Record details

    Textural evolution in the transition from subsolidus annealing to melting process, Velay Dome, French Massif Central
Statement of responsibility
    C. Dallain, Karel Schulmann, Patrick Ledru
    Dallain, C.
    Ledru, Patrick
    Schulmann, Karel
Source title - serial
    Journal of Metamorphic Geology
    Vol. 17, no. 1
    p. 61-74
    7 obr., 5 fot., 2 s.bibl.
    Zkr. název ser.: J. metamorph. Geol.
Subject group
    analýza petrografická
    analýza statistická
    podmínky P-T
    textura páskovaná
Geographical name
Abstract (in english)
   Petrographic analysis is a useful, but underused tool to aid in distinguishing between subsolidus and anatetic-related textures in migmatites. This study focuses on assessing the relative contributions of these two processes in the development of migmatic orthogneiss textures in the Velay Massif, French Massif Central. The results of this study show that subsolidus processes are more important in the development of migmatic textures in the orthogneiss than anatectic leucosome development. Four textural stage are identified from the mylonic non-anatectic orthogneiss, annealed, migmatic orthogneiss to diatexite. The monomineralic K-feldspar and plagioclase-quartz-muscovite banding was transformed with increasing temperature to polymineralic plagioclase-quartz-muscovite and K-feldspar-quartz-muscovite layers by the wetting of feldspar boudaries during heterogenous nucleation of quartz from a fluid phase at high surface energy triple points.
   A further increase of temperature led to the growth of K-feldspar probably related to production of small amounts of melt in plagioclase rich aggregates, controlled by muscovite abundance. Solid state annealing processes in conjuction with incipient anatexis resulted in the formation of apparent granitic-like textures in plagioclase dominated aggregates. By contrast, in K-feldspar dominated aggregates exclusively subsolidus processes prevail, leading to the development of coarse grained leucosome. With the onset of biotite dehydration melting the plagioclase-dominated aggregates are destroyed by the melt whereas the K-feldspar aggregates may be preserved
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
Entered date
    18. 2. 2008
Import date
    8. 8. 2012