NEW K-AR AGES FOR BASALTS FROM FRANZ JOSEF LAND

Abstract

New K-Ar age determinations on basalt samples from three drillholes and outcrops on Franz Josef Land suggest that flood volcanism throughout the archipelago fits in a very narrow age interval (116 +- 5 Ma). For 95% of the samples we studied, age scatter is within analytical uncertainty. New data on basaltic bulk-rock, trace element, and REE compositions point to mantle plume affinity for the Early Cretaceous magmatism on Franz Josef Land, which preceded the onset of seafloor spreading in the Canada Basin.