Coastal Alluvial Fans and Associated Marine Facies in the Miocene of S.W. Turkey

A thick sequence (c. 1000 m) of Miocene clastic sediments was derived from a Mesozoic ophiolitic complex during its tectonic emplacement. The upper 350 m of the sequence, the Kasaba Formation of Upper Miocene age, consists of a diverse assemblage of coastal alluvial fan and shallow marine facies. Alluvial fan deposits in proximal areas consist of dominantly clast-supported massive conglomerates, interpreted as stream deposits, interbedded with subordinate, matrix-supported conglomerate deposited by debris-flows. These pass down palaeoslope into interbedded conglomerates, sandstones and mudstones which form distinct fining-upward units up to 15 m thick. These are considered to have been deposited on an alluvial braid-plain. Pedogenic calcretes and reddened horizons attest to an arid or semi-arid environment. Shallow marine deposits are the downslope equivalent of the alluvial braid-plain sediments. Patch reefs which developed along the shoreline protected the shoreface from extensive wave and storm reworking. Offshore material finer than pebble gravel was reworked sporadically, probably by storm-induced currents. The overall depositional setting is interpreted to be a narrow coastal plain where alluvial fans prograded directly into a shallow microtidal sea.