Podrobnosti záznamu

Název
    Petrology and geochemistry of high-Mg mafic metavolcanic rocks from the Neoproterozoic sequence of Sedlčany-Krásná Hora metamorphic "Islet", Central Bohemian Pluton, Czech Republic
Údaj o odpovědnosti
    Petra Vítková, Václav Kachlík
Další názvy
    Petrologie a geochemie vysokohořečnatých mafických metavulkanitů neoproterozoické sekvence sedlčansko-krásnohorského metamorfovaného ostrova, středočeský pluton, Česká republika
Autor
    Kachlík, Václav
    Vítková, Petra
Jazyk
    anglicky
Zdrojový dokument - seriál
    Krystalinikum
Svazek/č.
    Vol. 27
Strany
    p. 7-25
Rok
    2001
Poznámky
    1 obr., 14 diagr., 2 fot.
    Bibliografie na s. 23-25
    České resumé
    il.
    Zkr. název ser.: Krystalinikum
Klasifikační znak
    550.4
    552
Skupina konspektu
    552
Předmětová skupina
    analýza petrografická
    chemismus hornin
    hořčík
    metabazit
    pluton
    proterozoikum
    prvky stopové
    středočeská ostrovní zóna
    vzácné zeminy
Geografické jméno
    ČR-Čechy
    Krásná Hora nad Vltavou (Příbram, Sedlčany)
    Sedlčany (Příbram, Sedlčany)
Klíčové slovo
    Bohemian
    Central
    Czech
    Geochemistry
    High-Mg
    Hora
    Islet
    Mafic
    Metamorphic
    Metavolcanic
    Neoproterozoic
    Petrology
    Pluton
    Republic
    Rocks
    Sedlčany-Krásná
    Sequence
Abstrakt (anglicky)
   Presented work brings and summarized results of a study of Sedlčany-Krásná Hora (SKI) metavolcanic rocks. The bimodal metavolcanic rocks are present mostly within the metasedimentary sequence of the Neoproterozoic Svrchnice Fm. The mafic metavolcanic rocks (primarily basalts and basaltic andesites) prevail over felsic rocks (metamorphosed rhyolites) in the metavolcanic suite. Two texturally and chemically defined types of mafic rocks were distinguished: porphyritic (P-group) types. The defined types of mafic rocks were distinguished porphyritic (P-group) and fine-grained (F-group types. The present mineral association of both types usually consists of pyroxene, amphibole, plagioclase and opaque minerals. The magmatic mineral assemblage of these rocks is obliterated due to regional and contact metamorphism, which produced amphibole, epidote, chlorite and diopsidic pyroxene.
   In the TAS classification diagram, the mafic metavolcanic rocks plot into the field of basaltic andesites and basaltic trachyandesites (in order of their decreasing abundance), with high contents of Mg and lower contents of K and Ti. Acid metavolcanic rocks are rare. The P-group is characterized by high contents of MgO, Cr, Ni and Co but low TiO2 and LREE contents. Some rocks of this group overlap to the Ca-rich boninitic magmas. The F-group is compositionally less coherent that the P-group due to strong metamorphic and alteration. Compared with the P-group, the F-group is characterized by lower MgO, Cr, Co and Ni, and higher TiO2 and LREE contents. These rocks are comparable with low-Ti tholeiites, which are known from island-arc settings. Major and trace element compositions of the rocks were locally modified by mobile-element concentration changes during the Variscan tectonism.
   The SKI metavolcanic rocks generally display typical subalkaline tholeiitic patterns of the chondrite-normalized trace element distributions. Among metavolcanic rocks of the SKI, subvolcanic intrusive forms (dykes, sills) prevail over effusive types, which are quite common in the neighbouring Jílové Zone
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    12. 9. 2006
Datum importu
    8. 8. 2012