Paleoenvironmental and Paleoclimate Changes in the Gulf of Edremit (Northern Aegean Sea) during the Holocene based on Sedimentological and Geochemical Multi-Proxy Records

Understanding the dynamics between past global climate events and their impact on marine ecosystems and paleoclimate is essential for the estimation of potential future changes. Accordingly, sedimentary archives accumulating on the seafloor provide crucial information on climate-driven environmental variability during the late Quaternary. Sediment cores were taken from the Gulf of Edremit, which is located in the northern Aegean Sea. We aimed to provide a preliminary, multi-proxy parameters, including sedimentological and geochemical records during the Holocene. During the marine survey with the R/V TÜBİTAK MARMARA Research Vessel, three sediment cores (E-01, E-02, and E-03A) obtained from different water depths across the gulf were investigated. Lithological observations from all cores indicate a sedimentation pattern dominated by fine-grained clay- and silt-sized deposits. However, locally occurring black laminae and FeS bands reflect depositional conditions sensitive to variations in bottom-water oxygenation. Fluctuations in the density and magnetic susceptibility measured by MSCL further support variability in sediment input and depositional processes at the sea floor. TOC data from core E-02 (at a water depth of 86 m) show low values (0.8–1.0 wt%) in the lower part, indicating low productivity and/or poor preservation of organic matter. TOC then rises to ~1.0–1.5 wt% further up the core, suggesting improved productivity or preservation. The highest values (1.5–2.0 wt%) in the uppermost 0–10 cm may reflect the presence of sapropelic material. XRF data from core E-03A reveal a Sr/Ca peak at 40–50 cm, which indicates increased salinity during drier periods. At 140–150 cm, the Sr/Ca ratio decreases while the Ca/Ti ratio increases, suggesting enhanced carbonate deposition relative to detrital input. In core E-01, a Mn/Fe peak at 10–15 cm reflects changes in redox and oxygen conditions. There is strong variability in Ca/Ti and Sr/Ca at 45–50 cm: higher Sr/Ca above this depth indicates greater carbonate production, while lower Ca/Ti implies reduced clastic input. Below 65 cm, falling Sr/Ca and rising Ca/Ti suggest diminished carbonate production and a return to lithogenic dominance. As a conclusion, sedimentation in the Gulf of Edremit appears to be highly sensitive to climate and carbon cycle changes.

This study was granted and supported by the TÜBİTAK (The Scientific and Technological Research Council of Türkiye) with Project number 123Y108.

Keywords: Gulf of Edremit, Holocene, multi-proxy analysis, TOC, XRF.