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On the development of kink-bands; a case study in the Westasturian-Leonese Zone (Variscan Belt, NW Spain)

Jesus Aller, Fernando Bastida and Nilo C. Bobillo-Ares
On the development of kink-bands; a case study in the Westasturian-Leonese Zone (Variscan Belt, NW Spain)
Bulletin de la Societe Geologique de France (2020) 191 (1)

Abstract

A field analysis of kink bands developed in slates from three areas (Grandas, Boal and Luarca areas) of the Westasturian-Leonese Zone (Iberian Variscan belt) is presented. The analysis of the main parameters that characterize the geometry of the studied kink bands shows that those of the Grandas and Luarca areas exhibit a different evolution than those of the Boal area. In this latter area, the interlimb angle of the kink bands has lower values than those developed in the former areas and it involves rotation of the foliation inside and outside the band. In the areas with higher bulk shortening associated with the development of kink bands, chevron folds formed by juxtaposition of kink bands. Slip between folia and their rotation was probably the dominant mechanism in the formation of the kink bands, as deduced from the different values of the angle between the kink plane and the foliation inside (phi K) and outside (phi ) the band, and the occurrence of fractures along the kink planes and small steps between folia cross-cutting these fractures planes. The fractures along the kink planes prevented subsequent hinge migration. Geometrical analysis of kink bands formed by slip between folia and their rotation provides an estimation of the changes in area and thickness, and the strain inside the kink band. For angles of folia rotation psi <50 degrees , the ratio between the strain ellipse axes is <3 inside the band; this ratio is almost independent of the orientation of the kink planes with respect to the foliation outside the band (angle phi ).


ISSN: 0037-9409
EISSN: 1777-5817
Coden: BSGFAE
Serial Title: Bulletin de la Societe Geologique de France
Serial Volume: 191
Serial Issue: 1
Title: On the development of kink-bands; a case study in the Westasturian-Leonese Zone (Variscan Belt, NW Spain)
Affiliation: Universidad de Oviedo, Departamento de Geologia, Oviedo, Spain
Pages: Article 6
Published: 2020
Text Language: English
Summary Language: French
Publisher: Societe Geologique de France, Paris, France
References: 43
Accession Number: 2020-041608
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch map
N43°00'00" - N44°00'00", W07°00'00" - W06°25'00"
Country of Publication: France
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Abstract, Copyright, Societe Geologique de France. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202026
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