The occurrence of pre-collisional structural and metamorphic fabrics may control the development of new structures during subsequent orogenic deformation. Structural, petrological and geochronological analyses have been performed on selected samples collected along a NW-SE cross section of the Kalak Nappe Complex (KNC) exposed on Kvaløya Island (Finnmark, Norway), in order to define pre-Caledonian or Caledonian affinity of deformation fabrics. Nappes within the KNC experienced different pre-collisional tectonometamorphic histories, resulting in contrasting pre-Caledonian fabrics, which in turn controlled orogen-scale strain partitioning and metamorphic re-equilibration during Caledonian shortening. Caledonian deformation during top-to-SE-directed thrusting occurred at 550–675 °C and 0.8–1.0 GPa in the presence of fluids. Suitably-oriented pre-collisional fabrics were firstly exploited as zones of localized shearing internal to the KNC and subjected to metamorphic re-equilibration during shortening. Fold geometry during Caledonian thrusting was also controlled by the orientation of pre-Caledonian fabrics. SE-verging asymmetric folds were developed after minor tilting of pre-Caledonian upright folds with orogen-parallel hinge in the hinterland consistently with top-to-SE shearing. Shear-parallel folds displaying orogen-perpendicular hinge lines resulted from top-to-SE general shearing of pre-collisional upright folds showing pre-collisional orogen-perpendicular hinge lines. Caledonian metamorphism appears to have been accompanied by infiltration of radiogenic 40Ar-rich fluids, which affected the Ar isotopic system in synkinematic micas.

Structural and metamorphic inheritance controls strain partitioning during orogenic shortening (Kalak Nappe Complex, Norwegian Caledonides) / Ceccato A.; Menegon L.; Warren C.J.; Halton A.M.. - In: JOURNAL OF STRUCTURAL GEOLOGY. - ISSN 0191-8141. - ELETTRONICO. - 136:(2020), pp. 104057.1-104057.24. [10.1016/j.jsg.2020.104057]

Structural and metamorphic inheritance controls strain partitioning during orogenic shortening (Kalak Nappe Complex, Norwegian Caledonides)

Ceccato A.
Primo
;
2020

Abstract

The occurrence of pre-collisional structural and metamorphic fabrics may control the development of new structures during subsequent orogenic deformation. Structural, petrological and geochronological analyses have been performed on selected samples collected along a NW-SE cross section of the Kalak Nappe Complex (KNC) exposed on Kvaløya Island (Finnmark, Norway), in order to define pre-Caledonian or Caledonian affinity of deformation fabrics. Nappes within the KNC experienced different pre-collisional tectonometamorphic histories, resulting in contrasting pre-Caledonian fabrics, which in turn controlled orogen-scale strain partitioning and metamorphic re-equilibration during Caledonian shortening. Caledonian deformation during top-to-SE-directed thrusting occurred at 550–675 °C and 0.8–1.0 GPa in the presence of fluids. Suitably-oriented pre-collisional fabrics were firstly exploited as zones of localized shearing internal to the KNC and subjected to metamorphic re-equilibration during shortening. Fold geometry during Caledonian thrusting was also controlled by the orientation of pre-Caledonian fabrics. SE-verging asymmetric folds were developed after minor tilting of pre-Caledonian upright folds with orogen-parallel hinge in the hinterland consistently with top-to-SE shearing. Shear-parallel folds displaying orogen-perpendicular hinge lines resulted from top-to-SE general shearing of pre-collisional upright folds showing pre-collisional orogen-perpendicular hinge lines. Caledonian metamorphism appears to have been accompanied by infiltration of radiogenic 40Ar-rich fluids, which affected the Ar isotopic system in synkinematic micas.
2020
Structural and metamorphic inheritance controls strain partitioning during orogenic shortening (Kalak Nappe Complex, Norwegian Caledonides) / Ceccato A.; Menegon L.; Warren C.J.; Halton A.M.. - In: JOURNAL OF STRUCTURAL GEOLOGY. - ISSN 0191-8141. - ELETTRONICO. - 136:(2020), pp. 104057.1-104057.24. [10.1016/j.jsg.2020.104057]
Ceccato A.; Menegon L.; Warren C.J.; Halton A.M.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/849205
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