Podrobnosti záznamu

Název
    The geochemistry of phosphorus in different granite suites of the Western Carpathians, Slovakia: the role of apatite and P-bearing feldspar
Údaj o odpovědnosti
    Igor Broska, C. Terry Williams, Pavol Uher, Patrik Konečný, Jaromír Leichmann
Autor
    Broska, Igor
    Konečný, Patrik
    Leichmann, Jaromír
    Uher, Pavol
    Williams, C. Terry
Jazyk
    anglicky
Zdrojový dokument - seriál
    Chemical geology (including isotope geoscience)
Svazek/č.
    Vol. 205, no. 1-2
Strany
    p. 1-15
Rok
    2004
Poznámky
    7 obr.
    Bibliografie na s. 14-15
    il.
    Zkr. název ser.: Chem. Geol. (Isotope Geosci.)
Klasifikační znak
    550.4
    552
Skupina konspektu
    54
    552
Předmětová skupina
    apatit
    chemismus minerálů
    fosfor
    granit typu A
    granit typu I
    granit typu S
    petrogeneze
    vrásnění variské
    Západní Karpaty
    živec alkalický
Geografické jméno
    Slovensko
Klíčové slovo
    Apatite
    Carpathians
    Different
    Feldspar
    Geochemistry
    Granite
    P-bearing
    Phosphorus
    Role
    Slovakia
    Suites
    Western
Abstrakt (anglicky)
   The geochemical behaviour of phosphorus in granites, coupled with compositional variations in apatite, discriminate the different genetic suites of Variscan granitic rocks in the West-Carpathian orogenic belt. Meso-Variscan granites, mostly of S-type affinity, show a good correlation between SiO2 and P2O5, with decreasing amounts of P in the poorly and moderated fractionated granites, and increasing phosphorus in the most evolved and late differentiation products. The aluminium saturation index (ASI) correlates negatively with bulk P contents in I-type granites, and positively with P in S-type granites. The phosphorus content of alkali feldspar (mainly Kfs) is usually very low (typically <0.05 wt.per cent P2O5), or not detected in the slightly differentiated granites. In the lateVariscan I/S-type granitoids, phosphorus is hosted mainly in the early-magmatic apatite, but is present also in the late K-feldspar (up to 0.15 wt.per cent of P2O5) that formed from the residual melts.
   In the post-orogenic S-type granites, the bulk of the phosphorus occurs in alkali feldspar (& 0.3 wt.per cent P2O5), with a minor proportion present in primary early-magmatic apatite. Clusters of small secondary apatite grains with a distinctive composition are distributed in alkali feldspar grains of the post-orogenic S-type granites. This apatite has formed post-magmatically from P released from P-rich alkali feldspar during decreasing temperature, by reaction with a fluid rich in volatiles (including F and B), and alkali and alkali earth metals. A-type granites have the lowest bulk phosphorus contents. Consequently, phosphate minerals are relatively rare in this granite type, and the alkali feldspar has negligible P2O5 contents. Except for Sr, the minor element contents in apatite partly correlate with the bulk composition of their host rocks and partly reflect some thermodynamic properties of melt.
   The Mn contents of apatite increase with the peraluminous character of the melt and with decreasing fO2 and so apatite from the S-type granites has significantly higher Mn contents than apatite from the I-type granites. Apatite from A-type granites is enriched in Fe and HREE, reflecting the higher bulk Fe and HREE content of this granite type. Apatite from specialized S-type granites is enriched in Y and HREE. In general, the Cl and S content of apatite is higher in the basic members of the I-type affinity granitic rocks
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    25. 3. 2008
Datum importu
    8. 8. 2012