Larger foraminiferal palaeobiogeography of the Oligocene Western Tethys / Batı Tetis İri Bentik Foraminiferleri Oligosen Paleobiocoğrafyası

The Cenozoic shallow-water carbonate platforms of the Western Tethys are characterised by larger foraminifera (LF, benthic unicellular, eukaryotic, symbiotrophic organisms), which represent dominant benthic biogenic components of different facies successions. This study focuses on the origin of Oligocene LF faunas of the Mediterranean/Iranian area. Their distribution is outlined and the influence of the palaeoclimate, trophic and ecological gradients is evaluated. Porcellaneous imperforated and hyaline perforated LF assemblages are therefore investigated from the Mediterranean-Tethyan area. This area was characterized by four geographic connections with the Atlantic Ocean, North Sea Basin, Paratethys and Indo-Pacific Ocean. Data from a comprehensive literature survey show that the number of LF species underwent a latitudinal reduction in the Mediterranean–Tethyan region throughout the Oligocene. During the studied time slice, larger foraminiferal faunas generally show a diversity gradient from the southern Mediterranean–Tethyan margins to the northern Paratethys region reflecting both historical processes and ambient physical environments.