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

In palaeolimnological studies of closed-basin lakes, diatoms provide an exc ellent 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 comparis on with other proxy indicators, such as stable isotopes. The sensitivity of different lake systems to climate change (changes in the ratio of precipit ation to evapotranspiration) depends to a large extent on the character of the basin hydrology. Here, we compare evidence for Late Quaternary palaeohy drological change in two lakes which have contrasting groundwater hydrology , located in close proximity to each other in the Konya Basin, southern cen tral Turkey, and whose sediment core chronologies show considerable overlap . Suleymanhaci golu has alternated between being hydrologically closed and open during its history, and the diatom record shows clear evidence for cha nges 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 p ool, Pinarbasi, indicates that it remained fresh throughout the Late Pleist ocene; it is subject to major aquifer flow and behaves effectively as an op en system. In this case the complacency of the diatom record is important i n allowing inferences on temperature effects to be drawn from relatively su btle shifts in stable isotope values. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.