Luis C. Sánchez de Posada

THE MID-CARBONIFEROUS BOUNDARY IN NORTHERN SPAIN: DIFFICULTIES FOR CORRELATION OF THE GLOBAL STRATOTYPE SECTION AND POINT

The stratigraphy of latest Arnsbergian to early Chokierian (Serpukhovian/Bashkirian) is described for the Barcaliente Formation in the Cantabrian Mountains. The conodont content has been studied at the Millaro section, where the appearance of Declinognathodus noduliferus Ellison & Graves, in the lower metres of the Barcaliente Formation is confirmed, and the location of the Mississippian/Pennsylvanian boundary is discussed. The new subspecies D. noduliferus bernesgae is described and other records are also studied from the Pyrenean Azkarate section. First occurrences of Declinognathodus species are discussed from different basins, and a sequence of first appearances is applied for world-wide correlation. The lowest occurrence of D. inaequalis at the Mid-Carboniferous boundary GSSP is preferred as the primary correlation marker, because D. noduliferus s.l. includes several different taxa. Gnathodus and Lochriea species persist above the base of the Pennsylvanian and disappear in the Chokierian (early Bashkirian), as described elsewhere.

KIRKBYOID OSTRACODES (UPPER CARBONIFEROUS) FROM THE CANTABRIAN MOUNTAINS (SPAIN) AND CARNIC ALPS (AUSTRIA AND ITALY)

Abstract Silicified kirkbyoid ostracodes from the Cantabrian Mountains (Spain) bear a striking resemblance to those of the Carnic Alps (Austria and Italy). The Spanish ostracodes come from the upper part of the Cuera Limestones (Bashkirian-upper Moscovian), which are exposed along the Playa de la Huelga section (Ponga Nappe) in the coastal area of eastern Asturias, northern Spain. These fossils were collected from upper Moscovian limestones deposited in an outer-platform environment. Most of the material from the Carnic Alps was obtained from the Nassfeld Pass area (eastern Carnic Alps), near the Austrian-Italian border, in limestones of the Kasimovian-Gzhelian Auernig Group and the Lower Permian Rattendorf Group. The several Auernig Group limestones that contain silicified ostracodes were deposited in a shallow-marine environment. Despite the differences in age (according to fusulinids and conodonts), these kirkbyoids are very similar and in some cases identical. Coronakirkbya pramolla new species and Kirkbya carniacantabrica new species occur in both areas. Two other pairs of species, Coronakirkbya krejcigrafi Becker, 1978, and Coronakirkbya carina new species, and Aurikirkbya cf. beckeri (Kozur, 1990) and Aurikirkbya carinthica new species, show close affinities, though they are considered to be different species. Most of the species described herein are either very rare or absent in other regions. The close paleobiogeographic relationships between the Cantabrian Mountains and the Carnic Alps, documented previously only by brachiopods, are confirmed.

Gondolellidae (Conodonta), del Carbonífero Superior de la Zona Cantábrica (N. de España). Sistemática e implicaciones paleotérmicas

Resumen Los hallazgos de gondolelidos en el Carbonifero Superior son escasos. Este trabajo se ocupa del estudiode tres especies de los generos Gondolella y Neogondolella encontrados en tres secciones de la Zona Cantabrica (N. de Espana). La fauna consiste en elementos pectiniformes de Gondolella laevis Kossenko & Kozitskaya , Gondolella nov. sp. 1 y Neogondolella clarki ( Koike ). Tanto G. Laevis como N. clarki se conocen en Norteamerica y la antigua URSS. La segunda de estas especies, ha sido descrita originalmente del Japon. Los valores de CAI de estos elementos y de otros procedentes de las mismas unidades estructurales permiten discutir las condiciones termicas a las que han estado sometidas las rocas de donde proceden.

Late Paleozoic Ostracodes of Western Europe and North America: A Review

Abstract It is perhaps due to the fact that ostracodes have proved to be successful in so many different environments adapting themselves to every variation in temperature, salinity, water energy, substratum, depth, that they often seem less useful for biostratigraphical applications, at least as far as long—distance correlations are concerned. On the one hand we observe several long—ranging species, which persist in diachronous facies and on the other hand there exist many groups which are able to survive small facies changes with small changes in their morphology. The biostratigraphic use of Paleozoic ostracodes is further hampered by the fact that up to now we have only the rather isolated results of work on ostracodes from different areas and environments at our disposal. This situation may improve within the forthcoming years as has been shown by the discovery of so—called silicified Devonian faunas and Devonian—Carboniferous entomozoacean faunas. However, at the present time these are only known from northwestern Europe, Spain, Portugal, and North America. At the same time attempts are being made to come to long—distance correlations of Upper Devonian and Dinantian assemblages between the USSR and western Europe by Russian ostracodologists. In Europe, the attention of Devonian to Permian ostracode workers has up to now mainly been concentrated on descriptive palaeontology and in the last decade on palaeoecology.