The age of the Ottfjället dolerites of Särv Nappe, Swedish Caledonides: Some comments

Abstract

The five French geologists who took part in the Swedish Geodynamics Project comment on the paper by Stefan Claesson in GFF, Vol. 98, pp. 370–374. They disagree with the Swedish group about the age to be attributed to the basic dykes which intrude the Särv Nappe. The Swedish group suggests that the K—Ar ages greater than 735 ± 260 Ma are due to excess Ar. The French group, with similar analytical results, does not deny that there is some excess Ar but argues for older ages and suggests a minimum age of 1800 Ma.