The geological column in northern Utah has had very little detailed study. Those who have made reports on this section have done so only in a very general way, making no detailed sections of any part of the column, excepting that of the Cambrian made by Walcott. Other work has been done by Mansfield in southeastern Idaho and a general section of the Devonian made in Green Canyon, Bear River Range, Utah by kindle.

Lower and Middle Devonian strata crop out on the former stable carbonate platform that existed in the Quinn Canyon Range, through the carbonate shelf edge in the Pancake Range, to the carbonate slope and outer-shelf basin in the Reveille Range. The strata of the Reveille Range record a transition from deposition on the carbonate platform in the Lower Devonian, to deposition at the carbonate platform margin, to deposition in the outer-shelf basin in the Middle Devonian. Conodonts collected from the base of the Sevy Dolomite yield a kindlei-Zone age, an indication that the Sevy Dolomite is younger than previously recognized. Throughout the Lower and Middle Devonian, carbonate strata of the Pancake Range and Quinn Canyon Range were deposited on the shallow carbonate platform. Conodonts collected from the base of the Lower Alternating Member of the Simonson Dolomite in the Quinn Canyon Range have a slightly older age (serotinus- to costatus Zone) than other eastern Nevada locations. The Lower Devonian Sevy Dolomite was deposited in a shallow carbonate subtidal through supratidal environment and is similar in outcrop throughout the ranges. Petrographic studies show that the samples are lithologically and diagenetically similar, indicating a similar intensity of dolomitization from the precursor calcareous mudstone. The Formation classifies as bioturbated mudstone and wackestone. The Middle Devonian Simonson Dolomite was deposited in shallow carbonate subtidal through supratidal environments. The Simonson Dolomite was affected by Milankovitch Cycles, glacioeustatic oscillations of sea level, producing a characteristic rhythmic bedding. The Middle Devonian Sadler Ranch Formation and Denay Limestone are lithologically and diagenetically different from the shallow water deposits of the Lone Mountain Dolomite, Sevy Dolomite, and Simonson Dolomite. The Sadler Ranch Formation and Denay Limestone were deposited at the carbonate platform edge and on the carbonate slope and outer-shelf basin, respectively. The Sadler Ranch Formation is dolomitized and may be classified as fossiliferous wackestone and mudstone. The Denay Limestone is not dolomitized and is classified as mudstone and fossiliferous grainstone and packstone. Dolomitization in the Paleozoic strata of Nevada is a secondary feature, an early diagenetic replacement of strata which were originally limestone. This replacement process was controlled by transgressions and regressions of the shoreline. Shallow carbonate platform deposits (shelfal and tidal-flat) are dolomitized, whereas deep water outer-shelf basin and slope deposits are not. / Graduation date: 1997

The geological column in northern Utah has had very little detailed study. Those who have made reports on this section have done so only in a very general way, making no detailed sections of any part of the column, excepting that of the Cambrian made by Walcott. Other work has been done by Mansfield in southeastern Idaho and a general section of the Devonian made in Green Canyon, Bear River Range, Utah by Kindle. Due to the lack of any detailed work of this nature being done in the Bear River Range, suggested the matter of making a section and describing the Devonian System of this range, because, probably less is known of this system than of any other one. Stratigraphic relations were studied in several sections where outcrops were good. Conditions for the study of these outcrops are very favorable, because, within a very short distance of 6 or 7 miles there are 6 canyons cutting the range at approximately right angles to the general trend of the structure, giving satisfactory sections of the greater part of the Paleozoic Era. Blacksmith Fork Canyon gives the best section of the Devonian System in the area studied. Because of easy access and good exposures, this canyon was chosen for a graphic section. Another section was made in Logan Canyon as a matter of comparison.

The Campbellton Formation, ~1 km thick, has long been recognized for early plants, arthropods, and fishes. The sedimentology of two basins is described with six facies associations to provide a framework for the fossil assemblages. The western basin contains aquatic fauna and coastal flora within a basal rhyolite breccia and coastal deltaic strata, and a braided river facies association is also present. Lower eastern basin strata primarily comprise lacustrine facies, where a thick marginal association deposited by sediment-laden underflows contains a lake-side plant assemblage. Other lacustrine associations include a fine-grained association in areas with restricted circulation, and a near-shore association. Upwards, a plant-rich fluvial landscape had wide sandstone and conglomerate channels and high-diversity wetlands containing terrestrial arthropods. A proximal alluvial facies association with hyperconcentrated flows contains plants and Prototaxites, possibly from adjoining uplands. All plants groups were well-established throughout the formation, with no apparent landscape partitioning between groups.

No description available.

No description available.

No description available.

La dichotomie environnementale qui caractérise la Terre, à savoir la présence de milieux aquatiques et de terres émergées, a joué un rôle important au cours de l’évolution de la vie. L’histoire évolutive des vertébrés, par exemple, a continuellement été ponctuée d’épisodes de sorties des eaux et de retours aux milieux aquatiques, souvent soulignés dans le registre fossile par des radiations biologiques majeures. L’exemple le plus célèbre concerne probablement les épisodes de sorties des eaux des premiers tétrapodes qui bouleversent les écosystèmes terrestres il y a environ 360 millions d’années, au moment de la transition Dévonien-Carbonifère. A l’échelle des temps géologiques, ces transitions écologiques ont pu revêtir un caractère soudain ; une instantanéité apparente résultant cependant, bien souvent, de l’incomplétude du registre fossile. Au fur et à mesure que les données paléontologiques s’étoffent ces transitions écologiques nous content des histoires d’une grande complexité, s’inscrivant dans des durées de l’ordre du million, voire de la dizaine de millions d’années ! La compréhension de toutes ces histoires nécessite de connaître avec précision les milieux de vie de leurs principaux acteurs, les espèces éteintes de vertébrés. Traditionnellement, l’étude des environnements de vie des espèces fossiles s’appuie sur les analyses morpho-fonctionnelles et sédimentaires. Cependant, ces deux méthodes permettent seulement de reconstruire un environnement fonctionnel et un environnement de dépôt, qui peuvent être différents de l’environnement de vie. L’objectif principal de cette thèse est de démontrer l’intérêt de l’analyse de la composition isotopique du soufre dans les apatites de vertébrés afin de reconstituer leurs milieux de vie. Nous avons tout d’abord démontré la capacité du système VarioPyrocube©, couplé en flux continu à un spectromètre de masse à ratio isotopique, à analyser avec précision la composition isotopique du soufre dans les apatites biogènes. Nous avons ensuite démontré que l’analyse conjointe des isotopes de l’oxygène et du soufre de l’apatite de nombreuses espèces de vertébrés actuels permettait de tracer leur environnement de vie. Nous avons ensuite appliqué ce nouvel outil isotopique aux assemblages de vertébrés du Dévonien supérieur et mis en évidence l’enregistrement d’une influence marine dans les apatites de ces espèces généralement considérées comme dulçaquicoles. En guise de perspectives, nous avons souligné une première piste diagénétique susceptible de perturber la composition isotopique originelle. Face à ce problème, nous suggérons finalement d’adopter une démarche empirique, consistant à analyser la composition isotopique du soufre de nombreuses apatites fossiles afin d’obtenir une vision exhaustive de son potentiel en tant que marqueur environnemental / -

The depositional environment that existed during the accumulation of Devonian - Mississippian black shales of the eastern US has been a topic of debate in recent decades. In this study, pyrite framboid size distribution was evaluated for four cores from the Devonian outcrop belt of central Kentucky to determine the role that anoxic-euxinic conditions may have played in the accumulation of these black shales. For samples from the Appalachian Basin, pyrite framboid size distributions suggest that the Sunbury Shale and the upper part of the Huron Shale Member of the Ohio Shale were deposited under predominantly euxinic conditions, whereas the lowermost part of the Huron Member and the Cleveland Member of the Ohio Shale were deposited under predominantly dysoxic to oxic conditions. For samples from the Illinois Basin, pyrite framboid size distributions suggest that the Clegg Creek and the Morgan Trail members of the New Albany Shale indicate dysoxic to oxic conditions were present, whereas data for the Camp Run Member suggest the sediments were deposited during repeated intervals of euxinic deposition followed by predominant dysoxic - oxic conditions which allowed development of the bioturbated fabric seen in these gray shales. These results are not completely in agreement with previous research that utilized C-S-Fe and trace element relationships to establish depositional conditions during organic-rich sediment accumulation. For example, previous research has indicated that the Cleveland Member of the Ohio Shale and the Clegg Creek Member of the New Albany Shale were deposited under euxinic conditions. Reasons for these differences in interpretation may include syngenetic and diagenetic processes including winnowing of framboids in the depositional environment and atypical growth of the framboids.

No description available.