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Wyszukujesz frazę "Creaser, R. A." wg kryterium: Autor


Wyświetlanie 1-2 z 2
Tytuł:
Isotopic Re-Os age of molybdenite from the Szklarska Poręba Huta Quarry (Karkonosze, SW Poland)
Autorzy:
Mayer, W.
Creaser, R. A.
Mochnacka, K.
Oberc-Dziedzic, T.
Pieczka, A.
Powiązania:
https://bibliotekanauki.pl/articles/2059392.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Karkonosze granite
hydrothermal mineralisation
Re/Os isotopic age
Opis:
New Re/Os isotopic data for molybdenite from the Szklarska Poręba Huta Quarry provide ages of 307 ± 2 Ma and 309 ± 2 Ma, respectively. The quarry is dominated by the porphyritic (“central”) and equigranular (“ridge”) varieties of the Karkonosze granite. Ore mineralisation hosted in aplogranite includes an assemblage of sulphides, sulphosalts, oxides and various rare phases. The molybdenite ages obtained are consistent with a previously published isotopic age of leucogranite (aplogranite?) from the same quarry and are only slightly older than a recently published, refined 2 6Pb/238U age of untreated zircons from the Szklarska Poręba Huta porphyritic granite. The age of the molybdenite corresponds moderately well to the younger stage of post-magmatic, pneumatolitic/hydrothermal activity of the Karkonosze granite (about 312 Ma).
Źródło:
Geological Quarterly; 2012, 56, 3; 505--512
1641-7291
Pojawia się w:
Geological Quarterly
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
    Wyświetlanie 1-2 z 2

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