Description:    Concretions, with abundant calcite-dolomite cement-replacement textures originally hosted in shallow-marine sandstones, were reworked into Lower Cretaceous fluvio-deltaic conglomerates and shoreface sandstones (External Zones, Betic Cordillera). A cycle of host sand deposition, early diagenetic concretion formation and concretion reworking is documented: (1) Well-sorted shoreface sandstone deposited. (2) Spherical to ovoid, non-ferroan calcite-cemented concretions formed below flooding surfaces at shallow-burial depths during early eodiagenesis. Non-ferroan calcite cements were precipitated from the bicarbonate derived from seawater and from dissolution of marine bioclasts, as shown by isotope analyses. (3) Concretions were reworked and exposed on the seafloor in a high-energy setting as indicated by the presence of numerous bivalve borings ( Entobia ichnofacies), laminated micritic microbial crusts around the concretions, and epilithobionts (oysters, barnacles and corals) on the concretion surface. Concretions also appear as erosional remnants on the floor of channels which were incised into the shoreline sandstone when sea-level fell. (4) The fluvio–deltaic channels were filled with sediment during flooding in the late lowstand of sea-level. (5) The concretions are partly dolomitized, and the presence of siderite, pyrite and barite in the outer part of the concretions precipitated before the dolomite, suggests that the latter formed during shallow burial. Content Type Journal Article Category Original Article Pages 1-19 DOI 10.1007/s10347-012-0335-z Authors F. García-García, Dpt. de Geología, Facultad de Ciencias Experimentales, Universidad de Jaén, Campus Universitario, 23071 Jaén, Spain R. Marfil, Dpt. de Petrología y Geoquímica, Facultad de Ciencias Geológicas, Universidad Complutense, 28040 Madrid, Spain G. A. De Gea, Dpt. de Geología, Facultad de Ciencias Experimentales, Universidad de Jaén, Campus Universitario, 23071 Jaén, Spain A. Delgado, Laboratorio de Isótopos estables, Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), 18100 Armilla, Granada, Spain A. Kobstädt, Dpt. de Petrología y Geoquímica, Facultad de Ciencias Geológicas, Universidad Complutense, 28040 Madrid, Spain A. Santos, Dpt. de Geodinámica y Paleontología, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva, Spain E. Mayoral, Dpt. de Geodinámica y Paleontología, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva, Spain Journal Facies Online ISSN 1612-4820 Print ISSN 0172-9179