Cenomanian canaliculate rudists (Bivalvia) from the Geyik Dağı-Hadim area (Central Taurides, S Turkey): systematic paleontology, stratigraphic importance and depositional environment

Abstract

A rudist fauna consisting of Cenomanian canaliculate rudists is described from the Geyik Dağı-Hadim area, Central Taurides-south of Turkey. The stratigraphic section was measured on the eastern slope of Geyik Dağı, at an altitude of about 2700 m. The rudists are observed in the uppermost part of the Bajocian-Cenomanian Polat Limestone of the Anamas-Akseki autochthon (=Geyik Dağı unit). In the study area, only the Cenomanian part of the Polat Limestone crops out. The rudist-bearing limestones are overlain with sharp contact by the Maastrichtian-Lutetian pelagic Kuşça Limestone. The rudist fauna consists mainly of canaliculate rudists such as ichthyosarcolitids (I. triangularis, I. monocarinatus, I. bicarinatus, I. rotundus), caprinids (Caprina baylei, Caprina cf. schiosensis, Sphaerucaprina woodwardi) and caprinulids (Caprinula sharpei, Neocaprina gigantea). Rudists are dominant and are accompanied by nerineid gastropods, corals and Conicorobitolina conica. The fossil content indicates an early-middle Cenomanian age for the rudist-bearing limestones, contrary to the Campanian-Maastrichtian age previously suggested. Four main lithofacies have been recognized: (1) scarce ichthyosarcolitid-gastropod packstone, (2) canaliculate rudist packstone-floatstone-rudstone, (3) packstone-grainstone-rudstone with canaliculate rudist-gastropod-coral fragments and whole shells and (4) mixed canaliculate rudist-gastropod-coral fragments rudstone-grainstone and rudstone. The facies characteristics indicate a middle carbonate ramp depositional environment with slightly to moderately and strongly agitated-water conditions for the rudist-bearing limestones. Their faunal and facies characteristics shows similarities with those from central region of the Mediterranean Tethys.