Parasecuencias transgresivo-regresivas: ejemplos de afloramiento en el Eoceno de la sierra de Entzia (provincia de Araba)

Abstract

Two main fades associations coexist in the Middle Eocene limestones of the Entzia ridge (Araba provincej, one representative of a tidal flat environment, the other of a mariné ramp setting. Analysis of their sequential arrangement has made it evident the existence of two orders of parasequence organization. Each of the parasequences of the lower (4th?) order was built during a progressive transgression and ended with a rapid regression. Parasequences of the higher (5th ?) order began with minor transgressions and continued with minor regressions. Parasequences have often been thought to represent simple upward-shoaling successions bounded by flooding surfaces. Our findings indicate a greater complexity and diversity in parasequence development. The significance of such variability, however, still needs further studies