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A Lower Pleistocene to Holocene terrestrial record from the Eskişehir Graben (Central Anatolia): Paleoclimatic and morphotectonic implications

Ocakoğlu, Faruk, Akkiraz, Mehmet Serkan
Quaternary international 2019 v.510 pp. 88-99
carbonates, climate change, floodplains, forests, paleoclimatology, pollen, primary productivity, risk assessment, soil, vegetation cover, Turkey (country)
As one of the rare terrestrial archive with continuous sedimentation back to almost 1 Ma in Anatolia, the Eskişehir Graben was investigated in outcrops and cores by multi-proxy analysis regarding chronology and paleoclimatology. The present study comprises significant implications for both the impact of climate changes on fluvial systems in the timescales of the Milankovitch band and the controversial age and rate of the crustal extension in western Anatolia. Our findings indicate that LOI950 and δ18Ocarb, which are indicators for the amount of soil carbonate and paleo-temperature respectively are collectively capable of distinguishing between glacial and interglacial periods in the predominantly floodplain deposits of the graben infill. Secondarily, LOI550 and δ13Ccarb values further help this discrimination via primary production and composition of vegetation cover respectively. Pollen data, albeit highly discontinuous due to poor preservation under subaerial conditions, point out a steppe-like vegetation cover where the forest components expand particularly in the wet interglacial periods. In the other hand, the chronological frame provided by astronomical calibration of certain proxy-records strongly suggest that the Eskişehir Fault Zone initiated as a boundary fault of a half-graben some 900 ka. The rate of vertical movement on its southern branch since the last 70 ka is unexpectedly high (2.3 mm/a), a phenomenon that requires urgent risk assessment analysis in the vicinity of the Eskişehir city.