Abstract
Geology and petrology of the Lower Tertiary plateau basalts of the Scoresby Sund region, East Greenland
Highlights
The basalts rest on Mesozoic sediments in the east and on Precambrian gneiss in the west
East of Terrassevig the Magga Dan and Milne Land Formations have sunk below sea level, and the south coast of Scoresby Sund is dominated by high, steep basalt cliffs of the Geikie Plateau Formation
The lavas in Scoresby Sund have a dominance of quartz normative flows in the lower part (Magga Dan, Milne Land and lower Geikie Plateau Formations) while the middle and upper part are almost exclusively olivine normative
Summary
The East Greenland Tertiary magmatic province stretches from Kap Gustav Holm in the south to Shannon in the north, a distance of approx. 1200 km (fig. 1). East of Terrassevig the Magga Dan and Milne Land Formations have sunk below sea level, and the south coast of Scoresby Sund is dominated by high, steep basalt cliffs of the Geikie Plateau Formation. It is probable that the activity in the south-east increased with time - the latest flows in the Geikie Plateau Formation in the Kap Dalton - Rømer Fjord area have no counterparts in the inland areas (Plate 2: titano-tholeiites in profile 102) and are considered local eruption products. The lavas in Scoresby Sund have a dominance of quartz normative flows in the lower part (Magga Dan, Milne Land and lower Geikie Plateau Formations) while the middle and upper part (most of Geikie Plateau, Rømer Fjord, Skrænterne and Igtertivå Formations) are almost exclusively olivine normative. In the north this magma type does not appear to have had a separate plumbing system, and the magma had probably migrated laterally from large storage chambers of this magma type in the Kangerdlugssuaq area (see section on origin of magma types)
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