Podrobnosti záznamu

Název
    Behavior of trace elements in quartz from plutons of different geochemical signature: A case study from the Bohemian Massif, Czech Republic
Autor
    Ackerman, Lukáš
    Breiter, Karel
    Müller, A.
    Svojtka, Martin
Jazyk
    anglicky
Typ dokumentu
    článek v odborném periodiku
Zdrojový dokument - seriál
    Lithos
Svazek/č.
    175/176, 15 August
Strany
    s. 54-67
Rok
    2013
Poznámky
    Projekt: GAP210/10/1105, GA ČR3cav_un_auth*0263315
    Rozsah: 14 s. : E
Předmětová kategorie
    Bohemian Massif
    fractionation
    granites
    Quartz
    trace elements
Klíčové slovo
    Behavior
    Bohemian
    Case
    Czech
    Different
    Elements
    Geochemical
    Massif
    Plutons
    Quartz
    Republic
    Signature
    Study
    Trace
Abstrakt (anglicky)
   The trace-element content in igneous quartz from granitoids of different geochemical types was investigated using the laser ablation ICP-MS technique. The Variscan granitoids in the Bohemian Massif provide an excellent opportunity to study the chemical composition of magmatic quartz from the following granite types: (1) geochemically primitive I-type tonalites and granodiorites, (2) peraluminous S-type two-mica granites, (3) moderately fractionated A-type volcano-plutonic complexes of the Teplice caldera, and (4) highly fractionated S- and A-type rare-metal granites. This diversity of granitoids permitted the study of the chemical composition of magmatic quartz as result of (i) different magma protoliths and (ii) variable degrees of differentiation.
   There were only small differences in the quartz trace-element contents, ranging from weakly to moderately differentiated plutons of all geochemical types: Al (mostly 20-250 ppm), Ti (mostly 20-110 ppm), B (<13 ppm), Be (<0.7 ppm), Ge (<1 ppm), Li (<30 ppm), and Rb (<2 ppm). Only the S-type granites from western Erzgebirge contain Al-enriched quartz (200-400 ppm Al) since the beginning of its evolution. However, quartz from the highly fractionated granites (group 4) differs significantly: it is poor in Ti (<20 ppm Ti) and enriched in Al (up to 600 ppm in A-type, and up to 1000 ppm in S-type granites), Be (up to 3.2 ppm), Ge (up to 5.7 ppm), Li (up to 132 ppm, particularly in the S-type granites), and Rb (up to 15 ppm). The input of Ti into quartz is controlled mainly by the temperature and pressure, the entry of Al into quartz increases as a function of the water and fluorine content of the residual melt. Ge and Li increase significantly with the fractionation of parental melt.
   Their concentrations are controlled by the order of crystallization of minerals: comb quartz crystallizing before Li-mica is strongly Li-enriched, whereas groundmass and snowball quartz crystallizing after mica is enriched in Ge.
Přispěvatel
    AV ČR Brno, Geologický ústav
Kód přispěvatele
    AV ČR, GLÚ
Zdrojový formát
    U
Datum importu
    23. 10. 2014