Upper Cretaceous planktonic foraminiferal biostratigraphy from NW Turkey: calibration of the stratigraphic ranges of larger benthonic foraminifera

Planktonic and larger benthonic foraminifers of the Upper Cretaceous (Santo nian-Maastrichtian)-Lower Tertiary (Danian) rock units from north, northwes t and central Anatolian fore-are basins have been investigated in order to improve the biostratigraphic resolution of this time interval. Total abunda nce and diversity of planktonic foraminifers vary from rare (the sequence f rom the Haymana region) to high (the sequences from the Cide, Caycuma, Hano nu and Yenikonak regions) and preservation is poor to moderate due to litho logic variation. First and last appearances of the planktonic foraminifera evaluated as major bio-events have been used to establish the biostratigrap hic framework. Planktonic foraminiferal zonation from bottom to top of the succession consists of zones defined by Dicarinella concavata, Dicarinella asymetrica, Globotruncanita elevata, Globotruncana, ventricosa, Radotruncan a calcarata, Globotruncanella havanensis, Globotruncana aegyptiaca, Gansser ina gansseri, Abathomphalus mayaroensis and Morozovella pseudobulloides. Te n Orbitoides and Lepidorbitoides species have been identified. The differen t phylogenetic development stages of Orbitoides and Lepidorbitoides populat ions and other larger benthonic foraminifers, Pseudosiderolites vidali, Sid erolites calcitrapoides, Siderolites denticulatus, Omphalocylus macroporus, Cideina sozerii, Hellenocyclina beotica, and Clypeorbis mamillata have bee n calibrated with the planktonic foraminiferal zonation established in the same successions. Hence, an integrated zonational scheme composed of plankt onic foraminifers and larger benthonic foraminifers has allowed a detailed stratigraphy of these successions to be erected. Copyright (C) 1999 John Wi ley & Sons, Ltd.