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[EN] The study of the Upper Jurassic-Lower Cretaceous deposits (Higueruelas, Villar del Arzobispo and Aldea de Cortés Formations) of the South Iberian Basin (NW Valencia, Spain) reveals new stratigraphic and sedimentological data, which have significant implications on the stratigraphic framework, depositional environments and age of these units. Moreover, these new data encourage revising the previously proposed stratigraphic correlations between the studied units and those deposited in adjacent areas of the Iberian Basin. The Higueruelas Fm was deposited in a mid-inner carbonate platform where oncolitic bars migrated by the action of storms and where oncoid production progressively decreased towards the uppermost part of the unit. The overlying Villar del Arzobispo Fm has been traditionally interpreted as an inner platform-lagoon evolving into a tidal-flat. Here it is interpreted as an inner-carbonate platform affected by storms, where oolitic shoals protected a lagoon, which had siliciclastic inputs from the continent. The Aldea de Cortés Fm has been previously interpreted as a lagoon surrounded by tidal-flats and fluvial-deltaic plains. Here it is reinterpreted as a coastal wetland where siliciclastic muddy deposits interacted with shallow fresh to marine water bodies, aeolian dunes and continental siliciclastic inputs. The contact between the Higueruelas and Villar del Arzobispo Fms, classically defined as gradual, is interpreted here as gradual and rapid, because the transition between both units comprises few meters. More importantly, the contact between the Villar del Arzobispo and Aldea de Cortés Fms, previously considered as unconformable, is here interpreted as gradual. The presence of Alveosepta in the Villar del Arzobispo Fm suggests that at least part of this unit is Kimmeridgian, unlike the previously assigned Late Tithonian-Middle Berriasian age. Consequently, the underlying Higueruelas Fm, previously considered Tithonian, should not be younger than, [ES] El estudio de los depósitos del Jurásico Superior-Cretácico Inferior (formaciones Higueruelas, Villar del Arzobispo y Aldea de Cortés) de la Cuenca Suribérica (NO provincia de Valencia, E España) ha revelado nuevos datos estratigráficos y sedimentológicos, que tienen implicaciones importantes sobre el marco estratigráfico, el ambiente sedimentario y la edad de estas unidades. Además, estos nuevos datos sugieren que se deberían revisar las correlaciones estratigráficas realizadas previamente entre las unidades estudiadas y aquéllas depositadas en otras áreas adyacentes de la Cuenca Ibérica. La Fm Higueruelas se depositó en la parte media de una plataforma carbonática en la que migraban barras oncolíticas por la acción de las tormentas y en la que la producción de oncolitos disminuía progresivamente hacia la parte alta de la unidad. La Fm Villar del Arzobispo suprayacente ha sido interpretada tradicionalmente como una plataforma interna-lagoon que evolucionó a una llanura mareal. En este trabajo se reinterpreta como una plataforma carbonática interna afectada por las tormentas y en la que se desarrollaban bajíos oolíticos que protegían un lagoon. Esta plataforma también estaba afectada por la llegada de material siliciclástico del continente. La Fm Aldea de Cortés ha sido interpretada previamente como formada en un lagoon bordeado por llanuras mareales y por llanuras deltaicas fluviales. En este trabajo se reinterpreta como depositada en un humedal costero en el que interaccionaban depósitos lutíticos, cuerpos de agua someros de salinidades dulces a marinas, dunas eólicas y descargas continentales de material siliciclástico. El contacto entre las Formaciones Higueruelas y Villar del Arzobispo, definido clásicamente como gradual, es interpretado en este estudio como gradual y rápido, ya que la transición entre ambas unidades ocupa muy pocos metros. De forma más importante, el contacto entre las Formaciones Villar del Arzobispo y Aldea de Cortés, considerado previa

Esta tesis doctoral es el primer estudio exhaustivo de la Formación (Fm) Leza, una unidad carbonático-clástica del Cretácico Inferior que aflora en el borde norte de la Cuenca de Cameros (La Rioja, España). El objetivo fundamental de la tesis es responder los interrogantes previamente planteados sobre esta unidad: su sedimentología y su edad, así como los posibles controles tectónicos y eustáticos en su sedimentación. Además, a lo largo del desarrollo de esta tesis se han descubierto en la Fm Leza gran variedad de microbialitas, que son descritas e interpretadas por primera vez. El estudio sedimentológico detallado presentado en esta tesis permite concluir que la Fm Leza se formó en un complejo sistema deposicional con influencia continental (evidenciada por restos de vertebrados terrestres y carofitas clavatoráceas) y marina (evidenciada por estructuras sedimentarias de origen mareal, algas dasycladales Salpingoporella urladanasi, foraminíferos bentónicos Istriloculina y carofitas porocaráceas indicadoras de medios costeros salobres). Este sistema deposicional incluiría: abanicos aluviales; canales oncolíticos; gran variedad de cuerpos de agua con diferentes salinidades (dulces, salobres, salados o hipersalinos) o con salinidades variables; y amplias zonas vegetadas. Esta complejidad no encaja en los sistemas deposicionales tradicionalmente utilizados en sedimentología, por lo que, al comparar con sistemas modernos, se ha concluido que se trataría de un sistema de humedales costeros. Como no existe un modelo sedimentológico establecido para estos sistemas, se proponen una serie de características para facilitar la interpretación de los humedales costeros en el registro geológico. La cartografía geológica detallada revela que el sistema de humedales costeros de la Fm Leza estuvo tectónicamente controlado. Se interpreta que en el área de estudio la extensión del Cretácico Inferior interaccionó con la estructuración tardivarisca previa produciendo zonas extensionales

[EN] This Ph.D. thesis, entitled “Sedimentology and paleogeography of the coastal wetland systems of the Leza Fm (Early Cretaceous, Cameros Basin): Implications on the origin and development of associated microbial deposits”, presents the results of the first detailed and thorough study of the Leza Formation (Leza Fm), a mainly carbonate unit (but also including clastic deposits and originally evaporitic deposits, currently preserved as pseudomorphs), which crops out in the region of La Rioja, Northern Spain. The Leza Fm was deposited in the tectonically-active northern margin of the Cameros Basin, a Late Jurassic- Early Cretaceous intraplate extensional basin of the Iberian tectonic plate. No previous works have focused on the Leza Fm as a whole, but many previous authors who studied the geology of the Cameros Basin have mentioned its deposits, and some of them have made interpretations of partial aspects of the unit, especially regarding its age and lateral relationship with other units of the basin, its tectonic context, and its sedimentological origin. Thus, the Leza Fm is a challenging unit with uncertain stratigraphy and age, due to the scarcity of chronostratigraphic markers, and with uncertain sedimentology, due to the occurrence of fossils of both continental and marine affinities. In addition, during the development of this research, an unusual diversity and abundance of microbialites has been discovered in the Leza Fm deposits, adding further complexity to the study of the system., [ES] El objetivo principal de esta tesis doctoral es proponer una reconstrucción paleoambiental y paleogeográfica general de todo el registro de la Fm Leza, realizada a partir de interpretaciones estratigráficas, sedimentológicas, paleontológicas, tectónicas, y relativas a las microbialitas. Una reconstrucción que, a su vez, se integre dentro de contextos mayores, tanto a escala de la Cuenca de Cameros como de la Placa Ibérica.

The Leza Formation is a carbonate unit of the northern Cameros Basin (N Spain) with controversial age, stratigraphic position, and sedimentological interpretation. It was deposited in a series of fault-bounded tectonic depressions along the northern margin of the basin. The Leza Fm overlies and changes laterally to the siliciclastic Jubera Fm, and the thickness of both units is also controlled by faults. Although the Leza Fm has been traditionally interpreted as lacustrine with sporadic marine incursions, detailed sedimentological analysis reveals new and very abundant evidences of marine influence: sedimentary structures of tidal origin, common marine fossils (dasycladales and foraminifers), and homogeneous populations of porocharacean charophytes, indicative of brackish conditions. Thus, this unit is interpreted as deposited in a system of coastal-wetlands with both fresh-water and sea-water influence, laterally related with the alluvial deposits of the Jubera Fm and the fluvio-lacustrine deposits of the Enciso Gr towards the centre of the basin. Using the chronostratigraphic ranges of the marine fossils and the lateral relationship with adjacent units, the Leza Fm is confirmed as part of a depositional sequence late Barremian - early Aptian in age. Furthermore, a transgressive trend is defined in the Leza Fm, which is compared with the eustatic evolution of the neighbouring Basque-Cantabrian, Iberian and Pyrenean marine basins, allowing correlation of the upper part of this unit with the widespread eustatic maximum of the middle-upper part of the early Aptian. This eustatic influence provided additional accommodation space to that created by tectonics. These data from the Cameros Basin are contrasted with a thorough compilation of paleogeographic data, showing that, during the early Aptian transgression, marine influence was likely to reach the northern Cameros Basin, not only coming from the SE Iberian Basin, as previously interpreted, but also from the NW Basqu, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

The Berriasian Oncala Group of the eastern Cameros Basin is a key element for the paleogeographic reconstruction of NE Iberia during this period of time, due to its intermediate position between the Basque-Cantabrian, southern Iberian, and Pyrenean Basins. The Oncala Group, which comprises up to 2500 m of sediments, consists of siliciclastic deposits in western areas of the basin, which pass gradually eastwards and upwards to carbonate-evaporitic deposits. The siliciclastic deposits consist of an alternation of laterally extensive laminae of siliciclastic mudstone and sandstone, and meander loop bodies. The carbonate deposits are made up of an alternation of laminae of carbonate mudstone and pseudomorphs after gypsum, interbedded with shales and carbonate breccias. These deposits had been traditionally interpreted as formed in fluvial and alluvial systems, and laterally related lakes, but recent and new sedimentological data discussed in this paper suggest that they were deposited in broad, siliciclastic tidal flats, laterally associated with a fluvial system to the west, and with shallow, coastal, carbonate-sulphate water bodies to the east. The development of these coastal environments in the Oncala Group indicates that a wide, shallow, coastal embayment was developed in the eastern Cameros Basin during the Berriasian. This new paleoenvironmental interpretation makes necessary a revision of the paleogeographic reconstruction of this area of Iberia during the Berriasian because it implies that the connection of the Cameros Basin with marine areas was much more important than previously considered. The presence of very similar facies associations in the Basque-Cantabrian Basin, which include siliciclastic tidal and lagoonal deposits in the western areas, and evaporites and carbonates of restricted marine environments in the eastern areas, the similar sulphur isotope compositions of the sulphates of the Basque-Cantabrian and Cameros Basins, and the similar vertical e, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub