Podrobnosti záznamu

Název
    A tale of two orogens: the contrasting T-P-t history and geochemical evolution of mantle in high- and ultrahigh-pressure metamorphic terranes of the Norwegian Caledonides and the Czech Variscides
Údaj o odpovědnosti
    Hannes K. Brueckner, L. Gordon jr. Medaris
Další názvy
    Fifth International Eclogite Conference 1997 (Variant.)
Autor
    Brueckner, Hannes K.
    Medaris, L. Gordon, jr.
Jazyk
    anglicky
Zdrojový dokument - seriál
    Schweizerische mineralogische und petrographische Mitteilungen
Svazek/č.
    Roč. 78, č. 2
Rok
    1998
Poznámky
    8 obr., 3 s.bibl.
    Zkr. název ser.: Schweiz. mineral. petrogr. Mitt.
Předmětová skupina
    Český masiv
    datování Sm/Nd
    eklogit
    granáty
    granulit
    kolize desek
    metamorfóza vysokotlaká
    moldanubikum
    peridotit
    podmínky P-T
    vrásnění kaledonské
    vrásnění variské
Geografické jméno
    Bečváry (Kolín)
    Biskupice (Třebíč)
    Česká republika
    Mohelno (Třebíč)
    Níhov (Žďár nad Sázavou)
    Norsko
    Úhrov (Havlíčkův Brod)
Klíčové slovo
    Caledonides
    Contrasting
    Czech
    Evolution
    Geochemical
    High-
    History
    Mantle
    Metamorphic
    Norwegian
    Orogens
    T-P-t
    Tale
    Terranes
    Two
    Ultrahigh-pressure
    Variscides
Abstrakt (anglicky)
   arnet peridotite (GP) massif within collisional orogenic belts provide windows into deeper levels of the mantle (100 to possibly 400 km) than do spinel peridotites. A geochemical, isotopic and petrological study of GP from high- and ultrahigh-pressure metamorphic terranes in the Western Gneiss Region, Northwegian Caledonides, and the Gföhl Nappe, Bohemian Massif, Czech Variscides, suggest that more than one type of mantle can be involved in continentinent collision. GP from the Western Gneiss Region are chemically, give consistent LT-HP estimates of garnet equilibration, and define old (Pre-Caledonian) Sm-Nd mineral crystallization and recrystallization ages. These ages match similarly old ages in the associated crust, implying that the mantle and crust were coupled.
   The Norwegian peridotites apparently sat in a cold, static mantle environment for a long time before they were incorporated into the Caledonian orogen and are excellent examples of cold, melt-depleted, LIL-poor, buoyant lithosphere of the type that would be expected beneath the Baltic or Laurentian Shield prior to Caledonian collision. GP from the Gföhl Nappe in the Bohemian Massif are more complex than the Norwegian peridotites. Relative to Norwegian GP, they are chemically and mineralogically more heterogenous, some are much more depleted, others are more metasomatized, TP equilibration estimates are much more variable but all formed at significantly pre-Variscan. They seem to represent hot, active mantle that was depleted, metasomatised, recrystallized and stirred by convenction shortly before and during the Variscan Orogeny.
   Some GP (sensu stricto) are believed to represent the lithospheric mantle metasomatized by at least two stages of melt migration that presumably occurred above a subduction zone during the closure of the sea or seas that separed Gondwana and Laurussia. Other "transitional" (i.e. spinel-bearing) GR are believed to represent hot asthenosphere that penetrated the lithosphere and rose to the base of the orogen during the colli
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    18. 2. 2008
Datum importu
    8. 8. 2012