Stable Isotopes Evidence for Holocene Paleoenvironmental Changes in Khor Abdullah Southern Iraq

Stable isotopes have emerged as valuable tools in the geosciences, particularly for thermometry and research on climate change. The essential comprehend depositional environments and paleoclimate interpretations. This understanding hinges on gathering insights from various lithological units and their depositional architecture. Sedimentary units are vital for analyzing changes in sea levels and sediment supply over time. However, studies involving stable isotopes in this region are limited, highlighting the necessity for this research. In this study, sub-bottom marine core in Khor Abdullah, specifically the Grand Faw Port were analyzed from a depth of 40 meters in the northwest Arabian Gulf region of southern Iraq. Ten bulk representative sediment samples were examined using a Mass Spectrometer, specifically an Iso-Analytical device, to calculate stable isotopes, including δ13C, δ18O, δ15N, and δ2H (in ‰) for each sample. The z-values ​​in the study area ranged between 121.37 and 60.41, the study employed (Z) values to determine whether the environments were marine, fresh, or mixed. The oxygen isotope δ18O values ranged from 23.15 to 5.36‰, while δ13C values ranged from -26.63 to -19.86‰. The analysis identified warm periods associated with marine transgression and cold periods tied to marine regression. Additionally, a positive relationship was found between Total Organic Carbon (TOC%) and the isotopes δ13C and δ18O. This relationship is influenced by climatic factors such as variations in humid-dry and cold-warm conditions, which affect peat composition. Furthermore, changes in the proportions of calcium carbonate were also found to play a significant role in these dynamics.