Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı 2

Lıtho-Bıo-Chemo-Stratıgraphıcal Propertıes Of Lake Bafa Sedıments And Quaternary Ecosystem
Lake Bafa is characterized as one of the largest inland lakes around the Aegean coast of the Eastern Mediterranean. Contemporarily, lake exhibits the maximum water depth of 21m and a surface area of about 70 km2. Litho-bio-chemical stratigraphical characteristics of the lake sediments are investigated within the frame of the study. Furthermore, time dependent changes in lake and surrounding paleoecological processes are identified. Wihtin the purpose, collected cores (karot numaraları) and dirilled section from the western swamp area ((BAP (ACİP): 17828 project, TÜBİTAK 113Y070 project and BAP (YADOP) 37190 project)) were used. High resolution sample set (2cm resolution) were identified in terms of lithological characteristics of the sediments, such as colour, water content, shells. Furthermore grain size distributions are investigated for BAF37, BAF17, BAF15, BAF9, BAF3 cores. Benthic foraminifera distributions were determinated to reconstruct the biostratigraphical frame of the study. Furthermore, sediments were characterizied applying ICP-MS, SHIMATZU and inorganic carbon analysis. Analytical dataset were used to identify the energy level, clastic input, water salinity, primary weathering conditions, redox conditions and organic matter productivity.
First 50cm interval indicates characteristic swamp muds with plant residues. 50-712cm interval was characterisied as laminated lake sediments, laminated clay-silt intercolations and sand layers. Detailed characterisation of the lake sediments indicates high water containing homogenous clays (0 to 90cm interval), greenish homogenous and organic matter rich black clays (370 to 417cm interval), and dark banded or laminated and shell containing fine and coarse clays. Sediments collected along an east west direction within the lake indicates enhanced grain size distribution through the eastern parts, probably related to shallow water conditions. Furthermore, chemical composition of the sediments would allow us to determinate energy level, sediment input, water chemistry. Selected parameters in the sediments collected from the BS section indicates variations of sediment supply (K/Al; 0.2-0.1, Ti/Al; 0.07-0.03), eolian affect (Zr/Al;29.0-8.0) and energy level (Zr/Rb 4.5-1.0). Same parametres are determinated in the different ranges along the recent lake sediments ( K/Al;0.3-0.2; Ti/Al; 0.05-0.04; Zr/Al; 9.0-6; Zr/Rb; 1.0-0.3). Additionally, redox conditions and salinity variations are determinated in similar ranges in recent lake sediments and swamp section (BS:Th/U;5.0-2.5, Mg/ Ca;0.7-0.2; BAF37: Th/U; 5.7-1.5, Mg/ Ca; 0.4-0.2). Lithostratigraphical and biostratigraphical corelations within the previous studies indicated that the sediment archive records the last 5750 years. Biostratigraphical investigations reflects the unsignificant changes of benthic foraminifera distributions and lake conditions.
Consequentelly, recent to 2350yr BP and 4400 to 5600yr BP periods indicates low water level and 2350 to 4400yr BP interval reflect relatively high water level signatures. Simultaneously during the high water level phases, water chemistry shows a tendency through the relatively high oxygen level and fresh water conditions. Additionally, eolian affect also was an important factor during the period of high energy environment during the 1990 to 2700yr BP interval. Chemical alterated sediments are were also contributed in to the sediments during this specific phase.