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Heterogeneous deformation and mylonitization of a granulite complex, jotun‐valdres nappe complex, Central South Norway
Author(s) -
Koestler Andreas G.
Publication year - 1988
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.3350230101
Subject(s) - nappe , geology , mylonite , felsic , shear zone , granulite , geochemistry , mafic , pegmatite , quartz , deformation (meteorology) , isograd , tectonics , petrology , shear (geology) , tectonic phase , mineralogy , geomorphology , metamorphic facies , seismology , facies , structural basin , paleontology , oceanography
The Helgedal Zone is the Caledonian, heterogeneously deformed base of the Jotun Complex, within the Jotun‐Valdres Nappe Complex (Sognefjell, South Norway). It consists of an anastomosing system of shear zones isolating lozengeshaped lenses of less deformed rocks. Structural and geometrical features are described to define the type of deformation and to evaluate the tectonic significance of this zone. Granulitic gabbros and pegmatitic dykes are deformed together in the highly strained mylonitic zones. Microtextural investigations indicate that the quantitative relation between mafic and felsic minerals and the content of quartz determine the different behaviour of the two rock types during deformation.