U-Pb and Rb-Sr isotopic data on an Ordovician volcanic-subvolcanic complex from the Tjopasi Group, Koli Nappes, Swedish Caledonides
Titel:
U-Pb and Rb-Sr isotopic data on an Ordovician volcanic-subvolcanic complex from the Tjopasi Group, Koli Nappes, Swedish Caledonides
Auteur:
Claesson, Stefan Klingspor, Inger Stephens, Michael B.
Verschenen in:
GFF
Paginering:
Jaargang 105 (1983) nr. 1 pagina's 9-15
Jaar:
1983-11-15
Inhoud:
U-Pb and Rb-Sr whole-rock isotopic data for an albite trondhjemite in northernmost Jamtland, Swedish Caledonides, are presented. Four zircon fractions, three of them almost concordant, define a discordia line with the upper intercept age 488±5 Ma. This age, which is considered to date the volcanic-subvolcanic complex, is consistent with the inferred stratigraphical age. The Rb-Sr system in the rock has been disturbed, probably during predeformational alteration (spilitization), and does not provide any chronological information.