Coralline red algae from the Lower Pliocene Shagra Formation of Wadi Wizer, Red Sea coast, Egypt: Biofacies analysis, systematics and palaeoenvironmental implications

Abstract

Coralline red algae are highly abunadant and well diversified in the well exposed carbonate deposits of the Lower Pliocene Shagra Formation at Wadi Wizer, Red Sea coast, Egypt. Lithostratigraphically, the Shagra Formation unconformably overlies the Late Miocene Marsa Alam Formation and underlies the Quaternary deposits. This carbonate facies is dominated by different assemblage of coralline red algae in the form of in situ crusts, rhodoliths, fragments and corals, bivalve shell fragments, bryozoans, benthonic and palnktonic foraminifera. The systematic study and the taxonomic investigations carried out on the coralline red algae, twenty one coralline algal species were recognized and described for the first time (most of which belonged to nongeniculated coralline algae, . Detailed microfacies analysis of the Lower Pliocene Shagra Formation led to the recognition of eight microfacies types (six of carbonate facies and two of siliciclastic facies) on the basis of Lithological characters, faunal content and sedimentary strutcures, indicating that the Lower Pliocene sequence was deposited in transgressive – regressive cycles ranged from near shore, warm shallow inner to middle neritic marine water environments with development of reefal facies.