Cyclic sedimentation in a large wave- and storm-dominated anoxic lake; Kap Stewart Formation (Rhaetian-Sinemurian), Jameson Land, East Greenland

During Rhaetian-Sinemurian times a large wave- and storm-dominated lake was situated in the Jameson Land Basin, East Greenland. Sandy and pebbly alluvial material was transported into the lake from source areas to the east, west and north. Lake deposits consist of alternating black unfossiliferous mudstones and sheet sandstones. A high-resolution sequence-stratigraphic interpretation of the succession suggests that the mudstones were deposited in periods of rising and large highstands of lake level, whereas progradation of the deltaic sheet sandstones took place during forced regressions, caused by significant falls. The lake thus experienced abundant high-frequency and fairly high-amplitude changes in level. These high-frequency lake-level changes may reflect Milankovitch-type climatic cycles. The lake-level curve is interpreted to show a high-periodicity climatically induced signal superimposed on a long-periodicity eustatic signal. -from Authors