Latest Priabonian larger benthic foraminiferal assemblages at the demise of theSoğucak Carbonate Platform (Thrace Basin and Black Sea shelf, NW Turkey): implications for the shallow marine biostratigraphy

Abstract

The Eocene-Oligocene transition corresponds to a significant biotic turnover globally. In shallow marine realms, the larger benthic foraminifera (LBF) belonging to most nummulitids and all orthophragminids became extinct at or near the Eocene/Oligocene boundary, reflecting the environmental deterioration. We here record the advanced developmental stages of midlatitude LBF from the Soğucak Carbonate Platform in NW Turkey on the brink of their extinction in the Tethys. The LBF assemblages in the uppermost part of the platform, exposed in Gökçetepe and Karaburun in the Thrace Basin and Black Sea shelf, are represented by the dominant occurrence of

Biostratigraphy and paleoenvironments of the Oligocene succession(İhsaniye Formation) at Karaburun (NW Turkey)

“…Both Thrace and the Karaburun regions have a common shallow marine carbonate unit underlying the Oligocene sequence. This is the Soğucak Formation (Figure 8), agecalibrations by benthic foraminifera demonstrating that it is diachronous within the Middle-Late Eocene, although Priabonian in the Karaburun region Less et al, 2011;Okay et al, 2019;Yücel et al 2020). In the Thrace Basin, the Soğucak Formation is succeeded by a relatively thick regressive siliciclastic sequence ranging from Late Eocene to Early Oligocene in age ( Figure 8).…”

“…A succession approximately 60-m thick is well exposed within old quarries on Cape Karaburun to the north of Karaburun town where the limestones are massive to thickly bedded, with some beds consisting of coral bioherms. The occurrence of larger foraminifera (Heterostegina gracilis, Spiroclypeus carpathicus, Asterocyclina stella) enabled Less et al (2011), Okay et al (2019, and Yücel et al (2020) to assign the succession to Standard Larger Benthic Foraminifera Biozone (SBZ) 20 which suggests a latest Eocene (late Priabonian) age (Serra-Kiel et al, 1998) ( Figure 10). In our material from the uppermost Soğucak Formation at Cape Karaburun, we recorded Orbitolites sp.…”

Integrated biostratigraphy and benthic foraminifera of the middle-upper Eocene deposits of Urtsadzor section (Southern Armenia)

“…Most of these lineages are interpreted as species and arbitrarily subdivided into chronosubspecies by Less (1987Less ( , 1998. In recent years, the Bartonian and Priabonian orthophragmines have been studied by , Özcan et al (2006, 2018, 2019a), and Yücel et al (2020). The most updated summary of the subspecific subdivision of orthophragminid species (lineages) can be found in Zakrevskaya et al (2011), which is not repeated in the descriptions below provided no changes happened since then.…”

“…on the P-X (proloculus diameter versus the number of undivided postembryonic chambers) bivariate plot (X is on a logarithmic scale) with the specific subdivision of Eocene Spiroclypeus. Information on localities in Turkey and Europe was given by , Özcan et al (2010), Less et al (2011), and Yücel et al (2020).…”

Foraminifera of shallow and very shallow facies from the upper Eocene–lower Oligocene Kazandere Member, Soğucak Formation, Thrace Basin, northwest Turkey

“…Okay et al (2017) described in Çatalca the connection between the west Black Sea and the Thrace Basin during the late Eocene to the early Oligocene. Recently Okay et al (2020), Özcan et al (2020) and Yücel et al (2020) have investigated the biostratigraphy of foraminifera in the Thrace Basin.…”