BENTHIC FORAMINIFERA IN CARBONATE FACIES OF A COASTAL SABKHA, RED-SEA COAST, SAUDI-ARABIA

On the basis of a sedimentological analysis, various types of carbonate and clastic facies have been described from the coastal sabkha of the Saudi Arabian Red Sea. The Holocene part of this sabkha comprises a carbonate transgressive phase and subsequent evaporite sediments representing the regressive phase of the cycle. The identified foraminifera, which are subdivided into three groups according to the wall composition of their tests, are: (i) porcelaneous foraminifera (70-98%), represented by five genera (Quinqueloculina, Triloculina, Peneroplis, Sorites and Spirolina), (ii) hyaline foraminifera (3-30%), including two genera (Ammonia and Elphidium), and (iii) agglutinated foraminifera (1-2%), comprising only one genus, Clavulina. The striking dominance of the porcelaneous foraminifera in the carbonate transgressive phase indicates the typical character of the hypersaline subtropical lagoonal environment. The restricted position of this assemblage of benthic foraminifera in the carbonate transgressive phase allows the tracing of this phase in the Quaternary sediments of the Saudi Arabian Red Sea coast. This study therefore demonstrates the use of benthic foraminifera as a tool for tracking transgressions and regressions even in lagoons connected to the open sea.