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dc.contributor.authorGraziani, Ren
dc.contributor.authorMontomoli, Cen
dc.contributor.authorIaccarino, Sen
dc.contributor.authorMenegon, Len
dc.contributor.authorNania, Len
dc.contributor.authorCarosi, Ren
dc.date.accessioned2022-02-14T14:25:38Z
dc.date.available2022-02-14T14:25:38Z
dc.date.issued2020-11-01en
dc.identifier.issn0016-7568en
dc.identifier.urihttp://hdl.handle.net/10026.1/18770
dc.description.abstract

The Posada-Asinara Line is a crustal-scale transpressive shear zone affecting the Variscan basement in northern Sardinia during Late Carboniferous time. We investigated a structural transect of the Posada-Asinara Line (Baronie) with the aid of geological mapping and structural analysis. N-verging F2 isoclinal folds with associated mylonitic foliation (S2) are the main deformation features developed during the Posada-Asinara Line activity (D2). The mineral assemblages and microstructures suggest that the Posada-Asinara Line was affected by a retrograde metamorphic path. This is also confirmed by quartz microstructures, where subgrain rotation recrystallization superimposes on grain boundary migration recrystallization. Crystallographic preferred orientation data, obtained using electron backscatter diffraction, allowed analysis of quartz slip systems and estimation of the deformation temperature, vorticity of flow and rheological parameters (flow stress and strain rate) during the Posada-Asinara Line activity. Quartz deformation temperatures of 400 ± 50 °C have been estimated along a transect perpendicular to the Posada-Asinara Line, in agreement with the syn-kinematic post-metamorphic peak mineral assemblages and the late microstructures of quartz. The D2 phase can be subdivided in two events: an early D2early phase, related to the metamorphic peak and low kinematic vorticity (pure shear dominated), and a late D2late phase characterized by a lower metamorphic grade and an increased kinematic vorticity (simple shear dominated). Palaeopiezometry and strain rate estimates associated with the D2late deformation event showed an intensity gradient increasing towards the core of the shear zone. The D2early deformation developed under peak temperature conditions, while the D2late event was active at shallower structural levels.

en
dc.format.extent1898 - 1916en
dc.language.isoenen
dc.titleStructural setting of a transpressive shear zone: Insights from geological mapping, quartz petrofabric and kinematic vorticity analysis in NE Sardinia (Italy)en
dc.typeJournal Article
plymouth.issue11en
plymouth.volume157en
plymouth.publication-statusPublisheden
plymouth.journalGeological Magazineen
dc.identifier.doi10.1017/S0016756820000138en
plymouth.organisational-group/Plymouth
plymouth.organisational-group/Plymouth/Faculty of Science and Engineering
plymouth.organisational-group/Plymouth/REF 2021 Researchers by UoA
plymouth.organisational-group/Plymouth/REF 2021 Researchers by UoA/UoA07 Earth Systems and Environmental Sciences
dc.identifier.eissn1469-5081en
dc.rights.embargoperiodNot knownen
rioxxterms.versionofrecord10.1017/S0016756820000138en
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.typeJournal Article/Reviewen


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