Miocene Brackish Water and Lacustrine Deposition in the Suez Rift, Sinai, Egypt

Abstract

Abstract From its inception during the early Miocene, the Suez Rift has been dominated by marine sedimentation. New high-resolution biostratigraphic and sedimentologic analyses of synrift deposits have resulted in the recognition of late Burdigalian-early Langhian brackish water and lacustrine deposits in the Wadi Abu Gaada-Gebel Gushia area, Sinai Peninsula. The Abu Gaada section is unique because: (1) it is an anomalously thick section of non-calcareous shale and mudstone in the Lagia Member of the Ayun Musa Formation; and (2) the mudstones contain an abundant microflora consisting of marine and nonmarine diatoms and freshwater algae that indicate they were deposited in a freshwater to brackish water environment. The abundant freshwater and shallow marine algae include the nonmarine diatoms Aulacoseira Thwaites, Fragilaria construens (Ehrenberg) Grunow, Synedra ulna (Nitzsch) Ehrenberg, and SurrirellaTurpin, as well as the freshwater algae Botryococcus Kutzing and Pediastrum Meyen. Shallow marine diatom...