Post-miocene sedimentation in the gulf of Suez, Egypt

الملخص EN

Stratigraphie correlation of Post-Miocene sediments penet- rated by two deep wells (BB-80 and GS-78) drilled in the northern part of Gulf of Suez exhibited marked lithological and thickness variations from one locality to another.

Representative bulk samples from the two sections under consideration, were mineralogically and chemically analysed using the X-ray diffractometry.

X-ray fluorescence and polarizing microscope.

The obtained data revealed that the studied Post Miocene subsurface sediments are mainly represented by two facies: terrigenous and chemical facies.

Terrigenous facies is composed of interbedded alluvial sand, gravels and shales probably delivered into the gulf by its affluents of which the fans play the most important role.

Its sedimentation was rapid and took place to some extent in small active fault-controlled basins.the chemical facies con- sists mainly of evaporates; represented by anhydrite and gypsum minerals and limestones (calcite and dolomite).

Geochemical investigation indicates that the chemical facies shows USU- ally highCaO, MgO and Sr contents.

The fact that high Sr-concentration as- sociated with high sulfate content indicates marine and/or coastal sabkhas (supratidal flats) where no organisms could survive in supersaline environ- ment.

The contents of other major oxides and Ba, Zr, Rb, Cr, Ni and Zn in- crease considerably with increase of the terrigenous constituents.

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