PETROFÁBRICA DE MIGMATITOS DOS ARREDORES DE AMPARO, SP

EBERHARD WERNICK, ANTÔNIO CARLOS ARTUR

Resumo


This paper presents the results of a microtectonic study of migmatitic rocks from the Amparo Group (State of São Paulo, Brazil) involving minerals of melanosome (biotite) and leucosome (quartz). The authors concluded that melanosome reveals structures grading from S-tectonites to L-tectonites (S-L system) respectively modified by one or more co-planar linear components and by co-axial planar components. Leucosome exhibits structures mainly of L-tectonite grading to isotropic structural patterns. Such differential behavior has been interpreted as a result of migmatization processes, in which the remobilized Si-Al metateet tends to be dislocated to places of lower pression with increasing structural degree of freedom. However microtectonic information is clear enough to permit correlation of the metatectic material with the high intensity metamorphic phase. The authors also analyse the structural characterists of the rocks as a whole and conclude that they show apparently only one global tectogenic event which, however, do not exclude the possibility of sucessive homoaxial superposed deformation or the vanishing of prior deformation by later tectonic overprinting.

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