Rb-Sr isochron ages from east Milne Land, Scoresby Sund, East Greenland

Abstract

A prominent NNE-SSW trending fault in central Scoresby Sund, separates the eastern part of Milne Land geologicaIly from the rest of the island. This east Milne Land fauIt block, comprises metasediments bounded by a variety of post-kinematic intrusions in which three major plutonic rock types are found. Field investigations indicate the oldest plutonic rock to be a granodiorite, followed by a coarse-grained mafie, quartz syenite, and the youngest bodies to be of granitie composition. In the southern part a large area is covered by Mesozoic sediments whieh eross the fault-line without displacement. Locally, outliers of Tertiary plateau basalts rest on the Mesozoie rocks (fig. 33). The geology has been outlined by Henriksen & Higgins (1971, 1973) and preliminary age determinations were published by Hansen et al. (1972) and Hansen & Steiger (1976). This more extensive study deals with Rb-Sr whole-roek and mineral analyses on samples from two post-kinematic intrusions and from the metasediments in the northern area.