Resumen de Evolución de rampas carbonatadas aptienses: tectónica sinsedimentaria y eutrofización (Jorrios, Bizkaia)

Arantza Aranburu Artano, Miguel Ángel López Horgue, Pedro Angel Fernández Mendiola, Joaquín García Mondéjar

• The facies and stratigraphic framework analysis of the carbonate ramp systems of the Aptian of Jorrios (Bizkaia, N Spain) indicates a vertical evolution from a homoclinal ramp (Mercadillo) to distally steepened ramp (Juncal ramp). The biotic constituents also differ: oligotrophic lower unit versus eutrophic upper unit. Between both ramps stands a key intermediate glauconitic interval.

  Its formation reflects low sedimentation rates, rising relative sea-level, hypoxic botton water and reduced oceanic circulation. The vertical change in depositional and faunal style is related to a combination o f factors including: tectonic activity, cold-water masses and environmental eutrophization.