Environmental, vegetational and climatic investigations during the Plio-Pleistocene in SW-Anatolia: A case study from the fluvio-lacustrine deposits in Usak-Karahalli area

Abstract

The Plio-Quaternary fluvio-lacustrine sediments located in the Usak-Karahalli area (SW- Anatolia) have been investigated with multidisciplinary approaches to highlight their depositional processes and palaeovegetational history. For this purpose, samples from seven different core sites drilled in the area have been used besides field observations. According to sedimentological analysis, three depositional environments were determined: alluvial fan, fluvial and lacustrine. The first two of them are mainly composed of Pliocene aged coarse-medium grained clastics. In the meantime, lacustrine deposits mainly composed of Pliocene aged fine-grained clastics (mudstone, coal), and carbonates (clayey limestone, marl) were deposited. Later, (?)Early-Middle Pleistocene aged clayey limestone, marl, and travertines were precipitated in this lacustrine system. The Th-230 measurements on travertines obtained from core samples indicate that these terrestrial carbonates continued to precipitate during the Middle Pleistocene (similar to 288 ka). Moreover, Pliocene palynoflora is mainly represented by hydrophytic plants and gymnosperms, according to palynological investigations. These palynomorph association could be indicated the swamp environment and low-middle altitude area souround the deposition area. The Middle Pleistocene (MIS 10) microflora unlike the Pliocene palynoflora is characterised by widespread open vegetation areas consisted of herb plants in general. The palaeoclimatic signals in the Usak-Karahalli area during the Middle Pleistocene show that temperate climate mainly prevailed, and also the humidity has changed from dry to wet. All findings suggest that the sedimentation of clastic and carbonate deposits is influenced by topography, tectonic activity, and climate. Tectonic structures such as growth faults have very important role in the lake infill, causing subsidence, which affected the sedimentation rate. Additionally, hydrothermal water influx played an important role in forming travertine precipitation and this could be strongly concerned with the active fault systems in the study area.