Sedimentary and geochemical characteristics of coastal deposits in Hormoz Island in the south of Iran

Hormuz Island at the entrance of the Persian Gulf and Oman Sea is a symbol of Iranian diapirism and the Hormuz series. In considering the location of the island and the development plans for Hormuz Island, it is important to know the composition and characteristics of the island's coastal sediments. This study was conducted to study the sedimentary, mineralogical, and geochemical properties of the coastal sediments of this island. For this purpose, In this study, 20 thin sections were made from gravelly rock samples as well as 27 surface sediment samples from nine stations has been collected. Routine sedimentologic tests have been done on these samples including quantitative mineralogy by XRD, separation, and identification of heavy minerals using bromoform solution and magnetic property, heavy metals and primary oxides were analyzed by XRF and petrographic study using a polarizing microscope. The results indicate that the sediments are sandy to gravel in terms of grain size. The average amount of calcium carbonate is 32 to 62 percent. The mineralogy of sediments shows that suite of calcite, quartz, feldspar, plagioclase, dolomite, aragonite, clay minerals (Kaolinite and Illite) and heavy minerals (magnetite, hematite, oligiste, epidote, pyroxene, pyrite, goethite, limonite, apatite, barite,) are other components of superficial sediments. The study of thin sections under the polarizing microscope shows that most gravels on the coast have an igneous origin (rhyolitic and trachytic). The findings of this study indicate that the main source of these sediments is the alteration and erosion of the Hormoz Serie (the Late Precambrian–Cambrian) in the center of the island under wet, humid conditions.