Podrobnosti záznamu

    Garnet peridotites in Eurasian high-pressure and ultrahigh-pressure terranes : a diversity of origins and thermal histories
Údaj o odpovědnosti
    L. Gordon Medaris jr.
    Medaris, L. G., 1936-
Zdrojový dokument - monografie
    Ultrahigh pressure metamorphism and geodynamics in collision-type orogenic belts
    s. 57-73
    7 obr., 1 tab.
    Obsahuje bibliografické odkazy
Klasifikační znak
Skupina konspektu
Předmětová skupina
    Český masiv
    geologie dynamická
    geologie regionální
    podmínky P-T
    tektonika desková
    vysoký tlak
Geografické jméno
    Česká republika
Klíčové slovo
Abstrakt (anglicky)
   Garnet peridotites and pyroxenites have been reported from 11 of the 15 or so high-pressure/ ultrahigh-pressure (HP/UHP) terranes in Eurasia. Most of these ultramafic rocks are Mg-Cr types, derived from depleted upper mantle, but some are more Fe-rich and originated by crystallization in ultramafic-mafic igneous complexes. The peridotites are polymetamorphic, with HP/UHP garnet-bearing assemblages being followed by a succession of retrograde assemblages related to exhumation and cooling; some also contain evidence for a pre-HP/UHP stage, such as spinel inclusions in garnet or the presence of Ti-clinohumite.
   Equilibration conditions have been calculated from all available analyses of garnetiferous assemblages, by application of the olivine-garnet Fe-Mg exchange thermometer and the Al-in-orthopyroxene barometer, resulting in two distinct P-T regimes for garnet peridotites|one at high P/T in the coesite and diamond fields, and another at low P/T in the vicinity of the spinel-to-garnet transition.
   Garnet peridotites are thought to have evolved in at least four different tectonothermal settings, including: (1) emplacement of peridotites into oceanic or continental crust, followed by transport of peridotites and associated crust to UHP conditions by a subducting plate; (2) transfer of peridotites from a mantle wedge to the crust of an underlying, subducting plate; (3) origination from upwelling asthenosphere that passed through a high-temperature spinel peridotite stage, followed by cooling into the garnet peridotite field; and (4) extraction of garnet peridotites from ancient subcontinental lithosphere, perhaps by deep-seated faulting within a continental plate
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
Datum vložení
    5. 12. 2006
Datum importu
    8. 8. 2012