Unidades estratigráficas genéticas del margen septentrional de la Cuenca de Organyá (Unidad de Senyús, Aptiense superior, Pirineo Central)

Abstract

This paper focuses in the sedimentary history during the upper Aptian of the distensive Organyà Basin, now preserved in the Boixols thrust. The upper Aptian succession has been divided in seven parasequences bounded by flooding surfaces, which allow us to interpret them as genetic stratigraphic sequences. One of these surfaces is a hardground recognised all over the study area that marks a turnover in the stacking pattern of the parasequences. Thus, the four parasequences situated below this limit show an agradational pattern, whereas the three upper ones show a progradational trend. These changes in accomodation space are related to the tectonic activity: pulses of high activity causes flooding of the carbonate platform. So that different tectonic pulses given rise to distinct parasequences. The internal sedimentary organisation of each parasequence differs from ramp without bars to ramp with bars or buildups, that in some cases enclose lagoon environments.