Record details

    Fingerprinting sources of orogenic plutonic rocks from Variscan belt with lithium isotopes and possible link to subduction-related origin of some A-type granites
    Janoušek, Vojtěch
    Kohút, Milan
    Magna, Tomáš
    Oberli, Felix
    Wiechert, Uwe
Publication type
    článek v periodiku
Source title - serial
    Chemical Geology
    Roč. 274, č. 1-2
Thesaurus term
    lithium isotopes,neodymium isotopes,granitic typology,lower crust,subduction,A-typegranite,Western Carpathians
Abstract (in english)
   Lithium data are presented for plutonic rocks from the Western Carpathians, Slovakia, that were generated throughout the complete Variscan orogenic cycle. I-type granites show a limited range of ?7Li, contrasting with the large variations found in S-type granites and orthogneisses of distinct ages. An exclusively heavy Li isotope signature (?7Li > 4.7?) found in A-type granites rules out several commonly accepted petrogenetic scenarios. It most probably reflects a derivation of A-type granites from a mantle wedge modified by slab-derived fluids. Mafic rocks (gabbros and diorites), associated with occurrences of granites, are uniformly Li-rich and isotopically light (< - 0.5?), precluding a direct derivation from the mantle. These signatures testify to their cumulate origin. The presumed dichotomy between the sources and processes leading to generation of S- and I-type granitic magmas does not seem to be reflected by Li isotope signatures in a simple and globally valid manner.
    Česká geologická služba
Contributor code
    ČGS (RIV)
Source format
Import date
    15. 10. 2014