Late Eocene to Late Miocene palaeoecological and palaeoenvironmental dynamics of the Eregli-Ulukisla Basin (Southern Central Anatolia)

The Eregli-Ulukisla Basin which is the focus of this study is situated at the south-eastern edge of the Central Anatolian Cenozoic basins (Tuzgolu, Haymana, cankiri-corum, and Sivas), and is divided into two sub-basins, the Aktoprak (AT) and Hacibekirli-Tepekoy (HT). These sub-basins mainly comprise a stratigraphically discontinuous and laterally variable series, represented by 'fluvio-lacustrine' siliciclastic and carbonate sediments deposited over a wide range of environments, including meandering and braided rivers, coastal fluvial and fan deltas, mixed carbonate-siliciclastic shores, dry lake flats, and coal-bearing swamps. In the Eregli-Ulukisla Basin, higher palaeotopographic conditions existed in the AT because of the uplift of the Central Anatolian Plateau during late Middle Miocene (Serravallian)-early Late Miocene (Tortonian) and the subsequent uplift of the Taurus Mountains in the latest Miocene (Messinian) as deduced in the Tepekoy region (northeast) of the HT sub-basin. Diversity and abundance of archaic pollen (Normapolles) in the pollen biostratigraphy decreased from the Eocene to Oligocene, while forms with advanced angiosperm morphology (post-Normapolles), were observed with the increase in post-Normapolles during the Miocene. The dominance of woody angiosperms in the pollen assemblages, and increasing variety and abundance of 'open herbs' and shrub pollen from the Early Miocene to Late Miocene defines an important change in flora. Furthermore, the palaeoclimatic conditions changed from humid-subtropical to warm-temperate during the sediment deposition in the Eregli-Ulukisla Basin. Recurrent arid phases during the Late Miocene are indicated by the deposition of reddish caliche conglomerates in broad dry lake flats (HT), and evaporites in local playa lakes (AT), respectively.

Automated summary

The Eregli-Ulukisla Basin in the southeastern Central Anatolian Cenozoic basins is divided into two sub-basins with different palaeotopographic conditions, showcasing changes in flora and climate during the Late Miocene. The study reveals a transition from archaic to advanced angiosperm morphology in pollen assemblages along with recurrent arid phases during sediment deposition.