Gravelmetry and Petrogenesis of the Coastal rock boulders, Mersa Matruh, North Western of the Egyptian Mediterranean.

Abstract

Large Coastal rock boulders are found at great distances inland or supratidal zone and upslope from the subtidal zone on Romel and Alam El Rum coastal shorelands of Mersa Matruh. It proves that large waves like tsunamis and high energy storms have detached, dislocated and triggering them from the submerged plateform of Pleistocene ridge shoreward. Most of coastal rock boulders of Romel and Alam El Rum are bladed to disc shape indicating that these coastal rock boulders are transported and deposited by sea waves. Coastal rock boulders are mainly transported through rolling or saltation rather than sliding. Petrographical characters prove that the dominant cements precipitated are low Mg – calcite and aragonite. There are two main types of cements which are meniscus indicating fresh water vadose zone and isopachous indicates active marine phreatic zone. These cements are formed on marine beaches by fibrous aragonite. Two main types of porosity which are intergranular and vuggy porosity indicate shallow and marginal marine environments. The neomorphism, which has recognized is of aggrading type, leading to the enlargement of crystal sizes.