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                                       Details van artikel 6 van 17 gevonden artikelen
 
 
  Isotopic age determinations in South Norway III: Rb-Sr isotope systematics of the coronitic Vestre Dale Gabbro and its country rocks, Bamble Sector
 
 
Titel: Isotopic age determinations in South Norway III: Rb-Sr isotope systematics of the coronitic Vestre Dale Gabbro and its country rocks, Bamble Sector
Auteur: De Haas, Geert-Jan L. M.
Verschure, Rob H.
Maijer, Cornelis
Valbracht, Peter J.
Verschenen in: GFF
Paginering: Jaargang 114 (1992) nr. 4 pagina's 417-422
Jaar: 1992-12-10
Inhoud: Rb-Sr whole-rock isotope data of the coronitic Vestre Dale Gabbro and its country rocks are presented together with Rb-Sr and K-Ar isotope data of biotites and muscovites from the country rocks. The Rb-Sr whole-rock errorchron age of the Vestre Dale Gabbro, 1.26±0.09 Ga (87Sr/86Sr(I) = 0.70310±0.00010), falls within the error limits of the Sm-Nd whole-rock age and a Sm-Nd whole-rock-mineral age of this gabbro, suggesting that the Rb-Sr system remained closed during the Sveconorwegian orogeny, at least on hand-specimen scale. The leucocratic rocks, which constitute part of the agmatitic structures along the margins of the gabbro, yield a comparable errorchron age: 1.28±0.09 Ga (87Sr/86Sr(I) = 0.70516±0.00107). Emplacement of the gabbro disturbed the Rb-Sr systematics of the surrounding migmatites. It appears that complete homogenization of the Rb-Sr systematics was not achieved in these rocks, resulting in a poorly defined errorchron (MSWD = 151). Rb-Sr ages of the biotites (0.89 ± 0.02 Ga) and muscovites (0.94 ± 0.02 Ga) are, like the K-Ar ages (0.85-0.90 Ga), related to cooling after the Sveconorwegian orogeny. Comparison with K-Ar ages from other parts of the Sveconorwegian province suggests that a westward younging of the K-Ar biotite ages exists, concurrent with the well known overall westward younging of intrusive ages in the Sveconorwegian province.
Uitgever: Taylor & Francis
Bronbestand: Elektronische Wetenschappelijke Tijdschriften
 
 

                             Details van artikel 6 van 17 gevonden artikelen
 
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