Repository logo

Browsing by Subject "leukogranulity"

Filter results by typing the first few letters
Now showing 1 - 1 of 1
  • thumbnail.journal.alt
    Item type:Thesis, Access status: Restricted ,
    Metamorphic evolution of the Seve Nappe Complex in the Scandinavian Caledonides of west-central Sweden
    (Data obrony: 2012-09-12) Klonowska, Iwona
    Wydział Geologii, Geofizyki i Ochrony Środowiska
    The Seve Nappe Complex in the Caledonides of western Jämtland (Sweden) is composed of high grade metamorphic rocks, mainly amphibolite facies metasediments and granulite facies gneisses, locally migmatized, with rare eclogites and peridotites. Within ?reskutan Nappe of west-central Jämtland (studied area), kyanite-bearing leucogranulites are found. Conventional geothermobarometry and thermodynamic modeling were utilized to constrain metamorphic conditions. Phg (Si apfu), Grt-Phg, Grt-Phg-Ky-Qtz geothermobarometers and modeled phase equilibria for high pressure assemblages (garnet, phengite) in NCKFMMnASH system indicate peak pressure conditions of 24-32 kbar at temperature of ~700°C. The decompression stage together with partial melting is inferred from GASP barometer, ternary feldspar modeling, kyanite-sillimanite transition, assemblages of biotite-plagioclase and melt occurrence (phase diagrams). Decompression to pressures of ~5kbar is simultaneous with increase of temperature to ~800-820°C and partial melting initiated by micas, what was followed by cooling and crystallization of melt. Geothermobarometry and modeling approach connected with field work observations and microtextures analysis show the innovative conception of ?reskutan’s Nappe HP and HT history. It enabled getting a more complete picture of the SNC evolution during Caledonies orogeny formation.