2009: The new chronostratigraphic classification of the Ordovician System and its relations to major regional series and stages and to δ 13 C chemostratigraphy. Lethaia , Vol. 42, The extensive work carried out during more than a decade by the International Subcommission on Ordovician Stratigraphy has resulted in a new global classification of the Ordovician System into three series and seven stages. Formal Global Boundary Stratotype Section and Points (GSSPs) for all stages have been selected and these and the new stage names have been ratified by the International Commission on Stratigraphy. Based on a variety of biostratigraphic data, these new units are correlated with chronostratigraphic series and stages in the standard regional classifications used in the UK, North America, Baltoscandia, Australia, China, Siberia and the MediterraneanNorth Gondwana region. Furthermore, based mainly on graptolite and conodont zones, the Ordovician is subdivided into 20 stage slices (SS) that have potential for precise correlations in both carbonate and shale facies. The new chronostratigraphic scheme is also tied to a new composite δ 13 C curve through the entire Ordovician. ᮀ Chemostratigraphy , chronostratigraphy , classification , Ordovician System , stage slices . Stig M. Bergström [stig@geology.ohio-state.edu],

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Las formaciones del Ordovícico Medio del Anti-Atlas (sur de Marruecos) han librado un variado registro de trilobites, moluscos, equinodermos, braquiópodos, graptolitos, microfósiles e icnofósiles en alrededor de 180 localidades. Gran parte de ellas fueron descubiertas durante la realización de la cartografía geológica a escala 1:200.000 y la mayoría del material paleontológico permanece inédito. En este trabajo se revisa el marco geológico de todas las localidades fosilíferas conocidas (tanto las publicadas como las inéditas), poniéndose en evidencia numerosas discrepancias litoestratigráficas en relación con estudios precedentes. Además de la reevaluación estratigráfica, se revisa el contenido paleontológico de cada formación y localidad, actualizando la taxonomía de muchas de las formas identificadas. Desde el punto de vista cronoestratigráfico, el conjunto de la Formación Tachilla y las cinco formaciones del Grupo Primer Bani se adscriben por vez primera a la escala regional mediterránea. Los límites Oretaniense-Dobrotiviense y Dobrotiviense-Berouniense se sitúan, respectivamente, en la Formación de Bou-Zeroual y en el techo de la Formación Izegguirene. El tránsito Oretaniense inferior-superior se emplaza provisionalmente en el tercio superior de la Formación Tachilla, y el límite Dobrotiviense inferior-superior hacia la base o en la parte inferior de la Formación Ouine-Inirne. También se aporta la correlación general de las unidades del Ordovício Medio antiatlásico con respecto a la escala estándar o global del sistema Ordovícico. La base de la Serie Ordovícico Superior se sitúa probablemente en la parte inferior de la región como un centro importante de diversificación para numerosas faunas mediterráneas, las cuales experimentan una amplia dispersión posterior en las plataformas marinas del norte de Gondwana.

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The upper Aeronian to lower Telychian (Llandovery Series, lower Silurian) strata at the east end of El Pintado reservoir, Seville Province, Spain are documented in terms of their lithologies, graptolite biostratigraphy and δ 13 C org record. This is the first time that a continuously graptolitic section throught the Aeronian/Telychian boundary has been studied in detail. The upper Aeronian part of the section is assigned to the Stimulograptus halli Biozone which is divisible into three, the middle part being referred to the Lituigraptus rastrum Subzone. The Telychian strata are assigned to the Spirograptus guerichi Biozone and lower Sp. turriculatus Biozone. Unusually, two specimens of Sp. turriculatus were found at a level low in the guerichi Biozone. 118 graptolite species are recorded, 18 of which are new and described here together with other species for which the El Pintado material provides new information. Diversity increases considerably in some genera (Glyptograptus, Parapetalolithus, Rastrites, Streptograptus) in the upper halli Biozone and/or lower to middle guerichi Biozone only to decline again (except for Streptograptus) in the upper part of the guerichi Biozone as part of the "utilis Event". This diversity decline coincides with an interval of elevated δ 13 C org values. There are no major δ 13 C org excursions present in the El Pintado sections. The δ 13 C org record through the guerichi Biozone is very similar to that in Arctic Canada. Portsmouth, Burnaby Road, Portsmouth PO1 3QL, UK; david.loydell@port.ac.uk • Jiří Frýda, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21, Praha 6 and Czech Geological Survey, Klárov 3, 118 21 Praha 1, Czech Republic;, Facultad de Ciencias Geológicas, E-28040 Madrid, Spain; jcgrapto@ucm.es Our knowledge of the geological column is remarkably patchy. For some stratigraphical intervals numerous papers exist documenting sections, their contained fossils and chemostratigraphical record. Other intervals -unfortunately these are often around chronostratigraphical boundaries -are remarkably bereft of useful published stratigraphical data. This is usually because of the paucity or even absence of sections without major facies changes that are continuously fossiliferous. One such "unknown" interval has been the uppermost Aeronian to lowermost Telychian (middle to upper Llandovery Series). Recognition that the GSSP for the base of the Telychian Stage is unsatisfactory from a number of viewpoints (Temple 1988;Loydell 1993a;Davies et al. 2011Davies et al. , 2013 has heightened recent interest in the search for more informative sections. The aim of this paper is to document the upper Aeronian and lower Telychian graptolitic strata through sections on the shores of El Pintado reservoir in Seville Province, Spain and to discuss the bio-, chrono-and chemostratigraphy of this part of the Silurian System. The paper commences with a review of published sections, to indicate why the El Pintado sections are so important. It contin...

The Fezouata Lagerstätte, discovered in the Lower Ordovician rocks of Morocco, is a Konservat‐Lagerstätte of prime scientific importance. It provides access not only to the ‘shelly’ (skeletonized) part of its fossil assemblages, but also to non‐biomineralized to lightly sclerotized organisms and to exceptionally preserved soft tissues of a complex ecosystem, mixing elements of both the ‘Cambrian Explosion’ and the ‘Great Ordovician Biodiversification Event’ (GOBE). The Fezouata Lagerstätte occurs at different intervals in the Fezouata Shale, a formation ranging from the lower Tremadocian to the upper Floian (Lower Ordovician). In spite of recent major advances in the detailed biostratigraphy of the Fezouata Shale, there is currently no consensus on the precise age of the fossiliferous levels yielding exceptionally preserved assemblages. Consequently, all available biostratigraphical evidence based on several fossil groups is here critically reviewed and discussed. It can be concluded that exceptional preservation is restricted to a few thin, discontinuous, lens‐shaped horizons occurring in two distinct parts of the Fezouata Shale: a lower interval (260–330 m above the base of the formation) and an upper interval (570–620 m). Integrated biostratigraphical studies, essentially based on investigations of graptolites, acritarchs and conodonts, indicate that the lower interval can be correlated with the upper Tremadocian, whereas the upper interval corresponds to the middle Floian.