Systematics, biostratigraphy and paleoenvironmental investigation of early Ypresian Alveolina assemblages in the northern part of Isparta Angle (Keçiborlu, Isparta, SW Turkey)

Abstract

Thanetian-early Ypresian (middle Ilerdian) limestones from the northern part of Isparta Angle (Keçiborlu, Isparta, SW Turkey) contain rich benthic foraminiferal assemblage. Ilerdian beds of the Büyükkırtepe formation are characterized by high diversity of the following Alveolina species: Alveolina (Glomalveolina) karsica, A. (G.) aff. karsica, A.(G.) lepidula, A.(G.) cf. subtilis, A. (Alveolina) aragonensis, A. (A.) cemali, A. (A.) corbarica, A. (A.) cf. coudurensis, A.(A.) decipiens, A.(A.) dedolia, A.(A.) ellipsoidalis, A.(A.) erki, A.(A.) guidonis, A.(A.) cf. ilerdensis, A.(A.) montanarii, A.(A.) moussoulensis, A.(A.) pasticillata, A.(A.) pisella, A.(A.) rotundata kazancii, A.(A.) trempina, A.(A.) varians, and A.(A.) vredenburgi. In this study, 30 different Alveolina species including two new species and a new subspecies namely as A. (A.) acari n. sp., A. (A.) ozbahcensis n. sp., and A.(A.) avsari fusunae n. ssp. were identified for the first time. Besides, some probable new subspecies that were unnamed yet due to the insufficient number of individuals were also defined and proposed. Despite having close stratigraphic distributions with coeval assemblages described in different regions of Tethyan Province, Alveolina assemblages of the study area exhibit some stratigraphical range differences and present SBZ 3-SBZ 8 biozone intervals. The obtained data show that the study area was a lagoon to low en rgy shallow marine paleoenvironment with normal salinity in Thanetian – middle Ilerdian interval.

Keywords

• alveolina
• biostratigraphy
• paleoenvironment
• eocene
• isparta.