Chronology and stratigraphy of Late Quaternary sediments in the Konya Basin, Turkey: Results from the KOPAL Project

The Late Quaternary environmental history of the Konya plain, in south cent ral Turkey, is used to examine sediment facies changes in a shallow non-out let basin which has experienced major climatically driven changes in lake e xtent. Two principal types of sedimentary archive are used to reconstruct a palaeoenvironmental record, namely alluvial sequences on the Carsamba allu vial fan and sediments from residual lakes. The latter have been used to in vestigate broader climatic and vegetational histories via palaeolimnologica l techniques including pollen, diatom and stable isotope analysis. These ch anges are dated here by radiometric techniques including radiocarbon (AMS a nd conventional), OSL, and U-Th. Chronological agreement is generally good between the different dating techniques, although typically there is greatl y reduced precision beyond ca. 25 ka. Lake sediment cores investigated have basal ages beyond the range of C-14 dating, but contain hiatuses as a resu lt of subsequent alternation between phases of lacustrine sedimentation and aeolian deflation. In contrast to most deepwater non-outlet lake systems, the Konya basin may have been occupied by a single extensive lake for as li ttle as 10% of Late Quaternary time, mainly around the time of the LGM. Thi s lake highstand was followed by an important arid interval. In the absence of unbroken chronostratigraphic sequences, palaeohydrological investigatio n of shallow non-outlet lakes may require analysis of basin-wide changes in sedimentation rather than reliance on single core records. Stratigraphic c ontinuity in such sedimentary environments cannot be assumed, and requires independent chronological control through radiometric dating. (C) 1999 Else vier Science Ltd. All rights reserved.