Sedimentology and mineralogical characteristics of the coastal sediments in the southern part of the Caspian Sea (Iran)

Caspian Sea isa unique laboratory, for studying all aspects of oceanography and coastal geology. The main aim of this study was to investigate: textural andmineralogicalcharacteristics ofcoastlinedeposits in the south Caspian Sea. Initially, 100 sediment sampleswere taken in summer2014, along 700 km of the southern Caspian Sea coasts (from HosseinGholi Bay to Astara, one sample per 5-8 km).In addition, after sampling, coastal geomorphology and structures were evaluated and manypictures were taken. Optical mineralogy and grain size analysis were performed on sediments. Heavy mineralsincluding ilmenite, magnetite and goethite, pyroxene, apatite, zircon and garnet and also light minerals included quartz, plagioclase, orthoclase, carbonate fragments and bivalveswere identified. Mapping the distribution of minerals showed that eastern coastline sediments are rich in light minerals and carbonate fragments derived mainly from the erosion of Kopeh-Dagh Mountains. The central and western coast is dominated by heavy minerals, primarily ilmenite and magnetite that are supplied by the Sefidrud River. The moderate abundance of light minerals in the central region results from the sediment flux of the rivers that drain the Cenozoic and Quaternary volcanic coverage and Mesozoic sedimentary deposits.A closer look and compliance with regional geological maps, mineral distribution and beach slope,it was found that in the regions of the study area that the sea slope in the shallow parts are steep and slope of the beach is gentle (east Mazandaran and central parts of gilan province) distribution of heavy minerals such as magnetite and goethite is higher than other areas, while the distribution of Gabbro-Dioritic, and carbonate fragments are more in steep beachareas andareas of sea bed with gentle slope (West of Gilan and Mazandaran). Also gravely coasts are formed in the steep sea bed and beach areas, as the small particles and light mineralsare washed away in these areas.