Abstract A collection of terrestrial and freshwater snails from the Late Eocene to earliest Early Oligocene Zalumah Formation at Wadi Darbat, near Salalah, Oman is of importance on account of its taxonomic composition, its palaeoecological indications and its biogeographic affinities which are clearly tropical African; these are very different from the extant non-marine snail fauna of Oman which is typical of the Mediterranean belt. In addition, these fossil snails are by far the oldest-known representatives of their respective genera. The Late Eocene Zalumah deposits which yielded the molluscs accumulated just above sea level, as revealed by the admixture of marine, brackish water and freshwater taxa as well as fully terrestrial gastropods. These deposits now vary in altitude from near sea level at Taqah (Wadi Darbat) to over 930 m at Thaytiniti. Uplift of the Dhofar Plateau therefore must have occurred later than the Early Oligocene. The biogeographic affinities of the snails confirms that the Arabian Peninsula was part of the African continent at the time of deposition and that the opening of the Red Sea and the Gulf of Aden occurred later than the Early Oligocene.

Abstract In western Turkey, the Alaşehir and Büyük Menderes grabens form east–west trending major tectonic structures. Their sedimentary fill is important for regional tectonic models for the late Cenozoic evolution of the Aegean region. These deposits are divided into four units dated between the early Miocene and Quaternary. We studied the magnetostratigraphy of two sections in the Alaşehir graben and one in the Büyük Menderes, partly covering the first and second sedimentary units. Detailed palaeomagnetic analysis allowed us to determine ChRM component for these rocks. The Zeytinçayı river and road sections (Alaşehir graben) record several polarity reversals, which are tentatively correlated to the interval C5Cn.3n–C5ADr (approximately between 14.6–16.6 Ma) of the ATNTS2004. This correlation is also supported by palaeontology and radiometric dating of syn-extensional intrusions. In the Eycelli section (Büyük Menderes graben) only three polarity zones are recorded, and their tentative correlation with the interval of C5Bn.1r–C5Br (14.88–15.97 Ma) is in overall in agreement with the record of Eskihisar sporomorph association in this formation. These results place the initiation of the Alaşehir and Büyük Menderes grabens in the early Miocene. The palaeomagnetic declinations from the Alaşehir graben indicate about 25° anticlockwise rotation, whereas that of the Büyük Menderes graben indicate a clockwise rotation of about 30–40°. These contradictory vertical-axis rotations might be explained by detachment faults in the region. In Tertiary formations of western Turkey, contradictory block rotations are common and likely reflect thin-skinned deformation in the area rather than rigid crustal movements. Therefore, average anticlockwise rotations in western Turkey cannot be used as evidence for the model of back-arc spreading in the Aegean region.