GEOMETRY, PALEOENVIRONMENTS AND RELATIVE SEA-LEVEL (ACCOMMODATION SPACE) CHANGES IN THE MESSINIAN MURDJADJO CARBONATE PLATFORM (ORAN, WESTERN ALGERIA) - CONSEQUENCES

The Messinian carbonate platform of the Djebel Murdjadjo (western Alge ria) is composed of six sedimentary units arranged in generally aggrad ational-progradational sequences commencing at the major Tortono-Messi nian transgression and terminating at the onset of the ''Salinity Cris is''. Palinspastic reconstruction, combined with microfacies analysis, has allowed recognition of inner platform to outer platform environme nts and provides a new interpretation for platform building with respe ct to relative sea-level (accommodation space) changes. Following the deposition of the bioclastic limestones of the first transgressive uni t, the upper red-algae limestones, a reef-complex and a part of the '' Terminal Complex'' were successively deposited during stillstands. The se three episodes were each separated by decametre-amplitude rises in relative sea-level (accommodation space). No major sea-level drop appe ars to have been associated with the deposition of Messinian evaporite s.