Title : A new record of geniculate coralline algae from the Pliocene - Pleistocene carbonates of Marsa Alam area, red sea coastal plain, Egypt
Abstract:
The Pliocene-Pleistocene succession along the Red Sea coast is subdivided in the Marsa Alam area into the Gabir, Shagra and Samadai formations in addition to the Pleistocene raised beaches and coral reefs. The coralline algal limestone of Shagra and Samadai formations contain well preserved geniculate coralline algal species of genus Amphiroa. The present paper documents ten coralline algal species of genus Amphiroa namely Amphiroa anchiverricosa, A. ephedraea, A. fortis, A. fragilissima, A. prefragilissima, A. rigida, A. prefragilissima, and one new species Amphiroa dabbabensis Hamad for the first time. The present geniculate coralline algal assemblage is associated with the nongeniculated and dasycladalean algae and this association points that the coralline algal limestone of the Shagra and Samadai formations was deposited in the intertidal to shallow subtidal environments at a depth of 10-30 m in a shallow warm marine water environments under low-energy conditions favourable for reefal and rhodoliths formation. The fossiliferous arkoses and conglomerates, alternating with the coralline algal limestone of Shagra and Samadai formations, were derived from the nearby Precambrian basement, transported by streams during short-lived pluvialepisodes and deposited in a very shallow intertidal- beach environment
