The Global Boundary Stratotype section and Point (GSSP) of the Messinian Stage (uppermost Miocene)

The GSSP of the Messinian Stage. which per definition marks the base of the Messinian and, hence, the boundary between the Tortonian and Messinian Sta ges of the Upper Miocene Subseries, has recently been defined and ratified by the IUGS. The boundary stratotype section is Oued Akrech (Morocco) where the Messinian GSSP is now formally designated at the base of the reddish l ayer of sedimentary cycle no.15. This point coincides closely with the firs t regular occurrence (FRO) of the planktonic foraminiferal Globorotalia mio tumida group and the first occurrence (FO) of the calcareous nannofossil Am aurolithus delicatus, and falls within the interval of reversed polarity th at corresponds to C3Br.1r. The base of the reddish layer and, thus, the Mes sinian GSSP has been assigned an astronomical age of 7.251 Ma.