Late Miocene breccia of Menorca (Balearic Islands) a basis for the interpretation of a Neogene ramp deposit

Neogene (Tortonian) ramp facies associations crop out in the southern sector of Menorca (Balearic island). These are made mainly by sigmoidal and oblique clinoform units comprising rhodoliths, bryozoans, molluscs and foraminifera. These units are interpreted as outer-ramp deposits. A breccia deposit infilling an erosional surface is found at the top of the carbonate ramp sequence. The breccia components (mainly rhodoliths and oolite clasts) may represent erosion of the underlying ramp deposits and inner-ramp counterparts, which do not crop out on the island. The study of components in the breccia deposits confirms the indigenous character of the outer-ramp facies associations, which suggests that the ramp was steepened distally. The breccia deposits correspond laterally to a discontinuity surface locally showing karstic features. Transgressive sediments (including a phosphatic crust) are found above the discontinuity surface. All together these features, and the dolomitisation of the uppermost ramp sediments and breccia deposits, suggest that the breccia originated from erosion of the ramp after a major relative sea-level fall. The breccia and discontinuity surface separate the ramp sequence from an overlying prograding sequence. A correlation of this sequence boundary to other areas in the western Mediterranean is proposed. © 1993.