Resumen de Biofacies del sistema de rampa carbonatada de Venta Laperra (Albiense inferior basal, Región Vasco-Cantábrica occidental)

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

• In the western area of the Basque-Cantabrian Region of northern Spain, the first Albian deposits form extensive carbonate homoclinal ramps, with facies rich in both metazoans and foraminifera.

  One of these deposits, the Venta Laperra ramp system, shows an internal facies architecture with four main biofacies: I) proximal restricted micrites with Chondrodonta and miliolids; 2) micriticrequienid mud-mound belt facing to open sea and protecting the lagoon from currents (barrier);

  3) forebarrier bioclastics with orbitolinids, sponges and corals; and 4) open-sea bioclastics dominated by textulariids, echinoids and sponges. Photic zone base-level is considered to be a main controlling factor on the development of the biofacies. The barrier-effect of the mound zone protected proximal areas from open-sea occasional currents rich in suspended material (silt) and nutrients.