Concreciones de arenisca como criterio de identificación y correlación estratigráfica de regresiones forzadas. Un ejemplo desde las areniscas cretácicas de la Formación Cerrajón (Zonas Externas de la Cordillera Bética)

Abstract

Calcite-cemented concretions were studied from Lower Cretaceous forced-regressive shoreface sandstones (Cerrajón Fm, External Zones, Betic Cordillera). During early diagenetic, patchy calcite cement consolidates clean and well-sorted sand in the form of concretions of spheroidal to oval shape within host sand uncemented. Then a new relative sea level fall characterised by incised valleys cutting the overlying TST and HST pelagic marls and also cutting shoreface sandstones (concretions host) is reported. Coastal and presumably subaerial reworking of exposed sandstone concretions by relative sea-level fall erosion (intensively bored by lithophaga, Fe-oxidized surface, oysters and corals attached) fill the incised valleys in proximal areas and they are also found isolated into distal marls