From Pleniglacial to Holocene: a C-14 chronostratigraphy of environmental changes in the Konya Plain, Turkey

In the endoreic, semi-arid Konya basin on the central Anatolian plateaux, l ong-term hydrological evolution has left various landforms and lacustrine d eposits reflecting the regional climatic evolution, as well as human influe nce on the local environments. This paper presents results from a cooperati ve programme grouping several institutes from Turkey and France, on lacustr ine, marshy and aeolian sediment sequences of Upper Pleistocene and Holocen e age. The detailed study of environmental evolution is based on the recons truction as well as on the characterization of the extension and contractio n phases of wetlands occupying the lowest parts of the Konya plain. A soil and a marsh layer are C-14 dated ca. 28,000 to 25,000 yr sp. Three phases o f Pleniglacial (from ca. 22,000 to 17,000 yr sp) high lake levels are disti nguished. Complementary OSL dates on aeolian dunes confirm the occurrence o f two drought periods: the first occurs around the start of the Late Glacia l, the second after the Mid-Holocene climatic optimum, the latter being 'in phase' with a similar drought in other Eastern Mediterranean regions. Afte r 17,000 yr sp, no lacustrine phase reached as high a level as the Plenigla cial lake. During the Late Glacial, a shallow freshwater lacustrine phase i s identified from >12,500 to 11,000 yr sp. The Late Glacial to Holocene tra nsition corresponds to a general absence of deposits and dateable material, thus suggesting a period of drought, to which no aeolian features have so far been related. The Holocene environmental evolution shows a period of ma rsh and shallow lake extansion from 6000 to 5500 yr sp; this wetter period is interrupted by the second drought (ca. 5500 yrs sp) as indicated by aeol ian dune activity. During the Late Holocene, a renewal of marshes, as well as soil development on slopes, can be interpreted either as climatic change s or as impacts of human use of water and soil resources during prehistoric and historic times. (C) 1999 Elsevier Science Ltd. All rights reserved.