The Cotoncello shear zone is developed in the mafic and ultramafic rocks cropping out in the north-western Elba island (northern Apennines). The mylonitic fabrics documented in the field, are highlighted by a pervasive mylonitic foliation and by cm- to dm-thick high-strain transpressive shear zones with a top-to-the S/SE sense of shear. At the microscopic scale, the mylonitic foliation in the highstrain shear zones is made exclusively by isoriented Mg-hornblende and tremolite. In the less deformed domains, Mg-hornblende and tremolite rich-layers enveloped small domains preserving igneous fabric and/or older mylonitic fabric. Mineral assemblage on the amphibolitic-bearing mylonitic foliation indicates that the youngest mylonitic fabric occurred under amphibolites facies condition (T > 550°C, P: 0.6-0.8 GPa). © Società Geologica Italiana, Roma 2013.
Shear deformation in mafic-ultramafic complex in north-western Elba island (Northern Tyrrhenian Sea)
Frassi, Chiara
;Musumeci, Giovanni;
2013-01-01
Abstract
The Cotoncello shear zone is developed in the mafic and ultramafic rocks cropping out in the north-western Elba island (northern Apennines). The mylonitic fabrics documented in the field, are highlighted by a pervasive mylonitic foliation and by cm- to dm-thick high-strain transpressive shear zones with a top-to-the S/SE sense of shear. At the microscopic scale, the mylonitic foliation in the highstrain shear zones is made exclusively by isoriented Mg-hornblende and tremolite. In the less deformed domains, Mg-hornblende and tremolite rich-layers enveloped small domains preserving igneous fabric and/or older mylonitic fabric. Mineral assemblage on the amphibolitic-bearing mylonitic foliation indicates that the youngest mylonitic fabric occurred under amphibolites facies condition (T > 550°C, P: 0.6-0.8 GPa). © Società Geologica Italiana, Roma 2013.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
