Foliation trajectories, superposed to classical lithological information, have been used in this essay to represent the tectonometamorphic evolution of metamorphic rocks at the map scale. Each trajectory is characterized by a chronological connotation (dot pattern) and by a metamorphic connotation (colour); the relative timing of tectonic imprints has been reconstructed by means of the superposition of structures, while the metamorphic terms have been attributed on the basis of a meso- and microstructural-petrographic analysis of the metamorphic assemblages supporting all fabric elements (e.g. foliations, lineations). In addition, fabric gradients have been reported where pre-existing, quasi-isotropic rocks could be utilised (e.g. igneous rocks); these have been represented as colour gradients: from light colours (low strain domains = coronitic fabrics) to full colours (high strain domains = mylonitic fabrics). This new mapping approach, applied to a section of the Austroalpine domain of the Central Alps (Passo Mortirolo, Alta Val Camonica - Valtellina, Italy), which is characterized by polyphasic pre-Alpine and Alpine tectonometamorphic cycles, made the complete representation of lithostratigraphic and tectonometamorphic evolutions possible; therefore, this map is an example of a new method of representation of the full tectono-metamorphic history of a continental crust that underwent two superposed tectonic cycles (Variscan andAlpine) and successive structural stages related to a sequence of metamorphic re-equilibrations. Besides, this approach can be successfully applied in all tectonic and metamorphic settings generally recorded by metamorphic basements.
|Titolo:||Map of deformation partitioning in the polydeformed and polymetamorphic Austroalpine basement in Valtellina and Val Camonica, (Central Alps)|
|Autori interni:||SPALLA, MARIA IOLE (Penultimo)|
GOSSO, GUIDO GIUSEPPE MAGGIORINO (Primo)
ZUCALI, MICHELE (Ultimo)
SALVI, FRANCESCA (Secondo)
|Settore Scientifico Disciplinare:||Settore GEO/03 - Geologia Strutturale|
|Data di pubblicazione:||mag-2006|
|Tipologia:||Book Part (author)|
|Appare nelle tipologie:||03 - Contributo in volume|
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