Journal article
Strain softening induced ductile flow in the Särv thrust sheet, Scandinavian Caledonides
Journal of structural geology, Vol.8(3), pp.441-455
1986
DOI: 10.1016/0191-8141(86)90062-3
Abstract
The external zone of the Scandinavian Caledonides is characterized by thrust sheets composed of sedimentary rocks derived from the continent Baltica. The Särv thrust sheet is unique amongst them because the 4.5–6 km thick, flat-lying Tossåsfjället Group clastics were intruded by a sub-vertical tholeiitic dike swarm prior to thrusting. The Särv thrust sheet is a large horse (100 km long and 80 km wide) with a classical ramp-flat geometry. The original intrusive relationships of the dikes are preserved throughout most of the thrust sheet and deformation is concentrated at the base in a mylonite zone several tens of meters thick. In this zone, meter-thick dikes rotate into parallelism with the basal thrust and concordant mylonites of both lithologies are intercalated on a centimeter to millimeter scale. The overall rigid block geometry of the Särv thrust sheet, and the intense strain gradient recorded by the rotation of the dike swarm and the concurrent development of mylonites in the thrust zone, suggest that thrust emplacement took place by ductile yield and on-going pseudoplastic flow. Continual strain softening localized ductile flow in this zone by means of grain-size reduction, reaction-enhanced ductility and grain-boundary sliding — processes inferred from the microstructures.
Details
- Title: Subtitle
- Strain softening induced ductile flow in the Särv thrust sheet, Scandinavian Caledonides
- Creators
- Jane A Gilotti - Johns Hopkins UniversityRisto Kumpulainen - Stockholm University
- Resource Type
- Journal article
- Publication Details
- Journal of structural geology, Vol.8(3), pp.441-455
- Publisher
- Elsevier Ltd
- DOI
- 10.1016/0191-8141(86)90062-3
- ISSN
- 0191-8141
- eISSN
- 1873-1201
- Language
- English
- Date published
- 1986
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984229171102771
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