Mineralogical and Geochemical Studies on Some Early Miocene Sediments of Southwestern Sinai, Egypt

The present work provides a comparison and a contrast of the lithostratigraphy, mineralogy, and geochemistry of the early Miocene rocks exposed in El-Markha and Wadi Gharandal sections (Nukhul and Rudeis formations) at Southwest Sinai. Miocene succession of Southwest Sinai is classified from base to top into: Nukhul and Rudies formations. Rudies Formation unconformably overlies Nukhul Formation and unconformably underlies Kareem Formation. The Early Miocene sequence revealed the presence of calcite as the dominate minerals in the nonclastic rocks. Quartz is the main mineral in the clastic rocks, while goethite is most important minerals in the iron-rich sand, whereas halite is foremost minerals in evaporate samples. Hematite, kaolinite, halite and gypsum are the secondary minerals constituting the studied rock units with varying amount. The foremost clay minerals present in Nukhul Formation are montmorillonite and kaolinite. In Rudeis Formation, the main clay minerals is montmorillonite. Geochemically, the studied sections are characterized by higher percentage of SiO2 and Fe2O3 in iron-rich sand. SiO2, Fe2O3 and Al2O3 gathering to form the ferruginous and glauconitic sandstone. The high content of SiO2, Na2O, Cl, CaO and So3 as main elements of compound together and forming gypsum and evaporitic sandstone. On the other hand, the high content of CaO and MgO gathering to give limestone, dolomitic limestone and dolomite. So, through the light on the geochemical conditions the two different formations are deposited.