Early Tertiary lavas and sills on Traill Ø and Geographical Society Ø, northern East Greenland: petrography and geochemistry

Abstract

The Early Tertiary extrusion of flood basalts in East Greenland was accompanied by intrusion of numerous sills in the Upper Palaeozoic arid Mesozoic sediments of the N–S trending East Greenland rift zone. With a few exceptions the lavas and sills have low contents of Ti and other incompatible elements, indicating a genetic relationship with the lavas and sills north of Kejser Franz Joseph Fjord rather than with the lavas in the Scoresby Sund area. Two sills are described in greater detail. The first, from Geographical Society Ø, is 60 m thick and homogeneous throughout. The second, from southern Traill Ø, is more than 150 m thick and atypical as it ranges in composition from low-Ti tholeiite to diorite.