PUMA
Istituto di Geoscienze e Georisorse     
Molli G., Conti P., Giorgetti G., Meccheri M., Oesterling N. Microfabric study on the deformational and thermal history of the Alpi Apuane marbles (Carrara marbles), Italy. In: Journal of Structural Geology, vol. 22 (11-12) pp. 1809 - 1825. Elsevier, 2000.
 
 
Abstract
(English)
Marbles from different geometrical and structural positions within the Alpi Apuane metamorphic complex show a large variability in microfabric types as indicated by microstructure, c-axis orientation and temperature analysis. Statically recrystallized samples showing a granoblastic microstructure and polygonal grain boundaries are characterized by a grain size variation from east to west from 80-100 μm to 250-300 μm. This is correlated with an equilibration calcite-dolomite temperature from 360-380C to 420-430C. Two kinds of dynamically recrystallized microstructures have been investigated: a first one exhibiting coarse grains (150-200 μm) with lobate grain boundaries and a strong shape preferred orientation and a second one characterized by a smaller grain size (40-50 μm) and predominantly straight grain boundaries. These microstructural types, associated with localized post-thermal peak shear zones and meter- to kilometer-scale folds, are interpreted as related to high strain and high temperature crystal plastic deformation mechanisms (dislocation creep) associated with predominant grain boundary migration (type-B1) or subgrain-rotation recrystallization (type-B2). These differences in dynamically recrystallized microstructures are related to equilibration temperatures higher in type-B1 (390C) than in type-B2 (370-340C). We have been able to relate the development of the different microfabric types to the successive stages of deformation of the Alpi Apuane metamorphic complex.
URL: http://https://www.journals.elsevier.com/journal-of-structural-geology
Subject Italy
Alpi Apuane
marbles
microfabric types
microstructure
tectonic deformation


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