Mesozoic Evolution of Northeast African Shelf Margin, Libya and Egypt

Rolf K. Aadland, Steven Schamel

The present tectonic features of the northeast African shelf margin between the Nile delta and the Gulf of Sirte are products of (1) precursory late Paleozoic basement arches, (2) early Mesozoic rifting and plate separation, and (3) Late Cretaceous structural inversion. The 250 km-wide and highly differentiated Mesozoic passive margin in the Western Desert region of Egypt is developed above a broad northwest-trending Late Carboniferous basement arch. In northeastern Libya, in contrast, the passive margin is restricted to just the northernmost Cyrenaica platform, where subsidence was extremely rapid in the Jurassic and Early Cretaceous. The boundary between the Western Desert basin and the Cyrenaica platform is controlled by the western flank of the basement arch. In the mi ddle Cretaceous (100-90 Ma), subsidence accelerated over large areas of the Western Desert, further enhancing a pattern of east-west-trending subbasins. This phase of rapid subsidence was abruptly ended about 80 Ma by the onset of structural inversion that uplifted the northern Cyrenaica shelf margin and further differentiated the Western Desert subbasin along a northeasterly trend.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.