The grenvillian-sveconorwegian orogeny in fennoscandia: Back-thrusting and extensional shearing along the "mylonite zone"
New structural and geochronological investigations of the "Mylonite Zone" (MZ), an arcuate terrane boundary in southwest Scandinavia, contribute to a refined conceptual model for the Grenvillian-Sveconorwegian tectonic evolution of the Mesoproterozoic Sveconorwegian orogenic belt. During l...
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ftunibolognairis:oai:cris.unibo.it:11585/567418 2024-04-14T08:11:27+00:00 The grenvillian-sveconorwegian orogeny in fennoscandia: Back-thrusting and extensional shearing along the "mylonite zone" VIOLA, GIULIO Henderson, I. H. C. Bingen, B. Hendriks, B. W. H. Viola, Giulio Henderson, I. H. C. Bingen, B. Hendriks, B. W. H. 2011 STAMPA http://hdl.handle.net/11585/567418 https://doi.org/10.1016/j.precamres.2011.06.005 eng eng info:eu-repo/semantics/altIdentifier/wos/WOS:000295767500008 volume:189 issue:3-4 firstpage:368 lastpage:388 numberofpages:21 journal:PRECAMBRIAN RESEARCH http://hdl.handle.net/11585/567418 doi:10.1016/j.precamres.2011.06.005 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-80052720787 Core complex Crustal extension Exhumation Nappe stacking Structural analysi Sveconorwegian orogen Geochemistry and Petrology Geology info:eu-repo/semantics/article 2011 ftunibolognairis https://doi.org/10.1016/j.precamres.2011.06.005 2024-03-21T17:38:31Z New structural and geochronological investigations of the "Mylonite Zone" (MZ), an arcuate terrane boundary in southwest Scandinavia, contribute to a refined conceptual model for the Grenvillian-Sveconorwegian tectonic evolution of the Mesoproterozoic Sveconorwegian orogenic belt. During late convergence, around 970Ma, the MZ acted as a top-to-the-SE thrust that accommodated crustal shortening in the eastern part of the orogen by juxtaposing the Idefjorden Terrane in the hanging wall in the west against the "Eastern Segment" footwall in the east. The eastward vergence of the MZ and of similarly oriented second-order nearby shear zones is interpreted as reflecting late back-thrusting within the overall W-vergent orogeny. Back-thrusting was possibly promoted by the backstop role played by the rigid block formed by the 1810-1650Ma Transscandinavian Igneous Belt. During subsequent E-W crustal extension, the MZ thrust-related fabrics were reactivated in an extensional fashion with bulk top-to-the-W kinematics. This was triggered by gravitational instabilities resulting from crustal overthickening during the shortening phase. 40Ar-39Ar biotite and white mica ages from a greenschist-facies and extension-related mylonite range between 922 and 860Ma. This long-lived episode is expressed by extensional structures that evolved continuously from purely ductile to brittle during progressive exhumation of the footwall. The "Eastern Segment" is interpreted as an immature asymmetric core complex, exhumed in the footwall of the extensional MZ, through the antithetic normal displacement of the MZ itself and of the top-to-the-E Sveconorwegian Frontal Deformation Zone farther to the east. The core complex is bound to the north by the transtensional Hammarö Shear Zone, characterized by penetrative constrictional fabrics, interpreted as indicative of an overall transtensional regime. © 2011 Elsevier B.V. Article in Journal/Newspaper Fennoscandia IRIS Università degli Studi di Bologna (CRIS - Current Research Information System) Precambrian Research 189 3-4 368 388 |
institution |
Open Polar |
collection |
IRIS Università degli Studi di Bologna (CRIS - Current Research Information System) |
op_collection_id |
ftunibolognairis |
language |
English |
topic |
Core complex Crustal extension Exhumation Nappe stacking Structural analysi Sveconorwegian orogen Geochemistry and Petrology Geology |
spellingShingle |
Core complex Crustal extension Exhumation Nappe stacking Structural analysi Sveconorwegian orogen Geochemistry and Petrology Geology VIOLA, GIULIO Henderson, I. H. C. Bingen, B. Hendriks, B. W. H. The grenvillian-sveconorwegian orogeny in fennoscandia: Back-thrusting and extensional shearing along the "mylonite zone" |
topic_facet |
Core complex Crustal extension Exhumation Nappe stacking Structural analysi Sveconorwegian orogen Geochemistry and Petrology Geology |
description |
New structural and geochronological investigations of the "Mylonite Zone" (MZ), an arcuate terrane boundary in southwest Scandinavia, contribute to a refined conceptual model for the Grenvillian-Sveconorwegian tectonic evolution of the Mesoproterozoic Sveconorwegian orogenic belt. During late convergence, around 970Ma, the MZ acted as a top-to-the-SE thrust that accommodated crustal shortening in the eastern part of the orogen by juxtaposing the Idefjorden Terrane in the hanging wall in the west against the "Eastern Segment" footwall in the east. The eastward vergence of the MZ and of similarly oriented second-order nearby shear zones is interpreted as reflecting late back-thrusting within the overall W-vergent orogeny. Back-thrusting was possibly promoted by the backstop role played by the rigid block formed by the 1810-1650Ma Transscandinavian Igneous Belt. During subsequent E-W crustal extension, the MZ thrust-related fabrics were reactivated in an extensional fashion with bulk top-to-the-W kinematics. This was triggered by gravitational instabilities resulting from crustal overthickening during the shortening phase. 40Ar-39Ar biotite and white mica ages from a greenschist-facies and extension-related mylonite range between 922 and 860Ma. This long-lived episode is expressed by extensional structures that evolved continuously from purely ductile to brittle during progressive exhumation of the footwall. The "Eastern Segment" is interpreted as an immature asymmetric core complex, exhumed in the footwall of the extensional MZ, through the antithetic normal displacement of the MZ itself and of the top-to-the-E Sveconorwegian Frontal Deformation Zone farther to the east. The core complex is bound to the north by the transtensional Hammarö Shear Zone, characterized by penetrative constrictional fabrics, interpreted as indicative of an overall transtensional regime. © 2011 Elsevier B.V. |
author2 |
Viola, Giulio Henderson, I. H. C. Bingen, B. Hendriks, B. W. H. |
format |
Article in Journal/Newspaper |
author |
VIOLA, GIULIO Henderson, I. H. C. Bingen, B. Hendriks, B. W. H. |
author_facet |
VIOLA, GIULIO Henderson, I. H. C. Bingen, B. Hendriks, B. W. H. |
author_sort |
VIOLA, GIULIO |
title |
The grenvillian-sveconorwegian orogeny in fennoscandia: Back-thrusting and extensional shearing along the "mylonite zone" |
title_short |
The grenvillian-sveconorwegian orogeny in fennoscandia: Back-thrusting and extensional shearing along the "mylonite zone" |
title_full |
The grenvillian-sveconorwegian orogeny in fennoscandia: Back-thrusting and extensional shearing along the "mylonite zone" |
title_fullStr |
The grenvillian-sveconorwegian orogeny in fennoscandia: Back-thrusting and extensional shearing along the "mylonite zone" |
title_full_unstemmed |
The grenvillian-sveconorwegian orogeny in fennoscandia: Back-thrusting and extensional shearing along the "mylonite zone" |
title_sort |
grenvillian-sveconorwegian orogeny in fennoscandia: back-thrusting and extensional shearing along the "mylonite zone" |
publishDate |
2011 |
url |
http://hdl.handle.net/11585/567418 https://doi.org/10.1016/j.precamres.2011.06.005 |
genre |
Fennoscandia |
genre_facet |
Fennoscandia |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:000295767500008 volume:189 issue:3-4 firstpage:368 lastpage:388 numberofpages:21 journal:PRECAMBRIAN RESEARCH http://hdl.handle.net/11585/567418 doi:10.1016/j.precamres.2011.06.005 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-80052720787 |
op_doi |
https://doi.org/10.1016/j.precamres.2011.06.005 |
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Precambrian Research |
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189 |
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3-4 |
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368 |
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388 |
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