Igneous intrusions in the cored Upper Jurassic succession of the Blokelv-1 borehole, Jameson Land Basin, East Greenland

Abstract

The fully cored Upper Jurassic succession in the Blokelv-1 borehole in the Jameson Land Basin, East Greenland, is intersected by igneous intrusions at four levels; the intrusions comprise a c. 15 cm thick dyke and three sills with thicknesses of 0.7, 1.2 and 1.9 m. The sills consist of fine-grained, sparsely plagioclase-olivine-phyric basalt with chilled contacts to the sediments. Analyses of two sills gave very similar results. The sills are tholeiitic basalts with compositions similar to the main group of dykes and sills in the Jameson Land Basin, and the Blokelv-1 sills are thus considered to belong to this group which has been dated at c. 53 Ma. The intrusions form part of a 55–51 Ma suite of tholeiitic basalt intrusions that was emplaced over an area extending for over 500 km north-to-south within the sedimentary basins of East and North-East Greenland.