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A revised geochronology for the Blekinge Province, southern Sweden

Johansson, Ake ; Bogdanova, Svetlana LU and Cecys, Audrius LU (2006) In GFF 128. p.287-302
Abstract
Zircon grains from nine samples of metavolcanic rocks, gneisses, granitoids and migmatites from the Blekinge Province in southeasternmost Sweden have been dated by U-Pb using ion microprobe. The results suggest that most of the Blekinge bedrock was formed within a narrow time interval of 1.77-1.75 Ga, including the Vastana supracrustal formation and 'coastal gneisses' previously dated to c. 1.70 Ga. One sample, the 1.81 Ga Nattraby gneissic granite, appears to represent a sliver of slightly older proto-crust. An age of c. 1.75 Ga for an aplitic granite crosscutting the deformed Tving granitoids in eastern Blekinge brackets their deformation to between 1.77 and 1.75 Ga, whereas zircon grains of similar age from a migmatite neosome at Lindo... (More)
Zircon grains from nine samples of metavolcanic rocks, gneisses, granitoids and migmatites from the Blekinge Province in southeasternmost Sweden have been dated by U-Pb using ion microprobe. The results suggest that most of the Blekinge bedrock was formed within a narrow time interval of 1.77-1.75 Ga, including the Vastana supracrustal formation and 'coastal gneisses' previously dated to c. 1.70 Ga. One sample, the 1.81 Ga Nattraby gneissic granite, appears to represent a sliver of slightly older proto-crust. An age of c. 1.75 Ga for an aplitic granite crosscutting the deformed Tving granitoids in eastern Blekinge brackets their deformation to between 1.77 and 1.75 Ga, whereas zircon grains of similar age from a migmatite neosome at Lindo may be inherited, making the result inconclusive. Thin metamorphic zircon overgrowths and resetting of the U-Pb system in titanite indicate a regional tectonothermal event at 1.45 to 1.40 Ga, accompanying the intrusion of the Karlshamn-type granites. The crust of the Blekinge Province thus was formed at 1.77-1.75 Ga from relatively juvenile sources in a subduction-related environment along the southern edge of Fennoscandia. It was deformed and partly uplifted relative to the undeformed TIB-1 granitoids of the Smaland block further north, prior to the intrusion of the Karlshamn-type granites at 1.45 Ga. (Less)
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publication status
published
subject
keywords
Blekinge, zircon, U-Pb, ion microprobe, titanite, Sm-Nd, Rb-Sr, vastana, formation, Tving granitoids, coastal gneiss, southern Sweden
in
GFF
volume
128
pages
287 - 302
publisher
Taylor & Francis
external identifiers
  • wos:000243752400002
  • scopus:33846543673
ISSN
2000-0863
language
English
LU publication?
yes
id
46957a54-6576-4a79-a4f8-464befdedd85 (old id 677370)
alternative location
http://www.gff-online.se/site/article.asp?articleID=895
date added to LUP
2016-04-01 12:15:26
date last changed
2020-07-22 01:36:33
@article{46957a54-6576-4a79-a4f8-464befdedd85,
  abstract     = {Zircon grains from nine samples of metavolcanic rocks, gneisses, granitoids and migmatites from the Blekinge Province in southeasternmost Sweden have been dated by U-Pb using ion microprobe. The results suggest that most of the Blekinge bedrock was formed within a narrow time interval of 1.77-1.75 Ga, including the Vastana supracrustal formation and 'coastal gneisses' previously dated to c. 1.70 Ga. One sample, the 1.81 Ga Nattraby gneissic granite, appears to represent a sliver of slightly older proto-crust. An age of c. 1.75 Ga for an aplitic granite crosscutting the deformed Tving granitoids in eastern Blekinge brackets their deformation to between 1.77 and 1.75 Ga, whereas zircon grains of similar age from a migmatite neosome at Lindo may be inherited, making the result inconclusive. Thin metamorphic zircon overgrowths and resetting of the U-Pb system in titanite indicate a regional tectonothermal event at 1.45 to 1.40 Ga, accompanying the intrusion of the Karlshamn-type granites. The crust of the Blekinge Province thus was formed at 1.77-1.75 Ga from relatively juvenile sources in a subduction-related environment along the southern edge of Fennoscandia. It was deformed and partly uplifted relative to the undeformed TIB-1 granitoids of the Smaland block further north, prior to the intrusion of the Karlshamn-type granites at 1.45 Ga.},
  author       = {Johansson, Ake and Bogdanova, Svetlana and Cecys, Audrius},
  issn         = {2000-0863},
  language     = {eng},
  pages        = {287--302},
  publisher    = {Taylor & Francis},
  series       = {GFF},
  title        = {A revised geochronology for the Blekinge Province, southern Sweden},
  url          = {http://www.gff-online.se/site/article.asp?articleID=895},
  volume       = {128},
  year         = {2006},
}