Presentación :[del número extraordinario, año 1996, de la Revista española de paleontología]

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Catálogo de los braquiópodos españoles del Jurásico inferior depositados en el Museo Geominero (ITGE, Madrid)

Se revisan desde el punto de vista taxonómico y bioestratigráfico los braquiópodos españoles del Jurásico Inferior que constituyen la colección del Museo Geominero. La colección está compuesta por 1102 ejemplares procedentes de 98 localidades diferentes repartidas fundamentalmente por el sector nororiental de la Península Ibérica. Se han identificado 23 géneros (10 de rinconélidos, 3 de espiriféridos y 10 de terebratúlidos) y 59 especies (24 de rinconélidos, 5 de espiriféridos y 30 de terebratúlidos)

El Pliensbachiense de la Cordillera Ibérica

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Geológicas, leída en 1982.Fac. de Ciencias GeológicasTRUEProQuestpu

El Pliensbachiense de la Cordillera Ibérica

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Geológicas, leída en 1982.Fac. de Ciencias GeológicasTRUEProQuestpu

Bivalvos del Pliensbachiense en la Sección de Almonacid de la Cuba (Cordillera Ibérica, España)

Se ha realizado el estudio taxonómico detallado de unos ciento noventa especímenes de bivalvos pliensbachienses, procedentes de la región de Almonacid de la Cuba (Zaragoza), que ha dado como resultado la caracterización y descripción de veinte especies pertenecientes a catorce géneros de las subclases Pteriomorphia (14%; Mytiloidea, Pinnoidea, Limoidea, Ostreoidea y Pectinoidea) y Heteroconchia (86%; Lucinoidea, Cardioidea y Pholadomyoidea). El análisis del estado de conservación de los Pteriomorphia permite suponer que al menos una de las capas microestructurales que formaron la concha es de composición calcítica mientras que en los Heteroconchia, que sólo se han registrado como moldes internos, la composición de la concha era de naturaleza aragonítica. El 61% de los ejemplares estudiados pertenece a la superfamilia Pholadomyoidea, que es además la que muestra mayor diversidad taxonómica. El modo de vida de los bivalvos registrados en las formaciones pliensbachienses indica que se produjo una disminución relativa de la energía del medio entre las formaciones Río Palomar y Almonacid de la Cuba que sin embargo presenta episodios de más alta energía en su parte superior. El registro de bivalvos de la Formación Cerro del Pez permite inferir que la energía del medio debió ser incluso más baja que la de la Formación Almonacid de la Cuba, mientras que el notable aumento de formas cementantes y epifaunales bisadas en la Formación Barahona, apunta a la existencia de un ambiente con una energía considerablemente mayor que la supuesta para las formaciones anteriores. [ABSTRACT] A collection of one hundred ninety specimens Pliensbachian Bivalves from the Almonacid de la Cuba region (Zaragoza) has been analysed. As a result, twenty species included in fourteen genera are described. These species are included into the Subclass Pteriomorphia (14%; Mytiloidea, Pinnoidea, Limoidea, Ostreoidea y Pectinoidea) and mostly in the Subclass Heteroconchia (86%; Lucinoidea, Cardioidea y Pholadomyoidea). Preservation in the Pteriomorphia suggests that, at least one of the wall layer was originally calcitic, whereas in the Heteroconchia (only recorded as internal moulds), the wall composition was entirely aragonitic. The 61% of the studied specimens are included in the Superfamily Pholadomyoidea, which is also the Superfamily with a higher taxonomic diversity. The lifestyle of these Pliensbachian bivalves suggests that the energy in the environment decreased between the Río Palomar and Almonacid de la Cuba Formations. Nevertheless, in the upper pat of the latter, a period of high energy is recognised. The bivalves from Cerro del Pez Formation suggest that the energy in this formation was even lower than in the Almonacid de la Cuba Formation. The increase in the byssate epifaunal and cemented bivalves in the Barahona Formation suggests the highest energy environment of the all studied formations

Palinología del Cretácico Inferior de la sección de Montoria-La Mina (Cuenca Vasco-Cantábrica, España): polen de angiospermas primitivas

La sección del Cretácico Inferior de Montoria-La Mina se encuentra en el margen sur de la Cuenca Vasco-Cantábrica (España). Sus materiales están integrados por una sucesión de lutitas y arcillas con niveles de lignitos y areniscas que se depositaron en un cinturón deltáico, pudiéndose atribuir a la Formación Escucha. Se han obtenido asociaciones palinológicas bien conservadas con un número significativo de palinomorfos que ha permitido realizar estudios de tipo cuantitativo en ocho de los doce niveles analizados. Se ha puesto de manifiesto la existencia de una flora diversa, integrada por cuarenta y cuatro tipos diferentes de criptógamas vasculares y veintiocho de fanerógamas de las divisiones Bryophyta, Lycophyta, Pteridophyta, Pteridospermophyta, Coniferophyta, Cycadophyta/Ginkgophyta, Gnetophyta y Magnoliophyta. Las asociaciones palinológicas se encuentran dominadas por granos de polen anemófilo de Corollina obidosensis e Inaperturopollenites dubius y por esporas psiladas de Cyathidites australis, que indican la existencia de climas cálidos y secos. Es relevante el registro de polen de angiospermas primitivas en las asociaciones estudiadas, correspondiendo a formas de tamaño pequeño, reticuladas y, por lo general, columeladas. Se describen formas inaperturadas, operculadas, monosulcadas y tricotomosulcadas que se han atribuido a los grupos Pre-Afropollis, Clavatipollenites, Liliacidites, Retimonocolpites y Retimonoporites. La aparición de estos grupos polínicos permite relacionar las asociaciones registradas con las de la parte inferior de la Zona I del Grupo Potomac (Maryland, USA) y con las del Cretácico Inferior de Israel. [ABSTRACT] The Lower Cretaceous Montoria-La Mina section is located in the extreme southern part of the Basque–Cantabrian Basin (Spain). The succession might be included into the Escucha Formation and contains siltstones and clays with interbedded deltaic lignite and sandstone rocks. The palynological analysis of these rocks shows well preserved miospore assemblages with significant numbers of specimens in eight of the twelve analysed horizons. A diverse flora composed of forty four vascular cryptogams and twenty eight fanerogams are identified, included in the divisions Bryophyta, Lycophyta, Pteridophyta, Pteridospermophyta, Coniferophyta, Cycadophyta/Ginkgophyta, Gnetophyta and Magnoliophyta. The palynological assemblages are dominated by anemophilous pollen grains of Corollina obidosensis and Inaperturopollenites dubius, as well as psilate spores of Cyathidites australis, which suggest warm and dry climatic conditions. The occurrence of pollen grains of ancient angiosperms is significant in the studied assemblages. They were identified as small-sized, reticulate and generally collumelate miospores. Inaperturate, operculate, monosulcate and trichotomosulcate forms attributed to the Pre-Afropollis, Clavatipollenites, Liliacidites, Retimonocolpites and Retimonoporites pollen groups are described. The appearance of these palynological groups are compared to those in the lower part of Zone I of Potomac Group (Maryland, USA) and in the Lower Cretaceous of Israel

Sucessão de palinomorfos ao longo do Pliensbaquiano superior – Toarciano inferior no perfil de Peniche (Portugal

The Peniche section in the Lusitanian Basin (western Portugal) provides an exceptional, continuous record of the Portuguese Lower Jurassic, and is the candidate for the Global Boundary Stratotype Section and Point for the base of the Toarcian. This paper reports a palynological study of the Margaritatus, Spinatum, Polymorphum and Levisoni zones. Forty eight levels yielded representative and well preserved palynomorph assemblages. Fifty seven palynomorph taxa were recorded: 19 spore taxa, 20 pollen taxa, 11 acanthomorph acritarchs, 4 prasinophytes and 3 dinocyst taxa. The Pliensbachian levels show a characteristic predominance of Classopollis and a wide diversity of aquatic palynomorphs. The Toarcian levels are characterised by the pollen grains of Spheripollenites and a progressive reduction in the diversity of aquatic palynomorphs.O perfil de Peniche, localizado na Bacia Lusitânica (Oeste de Portugal), mostra um registo contínuo e exceptional no contexto do Jurássico Inferior português, que inclui o candidato a estratotipo do limite Pliensbaquiano–Toarciano. Neste âmbito foi desenvolvido um estudo palinológico envolvendo as zonas Margaritatus, Spinatum, Polymorphum e Levisoni, tendo sido analisados 48 níveis com associações representativas e bem preservadas de palinomorfos. Foram identificados 57 taxa de palinomorfos: 19 de esporos, 20 de pólenes, 11 de acritarcas Acanthomorpha, 4 de prasinófitas e 3 de dinocistos. Os níveis do Pliensbaquiano são caracterizados pela larga predominância de Classopollis e pela diversidade de palinomorfos aquáticos. Os grãos de pólen Spheripollenites e a diminuição progressiva da diversidade de palinomorfos aquáticos caracterizam os níveis do Toarciano.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Bivalves from Água de Madeiros Formation (Upper Sinemurian) of the Lusitanian Basin (Portugal)

Apresenta-se a distribuição estratigráfica dos taxa de moluscos bivalves ao longo da Formação de Água de Madeiros (Sinemuriano superior–extrema base do Pliensbaquiano) na Bacia Lusitânica. Estudaram-se as secções de S. Pedro de Moel e Peniche, por serem as mais completas e representativas do ponto de vista do registo paleontológico e seu significado biostratigráfico. Esta análise estratigráfica de alta resolução baseia-se em 2691 espécimes recolhidos em 180 estratos, o que permitiu um acréscimo significativo (31%) de novos taxa reconhecidos na bacia neste intervalo. Evidencia-se uma variação vertical na composição taxonómica das associações faunísticas com o surgimento de espécies oportunistas interpretadas como facultativamente pseudoplânctónicas. Este registo é observado na transição entre as cronozonas Oxynotum e Raricostatum, interpretando-se como tendo sido favorecido por mudanças na deposição, de que resultaram condições pelo menos disóxicas. O surgimento de formas de Pseudomytiloides e de Oxytoma durante o Sinemuriano terminal da bacia aponta para que estas ocorrências sejam as primeiras no contexto do Jurássico NO europeu.The stratigraphic distribution of bivalve molluscs throughout the Água de Madeiros Formation (Upper Sinemurian– lowermost Pliensbachian) at the Lusitanian Basin is present here. The work was carried out on the sections of S. Pedro de Moel and Peniche. This high-resolution stratigraphic analysis is based on 180 sampled beds and 2691 bivalve specimens. This new collection allows a significant improvement (31%) of the number of taxa already known for the basin, during this interval. The occurrence of a faunal turnover that allowed the spanning of opportunistic species, here interpreted as representative of a pseudoplanktonic habitat, is also shown. This record is noted around the Oxynotum–Raricostatum chronozone transition and inferred to have resulted from depositional changes linked with dysoxic conditions near the water-substrate interface. The appearance of Pseudomytilodes and Oxytoma forms in the Lusitanian Basin seems to be the earliest in the NO European Lower Jurassic provinceDepto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEFondo Europeo de Desarrollo Regional (FEDER)Ministerio de Ciencia e Innovación (MICINN)European Community Research Infrastructure Action - FP6pu

Palaeoclimatic oscillations in the Pliensbachian (Early Jurassic) of the Asturian Basin (Northern Spain)

One of the main controversial items in palaeoclimatology is to elucidate if climate during the Jurassic was warmer than present day, with no ice caps, or if ice caps were present in some specific intervals. The Pliensbachian Cooling event (Lower Jurassic) has been pointed out as one of the main candidates to have developed ice caps on the poles. To constrain the timing of this cooling event, including the palaeoclimatic evolution before and after cooling, as well as the calculation of the seawater palaeotemperatures are of primary importance to find arguments on this subject. For this purpose, the Rodiles section of the Asturian Basin (Northern Spain), a well exposed succession of the uppermost Sinemurian, Pliensbachian and Lower Toarcian deposits, has been studied. A total of 562 beds were measured and sampled for ammonites, for biostratigraphical purposes and for belemnites, to determine the palaeoclimatic evolution through stable isotope studies. Comparison of the recorded uppermost Sinemurian, Pliensbachian and Lower Toarcian changes in seawater palaeotemperature with other European sections allows characterization of several climatic changes of probable global extent. A warming interval which partly coincides with a negative δ13Cbel excursion was recorded at the Upper Sinemurian. After a "normal" temperature interval, a new warming interval that contains a short lived positive δ13Cbel peak, was developed at the Lower-Upper Pliensbachian transition. The Upper Pliensbachian represents an outstanding cooling interval containing a positive δ13Cbel excursion interrupted by a small negative δ13Cbel peak. Finally, the Lower Toarcian represented an exceptional warming period pointed as the main responsible for the prominent Lower Toarcian mass extinction