La sedimentación de afinidad Lago Mare (Messiniense) y la transgresión del Plioceno en Alicante (Cuenca del Bajo Segura)

Abstract

In the Alicante city and surrounding sectors the uppermost par t of the Messinian sequence (MII unit) is characterized by the stacking of shallowing upward cycles. The complete cycle star ts with beach sandstones and ends with lagoonal marls which contains ostracods (Cyprideis), benthic forams (dominated by the genus Ammonia) and chara algae. This fossil content is similar to that recorded in the well-known Lago Mare facies in the Mediterranean. The upper boundary of the MII unit is a subaerial erosional surface (end- Messinian unconformity) that shows paleovalley infilled by fluvial deposits and scree breccias (MIII unit). Over this erosional surface were deposited the Pliocene unit, which is composed by a lower system (P1) of marine marls enriched in planktonic fossils, and an upper system (P2) dominated by coastal and shallow marine clastic deposits. This Pliocene unit is the record of the marine flooding -Pliocene transgressionthat post-date the Lago Mare period in the Mediterranean.