m. (CEST, UTC+2:00) on 30 April 2011, by Wydmińskie Lake in northern Poland (54°00,53’N, 22°00,30’E). The Sołtmany chondrite is one of just 14 meteorites in which the activity concentration of the cosmogenic 52Mn has been determined, and one of the few ordinary chondrites where the concentration of organic matter has been defined. As a result, it was found out that unlike in carbonaceous CI chondrites, the composition of organic particles is dominated by less complex compounds (CHO and CHOS) than CHNO and CHNOS compounds. This may indicate the decomposition of more complex organic compounds into particles with simple structures during magmatic and metamorphic processes related to formation of type L ordinary chondrites.
    Źródło:
    Acta Societatis Metheoriticae Polonorum; 2016, 7; 93-122
    2080-5497
    Pojawia się w:
    Acta Societatis Metheoriticae Polonorum
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-3 z 3

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