Mid to late Holocene water level and inferred climate changes of Lake Salda (SW Anatolia/Turkey): evidence from high-resolution seismic and sediment-core records

The sedimentary sequence in Lake Salda has been first documented in detail by analyses of high-resolution seismic profiles and sediment cores together with onshore outcrops along the present shoreline of the lake. Such a multi-proxy approach provides a strong record of changing lake levels and depositional conditions in Lake Salda during the mid to late Holocene. The accurate determination of water-level oscillation and climate conditions relies on the confident deduction from C-14-dated onshore outcrops and sediment cores, which provide calibration for the chronostratigraphic units within high-resolution seismic records. The existence of a dry climate period during the transition from the middle to late Holocene caused the lake level to decrease until 1690 cal years BP. This prominent climate deterioration induced coastal progradation in the lake as inferred from the deltaic sequences in the high-resolution seismic record and favored stromatolite formation, given its oligotrophic water condition. The resultant lowstand of lake level during the late Holocene timely coincided with the Roman Climatic Optimum when a prominent erosional truncation surface and channel incision were formed as observed from the seismic profiles. The late Holocene, during 1690-1050 cal years BP, is represented by a transgressive condition due to lake-level increase, giving rise to a retreat of the deltaic deposit further inland. The ongoing deepening of the lake by contributions of both climate and tectonic activity during the last 650 cal years BP produced Gilbert-type fan deltas along the shoreline and a transgressive sedimentary unit with typical onlapping architecture in the seismic reflection profiles.