Multidisciplinary approach for palaeoclimatic signals of the non-marine carbonates: The case of the Sarıkavak tufa deposits (Afyon, SW-Turkey)

Abstract

Non-marine carbonates such as travertine, tufa and speleothem are quite sensitive for climatic fluctuations. This study presents the new dating and the first pollen records from Afyon (Sarıkavak) tufas, SW-Turkey, together with lithofacies descriptions, geochemical and petrographic results obtained from drilling cores (SL-2, SL-6 and SL-7). The data extensively provides insight into palaeoenvironmental and palaeoclimatic changes during the Middle-Late Pleistocene period. According to core samples, these fluvial tufa occurrences formed in high-gradient and stepped fluvial conditions have been defined as barrage-dammed and terraced-slope systems in the investigated area. The depositional lithofacies are moss tufa included macrophytes, bryophytes and vertical stems, phytoclastic tufa, peloidal tufa, micritic tufa, microbial tufa, intraclastic tufa, extra-formational tufa, lime-muddy clay and paleosol level, in respectively. The new U/Th radiometric dating and stable isotopes are evaluated together with previously published results. In regard to new radiometric data, tufa deposits occurred predominantly during the Marine Isotopic Stages, at 313.3 ± 21 (MIS 9), 295.8 ± 63 (MIS 8-9), 230.8 ± 42 (MIS 7d-e), 228.8 ± 12 (MIS 7d), 215.7 ± 17 (MIS 7c) and 188.2 ± 16 (MIS 6-7a) ka, respectively. The climatic changes occurring between glacial and interglacial periods (such as during the Middle –Late Pleistocene) might probably influenced the precipitation of tufas in the area. In addition, the less negative and the more positive carbon isotopic values (between -0.8 and + 1.3‰ V-PDB) could be related to the progressive downstream CO2 degassing from host rocks, enhanced by high-velocity current conditions, changes in the soil-CO2 contribution and photosynthesis. The changes of ?18O values (between -8.3 and -10.1‰ V-PDB) are most probably related to variable effects of evaporation in depositional environment. Palynofloral data, gives important clues about the paleovegetation and paleoclimate of the region. This field survey has been conducted the first time in this area. Both carbon values and palynological findings show that drought conditions were dominantly present in the Pleistocene period, but in some processes drought conditions decreased depending on the amount of rainfall. The increasing amount of gymnosperm pollens is more likely to appear in more humid conditions due to the decreasing of drought condition in this time interval. © 2019