Open AccessTertiary igneous activity at Giesecke Bjerge, northern East Greenland
Author(s) -
Niels Hald
Publication year - 1978
Publication title -
bulletin of the geological society of denmark
Language(s) - English
Resource type - Journals
eISSN - 2245-7070
pISSN - 0011-6297
DOI - 10.37570/bgsd-1978-si-12
Subject(s) - porphyritic , geology , geochemistry , basalt , igneous rock , sill , plagioclase , pyroxene , breccia , lava , phenocryst , volcano , andesite , quaternary , petrology , olivine , volcanic rock , paleontology , quartz
The Tertiary igneous activity at Giesecke Bjerge, northern East Greenland, was initiated by the eruption of plagioclase--porphyritic hyaloclastic breccias and lavas with tholeiitic affinity. These were succeeded by transitional and mildly alkaline lavas, mainly ankaramites and pyroxene-olivine porphyritic basalts. Tholeiitic sills, possibly contemporaneous with the older lavas, were intruded in the sediments beneath the volcanic sequence. Both the lavas and the sills were cut by bas_altic dykes. The older lavas at Giesecke Bjerge are similar to the bulk of Tertiary lavas in East Greenland while the younger lavas show a resemblance to the Quaternary volcanic products of Jan Mayen. It is suggested that the formation and emplacement of the transitional and alkaline lavas were related to a WNW trending fracture system following Kejser Franz Josephs Fjord.