Record details

Title
    Microthermometry of volatile-rich silicate melt inclusion in granitic rocks
Statement of responsibility
    Rainer Thomas, Dieter Rhede, Robert B. Trumbull
Author
    Rhede, Dieter
    Thomas, Rainer
    Trumbull, Robert B.
Language
    anglicky
Source title - serial
    Zeitschrift für geologische Wissenschaften
Vol./nr.
    Vol. 24, no. 3-4
Pages
    p. 505-526
Year
    1996
Notes
    10 obr., 2 fot., 5 tab., 3 s.bibl.
    Anglické resumé
    Zkr. název ser.: Z. geol. Wiss.
Subject group
    granit
    inkluze fluidní
    krušnohorský pluton
    křemen
    pegmatit
    tavenina
    těkavé látky
    teplota
    topaz
    viskozita
Geographical name
    ČR-Čechy
    Francie-Auvergne
    Horní Slavkov (Sokolov)
    SRN-Bayern
    SRN-Sachsen
Keyword
    Granitic
    Inclusion
    Melt
    Microthermometry
    Rocks
    Silicate
    Volatile-rich
Abstract (in english)
   Melt inclusions provide compositional information about granitic melts which cannot be obtained analysis of bulk rocks. This particularly true for the volatiles, which are depleted in rocks, even some vitrophyres, because of loss by degassing. Most natural melt inclusions are too small for direct in-situ chemical analysis by FTIR or SIMS techniques, and it is difficult or impossible to find enough large inclusions for a statistically significant number of measurements in a sample. This paper discusses a simples method of estimating total volatile contents in granitic melts from microthermometric measurement of melt inclusions as small as 5 m, which eliminates the size problem and thereby permits collection of large numbers of data. The method works in analogy to fluid inclusion microthermometry; however it takes into account the rate of melting reactions. We determine the beginning at the solidus temperature Ts of inclusions by a step-heating and quenching technique.
   We also demonstrate that homogenization in silicate melt inclusions is a diffusion-controlled process, and use this as a basis for determining volatile contents and viscosity. Using a constant duration for each experiment, we estimate the diffusion rate by measuring the size of the smallest inclusion which has homogenized in a given run. Differences in diffusion rate, at constant T. P and bulk composition, are a measure of total "volatility" of the melt, the most important contributors being H2O, CO2, F, P, Li. This "total volatility" in analogy to "total salinity" of fluid inclusions is expressed by the equivalent concentration of the most abundant volatile species, H2O (+-OH) and written "Cw as eq.-wt pour cent H2O". As a by-product of the method, estimated of melt viscosity can also be made.
   We present here values for volatile content (as eq.-wt pour cent H2O), solidus temperatures and the viscosity of melt inclusions in quartz and topaz from granitic and pegmatitic rocks of the Erzgebirge, Germany, the Slavkovský les (Czech Republic) and the Massif Central, Fran
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    20. 2. 2008
Import date
    8. 8. 2012