A new structural setting for the central part of the External Ligurian Briançonnais (CELB) is proposed. CELB is divided into kmscale tectonic units that still preserve pre-Alpine geological features at several stratigraphic levels. Macro-, meso- and microscale primary features, such as paleoescarpments, unconformities and depositional or diagenetic fabrics are thus well preserved and can be still mapped and studied in detail at many stratigraphic levels. Significant transposition of bedding is recorded only in Upper Cretaceous and Eocene marly limestones and shales and in major km-long shear zones, where intense development of closely spaced tectonic foliations occurred. Several features indicate that the CELB tectonic evolution took place at shallow crustal levels: 1) strong localization of deformation along the weakest stratigraphic levels; 2) absence of diffuse recrystallization of rocks; 3) minor occurrence or absence of transposition of bedding; 4) kinematic evolution of fold axial plane foliations into frictional slip cleavages. A gradual decrease in the intensity of deformation from the Internal Ligurian Briançonnais to CELB and Dauphinois Domain is observed, although the boundaries of these three domains correspond, in the study area, to several Km-long, transpressive shear zones whose kinematic role in the evolution of the southern termination of the Western Alps should be carefully considered.

New data on post-Eocene tectonic evolution of the External Ligurian Briançonnais (Western Ligurian Alps)

MUSSO, Alessia;BERTOK, Carlo;D'ATRI, Anna Raffaella;MARTIRE, Luca;PEROTTI, ELENA;MARTINOTTI, Giorgio
2009-01-01

Abstract

A new structural setting for the central part of the External Ligurian Briançonnais (CELB) is proposed. CELB is divided into kmscale tectonic units that still preserve pre-Alpine geological features at several stratigraphic levels. Macro-, meso- and microscale primary features, such as paleoescarpments, unconformities and depositional or diagenetic fabrics are thus well preserved and can be still mapped and studied in detail at many stratigraphic levels. Significant transposition of bedding is recorded only in Upper Cretaceous and Eocene marly limestones and shales and in major km-long shear zones, where intense development of closely spaced tectonic foliations occurred. Several features indicate that the CELB tectonic evolution took place at shallow crustal levels: 1) strong localization of deformation along the weakest stratigraphic levels; 2) absence of diffuse recrystallization of rocks; 3) minor occurrence or absence of transposition of bedding; 4) kinematic evolution of fold axial plane foliations into frictional slip cleavages. A gradual decrease in the intensity of deformation from the Internal Ligurian Briançonnais to CELB and Dauphinois Domain is observed, although the boundaries of these three domains correspond, in the study area, to several Km-long, transpressive shear zones whose kinematic role in the evolution of the southern termination of the Western Alps should be carefully considered.
128
353
366
PIANA F.; MUSSO A.;BERTOK C.; D’ATRI A.; MARTIRE L.; PEROTTI E.; VARRONE D.; MARTINOTTI G.
File in questo prodotto:
File Dimensione Formato  
Piana 353.pdf

Accesso riservato

Tipo di file: PDF EDITORIALE
Dimensione 5.18 MB
Formato Adobe PDF
5.18 MB Adobe PDF   Visualizza/Apri   Richiedi una copia
Piana et al 2009.pdf

Accesso aperto

Tipo di file: POSTPRINT (VERSIONE FINALE DELL’AUTORE)
Dimensione 9.48 MB
Formato Adobe PDF
9.48 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/99382
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 25
  • ???jsp.display-item.citation.isi??? 22
social impact