Aeolian morpho_logy preserved by lava cover, the Precambrian Mussartut Member, Eriksfjord Formation, South Greenland

Abstract

Investigations of sedimentary deposits in elastic interval 5 of the Mussartilt Member have revealed the occurrence of aeolian sandstones. The aeolian deposits rest on pebbly sandstones and conglomerates of fluvial origin, and the are sharply overlain by a c. 70 m thick lava flow. The aeolian sandstones comprise up to 10 m thick and 200 m wide dome-shaped bodies that are initiated by thin and patchily preserved aeolian sand sheet deposits. The bulk of the aeolian sandstone bodies constitute low-medium-angle, dipping lee-side deposits of dome-shaped dunes. The dome-shaped dunes migrated towards a zone of distal alluvial fans perhaps during the influence of prevailing NE trade winds. Superimposed smaller-scale dunes formed during periodic strong winds from the E. Erosion of the dunes at the base of the lava flow was insignificant and most of the original dome-shape form of the dunes seems to have been preserved. The dome-shaped dunes may represent part of a migrating erg system, but continued dune migration was stopped by extrusion of the lava flow.