Chabahar Bay with 17 Km length, 20 Km width and maximum 20 m depth in the mouth is the largest embayment in the Oman sea that located in southeast of Iran and east of the Persian Gulf. Present investigation is based on detailed analysis of 154 surface sediment samples collected from Chabahar Bay using Van Vein Grab. The samples were analyzed for sedimentological parameters and geochemical elements using international standard methods. The results of sedimentological data show distinct variations in the types of sediments. Most of the sediments are silisiclastic except for two small parts wherein carbonates are predominant. These carbonate sediments have distinguished source of coral patch reefs. Size of the Silisiclastic sediments mostly varies between silt and clay grade and comprised of quartz, clay minerals, detrital carbonates and heavy minerals. These sediments are originated from lithostratigraphic units viz. conglomerate, sandstone and marl, in and around the bay. Clay minerals identified are Chlorite, Illite and Kaolinite, their abundance increase from coast to the deeper parts of the bay and must have transported to the basin by rivers from hinterland areas. Biochemical carbonates predominantly consist of shells of granule size. Sediments of Chabahar Bay have been classified in to nine types based on size and association. They are Granule, Sand, Silt, Mud, Sandy silt, Sandy clay, Sandy mud, Silty sand and Muddy sand. Further, sediment samples were analyzed for following elements - SiO2, Al2O3, Fe2O3, CaO, MgO, MnO, TiO2, B, Bi, As, Sr, Cr, Cu, Ni, Ba, W. Elemental and oxide distribution maps were prepared by Arc GIS software. Also correlation between oxides, other elements, sediment size and depth of sampling were computed following Spearman method. It is specifically noted that CaO and Sr has a direct relation with sediments size. This must be because most of granules and sands in the bay have carbonate composition. SiO2, Al2O3, Fe2O3, MgO, MnO, TiO2 show positive correlation with fine grain sediments especially with muddy and muddy sand type of sediments and negative correlation with coarse grain sediments, this indicates that these sediments must be of detrital source and originated from clay minerals.
Elements Cr, Ni, Cu, Zn, B, Ba showed positive correlation with fine grain sediments and negative correlation with coarse grain sediments, specially with Granule and Sand types of sediments, indicating their source as detrital. The results of the present study also showed high concentration of some elements like Cr, Sr, W, Zn, Bi, As and Cu in and around Shahid Beheshti and Shahid Kalantari Jetties which are located in the Southeastern parts of the Bay and also in and around Naval Base jetty which is located in the Southwestern part of the Bay. This supports and confirms the influence of human activities at these locations which may lead to pollution.