La plataforma urgoniana aptiense del sur de Bilbao (valle de Bolintxu): organización estratigráfica y evolución

Abstract

An Aptian rudist limestone unit, up to 200m thick and extending more than 3km, lies 2km to the south of Bilbao. The stratigraphy and mapping of the limestones in the Bolintxu valley reveal diachronous lower and upper boundaries grading laterally to sandy and marly facies respectively. A carbonate ramp model with southeastwards backstepping in three pulses indicates a deepening upward trend. Depositional dip of the ramp down to the west suggests westward tilting and development of enhanced subsident areas to the west. The orbitolinids indicate an Early Aptian (Late Bedoulian) age for the nuclear part of the ramp