An evaluation of the diatom response to Late Quaternary environmental change in two lakes in the Konya Basin, Turkey, by comparison with stable isotope data

Abstract

In palaeolimnological studies of closed-basin lakes, diatoms provide an excellent source of palaeoclimate data owing to their sensitivity to salinity and lake-level change. One of the best ways of assessing the relationships between diatom species response, salinity and lake-level change is comparison with other proxy indicators, such as stable isotopes. The sensitivity of different lake systems to climate change (changes in the ratio of precipitation to evapotranspiration) depends to a large extent on the character of the basin hydrology. Here, we compare evidence for Late Quaternary palaeohydrological change in two lakes which have contrasting groundwater hydrology, located in close proximity to each other in the Konya Basin, southern central Turkey, and whose sediment core chronologies show considerable overlap. Süleymanhacı gölü has alternated between being hydrologically closed and open during its history, and the diatom record shows clear evidence for changes in palaeoconductivity and lake level which correspond well to inferred changes in evaporative concentration during the Late Pleistocene and part of the Holocene. In contrast, the diatom record of the karstic spring-fed pool, Pinarbaşi, indicates that it remained fresh throughout the Late Pleistocene; it is subject to major aquifer flow and behaves effectively as an open system. In this case the complacency of the diatom record is important in allowing inferences on temperature effects to be drawn from relatively subtle shifts in stable isotope values.