Record details

    A general model for the intrusion and evolution of "mantle" garnet peridotites in high-pressure and ultra-high-pressure metamorphic terranes
Statement of responsibility
    Hannes K. Brueckner, L. Gordon Medaris
Other titles
    Garnet peridotites and ultra-high-pressure minerals (Variant.)
    Brueckner, Hannes K.
    Medaris, L. Gordon
Other author; role
   Carswell, D. A.

   Liou, J. G.
Source title - serial
    Journal of Metamorphic Geology
    Vol. 18, no. 2
    p. 123-133
    3 obr., 1 tab., 2 s.bibl.
    Zkr. název ser.: J. metamorph. Geol.
Subject group
    kutnohorské krystalinikum
    metamorfóza vysokotlaká
    původ plášťový
    vrásnění kaledonské
    vrásnění variské
Geographical name
    Mohelno (Třebíč)
    Nové Dvory (Kutná Hora)
Abstract (in english)
   arnet-bearing peridotite lenses are minor but significant components of most metamorphic terranes characterized by hugh-temperature eclogite facies assemblages. Most peridotite intrudes when slabs of continental crust are subducted deeply (60-120 km) into the mantle, usually by following oceanic lithosphere down an established subduction zone. Peridotite is transferred from the resulting mantle wedge into the crustal footwall through brittle and/or ductile mechanisms. These mantle pridotites vary petrographically, chemically, isotopically, chronologically and thermobarometrically from orogen to orogen, within orogens and even within individual terranes. The variations reflect: (1) dervation from different mantle sources (oceanic or continental lithosphere; and (3) changes within the host crustal slabs during intrusion, subduction and exhumation.
   Peridotite caught within mantle wedges above oceanic subduction zones will tend to recrystallize and be contaninated by fluids derived from the subducting oceanic crust. These subduction zone peridotites intrude during the subsequent subduction of continental crust. Low-pressure protoliths introduced at shallow (serpentinite, plagioclase, peridotite) and intermediate (spinel peridotite) mantle depths (20-50 km) may be carried to deeper levels within the host slab and undegro high-pressure metamorphism along with the enclosing rocks. If subducted deeply enough, the peridotites will develop garnet-bearing assemblagse that are isofacial with, and give the same recrystallization ages as, the eclogite facies country rocks. Peridotites introduced at deeper levels (50-120 km) may already contain garnet when they intrude and will not necessarily be isofacial or isochronous with enclosing crustal rocks.
   Some garnet peridotites recrystalize from spinel peridotite precursors at very high temperatures (c. 1200°C) and may derive ultimately from the asthenosphere. Other peridotites are from old (1 Ga), cold (c.850°C), subcontinental mantle ("relict peridotites")
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
Entered date
    5. 9. 2007
Import date
    8. 8. 2012