Abstract
A historical review of geological research in North Greenland is followed by a summary of the main results of the 1978-80 GGU expeditions to the region. New outcrops of Archaean and early Proterozoic crystalline rocks are recorded only as xenoliths in dykes and volcanic centres. A revised stratigraphy is applied to the middle Proterozoic Independence Fjord Group sandstones, while petrographic and isotopic studies have been made of the cross-cutting Midsommersø dolerites and the overlying Zig-Zag Dal Basalt Formation. No convincing evidence has been found of a Carolinidian orogenic episode separating these units from succeeding late Proterozoic sedimentary sequences. Lower Palaeozoic sediments dominate North Greenland and are divided into southern shelf and northern trough successions; new or revised stratigraphies are now applied in both settings. The shelf-trough boundary can be shown to have moved south with time, and a major early Silurian expansion of the trough is related to shelf subsidence and a new phase of turbidite deposition derived from the rising East Greenland Caledonian mountains. Devonian - Middle Carboniferous (Ellesmerian) deformation brought deposition to a close and created the North Greenland fold belt, in which deformation intensity and metamorphic grade increase northwards. Thin-skinned thrusting in association with west or south-facing folds is important in southern areas; this is one of the main differences in interpretation compared to earlier work in the fold belt. New outcrops of post-ElIesmerian sediments (Wandel Sea Basin) have mainly been recorded as fault or thrust bounded sequences; a new stratigraphy is applied to the Wandel Sea Basin succession. Cretaceous - Tertiary events include a suite of volcanic centres, dyke swarms, the Kap Washington Group volcanics, and faults and thrusts of Tertiary (Eurekan) age; all have been studied anew, as have the Quaternary deposits.
Highlights
Greenland, north of latitude 80oN, is one of the world's most remote regions and generally difficult of access
The results of the GGU expeditions include a 1:500 000 geological map of Peary Land and four special 1:100000 map sheets; in addition there has been a considerable increase in knowledge in virtuaIly every aspect of North Greenland geology, resulting in a flood of new publications describing stratigraphy, structure and petrology
Detailed field work suggests that the Carolinidian orogeny as defined by Haller (1961) has not affected the rocks of eastern North Greenland; Jepsen & Kalsbeek state that no evidence has been found to support the concept of this late Proterozoic orogenic episode
Summary
North of latitude 80oN, is one of the world's most remote regions and generally difficult of access (fig. 1). North of latitude 80oN, is one of the world's most remote regions and generally difficult of access A gradual increase in geological activity took place during the 1970s, much of it in preparation for the major GGU expeditions to central and eastern North Greenland in 1978-80 and central and western North Greenland in 1984-85. A brief review of the principal geological results of the 1978-80 expeditions is presented here A brief review of the principal geological results of the 1978-80 expeditions is presented here (fig. 2)
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