Record details

Title
    Euhedral and Euhedral-Looking Ocelli in Mafic Bodies of Granitic Complexes
Statement of responsibility
    Marie Palivcová, Jarmila Waldhausrová, Vlasta Ledvinková
Author
    Ledvinková, Vlasta
    Palivcová, Marie
    Waldhausrová, Jarmila
Language
    anglicky
Source title - monograph
    Theophrastus' Contributions to Advanced Studies in Geology, Volume II
Pages
    s. 47-76
Notes
    2 obr., 8 fot., 5 s.bibl.
Subject group
    diorit
    gabro
    petrogeneze
    rekrystalizace
    středočeský pluton
    textura orbikulární
Geographical name
    ČR-Čechy
    Francie-Bretagne
    Itálie severní
    Kaliště (Příbram)
    Kuba
    Nepřejov (Příbram)
    Pecerady (Benešov)
    Smolotely (Příbram)
Keyword
    Bodies
    Complexes
    Euhedral
    Euhedral-Looking
    Granitic
    Mafic
    Ocelli
Abstract (in english)
   Mafic, mostly gabbroic rocks of the Adamello massif and the Central Bohemian Pluton (CBP) and of some other regions (e.g. Cuba, Bulgary, Ploumanac'h in France) contain, in addition to frequent rounded and irregular ocelli, rimmed polygonal ocelli. According to their shapes and cores compositions, the latter ocelli are of two types: (1) euhedral monocrystic ocelli and (2) "euhedral-looking" polymineral ocelli. The euhedral monocrystic ocelli are of bipyramidal quartz, less frequently of feldspar crystals. they are interpreted as xenocrysts with preserved original crystallographic shapes, captured from the country rocks. Some feldspar ocelli may be only euhedral-looking forms according to the cleavage. The polymineral euhedral-looking ocelli display similar shapes as euhedral ocelli monocrysts.
   Two alternative explanations are discussed for the polymineral ocelli, depending on the interpretation of their shapes: (1) The shapes are of apparent euhedral forms, the ocelli are explained as microxenoliths with pseudoeuhedral accidental shapes. (2) The shapes are truly euhedral shapes, i.e. the oceli are partially or completely pseudomorphosed original euhedral ocelli to some rounded ocelli are considered, too. Both kinds of ocelli (the monocrystic and polymineral ones) are supposed by us to recrystallize together and contemporanepously with the host rock. The recrystallization is an independent process subsequent to and superimposed on the process of the basic magma emplacement and crystallization. The recrystallization corresponds to the lower temperature stages of crystallization development of mafic host rocks, according to Fiala et al. (1975), and Ulrych (1985)
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    18. 2. 2008
Import date
    8. 8. 2012