The Messinian and Pliocene stratigraphic record of the northern sector of the Bajo Segura Basin has been
separated into three main allostratigraphic units (MI, MII and P). These units are composed of continental
to marine depositional systems. The aim of this paper is study the foraminiferal assemblages belonging to
lagoonal and marine systems. The distribution of these foraminiferal assemblages show two significantly
paleoenvironmental changes: 1) an abrupt change from marine to lagoonal foraminifer assemblages at the
MI/MII boundary, related with the beginning of the Lago Mare and Terminal Complex deposition; and 2) a
significant marine foraminiferal repopulation at the beginning of the Pliocene as a consequence of the
marine reflooding of the Mediterranean