The evolution of the East Greenland margin as revealed from fission-track studies

Abstract

A comprehensive dataset of fission-track analyses (mainly of apatite) covers the East Greenland margin between ca. 73°N (Geographical Society Island) and ca. 63°N (Skjoldungen). It consists of data from Archaean and Caledonian basement, post-Caledonian sedimentary rocks and magmatic rocks. The studied areas represent different aspects of the East Greenland evolution. We report new apatite fission-track (FT) analyses from the East Greenland gneissic basement south of Scoresby Sund to Skjoldungen and put them into context with existing data. A regional pattern along the East Greenland continental margin south of 73°N of deeply eroded shorelines and highstanding slowly eroding hinterland with remnants of old peneplain surfaces is overprinted in the central Kangerlussuaq area by Tertiary magmatic activity. To the northeast, the thermal evolution is dominated by a domal structure shown by apatite fission-track (FT) ages to have cooled in the Neogene. This pattern may result from rapid erosion of the locally uplifted basaltic pile in the area and heating caused by late sill intrusions, possibly enhanced on a regional scale by climatic deterioration. In the hinterland to the south and west of Kangerlussuaq, the data restrict the basalt cover to <ca. 2 km. The observed change in regional thermal evolution at Kangerlussuaq coincides with a marked change in other geological and geophysical parameters and may indicate the locus of an old deep-seated tectonic structure at Kangerlussuaq.