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    Late Paleocene Orthophragminae (foraminfera) from the Haymana-Polatli Basin, central Turkey) and description of a new taxon, Orbitoclypeus haymanaensis
    (MICROPALEONTOLOGY PRESS, 2001) Ozcan, E; Sirel, E; Altiner, SO; Colakoglu, S
    A transgressive shallow-marine succession suggested as a reference-section for early Thanetian by the 'Early Paleogene working group' (IGCP 286) was studied for its orthophragminid foraminifera from Haymana-Polath Basin in central Anatolia. Orthophragminae, closely associated with Assilina yvettae and Operculina heberti, have been identified in a friable clastic-carbonate sequence which contains Glomalveolina in its different horizons. Basinal sediments with planktonic taxa overlie the shallow-water deposits and preclude the study of orthophragminae higher in the succession. Orthophragminae, studied in oriented sections, were grouped into four categories considering the qualitative and quantitative aspects of megalospheric embryo and morphologic elements of equatorial and lateral chamberlets in equatorial and partly vertical sections. Thus, Discocyclina seunesi, Orbitoclypeus neumannae and Discocyclina sp.l have been identified and a new species, Orbitoclypeus haymanaensis, is erected. These assemblages were dated to Thanetian based upon the calcareous nannofossil and planktonic foraminifera identified in the overlying basinal sediments and also the benthonic foraminifera either associated with orthophragminae or present in different horizons of the shallow-marine succession.
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    Orthophragminid foraminiferal assemblages from an Ilerdian-early Cuisian reference section (Sakarya section, Haymana-Polatli Basin, central Anatolia-Turkey)
    (UNIV STUDI MILANO, 2003) Colakoglu, S; Ozcan, E
    The Sakarya section represents a highly fossiliferous part of the Haymana-Polath Basin succession (central Anatolia), consisting of mainly nummulitid, alveolinid and orthophragminid foraminifera. This section formerly proposed to serve as a reference section for early Ilerdian-early Cuisian Shallow Benthic Zones in Turkey by the 'Early Paleogene working group' was studied for its orthophragminid foraminifera, and a sequence of populations has been subjected to biometric analysis of the embryo and equatorial chamberlets. Discocyclina, which occurs throughout the section, is mainly represented by primitive specimens of Discocyclina archiaci, D. archiaci bakhchisaraiensis and Discocyclina sp.1 in the lowermost part, which is regarded as of middle Ilerdian age (orthophragminid zone 3). Upwards, different developmental stages of D. archiaci; transitional developmental stages of D. archiaci bakhchisaraiensis-staroseliensis and D. archiaci staroseliensis are accompanied sporadically by unribbed Orbitoclypeus, O. schopeni suvlukayensis and Discocyclina sp.1. This part of the section is regarded as middle-late Verdian in age (orthophragminid zone 4). A more diverse assemblage, represented by Nemkovella, Asterocyclina, ribbed and unribbed Orbitoclypeus accompanied by different Discocyclina species occurs in the uppermost part, which is thought to represent the transitional late Ilerdian-early Cuislan orthophragminid zones (orthophragminid zones 4/5). In these horizons, N. strophiolata fermonti, N. evae, primitive developmental stages of D. augustae sourbetensis, O. douvillei douvillei, D. fortisi fortisi, A. stella and O. munieri munieri are accompanied by D. archiaci staroseliensis, transitional developmental stages of D. arcbiaci staroseliensis-archiaci, O. scbopeni suvlukayensis and Discocyclina sp. 2. Biometric data allow refinements with respect to the stratigraphic ranges of some discocyclinid and orbitoclypeid foraminifera. This paper records the first descriptions of orthophragminids from the middle-late Ilerdian/early Cuislan marine deposits of Turkey.