FINGERSEG, Fingerprinting Caledonian tectono-thermal events in South-East Greenland using low temperature U-Th/Pb and Ar/Ar Geochronology

The project FINGERSEG is a geochronology-based study funded by Geocenterbevilling 62017. Aim of the project is to find evidence of Palaeozoic (i.e. Caledonian) tectono-thermal overprint on rock-samples collected in South-East Greenland. The collaboration between GEUS and the Geological Museum gave the possibility to analyse rock samples for U-Th/Pb and Ar/Ar age dating in order to investigate low temperature thermal events in South-East Greenland.

The reason to investigate for Caledonian-age events in South-East Greenland was due to a new analysis (Thomsen and Guarnieri pers. comm.) of detrital rutile obtained from a dropstone of red beds collected in the Ammassalik area (Lat. 66ºN) in South-East Greenland (Dawes, 1986). The rock analysed for detrital zircon showed Archaean to Palaeoproterozoic ages but the U-Th/Pb age of detrital rutile resulted in robust Silurian ages (ca. 430 Ma) in addition to a single Palaeoproterozoic rutile age at 1800 Ma. This surprising result came from an erratic rock, probably transported from the north-west, suggesting that such a type of rocks should be present nearby under the ice cap.