Taphonomy

Trabajo presentado en el II International Symposium on Lithographic Limestones celebrado en Cuenca.-- Field trip guide book.The taphonomic anal ysis of the Las Hoyas site is still at an early stage. This analysis is necessary since it is considered a prerequisite for paleoecological reconstructions (Shipman, 1981). Besides, taphonomic analysis has its own aims; in this case they could be summarized as the establishment of the temporal succession of processes which led to the formation of the site.Peer reviewe

Sedimentología y evolución paleogeográfica de la cubeta de Las Hoyas (Cretácico inferior, Serranía de Cuenca)

[ES] La cubeta de Las Hoyas (Serranía de Cuenca, Cordillera Ibérica) sufrió un relleno sedimentario complejo durante el Cretácico inferior. En un contexto de rift intracontinental, la cubeta de Las Hoyas se encontraba localizada sobre un bloque subsidente controlado por directrices tectónicas ONO-ESE y NO-SE. La variación a lo largo del tiempo del equilibrio entre la tasa de sedimentación y la tectónica sinsedimentaria activa, en interacción con una serie de factores intra y extracuencales (producción de carbonatos, llegada de aportes siliciclásticos, clima...) determinó una historia sedimentaria en tres episodios en los que la paleogeografía de esta cubeta estuvo dominada por diferentes arnbientes. En un primer Episodio se instaló una llanura aluvial distal. Un segundo Episodio está definido por la instalación en todo el área de un ambiente lacustre abierto. El tercer y último Episodio está representado por un ambiente de llanura aluvial distal con áreas lacustres marginales dominantes.[EN] Las Hoyas sub-basin (Serranía de Cuenca, Iberian Ranges) had a very complex sedimentary infilling during the Lower Cretaceous. This basin was settled on a subsident block, in a intracontinental rift context. This block was controlled by WNW-ESE and NW-SEtectonic lineations. lts sedimentary history was developped in three stages and was outlined by the interaction and the equilibrium among severa! factors: sedimentation rate, diferential subsidence, carbonate production, siliciclastic supply, climate... During the three stages the paleogeography was dominated by differents environments. During the first one a distal alluvial plain was installed in the area. A lacustrine environment was developped during the second stage. The third síage is represented by the installation of a distal alluvial plain dominated by marginal lacustrine areas.Peer reviewe

El registro estratigráfico del rifting Jurásico Superior-Cretácico Inferior en la región del Alto Tajo-Serranía de Cuenca (Cordillera Ibérica, España): Evidencias genéticas y estructurales para su revisión y nueva propuesta litoestratigráfica

[EN] The Southwestern Iberian Domain (Southiberian Basin) corresponds to one of the five palaeogeographic domains into which the Iberian Basin was divided during the Late Jurassic-Early Cretaceous rifting stage. Although it was already known that this domain was clearly separated into two sub-basins, Cuenca and Valencia, the same lithostratigraphic scheme was assumed to be applicable to the whole domain. In the last decades, new data have been incorporated to the knowledge of the Serranía de Cuenca and the Alto Tajo region, showing that this area underwent a separated palaeogeographic evolution and developed a different stratigraphic record. Evidences of such independence are, among others, the development of a Late Jurassicearly Barremian unconformity with unique features in the Iberian Basin and herein described for the first time. Syn-rift sedimentation was controlled by an intricate extensional geometrical and kinematic pattern of multiple and small half-graben basins, and it is represented by just two unconformity-bounded units, late Barremian and Aptian in age respectively. This work reviews, clarifies, and simplifies old and confusing stratigraphic nomenclatures and proposes a specific lithostratigraphic scheme for the Alto Tajo-Serranía de Cuenca region. It includes the new upper Barremian Tragacete Formation and the redefinition of La Huérguina Formation in terms of lithofacies, lower boundary, age and environmental interpretation.[ES] El Dominio Ibérico Suroccidental (Cuenca Suribérica) corresponde a uno de los cinco dominios paleogeográficos en los que se ha dividido la Cuenca Ibérica (actual Cordillera Ibérica) durante el ciclo de rifting intracontinental Jurásico Superior-Cretácico Inferior. Aunque se sabe que el Dominio Ibérico Suroccidental estuvo compartimentado en dos sub-cuencas diferentes, Cuenca y Valencia, hasta la actualidad se ha asumido que el relleno sedimentario de ambas era asimilable y se ha aceptado un único esquema litoestratigráfico para ambas. Varias décadas de estudio e integración de datos estructurales, estratigráficos, sedimentológicos y paleontológicos del área de la Serranía de Cuenca y el Alto Tajo (Cuenca y Guadalajara) han revelado que esta región sufrió una evolución paleogeográfica independiente y posee un registro estratigráfico particular, que no se refleja en los esquemas estratigráficos disponibles para el Dominio Suroccidental. Evidencias de esta singularidad son (1) el desarrollo de una discontinuidad estratigráfica Jurásico Superior-Barremiense inferior con características únicas en el contexto de la Cuenca Ibérica y descrita por primera vez en este trabajo; (2) el registro más tardío (Barremiense superior) del comienzo de la sedimentación sinrift en la Cuenca Ibérica. La sedimentación sinrift estuvo muy condicionada por el desarrollo de un complejo patrón extensional y cinemático que compartimentó la cuenca en múltiples cubetas de tipo graben y semi-graben, y está representada por dos unidades limitadas por discontinuidades. La primera unidad es Barremiense superior y está compuesta por dos unidades litoestratigráficas con rango de formación constituidas por sedimentos continentales que se superponen y presentan cambio lateral de facies: la Formación Tragacete, que se define formalmente por primera vez en este trabajo, y la Formación La Huérguina, que se redefine formalmente aquí en términos de litofacies, límite inferior, edad y ambientes sedimentarios. También se descarta la presencia y validez en el área de estudio de la Formación El Collado, hasta la actualidad considerada cambio lateral de facies de la Formación La Huérguina en su definición inicial. La segunda unidad es Aptiense y está compuesta por la Formación Contreras que cambia lateralmente de facies al Miembro Malacara (Formación El Caroch), y por el Miembro El Burgal (Formación El Caroch). Sobre ambas unidades limitadas por discontinuidades se apoya discordante el Grupo Utrillas (Albiense), no existiendo registro en esta cuenca de otras unidades aptienses y albienses recogidas en los esquemas estratigráficos tradicionales del Dominio Suroccidental. Además, en este trabajo se revisan y clarifican las diversas nomenclaturas que se han venido usando en las últimas décadas en trabajos publicados y mapas geológicos nacionales de la serie MAGNA correspondientes a esta región.This work is a contribution to project CGL2013-42643 of the Spanish Ministry of Economy and Competitiveness.Peer reviewe

Cenomanian vertebrates from Algora (central Spain): New data on the establishment of the European Upper Cretaceous continental faunas

The palaeontological area of Algora (Guadalajara Province, central Spain) provides the largest concentration of vertebrate macroremains for the Cenomanian of south-western Europe. The available faunal list for Algora, based on the analysis of scarce remains collected in geological surveys carried out more than thirty years ago, was never updated. Therefore, and despite the great potential of this site to reveal novel information about the composition of the vertebrate fauna from the base of the Upper Cretaceous in the continent, the previous determination of many of the taxa recognized there is identified here as inaccurate or erroneous (e.g., the identification of two actinopterygian fishes, a single crocodyliform, the helochelydrid turtle Helochelys danubina and carcharodontosaurid dinosaurs). Recent fieldwork campaigns have provided numerous remains, including those of clades poorly represented so far, as well as others hitherto unknown at this site. The new faunal list proposed here included the lepisosteoid Obaichthys africanus, the helochelydrid aff. Plastremys lata, the pleurodiran Algorachelus peregrina, an indeterminate elasmosaurid, a non-eusuchian neosuchian and a eusuchian crocodyliform, a likely abelisaurid theropod and a lithostrotian sauropod. The study of these taxa provides new information about the palaeobiogeography and temporal distributions of some lineages, and increases knowledge about the poorly-known transition between the Lower and the Upper Cretaceous faunas in Europe. This faunal replacement, in which several well-represented lineages in the uppermost Cretaceous were established, is recognized as strongly conditioned by climate changes that took place between the end of the Early Cretaceous and the beginning of the Late Cretaceous

Sedimentology of a distributive fluvial system: The Serra da Galga Formation, a new lithostratigraphic unit (Upper Cretaceous, Bauru Basin, Brazil)

The Bauru Basin of SE Brazil is a large (ca. 370,000 km2) Upper Cretaceous intracratonic feature, important for its fossil remains and of particular value as a source of regional palaeoclimatic information. Historically, lithostratigraphic reconstructions have been performed mainly for successions of the central and southern parts of the basin, resulting in a lithostratigraphic scheme that is not applicable to the northernmost regions. In particular, the northeastern deposits of the Marília Formation (Serra da Galga and Ponte Alta members) reveal lithological, stratigraphic, and palaeontological differences from southeastern and northwestern counterparts (Echaporã Member). Nevertheless, these deposits are considered as a single lithostratigraphic formation in the literature. To address this problem, this study demonstrates how the northeastern deposits of the Marília Formation do not show affinity to the rest of the unit. A more suitable lithostratigraphic model is proposed for the northeastern succession as a distinct and independent unit. Lithofacies and palaeopedological analysis, combined with lithostratigraphic mapping of the northeastern deposits, reveal 11 distinct lithofacies and three pedotypes over an area of ~450 km2. Sedimentary facies and pedotypes were assigned to six interbedded architectural elements: (a) type 1 channel fill, (b) type 2 channel fill, (c) type 3 channel fill, (d) interchannels, (e) palaeosols, and (f) calcrete beds. The succession is interpreted as a distributive fluvial system with overall direction of flow to the NNW, and which developed under the influence of a semiarid climate regime. This contrasts with deposits of the southeastern and northwestern Marília Formation, previously suggested to be of fine-grained aeolian affinity with interbedded poorly channelised deposits assigned to an aeolian sand sheet environment. By revising the existing lithostratigraphic scheme for the northeastern deposits, and contrasting them with laterally equivalent strata, this work demonstrates how the previously named Serra da Galga and Ponte Alta members reveal a unique set of lithological, architectural, and genetic signatures that permits to separate them from the Marília Formation. Finally, a new lithostratigraphic classification for the unit is proposed: the Serra da Galga Formation, whose deposition relates to an ancient distributive fluvial system.Fil: Soares, Marcus Vinícius Theodoro. Universidade Estadual de Campinas; BrasilFil: Basilici, Giorgio. Universidade Estadual de Campinas; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: da Silva Marinho, Thiago. Universidade Federal do Triângulo Mineiro; BrasilFil: Martinelli, Agustín Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Marconato, André. Universidade Federal de Ouro Preto; BrasilFil: Mountney, Nigel Philip. University Of Leeds.; Reino UnidoFil: Colombera, Luca. University Of Leeds.; Reino UnidoFil: Mesquita, Áquila Ferreira. Universidade Estadual de Campinas; BrasilFil: Vasques, Julia Tucker. Universidade Estadual de Campinas; BrasilFil: Junior, Francisco Romero Abrantes. Universidade Estadual de Campinas; BrasilFil: Ribeiro, Luiz Carlos Borges. Universidade Federal Do Triangulo Mineiro; Brasi