No description available.

No description available.

No description available.

The Upper Devonian of the central-southern Appalachians Valley and Ridge province of Virginia lacks stratigraphic resolution, revised formal nomenclature, and detailed biostratigraphic data. Eight of the most complete sections available in a three thousand square mile area were used to build a framework for revising the stratigraphy of the Upper Devonian strata in southwestern Virginia. Detailed lithologic descriptions of about four thousand feet (1.3 km) of rock were made at each outcrop. John Dennison's (1970 and 1976) nomenclature for the Upper Devonian along the Alleghany Front was successfully tested for it usefulness in Southwestern Virginia and are hereby applied to these rocks. The stratigraphic interval ranges in age from the Middle Devonian to the Lower Carboniferous. The stratigraphic units include the Middle Devonian Millboro Shale, the Upper Devonian Brallier, Scherr, Foreknobs (formally the "Chemung"), Hampshire, and the Lower Carboniferous Price Formation. The Brallier contains two members (Back Creek Siltstone and Minnehaha Springs), the Foreknobs is divided into five members (Mallow, Briery Gap, Blizzard, Pound, and Red Lick), and the lower Price is divided into three members (the Cloyd Conglomerate, Sunbury Shale, and the Ceres). 23046 fossils were collected and 160 taxa were identified. The biostratigraphic range of each taxon was compiled, analyzed, and then divided into biostratigraphic zones. 19 local biozones are described. The Frasnian/Famennian boundary is accurately placed based on occurrences of internationally known index fossils. The Frasnian/Famennian extinction event is recognized and is determined to have two pulses. The local biostratigraphic zonations doubled the resolution of previous studies. Lithostratigraphic and biostratigraphic data were combined to look at the timing and rates of events. The lithostratigrapic divisions were tested to see if their boundaries are or are not time transgressive. The Brallier/Foreknobs, Blizzard/Pound, and Pound/Redlick boundaries are crossed by biozones. Conversely the Frasnian/Famennian boundary crosses the lithologic boundary between the Pound and Red Lick Members. This documents the prograding nature of the clastic wedge. Composite biostratigraphic ranges correlate with ranges in New York and western Maryland. This detailed lithostraigraphic and biostratigraphic study documents a comprehensive and higher resolution understanding of the Upper Devonian in the Central-Southern Appalachian Basin. / Ph. D.

The Lower Devonian carbonate-clastic sequence of southwest Ellesmere Island accumulated in the Franklinian Basin at approximately 15(DEGREES)N latitude. A variety of depositional settings are represented, ranging from tidal flat to basinal environments. These environments can be recognized in Lower Devonian rocks across the Arctic Islands. / Progradation of the carbonate sequence of southwest Ellesmere Island occurred in the Early Devonian, but was periodically interrupted in the Zlichovian/Dalejan by transgressive events. Upward movement in the newly named Inglefield Uplift occurred throughout the Devonian, and shed clastic sediments westward that, in Middle to Late Devonian time, finally overwhelmed the marine carbonates and resulted in fluvial deposition on southern Ellesmere Island. / Certain formations in the Lower Devonian sequence are profusely fossiliferous, in particular the Blue Fiord Formation, which contains an abundant fauna including numerous species of coral and brachiopods. Both of these groups belong to the Old World Biogeographic Realm, and indicate a Zlichovian age for the lower Blue Fiord Formation of southern Ellesmere Island.

No description available.

No description available.

Apesar do grande número de estudosenvolvendo taxonomia esistemática de braquiópodes, poucos foramos estudos que utilizassema metodologia de análise cladística. Desta forma,no estudo aqui apresentado, foi feita uma análise cladística dos taxabasais da Ordem Spiriferida, comatenção especialà superfamília Delthyridoidea. Esta superfamília, Siluro-Devoniano, temcomointegrante o taxon Australospirifer, representante típico do Domínio Malvinocáfrico, e presente no Devoniano brasileiro. A análise cladística tambémtem por objetivo testar a hipótese filogenética apresentada por Lespèrance e Bizarro (1999) para a superfamília Delthyridoidea. Braquiópodes, bivalves, tentaculítideos e trilobitas, típicos representantes do Província Malvinocáfrica, foram descritos para o flanco norte da Formação Ponta Grossa (Eo-mesodevoniano), Estado de Goiás, Brasil, uma área compoucos estudos paleontológicos. Foi descrita uma nova espécie para o gênero Ptychopteria, e umnovo gênero e nova espécie de espiriferídeo, comafinidades filogenéticas ao gênero Australospirifer. A análise cladística foi realizada com enraizamento a posteriori no taxon Eospirifer.O cladograma semiestrito resultante, escolhido como proposta detrabalho, apresentou CI=0,40, RI=0,70, RC=0,30. Apesar da baixa resolução, este estudo aqui discutido apresenta uma acuidade maior emrelação ao anteriormente realizado por Lespèrance e Bizarro (1999), principalmente por conter um maior número de caracteres e taxa.Como resultado, pôde ser observado que alguns grupos tradicionalmente considerados basais emSpiriferida, como Delthyridoidea e Cyrtioidea não são considerados monofiléticos. Por outro lado Reticularioidea e Martinioidea (excluindo Tenellodermis) são confirmados comogrupos monofiléticos. Além disso, o gênero Australospiriferé considerado um metataxon, sendo basal emrelação a um grupo inteiro, que corresponde tanto a taxatípicos do Hemisfério Norte quanto ao taxonnovo aqui descrito. / Despite the large number of taxonomic studies on fossil brachiopods, few include cladistic analysis. This study is one of the first to apply thismethod to basal taxa amongs Spiriferida, with special attention to the superfamily Delthyridoidea. This superfamily, restricted to the Silurian and Devonian, includes the taxon Australospirifer, which is common in Devonian deposits of Brazil and representative of the Malvinocafric Realm. This analysis also tests the phylogenetichypothesis proposed by Lespèrance and Bizarro (1999) for the superfamily Delthyridoidea. Brachiopods, bivalves, tentaculitids and trilobites, typical elements of the Malvinocafric Realm,are describedfrom the Ponta Grossa Formation (Early to Middle Devonian) in the northern portion of the Parana Basin in the State of Goiás, Brazil, a region still poorly known paleontologically, especially for brachiopods, when compared to the southern portion of the basin. A new species ofthe genus Ptychopteria,and a new genus and species ofspiriferidhaving phylogenetic affinities with the genus Australospiriferare described. The cladistic analysis was carriedout with a posteriorirooting in the taxon Eospirifer. The resulting semistrict cladogram, the preferred working hypothesis, presented CI=0,40, RI=0,70 and RC=0,30. Despite its relatively low topological resolution, this cladogrampresents greater accuracy than that proposed by Lespèrance and Bizarro (1999), mainly because of the greater number of characters, and taxa utilized. As a result,some groups, traditionally considered as basal within the Spiriferida, such as Delthyridoidea and Cyrtioidea, can not be interpreted here as monophyletic. On the other hand, Reticularioidea and Martinioidea (excluding Tenellodermis) are confirmed as monophyletics groups. In addition, the genus Australospirifer is considered a metataxon, and basal not only to the group including typical Northern Hemisphere taxa but also to the new genus and species described here.

In 1948 Williams subdivided the Jefferson Formation of northeastern Utah into two formations. The upper formation was referred to as the Late Devonian Jefferson Formation and the lower formation the Early Devonian Water Canyon Formation (Williams, 1948, p. 1138). Since that ti.me detailed study of the Water Canyon Formation has not been made . It is the purpose of this investigation to describe in detail the lithology and paleontology of the formation and their implication as to the environment of deposition of Early Devonian time in northeastern Utah.

Cette étude est dédiée à la période charnière que constituent lEifélien et la base du Givétien en Belgique et les régions limitrophes, entre le Dévonien inférieur caractérisé par des dépôts détritiques et linstallation dune plate-forme carbonatée au Givétien. Létude sédimentologique détaillée que nous avons entreprise est le résultat de lintégration de différentes techniques danalyses : sur le terrain (levé et description banc par banc), en lame mince (pétrographie et microfaciès) et sur les échantillons (susceptibilité magnétique et analyses chimiques). Dans le cadre de ce travail, ce sont 14 coupes qui ont été levées, représentant une épaisseur totale de 1650 mètres. Les études de terrain ont permis de mettre en évidence une grande variété de faciès carbonatés, détritiques ou mixtes. Cette variété illustre parfaitement la variabilité latérale qui est la règle au sein de ces niveaux. Les analyses pétrographiques qui ont été menées sur 3352 lames minces, confirment cette diversité et aboutissent à la définition de 71 microfaciès. Ces microfaciès sont répartis sur un modèle de plate-forme et sur 6 modèles de rampe. Ces différents modèles de rampe se distinguent les uns des autres par une influence terrigène plus ou moins marquée, le développement ou non de bioconstructions ou encore la présence ou non de shoals. Les analyses de susceptibilité magnétique on permis de mettre en évidence trois paramètres sédimentologiques principaux linfluençant : lapport détritique (le continent étant la source principale des minéraux porteurs du signal), lagitation (qui peut empêcher le dépôt de ces mêmes minéraux) et la productivité carbonatée (qui peut diluer ces minéraux). Les analyses chimiques quant à elles permettent de clairement dégager 4 pôles parmi les minéraux présents dans les échantillons, chacun ayant sa contribution propre à la valeur de susceptibilité magnétique. Le premier est le contenu en carbonates qui est directement lié à la productivité carbonatée. Outre le quartz détritique, lapport terrigène comporte de son côté deux pôles distincts : lun sous forme dargiles et lautre sous forme de minéraux ferromagnétiques primaires. Le dernier pôle correspond à linfluence de la diagenèse par la dolomitisation et la cristallisation de pyrite, dhématite et éventuellement de magnétite. De par la répartition générale des trois paramètres sédimentologiques cités ci-dessus sur les profils de plate-forme et de rampes, trois types dévolution des courbes de susceptibilité magnétique se dessinent quand on la compare à lévolution des microfaciès. Certaines coupes ne montrent aucun lien entre les deux types de courbes, la susceptibilité magnétique restant relativement constante. Ensuite, un parallélisme peut sobserver entre les deux types de courbes (à une baisse de niveau marin, correspond une hausse de valeurs de susceptibilité magnétique et inversement). Enfin, une opposition peut être observée entre les deux types de courbes (à une baisse de niveau marin, correspond une baisse de valeurs de susceptibilité magnétique et inversement). Une fois identifiés, ces comportements relativement cohérents permettent lutilisation de la susceptibilité magnétique à des fins de corrélation. Lintégration de lensemble des données et interprétations aboutit à la proposition dun canevas de stratigraphie séquentielle. La généralisation de ce canevas à lensemble du bord Sud du Synclinorium de Dinant permet une meilleure compréhension du passage latéral entre la Formation de Couvin et la Formation de Jemelle et de linstallation de la plate-forme carbonatée à la transition Eifélien-Givétien.