Structure and stratigraphy of the Early Tertiary basalts of the Blosseville Kyst, East Greenland

Abstract

The central part of the 65 000 km 2 lava plateau in East Greenland between Kangerlussuaq and Scoresby Sund has been investigated by multi-model photogrammetry and profile sampling, and a three-dimensional framework for the lava plateau has been established. Post-volcanic movements have divided the region into several structural blocks with dips varying from 1–2° N-NE in the inland areas to 12°SE at the coast. A major N-S-trending fracture zone may reflect an underlying Caledonian structure. Early volcanic and sedimentary rocks are overlain by widespread plateau basalts, locally with an angular unconformity of 8°. The basalt stratigraphy established in the Scoresby Sund area has been extended over most of the region. The plateau basalts were erupted over a zone more than 150 km wide, from the present coast and inland. The succession attains a vertical thickness of more than 5.5 km in the central coastal areas and thins inland to 2–3 km. A differential sagging of the coastal areas by at least 2.3 km took place during the emplacement of the lavas, accelerating with time. The features suggest increasing focusing of the magmatic production into a developing rift zone close to the present coast.