Estratigrafía y biomagnetoestratigrafía del Messiniense en la sección del Garruchal (Cuenca del Bajo Segura). Implicaciones para la crisis de salinidad del Mediterráneo

Abstract

The Messinian and Pliocene stratigraphic record in the Garruchal section (Bajo Segura Basin) has been divided into three allostratigraphic units, whose timing were established through combined calcareous nannoplankton biostratigraphy and magnetostratigraphy. The T-MI Unit (late Tortonian – Messinian) recorded the pre-evaporitic marine sedimentation (pre-Messinian salinity crisis deposits). This Unit is limited at the top by the intra-Messinian unconformity, representing a subaerial erosive phase related to a first major sea-level fall. The MII Unit (late Messinian) is characterized by lagoonal sedimentation, related to the socalled Lago Mare episode of the Mediterranean. At the top of this MII Unit is located the end-Messinian unconformity, caused by a second major sea-level fall. Over this unconformity lies the P Unit (early Pliocene), represented by marine deposit which marks a transgression, and the subsequent final of the Messinian salinity crisis.