Stratigraphic evidence for an Early Aptian sea-level fluctuation: the Graua Limestone of south-eastern Ethiopia

The occurrence of a thin band of marine limestone (Graua Limestone) within a thick succession of fluviatile sandstones in south-eastern Ethiopia is di rect evidence of flooding of part of the East African craton (Horn of Afric a). According to the presence of abundant orbitolinid foraminifers (Palorbi tolina lenticularis Blumenbach and Praeorbitolina cormyi Schroeder), the ag e of the Graua Limestone can be referred to the Early Aptian. Stratigraphy and palaeogeographic reconstructions for the Early Cretaceous in the surrou nding regions (Kenya, Somalia, Yemen, Socotra, Oman, Syria, Lebanon, Israel , Egypt and Libya) show that the Early Aptian transgression was of regional extent. Our data seem to confirm that this transgression was of relatively short duration. This pulse cannot be related to tectono-eustatic mechanism s, which are too slow. A short-lived event should be invoked: either a regi onal tectonic pulse or the desiccation of the proto-South Atlantic. (C) 199 9 Academic Press.