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U-Pb baddeleyite ages and Hf, Nd isotope chemistry constraining repeated mafic magmatism in the Fennoscandian Shield from 1.6 to 0.9 Ga

Söderlund, Ulf LU ; Isachsen, CE; Bylund, Göran LU ; Heaman, LM; Jonathan Patchett, PJ; Vervoort, JD and Andersson, UB (2005) In Contributions to Mineralogy and Petrology 150(2). p.174-194
Abstract
The Palaeoproterozoic (1.90 - 1.60 Ga) crust of central Fennoscandia was intruded repeatedly by dolerite dikes and sills during the Neo- and Mesoproterozoic eons. We report 17 new baddeleyite U - Pb dates comprising six generations of dolerites ( in Ma): Blekinge-Dalarna dolerites 946 - 978 Protogine Zone dolerites 1,215 - 1,221 Central Scandinavian Dolerite Group 1,264 - 1,271 Tuna dikes and age equivalents in Dalarna 1,461 - 1,462 Varmland dolerites similar to 1,568 Breven-Hallefors dolerites similar to 1,595 The favoured tectonic model implies that the majority of these suites were related to active margin processes somewhere west ( and possibly south) of the Fennoscandian Shield. Dolerite intrusions are interpreted to reflect discrete... (More)
The Palaeoproterozoic (1.90 - 1.60 Ga) crust of central Fennoscandia was intruded repeatedly by dolerite dikes and sills during the Neo- and Mesoproterozoic eons. We report 17 new baddeleyite U - Pb dates comprising six generations of dolerites ( in Ma): Blekinge-Dalarna dolerites 946 - 978 Protogine Zone dolerites 1,215 - 1,221 Central Scandinavian Dolerite Group 1,264 - 1,271 Tuna dikes and age equivalents in Dalarna 1,461 - 1,462 Varmland dolerites similar to 1,568 Breven-Hallefors dolerites similar to 1,595 The favoured tectonic model implies that the majority of these suites were related to active margin processes somewhere west ( and possibly south) of the Fennoscandian Shield. Dolerite intrusions are interpreted to reflect discrete events of back-arc extension as the arc retreated oceanward. Initial Hf and Nd isotope compositions of the dolerite swarms fall between CHUR and normal-depleted mantle, and suggest a variably depleted and re-enriched mantle as the source for the here investigated 1.6 to 0.95 Ga old mafic rocks. Repeated recycling of older crustal components, mainly sediments ( dominated by material with short residence ages) in earlier subduction systems may have been very efficient at producing geochemically and isotopically variably enriched lithospheric mantle sections beneath the Fennoscandian Shield. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Contributions to Mineralogy and Petrology
volume
150
issue
2
pages
174 - 194
publisher
Springer
external identifiers
  • wos:000232401100004
  • scopus:27244457400
ISSN
0010-7999
DOI
10.1007/s00410-005-0011-1
language
English
LU publication?
yes
id
28d44189-9e6e-45ff-9c0c-6e91a300f6a5 (old id 220378)
date added to LUP
2007-10-05 14:54:22
date last changed
2017-11-19 03:40:26
@article{28d44189-9e6e-45ff-9c0c-6e91a300f6a5,
  abstract     = {The Palaeoproterozoic (1.90 - 1.60 Ga) crust of central Fennoscandia was intruded repeatedly by dolerite dikes and sills during the Neo- and Mesoproterozoic eons. We report 17 new baddeleyite U - Pb dates comprising six generations of dolerites ( in Ma): Blekinge-Dalarna dolerites 946 - 978 Protogine Zone dolerites 1,215 - 1,221 Central Scandinavian Dolerite Group 1,264 - 1,271 Tuna dikes and age equivalents in Dalarna 1,461 - 1,462 Varmland dolerites similar to 1,568 Breven-Hallefors dolerites similar to 1,595 The favoured tectonic model implies that the majority of these suites were related to active margin processes somewhere west ( and possibly south) of the Fennoscandian Shield. Dolerite intrusions are interpreted to reflect discrete events of back-arc extension as the arc retreated oceanward. Initial Hf and Nd isotope compositions of the dolerite swarms fall between CHUR and normal-depleted mantle, and suggest a variably depleted and re-enriched mantle as the source for the here investigated 1.6 to 0.95 Ga old mafic rocks. Repeated recycling of older crustal components, mainly sediments ( dominated by material with short residence ages) in earlier subduction systems may have been very efficient at producing geochemically and isotopically variably enriched lithospheric mantle sections beneath the Fennoscandian Shield.},
  author       = {Söderlund, Ulf and Isachsen, CE and Bylund, Göran and Heaman, LM and Jonathan Patchett, PJ and Vervoort, JD and Andersson, UB},
  issn         = {0010-7999},
  language     = {eng},
  number       = {2},
  pages        = {174--194},
  publisher    = {Springer},
  series       = {Contributions to Mineralogy and Petrology},
  title        = {U-Pb baddeleyite ages and Hf, Nd isotope chemistry constraining repeated mafic magmatism in the Fennoscandian Shield from 1.6 to 0.9 Ga},
  url          = {http://dx.doi.org/10.1007/s00410-005-0011-1},
  volume       = {150},
  year         = {2005},
}