Sedimentology, Petrography, Mineralogy and Geochemistry of Deposits off the Coast of the Caspian Sea in Babolsar City

Seas and coasts are the most interesting field of geopolitical competition in recent decades. The coastal areas of the Caspian Sea are one of the most important ecosystems in Iran. As the largest lake in the world, this sea has important and special features in terms of sedimentology and geochemistry. Sedimentary and geochemical evaluations are important for studying the evolution of sedimentation environments and the location of basins. Investigating the mineralogical and geochemical characteristics of Caspian Sea deposits can provide valuable information regarding the origin of sediments, hydrodynamic characteristics of the region, and sediment transport conditions. Therefore, the purpose of this research is to study the texture, mineralogy and geochemistry of deposits off the coast of the Caspian sea in Babolsar city. in order to investigate the sedimentary and mineralogical characteristics, petrography and geochemistry of Deposits off the Coast of the Caspian Sea in Babolsar City, it was started by using geological maps, topography of the area and choosing the appropriate navigation route to collect sediment samples. Then, in order to sample the sediments far from the coast, 41 samples were taken from the inside of the boat to sample the soft sediments on the sea surface from a small Van Veen Grab sampler belonging to the German Hydrobius Company. Granulation analysis, microscopic inspections, XRD and XRF were carried out on the collected samples. The findings indicated that silt and clay make up the majority of the particle size of this deposit. Examining the trend of changes in particle size also showed that at the entrances of Babelroud and Shazdehroud rivers to the Caspian Sea, the size of the particles is in the range of sand, and with the distance from the coast, the amount of sand decreases and the amount of silt and clay increases. These deposits often have a silty texture with some gravel and mixed sand. These deposits along the shore, where the energy is stronger, have superior textural properties than the deposits inland, where the energy is lower.  Most of the studied sediments are debris near the coast. Deposits off the Coast is more abundant with chemical and biochemical particles and intraclast allochems, bivalve fossils, and benthic forms.This deposit's primary mineral phases include quartz, calcite, feldspar, and occasionally Illite and Dolomite. The geochemical results also show the superiority of SiO2 oxide, which is generally associated with quartz minerals. Oxides of SiO2, Al2O3, Na2O, and K2O are deficient in these deposits, whereas Fe2O3, CaO, P2O5, MnO, and TiO2 oxides are abundant. In total, the results of this research indicated a direct relationship between the deposits off the coast of the Caspian sea and the mineralogical composition of the incoming deposits from the rivers leading to this coast. The conditions of the sedimentary environment of these deposits have also been involved in the formation of the geochemical and sedimentary characteristics of these deposits.