Upper Cretaceous rudist carbonate ramp facies in the SE Anatolia, Turkey: a comparison with the Arabian platform facies

Our recent studies on the stratigraphy and facies characteristics of the Mardin Group (Derdere and Karababa formations) around Kilis, Mardin, Adıyaman and K.Maraş show that the rudist-bearing limestones are widely distributed in the Upper Cretaceous of the Arabian Platform in SE Anatolia. Macro and microfacies analysis indicate a shallowing upward sequences through the upper parts of these formations which are characterized by the presence of rudists and their fragments. Up section of the Derdere Formation in the Sabunsuyu (Kilis) and Derik (Mardin) localities consists mainly of the packstone-floatstone-rudstone with recumbent ichthyosarcolitids forming a large cluster in a thick bed, rare elevator and isolated indivudials of radiolitids, indicating a middle-late Cenomanian age. They appear toppled and locally oriented, but could be considered deposited not far from their original environment. Rudists are accompanied by red algae, benthic foraminifera, gastropods, echinoids, bivalves and roveacrinoids. Planktic foraminifers and calcispheres are very scarce. The middle and upper parts of the Karababa Formation consist of the wackestone-packstone-floatstone with elevator radiolitids and hippuritids in growth position and their fragments suggesting a Coniacian-Santonian age. Large clusters in the Sabunsuyu (Kilis) section and small bouquets in the Derik (Mardin) section with the elevator radiolitids are commonly observed. Requieniids and indeterminable bivalves are also present. Hippuritids and radiolitids are usually elevator isolated individuals in the Saytepe (Adıyaman) section. Actaeonellid gastropods, benthic foraminifers, echinoids and algae are present in these rudist-bearing limestones. The facies characteristics indicate that the rudist-bearing limestones were deposited on a gently sloping mid-carbonate ramp on the northern shelf of the Arabian platform. It has a very shallow marine environment with varying energy conditions ranging from the slightly to strongly agitated during the middle-late Cenomanian and Coniacian-Santonian. The carbonate ramp rudist facies of SE Anatolia shows close similarities with those of the Arabian platform