[H-QR05] Quaternary, Diachronic dynamics of human-environment interactions

[HQR05-P15] Mid to late Holocene environmental reconstruction of central Anatolia in Turkiye using the diatom assemblages in Lake Eski Acigol ruins

*Kan Kinoshita¹, Kota Katsuki¹, Shiho Higashiura¹, Ryuji Tada², Kenta Suzuki², Toshihiro Tada², Nurcan Kucukarslan², Katsura Yamada³, Shuangning Tang ³, Sencer Sayhan⁴, Kimiyoshi Matsumura⁵, Sachihiro Omura⁵ (1.Shimane University , 2.Chiba Institute of Technology, 3.Shinshu University, 4.Kirsehir Ahi Evran Univ, 5.Japanese Institute of Anatolian Archaeology)

Keywords:Eski Acigöl, Diatom, Turkey, Paleo-climate, Hittites

Eski Acigol is a desiccated lake basin located in central Anatolia, Turkiye. It was a closed brackish lake before artificial drainage in 1972. In this research, the paleoenvironment, climate, and their social impacts of central Anatolia during the mid-to-late Holocene were reconstructed by using sediment cores (EA2301) obtained from the former lakebed of Eski Acigol. In August 2023, four sediment cores were collected from the lake basin by using a PC liner corer, and established a continuous sedimentary record reaching a depth of 5.6 m. Diatom analysis was conducted on the laminated sediments between 534 and 169 cm depth, with high-resolution (1 cm interval) analysis performed on selected layers. The total number of diatom valves per gram in core EA2301 fluctuated significantly at decadal to centennial scales. Overall, the total number of diatom valves showed high values in the late mid-Holocene and gradually declined. Finally, diatom valves in core EA2301 disappeared in the early late Holocene. Planktonic diatom taxa were mainly dominant in the late mid-Holocene. During the transition period from the middle to late Holocene, the dominant diatom taxa fluctuated between alkalophilic saline preferring taxa and epiphytic freshwater taxa. Total diatom valves increased when the epiphytic freshwater taxa dominated in this period. On the other hand, the alkalophilic saline preferring taxa temporarily increased in the sediment just below the layer where diatoms were absent. These findings suggest the following: The paleo Eski Acigol Lake reached its highest water level during the late mid-Holocene, experiencing centennial alternating phases of humid deep fresh lake conditions and semi-humid relatively shallow fresh lake condition. The climate gradually became drier toward the early late Holocene, and then, the paleo Eski Acigol Lake conditions fluctuated between relatively shallow freshwater and shallow alkaline saline lake. These environmental changes corresponded with past climate variations, which likely influenced the livelihoods and social dynamics of the Hittites who inhabited the region at the time. Therefore, this study discusses the relationships between regional climate variations and the history of ancient civilizations in the area.