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Distinguished multiple events of fracture mineralisation related to far-field orogenic effects in Paleoproterozoic crystalline rocks, Simpevarp area, SE Sweden

Drake, Henrik; Tullborg, Eva-Lena and Page, Laurence LU (2009) In Lithos 110(1-4). p.37-49
Abstract
Detailed investigations of fracture minerals have been carried out in the Simpevarp area, SE Sweden. in order to reveal the low-temperature evolution of the site and to discern different events of deformation, especially in the brittle regime. The study is part of the site characterisation programme for a potential deep-seated repository for spent nuclear fuel. The bedrock in the area is composed of generally un-metamorphosed 1.8 Ga crystalline rocks. Detailed SEM investigations of cross-cutting fracture mineralisations have revealed several generations of fillings formed at gradually lower temperatures during repeated events of fracturing and reactivation from the Paleoproterozoic until the Quaternary. Ar-40/Ar-39 geochronology, and... (More)
Detailed investigations of fracture minerals have been carried out in the Simpevarp area, SE Sweden. in order to reveal the low-temperature evolution of the site and to discern different events of deformation, especially in the brittle regime. The study is part of the site characterisation programme for a potential deep-seated repository for spent nuclear fuel. The bedrock in the area is composed of generally un-metamorphosed 1.8 Ga crystalline rocks. Detailed SEM investigations of cross-cutting fracture mineralisations have revealed several generations of fillings formed at gradually lower temperatures during repeated events of fracturing and reactivation from the Paleoproterozoic until the Quaternary. Ar-40/Ar-39 geochronology, and fracture orientation analyses have been used to relate each fracture filling generation to geological events, such as far-field effects from orogenies, as well as more local effects related to intrusions. Fracturing and formation of different fracture mineral parageneses during at least four different orogenies have been indicated: the waning stages of the Svecokarelian orogeny (> 1.75 Ga), the Danopolonian orogeny (similar to 1.47-1.44 Ga), the Sveconorwegian orogeny (similar to 1.1-0.9 Ga) and the Caledonian orogeny (similar to 0.5-0.4 Ga). The fracture minerals and greisen related to the Danopolonian orogeny mainly formed in relation to the intrusion of two indicatively Danopolonian-related granites nearby. Furthermore, periods of extension are indicated in the area by the presence of late-Sveconorwegian dolerites. Fractures filled with lower Cambrian sandstone are plausibly formed in relation to far-field extensional effects of the opening of the Iapetus Ocean. Fracture minerals of Paleozoic age or younger show influence of loading and unloading cycles. The youngest fracture minerals identified indicate precipitation from waters of similar composition as the present groundwater. (C) 2008 Elsevier B.V. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Sweden, Caledonian orogeny, Sveconorwegian orogeny, Formation temperatures, Ar-40/Ar-39 geochronology, Fracture minerals
in
Lithos
volume
110
issue
1-4
pages
37 - 49
publisher
Elsevier
external identifiers
  • wos:000266541500003
  • scopus:67349287418
ISSN
0024-4937
DOI
10.1016/j.lithos.2008.12.003
language
English
LU publication?
yes
id
5eaf1ab7-82ce-4671-b3dd-b95f7354fac1 (old id 1443529)
date added to LUP
2009-07-24 12:56:09
date last changed
2017-11-05 03:36:24
@article{5eaf1ab7-82ce-4671-b3dd-b95f7354fac1,
  abstract     = {Detailed investigations of fracture minerals have been carried out in the Simpevarp area, SE Sweden. in order to reveal the low-temperature evolution of the site and to discern different events of deformation, especially in the brittle regime. The study is part of the site characterisation programme for a potential deep-seated repository for spent nuclear fuel. The bedrock in the area is composed of generally un-metamorphosed 1.8 Ga crystalline rocks. Detailed SEM investigations of cross-cutting fracture mineralisations have revealed several generations of fillings formed at gradually lower temperatures during repeated events of fracturing and reactivation from the Paleoproterozoic until the Quaternary. Ar-40/Ar-39 geochronology, and fracture orientation analyses have been used to relate each fracture filling generation to geological events, such as far-field effects from orogenies, as well as more local effects related to intrusions. Fracturing and formation of different fracture mineral parageneses during at least four different orogenies have been indicated: the waning stages of the Svecokarelian orogeny (> 1.75 Ga), the Danopolonian orogeny (similar to 1.47-1.44 Ga), the Sveconorwegian orogeny (similar to 1.1-0.9 Ga) and the Caledonian orogeny (similar to 0.5-0.4 Ga). The fracture minerals and greisen related to the Danopolonian orogeny mainly formed in relation to the intrusion of two indicatively Danopolonian-related granites nearby. Furthermore, periods of extension are indicated in the area by the presence of late-Sveconorwegian dolerites. Fractures filled with lower Cambrian sandstone are plausibly formed in relation to far-field extensional effects of the opening of the Iapetus Ocean. Fracture minerals of Paleozoic age or younger show influence of loading and unloading cycles. The youngest fracture minerals identified indicate precipitation from waters of similar composition as the present groundwater. (C) 2008 Elsevier B.V. All rights reserved.},
  author       = {Drake, Henrik and Tullborg, Eva-Lena and Page, Laurence},
  issn         = {0024-4937},
  keyword      = {Sweden,Caledonian orogeny,Sveconorwegian orogeny,Formation temperatures,Ar-40/Ar-39 geochronology,Fracture minerals},
  language     = {eng},
  number       = {1-4},
  pages        = {37--49},
  publisher    = {Elsevier},
  series       = {Lithos},
  title        = {Distinguished multiple events of fracture mineralisation related to far-field orogenic effects in Paleoproterozoic crystalline rocks, Simpevarp area, SE Sweden},
  url          = {http://dx.doi.org/10.1016/j.lithos.2008.12.003},
  volume       = {110},
  year         = {2009},
}