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Wyszukujesz frazę "pyrite" wg kryterium: Wszystkie pola

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    Wyświetlanie 1-3 z 3
    Tytuł:
    Framboidy pirytowe jako wskaźniki paleośrodowiska
    Pyrite framboids as paleoenvironmental indicators
    Autorzy:
    Zatoń, M.
    Rakociński, M.
    Marynowski, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/2074589.pdf
    Data publikacji:
    2008
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    framboidy pirytowe
    redoks
    warunki środowiskowe oksyczne
    warunki środowiskowe dysoksyczne
    warunki środowiskowe euksyniczne
    jura
    dewon
    Polska
    pyrite framboids
    redox
    euxinia
    anoxia
    dysoxia
    Jurassic
    Devonian
    Polska
    Opis:
    The problemof application of pyrite framboids in reconstructions of the redox conditions is presented. The characteristics of pyrite framboids, their origin and principles of application in paleoenvironmental interpretations are given. The pyrite framboid diameter distribution as indicators of redox conditions was presented on the examples of the Middle Jurassic (Upper Bajocian-Lower Bathonian) ore-bearing clays of the Polish Jura, and Upper Devonian (Middle and Upper Famennian) dark grey and black shales from Kowala (Holy Cross Mountains). It has been shown, that during the sedimentation of the ore-bearing clays, the pyrite framboids formed in the sediment, below the oxic water column; however, some episodic oscillation around the dysoxic conditions cannot be entirely excluded. During the sedimentation of the Middle Famennian dark grey shales, the redox conditions at the sea-floor oscillated around dysoxia. In both examples, the framboids are characterized by wide range of their diameters and the presence of large, >10 "my"m, framboids. On the contrary, the Upper Famennian black shales, representing the Hangenberg event, were deposited below the euxinic conditions in the water column. It is indicated by a high frequency of small-size framboids, far below 6 "my"m in diameter, and the lack of the large ones. The overlying shales, on the other hand, show the transition to more oxic conditions. The redox conditions interpreted above are in agreement with the independent biomarker analyses and paleontological observations.
    Źródło:
    Przegląd Geologiczny; 2008, 56, 2; 158-164
    0033-2151
    Pojawia się w:
    Przegląd Geologiczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Studies on magnetite and pyrite mineralization, and on their early Palaeozoic ocean-floor host-rocks from the Leszczyniec Unit (West Sudetes, Poland)
    Autorzy:
    Oberc-Dziedzic, T.
    Mochnacka, K.
    Mayer, W.
    Pieczka, A.
    Creaser, R. A.
    Góralski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/191471.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    magnetite and pyrite mineralization
    metabasites
    ocean-floor metamorphism
    paragonite
    Leszczyniec Unit
    Sudetes
    Polska
    Opis:
    The Leszczyniec Unit extends along the eastern margin of the Karkonosze-Izera Massif. It comprises the Early Palaeozoic, MORB-like Leszczyniec complex composed of metabasites, metagranites and metasedi- ments. The metabasites host magnetite mineralization encountered in Jarkowice, whereas near Wieściszowice village the pyrite deposit occurs in metasediments and metabasites. The common feature of both sites is the almost complete absence of the accompanying ore minerals. Basing on petrographic, mineralogical, geochemical and microstructural studies, it was found that the metabasic rocks, which host magnetite mineralization, were lava flows, whereas the protoliths of pyrite-bearing schists were basic and acid tuffites accompanied by ocean-floor basalts. The igneous rocks from the Leszczyniec Unit were subjected to the ocean-floor metamorphism, whereas the accompanying sediments were altered by hydrothermal fluids enriched in sulphur ions, which reacted with iron derived from the sediment and promoted crystallization of pyrite. The sources of hydrothermal fluids were adjacent magmatic centres. The estimated age ~480 Ma for pyrite (Re-Os method) is similar to the previously known ~500 Ma age of metabasites (U-Pb, zircon method) from the Leszczyniec Unit, which establishes a temporal link between pyrite accumulation and the ocean-floor environment. The rocks of the Leszczyniec Unit, first altered by the ocean-floor metamorphism and the hydrothermal fluids, were subsequently subjected to the regional metamorphism at 360–340 Ma and the two-stage deformations of various intensities, followed by the third stage of deformations which caused the reorientation of the regional foliation. The zones of ductile and brittle deformations connected with the second deformation event host the accumulations of magnetite formed at the expense of Fe-bearing rock-forming minerals or from iron supplied from adjacent sources. In the pyrite-bearing schists, mineral assemblages formed during the hydrothermal alteration have been subjected to recrystallization and were included into domains defining foliation and lineation, which formed during the first stage of deformation. Pyrite crystals were affected by both deformation stages. At the end of the second stage, the invasion of fluids led to the dissolution of pyrite crystals and to the filling of cracks in pyrite crystals with chalcopyrite and tennantite. This process was followed by the formation of quartz veins with minor amounts of ore minerals.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2011, 81, No 2; 133-160
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    REE-bearing minerals in sediment-hosted stratiform pyrite mineralization zones of the Wiśniówka area (Holy Cross Mts., Poland)
    Autorzy:
    Migaszewski, Zdzisław M.
    Gałuszka, Agnieszka
    Zielińśki, Grzegorz
    Powiązania:
    https://bibliotekanauki.pl/articles/31342963.pdf
    Data publikacji:
    2023
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    siliciclastic rocks
    REE-bearing minerals
    geochemical analysis
    SEM-EDS
    EMPA
    REE-mineral provenance
    Wiśniówka area
    Polska
    Opis:
    There are two arsenical pyrite (As-FeS2mineralization zones cropping out in the Podwiśniówka and Wiśniówka Duża quarries where quartzites and quartzitic sandstones have been extracted for over a century. A large amount of pyrite in the Wiśniówka siliciclastics is unusual in the hard rock mining throughout the world. The pyritiferous beds contain a variety of REE-bearing minerals, including a crandallite series of aluminum-phosphate-sulfate (APS) minerals, e.g., predominant goyazite SrHAl3[(PO4)2(OH)6] with subordinate gorceixite BaHAl3[(PO4)2(OH)6] and very occasional crandallite CaHAl3[(PO4)2(OH)6]. By contrast, the other REE-phosphate minerals, e.g., xenotime YPO4, bur particularly monazite CePO4 occur in a lesser amount. Goyazite prevails somewhat in the Podwiśniówka beds whereas xenotime in the Wiśniówka Duża beds. Of the other REE-bearing minerals, bastnäsite REECO3(F,OH), florencite (REE)Al3(PO4)2(OH)6 and synchysite CaCe[CO3]2F occur in trace amounts. Interestingly, the quite common phosphate minerals, i.e., wavellite (Al.3[(OH,F)3|(PO4)2]×5H2O and variscite Al[PO4]×2H2O) are depleted in REEs with only Ce attaining 0.09 wt.% as documented by an electron-probe microanalysis. In contrast to quartzites/quartzitic sandstones, carbonaceous clayey-silty shales and bentonites/tuffites are distinctly enriched in REE-bearing minerals. This diversity is also mirrored in the mean total REE concentrations varying from 204 to 314 mg/kg, in clayey-silty shales and bentonites, attaining 457 mg/kg in some Podwiśniówka shale beds. Results of this and the previous petrographic, mineralogical and geochemical studies have indicated that REE-bearing minerals formed generally along with As-rich pyrite, nacrite/dickite and probably TiO2 polymorphs as a result of multiphase hydrothermal vent activity that took place in the Wiśniówka Late Cambrian sedimentary basin. This evidence is also backed up by the values of LREENASC/HREENASC (1.44–1.75) and Eu/EuNASC (1.24–1.30) coefficients in the clayey-silty shales. This positive Eu anomaly (31.20) points to the formation of REE-bearing minerals in a reducing environment.
    Źródło:
    Geological Quarterly; 2023, 67, 2; art. no. 17
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-3 z 3

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