Dissertations / Theses on the topic 'Stratigraphic Silurian'
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1
Kanō, Akihiro. "Deposition, palaeoecology, and diagenesis of the Silurian reef-like limestones on Gotland." Stockholm : Dept. of Geology and Geochemistry, University of Stockholm, 1990. http://catalog.hathitrust.org/api/volumes/oclc/23697432.html.
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Cramer, Bradley Douglas. "Application of integrated high-resolution biochemostratigraphy to Paleozoic chronostratigraphic correlation recalibrating the Silurian system /." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=osu1245178129.
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Hogan, John Patrick. "Mineralogical, chemical and isotopic diversity in plutonic rock suites from the Coastal Maine Magmatic Province:the role of source region heterogeneity, tectonic setting and magmatic processes." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39074.
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This dissertation represents an investigation of the mid-Paleozoic tectono-thermal and kinematic evolution of the crust in eastern coastal Maine as recorded by the plutonic rocks of this region.
The first chapter describes the plutonic rocks of the Coastal Maine Magmatic Province. A tectonic model is developed in which late Ordovician-Silurian bimodal magmatism is interpreted to reflect crustal melting as a result of intraplating of mantle melts at high crustal levels during a period of tension. Large scale melting of lower crustal source regions, represented by voluminous intrusion of Devonian granites, reflects a period of transpression during which upwelling mantle melts were confined to the base of the crust. The diversity of granitic plutons reflects changes in the mineral assemblages present during partial melting, and in some instances, modification as a result of mixing/mingling with mantle melts.
The second chapter examines the effect of accessory minerals on the initial Pb isotopic signature of anatectic granites. Their initial Pb isotopic composition reflects (a) the age, type, modal distribution, and heterogeneity in the initial U and Th content of the accessory phase(s) present in the source, (b) variation in melt composition and temperature during partial melting, (c) the fraction of the source melted, and (d) the extent to which the melt is homogenized prior to crystallization. It is shown that granitic plutons derived by crustal anatexis of a common source material are not required to have similar initial lead isotopic compositions.
The third chapter presents the results of a Pb isotopic investigation of selected plutonic rocks from the Coastal Maine MagmaticProvince. This study was designed to test and refine petrogenetic models presented in Chapter 1. The Pb isotopic signature of the granitic plutons reveals the presence of two lithologically heterogeneous source regions beneath the Avalon Composite Terrane. The upper crustal source region has an mean V-Pb age of -2.0 Ga and the high 207Pb/204Pb-206Pb/204Pb characteristic of Avalonian crust. The lower crustal source region has an average U-Pb age of -1.3 Ga and lower 207Pb/204Pb. This source region may represent either the autochthonous basement to the Avalon platform or the eastern extension of the basement to the Gander Terrane of central Maine.Ph. D.
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Chow, Andre M. C. (Andre Mu-Chin). "Sedimentology and paleontology of the Attawapiskat Formation (Silurian) in the type area, northern Ontario." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65494.
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Smith, Jason J. "A reinterpretation of the sedimentology and stratigraphy of the upper Silurian-lower Devonian Manlius Formation in upstate New York." Diss., Online access via UMI:, 2009.
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Vrazo, Matthew B. M. S. "Stratigraphic and Paleoecological Controls on Eurypterid Lagerstatten in the Mid-Paleozoic." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1468336974.
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Hughson, Robert Carl. "Upper silurian carbonates of Lake Memphremagog and lime ridge areas, Quebec." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63996.
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Clayer, François. "Sediment Dynamics and Stratigraphic Architecture of a Lower Silurian Storm-dominated Carbonate Ramp, Anticosti Island, Québec, Canada." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23149.
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The upper Llandovery succession across the Jupiter-Chicotte formational contact on Anticosti Island, Québec, allows us to study the sediment dynamics and stratigraphic architecture of a storm-dominated, carbonate ramp. The Anticosti paleotropical ramp was slowly subsiding and recording significant changes in sea level in a far field glacial setting during the early Telychian. Three facies associations, grouping nine facies, are recognized along the E-W outcrop belt, and from top to bottom as the: (FA-1) encrinitic carbonate facies, (FA-2) mixed siliciclastic and carbonate facies, and (FA-3) non-encrinitic carbonate facies. These mid to outer ramp sediments represent deposition mostly from episodic, high-energy storm events as evidenced by hummocky cross-stratification, large wave ripples, gutter casts, and wave-enhanced sediment-gravity flow deposits. Spatial and temporal changes in siliciclastic content imply basin margin depositional environments in the eastern sections and change in climate regime from arid to humid conditions. The Chicotte deposition marks a major faunal change with the domination of crinoids triggered by increasing siliciclastic supply, rapid sea level fluctuations and change in substrates. The recognition of one major transgressive-regressive (TR) sequence subdivided in distinct meter-scale cycles allows a high resolution E-W correlation. The development of the TR sequence and meter-scale cycles is driven by glacio-eustacy where the main sequence is 4th order (~400 Ky) with superimposed meter-scale cycles that are 5th and/or 6th order (~100 Ky). Nevertheless, erosional capping surfaces within the more proximal tempestites represent ancient rocky shorelines that developed during forced sea level falls. In order to explain this stratigraphic architecture, a carbonate open-ramp model is proposed with a concave-up profile and a narrow and steep inner ramp in equilibrium with a high-energy coastline.
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Santos, Werlem Holanda dos. "Análise estratigráfica do intervalo siluro-devoniano da bacia do Amazonas." Universidade do Estado do Rio de Janeiro, 2014. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=7129.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorO trabalho consiste na análise estratigráfica do intervalo siluro-devoniano da Bacia do Amazonas utilizando como base os conceitos da Estratigrafia Moderna, mais especificamente a sequência estratigráfica genética, proposta por Galloway (1989), a qual utiliza as superfícies de inundação marinha como os limites de uma sequência sedimentar. A principal razão para a utilização desta metodologia deve-se ao fato que o conteúdo rochoso compreendido no intervalo estudado teve a sua sedimentação relacionada às transgressões marinhas que faziam parte do contexto paleogeográfico da bacia durante o Siluriano e Devoniano. Desta forma, as superfícies de inundação máxima, representativas de eventos cronoestratigráficos, destacam-se nos perfis de raios gama e são tomadas como datum de correlação em treze poços exploratórios, os quais foram distribuídos em quatro seções (A-A, B-B, C-C e D-D) pela bacia. A análise destas seções permitiu a identificação de quatro sequências de terceira ordem (AB, BC, CD e DE), limitadas no topo e na base por superfícies de inundação marinha. Cada sequência é constituída por ciclos regressivo-transgressivos assimétricos, representados pelo trato de sistemas de mar alto e pelo trato de sistemas transgressivo. A análise destas seções integrada à interpretação de mapas estratigráficos (isópacas, isólitas e porcentagem de areias) possibilitou identificar o depocentro da bacia, bem como duas áreas principais como fonte de sedimentos arenosos (uma a oeste e outra a sul). Além disto, foi possível inferir que a comunicação marinha com o continente, durante as transgressões paleozoicas, responsável pela deposição de sedimentos pelíticos, seguiu uma orientação de norte para sul, evoluindo obliquamente em direção ao continente num trend nordeste para sudoeste. Por fim, a partir da análise cíclica em perfis de raios gama, as superfícies de inundação marinha, do intervalo Devoniano, das bacias do Amazonas e Parnaíba foram correlacionadas.
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Schmidt, David A. "Paleontology and sedimentology of calcifying microbes in the Silurian of the Ohio-Indiana region an expanded role of carbonate-forming microbial communities /." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1142964356.
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Gauthier, Eric L. "The potential of airborne synthetic aperture radar (SAR) imagery as a basic tool for stratigraphic investigations in forested areas: The Ordovician-Silurian carbonate succession of Anticosti Island, Gulf of St Lawrence, eastern Canada." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26373.
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Anticosti Island, located in the Gulf of St. Lawrence in eastern Canada, is one of the few places in the world where the Ordovician/Silurian boundary is well preserved and exposed. Its relatively undeformed shallow-water carbonate sequence of approximately 900 m in thickness is rich in fossils and is known to contain traces of hydrocarbons. The island has been for decades the subject of several geological studies, but its stratigraphic succession was never successfully mapped precisely because of its dense forest cover present over almost 95% of its vast territory.
This study provides new mapping tools and techniques to support the geological representation of the island stratigraphic succession. Airborne SAR (Synthetic Aperture Radar) data acquired with the active radar system onboard of the former CCRS (Canada Centre for Remote Sensing) Convair-580 aircraft, in single and fully polarimetric modes and with different viewing geometry, were qualitatively and quantitatively evaluated by means of image interpretation and polarimetric analysis for their mapping potential over the densely forested study area.
The airborne SAR data, supported with ancillary geoscience data sets and derivative topographic related products, have resulted in the availability of valuable and accurate terrain information such as topographic variations associated with the gently inclined recessive and resistant strata of the island succession. It also provided with information on the polarimetric scattering mechanism of the vegetation cover overlying the surface deposits and bedrock geology, suggesting a possible preferential distribution.
With almost 50% of the Canadian territory covered by forest, radar remote sensing, as demonstrated by this study, is a cost-effective tool to produce more accurate regional structural and geological map in areas where traditional mapping campaigns failed due to the presence of an extensive vegetation cover.
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Suchy, Daniel R. "Hudson Bay platform : silurian sequence stratigraphy and paleoenvironments." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70280.
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Trends in relative sea-level change, shown by curves drawn from drill core and outcrop sections in Llandoverian carbonates of the Hudson Bay Platform, were used to correlate individual parasequences among widely separated localities. Two sequences, bounded by regional disconformities, include: (1) the Severn River Formation, and (2) the Ekwan River, Attawapiskat, and Kenogami River Formations. Initial onlap of marine facies at the base of the Severn River Formation progressed from north to south, occurring first in the Hudson Bay Basin, then in the Moose River Basin; final retreat of the seas at the end of Attawapiskat time was in the opposite direction. The most extensive inundations occurred during Ekwan River and Attawapiskat depositional times. Large-scale trends in the curves delineate four major Early Silurian sea-level highstands also recognized in other basins.Reefs in outcrops along the Attawapiskat River represent one interval of reef growth, had a syndepositional relief of 8-10 meters, and were terminated by a relative sea-level fall. Their present distribution is controlled by variously uplifted fault blocks.
The most important diagenetic processes were early marine cementation and shallow burial diagenesis, and in the southwestern Moose River Basin early secondary dolomitization.
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Asses, Amar. "Analyse des diagraphies de forage, séquences sédimentaires et paléogéographie des séries argilo-gréseuses déposées au passage Silurien-Devonien dans la synéclise est-saharienne. : Bassin d'Illizi et partie algérienne du bassin de Ghadames." Pau, 1987. http://www.theses.fr/1987PAUU3020.
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Etude des bassins de Ghadames et d'Illizi au Silurien-Devonien. On définit cinq unités lithostratigraphiques à l'aide de marqueurs diagraphiques et des datations palynologiques. On reconstitue les paléoenvironnements à partir de l'analyse sédimentologique des lithofacies. Le silurien est caractérisé par une propagation de barres sableuses qui indique une régression marine vers le nord. Le Devonien est constitué par des chenaux fluviatiles au sud et des chenaux de marée au nord. L'évolution traduit l'amorce d'une transgression du nord vers le sud. On individualise un domaine littoral à influence continentale, un domaine marin et un domaine mixte. Le milieu de dépôt de la région étudiée est un bassin intracratonique structure par deux moles.
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Ray, David. "Event and subsurface stratigraphy of the Wenlock series (silurian) midland platform." Cincinnati, Ohio : University of Cincinnati, 2001. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin992281267.
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Ray, David Christopher. "EVENT AND SUBSURFACE STRATIGRAPHY OF THE WENLOCK SERIES (SILURIAN) MIDLAND PLATFORM , UK." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin992281267.
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Spengler, Alison Elizabeth. "Sequence Development on a Sediment-Starved, Low Accommodation Epeiric Carbonate Ramp: Silurian Wabash Platform, USA Mid-continent During Icehouse to Greenhouse Transition." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/44529.
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A study of 12 cores and 2 wells with cuttings through the Silurian (444 to 416 m..y.) succession of the Wabash Platform, Indiana was done to establish the high resolution sequence stratigraphy of a sediment-starved low-latitude epeiric sea platform during the transition from Ordovician icehouse to Devonian greenhouse. The Wabash Platform (approximately 200,000 square km area) is bounded to the north by the Michigan Basin, to the east by the Appalachian Basin, and passed to the southwest into the Vincennes Basin, which was open to the ocean.
Facies developed include: crinoidal grainstone-packstone sheets (updip shoals), buildup facies (stromatactis wackestone - lime mudstone, below storm wave-base settings; stromatoporoid skeletal wackestone - floatstone, storm wave-base to fair-weather wave-base; and crinoidal rudstone to packstone; flank facies); non-cherty, skeletal packstone, wackestone, mudstone (sub-fair-weather- to storm wave-base); and cherty, skeletal wackestone - mudstone and variably argillaceous carbonate mudstone (below storm wave-base).
Eight thin sequences (1.3 to 4 m.y. duration) occur and range from 2 m to 10 m, with the upper two sequences up to 20 m downdip; most of the sequences can be correlated to global cycles. Except for the lower three disconformity-bounded sequences, most sequences are relatively conformable and lack well defined sequence boundaries or subaerial exposure surfaces. The most easily mapped surfaces are the transgressive surfaces, given that the correlative conformities are cryptic. Lowstand system tracts probably include downdip grainy facies and the deep ramp seaward of updip late highstand deposits. Transgressive systems tracts are upward deepening, upward fining carbonate units, some of which become more argillaceous and silty upward. This contrasts with the usual association of clastic-prone units with lowstand to early transgressive systems tracts. Highstand systems tracts are subtly upward coarsening from carbonate mudstone to skeletal wackestone/packstone and rarely skeletal grainstone. During deposition of the uppermost two sequences, mudmound barrier banks grew upward into shallow water buildups to form a discontinuous raised rim (40 m relief) to the ramp.
Even though subsidence rates were very low (<1 cm/k.y.), the low sedimentation rates (0.3 cm/k.y. to 0.8 cm/k.y.) generally prevented the seafloor from building to sea level except for the basal three sequences in which Early Silurian third order glacio-eustacy generated disconformable boundaries. Thus the ramp remained subtidal through most of the relatively ice-free greenhouse later Silurian except over the buildups which locally shallowed to sea level. Parasequence development in high accommodation settings elsewhere in North America are compatible with the transition from moderate ice-sheets to an ice free world. However, this is poorly expressed on the Wabash Platform due to the dominantly deeper subtidal setting. The Silurian provides a window into climate change from a global cool period to global hothouse, which may have implications for understanding future climate change.Master of Science
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Daoust, Pascale. "High Resolution Stratigraphy of the Lower Silurian (Rhuddanian-Aeronian) Paleotropical Neritic Carbonates, Anticosti Island, Québec." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36645.
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Anticosti Island, located in Eastern Canada, displays one of the most complete, best exposed, and most fossiliferous carbonate successions spanning the Ordovician-Silurian (O/S) Boundary in the World. This study develops a new high-resolution framework for the post End-Ordovician extinction strata (~ 260 m thick) exposed in coastal outcrops and recovered from a continuous drill core (La Loutre #1), both located in the western part of the island. In total, eight facies, all associated with a storm-dominated carbonate system, were recognized and organized into a multi-order depositional cycles. A new high resolution isotopic curve with more than 300 data points from well-preserved bulk micrite samples covers the late Hirnantian to Early Aeronian time interval and corresponds to the upper Ellis Bay, Becscie, Merrimack and lower Gun River formations. Two distinct positive carbon isotope excursions are present in the late Hirnantian part of the Ellis Bay Formation (+5‰) and in the lower Aeronian part of the Gun River Formation (+2‰). These positive isotopic carbon excursions provide a distinctive chemostratigraphic signature for regional and global correlations with other O/S sections. Like the Quaternary δ18O marine signal, our δ18O record is largely coupled with multi-order cyclic facies changes. This study demonstrates the importance of glacio-eustasy following the End-Ordovician glacial maxima as one of the primary factors controlling the stratigraphic architecture of paleotropical neritic carbonates during the Early Silurian.
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Lubeseder, Stefan. "Silurian and devonian sequence stratigraphy of North America : Regional correlation and sedimentology (Morocco, Algeria, Libya)." Thesis, University of Manchester, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500476.
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Gouldey, Jeremy C. "Strontium and Carbon Isotope Stratigraphy of the Llandovery (Early Silurian): Implications for Tectonics and Weathering." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1221528660.
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Dekeyser, Lona Kate. "The Silurian Amabel and Guelph formations of the Bruce Peninsula: insights into stratigraphy and diagenesis from petrography and ground-penetrating radar." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2971.
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Regional study of the Silurian Amabel and Guelph (including the Eramosa Member) formations in the subsurface on the Bruce Peninsula provides petrographic details of these pervasively dolomitized rocks, defines lithofacies changes within each formation, and demonstrates the use of ground-penetrating radar as a tool for shallow subsurface stratigraphic mapping. Detailed stratigraphic logging of core provides insight on the complex depositional history of the pervasively dolomitized Amabel and Guelph formations by highlighting lateral facies changes that are not readily observable in outcrop. The Lions Head and Colpoy Bay members of the Amabel Formation are continuous in core across the Bruce Peninsula. These members contain characteristic dark grey mottles which are the result of increased porous zones and pyrite, and/or concentrations of undifferentiated organics. Chert nodules and the abundance of silica is most abundant in the upper Lions Head Member where silica-replaced fossils are recognized within the surrounding dolomite. Typical Wiarton Member crinoidal lithofacies from the upper Amabel Formation are more common in the southern half of the Peninsula. The Eramosa Member is more laterally continuous on the Bruce Peninsula than previously assumed. Although there is a lack of bituminous argillaceous Eramosa lithofacies within core, the laminated Eramosa Member is thick near Wiarton which suggests that a large restricted less-oxygenated area existed in that vicinity during the Silurian. Thick accumulations of tan-brown fossiliferous undifferentiated Guelph Formation dolostones occur at both the northern and southern ends of the Peninsula.
Petrographic analyses reveal that the Amabel and Guelph formations are dolomitized with no precursor limestone observed. Four types of dolomite were observed within these formations and differentiated based on crystal size. These dolomites are characterized by a uniform dull red luminescence, and range from inclusion-rich anhedral very finely (< 5 µm) crystalline dolomite to clearer euhedral coarsely (> 250 µm) crystalline dolomite. Petrographic analyses also revealed secondary minerals such as pyrite, calcite (and dedolomite), silica, sphalerite, fluorite, and glauconite.
Ground-penetrating radar surveys provided high-resolution data, which combined with detailed geologic observations of accessible quarry outcrops and borehole logs, support the conclusion that GPR is a useful tool for locating karstic features, vuggy porosity, and lateral and vertical facies changes in carbonate rocks. Radar profiles may have important implications for the aggregate and building-stone industries as a tool to locate carbonate units of exploration interest or to avoid zones with high impurities.
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Thomka, James R. "Dynamic linkages between stratigraphy, climate, oceanography, and biotic events in the middle Silurian of eastern Laurentia." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1445342455.
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Stouten, Craig A. "Subsurface Facies Analysis of the Clinton Sandstone, Located in Perry, Fairfield, and Vinton Counties." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1416147053.
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Oborny, Stephan C. "High-resolution event stratigraphy (hires) of the Wenlock—Pridoli interval in the eastern United States." Diss., University of Iowa, 2019. https://ir.uiowa.edu/etd/7003.
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Silurian strata of eastern North America have been thoroughly studied for nearly two centuries. Through these investigations a general understanding of unit distribution and correlative relationships were established throughout the region. Many of these interpretations remain valid still to this day, however, with advancements in stratigraphic methodologies in the last few decades (e.g., sequence-, chemo-, and biostratigraphy), numerous discrepancies have come to light with regards to the chronostratigraphic correlation of several stratigraphic intervals throughout the region. A number of these discrepancies within the lower Silurian (Llandovery—lower Wenlock) have been resolved in the last two decades permitting the establishment of refined depositional models and sequence stratigraphic hierarchies for strata deposited during this interval of time for the Appalachian, Illinois, and Michigan basins. Though these studies provided significant improvement to the chronostratigraphy of eastern North America, there remained a large under-evaluated stratigraphic interval spanning the remainder of the Silurian (Wenlock—Pridoli), which is host to expansive evaporite reserves and hydrocarbon resources throughout eastern North America. As such, it is critical that these strata are accurately and precisely correlated throughout the region and that temporal constraint be applied to these resources in order to evaluate their potential and develop predictive models for their future utilization.
The investigation herein provides high-resolution chronostratigraphic analyses of several core and outcrop from the eastern, southwestern, and western margins of the Appalachian Basin. These analyses included the integration of δ13Ccarb chemostratigraphy, conodont biostratigraphy, sequence stratigraphy, and subsurface geophysical data. The work herein now permits the establishment of global series and stage boundaries for the upper Silurian throughout the Appalachian and Michigan basins and also addresses regional miscorrelations within strata on both the eastern and western margins of the Appalachian Basin to provide a united sequence stratigraphic hierarchy between the Appalachian, Illinois, and Michigan basins.
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Sullivan, Nicholas B. "Refinements to the Depositional History of Lower Silurian Strata in the Northeastern United States by means of Conodont Biostratigraphy, d13C Chemostratigraphy, Sequence Stratigraphy, and Magnetic Susceptibility." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1378112630.
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Henniche, Messaouda. "Architecture et modèle de dépôts d'une série sédimentaire paléozoi͏̈que en contexte cratonique." Rennes 1, 2002. http://www.theses.fr/2002REN10097.
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Wickson, Steven. "High-Resolution Carbon Isotope Stratigraphy of the Ordovician-Silurian Boundary on Anticosti Island, Quebec: Regional and Global Implications." Thesis, University of Ottawa (Canada), 2011. http://hdl.handle.net/10393/28928.
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The end-Ordovician was a critical time in Earth history and marked the occurrence of a mass extinction and a period of continental glaciation. The Ellis Bay Formation on Anticosti Island in Quebec represents up to 100 meters of relatively undisturbed, continuous, low latitude, shallow water carbonate ramp deposits that span the Hirnantian Stage and terminate close to the Ordovician-Silurian (O-S) boundary. In this study, approximately 400 samples of micritic limestones were collected from six Ellis Bay sections ranging from the basin margin to more distal basin center of the Anticosti Basin. delta13C and delta18O isotopic ratios were measured from these samples and integrated within a recently proposed framework of sequence stratigraphy and biostratigraphy for the Ellis Bay Formation. The measured delta13C values in most sections show a positive excursion (∼2‰) in the lower Ellis Bay Formation followed by a larger excursion (∼4‰) in the upper Ellis Bay Formation. The delta 13C profile of the Ellis Bay Formation on Anticosti Island exhibits a pattern similar to those of other profiles in graptolite-rich Hirnantian basinal successions from the rest of the world. The delta13C record on Anticosti Island is not consistent with predictions and observations based on current models that describe the state and evolution of the global carbon cycle during the Late Ordovician.
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Pyle, Leanne J. "Stratigraphy, conodont taxonomy and biostratigraphy of Upper Cambrian to Lower Silurian platform to basin facies, Northern British Columbia." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ52769.pdf.
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Swift, Robert James Anthony. "Conodont Biostratigraphy and δ¹³C Chemostratigraphy of the Salina Group (Silurian) in Western Ohio and Eastern Indiana." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313675443.
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Snelling, Andrea Marie. "Characterisation of stratigraphy and palaeoceanography using graptolites : exploring new concepts in the Aeronian (Silurian) of Wales, Scotland and Northern Ireland." Thesis, University of Leicester, 2009. http://hdl.handle.net/2381/7532.
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Graptolites, extinct macrozooplankton of the phylum Hemichordata were a major element of the Early Palaeozoic seas. They are here investigated from Wales, Scotland and Northern Ireland and their use beyond biostratigraphy is considered. The leptotheca and convolutus biozones (Aeronian; Silurian) are characterized and correlated across Wales, Scotland and Northern Ireland, and in Scotland subdivision of the convolutus Biozone was possible through identification of Cephalograptus cometa extrema. In the Irish successions, previously unrecognized morphological intermediates within the established Petalolithus-Cephalograptus lineage were recognised and in Wales and Scotland, ‘pre-maxiculus’ morphotypes of Coronograptus are suggested. At all three localities Campograptus lobiferus is the dominant species with intraspecific variation recorded; the type material of this species from Scotland is shown to be unusually large. Use of X-ray images has enhanced biostratigraphy by enabling more specimens and taxa to be recorded, shown how graptolite number varies microstratigraphically and demonstrated that rhabdosomes are systematically aligned. The number and thickness of Aeronian ‘anoxic’ units varies within Wales, and between the Welsh and Scottish successions, indicating diachroneity of anoxia. A schema of microfacies types is constructed for the leptotheca Biozone anoxic unit in Wales and is applied to the Welsh convolutus Biozone anoxic units and to the gregarius to convolutus Biozone strata in Scotland. Facies with less clastic input and no burrows are associated with the best preserved graptolites, with pyrite formation being influenced by variations in palaeoproductivity and clastic input. Levels with well-preserved graptolites are not geochemically distinct, but differences in the major elements indicate provenance differences between the leptotheca and convolutus biozones. A reproducible &delta ^{13}C signal is obtainable from small amounts of carbon from graptolite periderm and periderm &delta^{13}C is different but not consistently so to whole-rock &delta^{13}C. Initial results suggest that periderm &delta^{13}C is not affected by physiology, life habit or metamorphic grade and that for chemostratigraphic study little regard is needed for species composition.
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Cramer, Bradley Douglas. "Glaciation CO2, and organic carbon burial during the early Silurian: carbon isotope stratigraphy from the mid-continent of North America." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406711650.
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Bekkouche, Djamel. "Le Silurien supérieur - Dévonien inférieur du bassin de Ghadamès (Sahara oriental Algérien) : lithostratigraphie, sédimentologie et diagenèse des réservoirs gréseux." Phd thesis, Grenoble 1, 1992. http://tel.archives-ouvertes.fr/tel-00759888.
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L'ensemble Silurien supérieur-Dévonien inférieur du Bassin de Ghadamès, équivalent du réservoir F6 du bassin d'illizi, est subdivisé en cinq unités (a, b, c, d, e) couvrant l'intervalle de temps du Ludlowien au Praguien sans discontinuité sédimentaire. L'analyse des faciès et la stratigraphie séquentielle ont permis de caractériser les milieux de dépôts et de retracer l'histoire spatio-temporelle des sédiments. Les sédiments argilo-gréseux, de l'unité "a" (Ludlowien - Pridolien) forment le prisme de haut niveau (PHN) de la séquence S1 (Ordovicien supérieur - Silurien supérieur); ils caractérisent une zone littorale dominée par l'action des vagues et des tempêtes. Les Grès massifs "b" (Lochkovien), prisme de bas niveau (PBN) de la séquence S2 (éodévonienne), sont constitués de dépôts fluviatiles de remplissage de vallées entaillées (IVF) au Sud du bassin (région Stah/Méreksen) et de dépôts de plaine côtière formant des prismes de progradation (LPW) en direction du bassin (Nord). Les sédiments ferrugineux de l'unité "C" (Lochkovien) sont des dépôts marins transgressifs (TST). Les sédiment de l'unité "d" (Praguien) et de l'unité "e" (Emsien) sont des dépôts de haut niveau marin (PHN) de la séquence S2. Les réservoirs rencontrés dans le Bassin de Ghadamès sont situés principalement dans les unités "b" et "c" (Lochkovien) où l'extension des grès est prouvée sur des milliers de km2 Par contre les réservoirs présentent des variations de porostté et de perméabilité, engendrées par les transformations diagénétiques qui ont affecté les grès. Le revêtement chloriteux des grains, ciment précoce, préserve la porosité intergranulaire et protège les grains des phénomènes diagénétiques ultérieures. Les grains épargnés par la chlorite, vont subir au cours de l'enfouissement des silicifications intense et la précipitation des ciments sulfatés et carbonatés qui engendrent une roche compacte. L'altération des feldspaths et la dissolution des carbonates créent des pores secondaires. La dernière phase de diagenèse est représentée par la cristallisation de la kaolinite et de l'illite.
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Cotter, Zachary M. K. "Depositional Controls Of A Guelph Formation Pinnacle Reef Debris Apron And Their Effect On Reservoir Quality: A Case Study From Northern Michigan." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1587141486161428.
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Pyle, Leanne. "Stratigraphy, conodont taxonomy and biostratigraphy of Upper Cambrian to Lower Silurian platform to basin facies, northern British Columbia." Thesis, 2000. https://dspace.library.uvic.ca//handle/1828/9100.
Full textAbstract:
This study establishes the stratigraphic framework and conodont biostratigraphy
of Lower Paleozoic strata of the Northern Canadian Cordilleran Miogeocline, which
document a non-passive tectonic evolution of the rifted margin of Laurentia. Only a few
reconnaissance stratigraphic studies have been conducted previously in the study area.
Nine key sections span an east-west transect from the Macdonald Platform to the Kechika
Trough (platform-miogeocline-basin) and 3 key sections comprise a transect across the
parautochthonous Cassiar Terrane. Over 12 000 m of strata from the Kechika and Skoki
formations and Road River Group in northeastern British Columbia were measured and
described, from which a total of 405 conodont samples (4-5 kg each) were taken. A total
of 39 526 conodonts have been used to refine the Upper Cambrian to Lower Silurian
conodont biostratigraphy across the transect.
The stratigraphy is revised to divide the Kechika Formation (late Cambrian to
early Arenig in age) into 5 formal members: Lloyd George, Quentin, Grey Peak.
Haworth and Mount Sheffield members. The Skoki Formation (early to late Arenig in
age) comprises 3 new formal members defined as: Sikanni Chief. Keily and Redfern
members. The Road River Group is divided into 3 new formations: Ospika (early
Arenig to Llanvim in age), Pesika (Lower Silurian in age) and Kwadacha (formerly the
Silurian Siltstone). The Ospika Formation is further subdivided into 5 formal members:
Cloudmaker, Finlay Limestone, Chesterfield, Finbow Shale and Ware.
Conodonts of Late Cambrian to Early Silurian age are described taxonomically from the Kechika, Skoki, Ospika and Pesika formations across the transect. A total of 39 526 identifiable conodonts recovered from 142 productive samples indicate high species diversity and abundance in shallow water facies and less diversity and abundance
with in deeper water facies. Elements are moderately to well preserved, typically with a colour alteration index (CAl) of 3-5.
A total of 197 species, representing 73 genera are identified and illustrated among
which 6 new genera and 39 new species are described. Fifteen of the 39 new species had
too little material and were described in open nomenclature. The new genera are
Graciloconus, Kallidontus, Planusodus and 3 new genera (A, B, C) treated in open nomenclature. The new species are Acodus kechikaensis n. sp., A. quentinensis n. sp., A. warenesis n. sp., Cordylodus delicatus n. sp., Colaptoconus
greypeakensis n. sp., ?Diaphorodus n. sp., Drepanoistodus minutus n. sp., Graciloconus
concinnus n. gen. n. sp., Kallidontus serratus n. gen. n. sp., K. nodosus n. gen. n. sp., K.
princeps n. gen. n. sp., Laurentoscandodus sinuosus n. sp., Macerodus cristatus n. sp., M
lunatus n. sp., Microzarkodina n. sp., Oepikodus n. sp., Oistodus n. sp., Paroistodus n.
sp., Planusodus gradus n. gen. n. sp., ?Prioniodus n. sp., Protoprioniodus n. sp.,
Rossodus kwadachaensis n. sp., R. muskwaensis n. sp., R. sheffieldensis n. sp.. R. subtilis
n. sp., Scolopodus amplus n. sp., Striatodontus strigatus n. sp., Triangulodus akiensis n.
sp., Tricostatus infundibulum n. sp., T. terilinguis n. sp., 3 unnamed new genera and 3
new species and 5 new species of Drepanoistodus (A, B. C, D, E).
The conodont zonation for Upper Cambrian to Lower Silurian strata is refined, using
Sections 4, 5, 13 and Grey Peak as reference sections. It allows close dating of
stratigraphic boundaries. The oldest zones in the Kechika are cosmopolitan and include
the Eoconodontus Zone (upper Cambrian), Cordylodus proavus and Cordylodus
lindstromi zones (uppermost Cambrian) and lapetognathus Zone (base of Tremadoc).
Ten higher zones are recognized and redefined for shallow water platform facies
containing faunas of the Midcontinent Realm. Four of these are new (Polycostatus
falsioneotensis, Rossodus tenuis, Scolopodus subrex and Acodus emanualensis zones)
and 10 new subzones are established. Those for the Kechika Formation include, in
ascending order, the Polycostatus falsioneotensis Zone (lower Tremadoc). Rossodus
tenuis Zone (lower Tremadoc); Rossodus manitouensis Zone with R. muskwaenesis and
R. sheffieldensis subzones (middle Tremadoc), Low diversity interval (upper Tremadoc), Scolopodus subrex Zone with Graciloconus concinnus and Colaptoconus bolites subzones (lower Arenig) and Acodus kechikaensis Zone with Kallidontus serratus.
Diaphorodus russoi and Kallidontus nodosus subzones (lower Arenig). Those for the
Skoki Formation include the Oepikodus communis Zone with Tropodus sweeti,
Bergstroemognathus extensus and Juanognathus variabilis subzones (middle Arenig).
The O. communis Zone spans the Kechika-Skoki boundary and the uppermost Kechika
lies within the lowermost part of the O. communis zone underlying the T. sweeti Subzone.
The Skoki Formation also contains the Jumudontus gananda Zone (middle Arenig) and Tripodus laevis Zone (upper Arenig). The Phragmodus undatus Zone (Upper
Ordovician) lies within the Road River Group in the Cassiar Terrane.
Thirteen deep water zones are recognized for basinal facies containing faunas of
predominantly the North Atlantic Realm. Five new zones are established
(Drepanoistodus nowlani, Acodus deltatus, Paracordylodus gracilis, Paroistodus
horridus and Dzikodus tableheadensis zones) and one new subzone within the P. gracilis
Zone is proposed. Those within the Kechika Formation include Cordylodus angulatus
Zone (lower Tremadoc), Paltodus deltifer Zone (middle Tremadoc), Drepanoistodus
nowlani Zone (middle Tremadoc), Acodus deltatus Zone, (middle Tremadoc),
Paroistodus proteus Zone (upper Tremadoc), Paracordylodus gracilis Zone with
Oelandodus elongatus Subzone (upper Tremadoc) and Prioniodus elegans Zone (base of
Arenig). Those within the Skoki and Ospika formations include Oepikodus evae Zone
(Skoki Formation, middle Arenig), Paroistodus originalis Zone (Skoki and Ospika
formations, upper Arenig), Paroistodus horridus and Dzikodus tableheadensis zones
(both within the Ospika Formation, lower Llanvim). The Amorphognathus tvaerensis
Zone lies within the Road River of the Cassiar Terrane (Upper Ordovician). The
Distomodus staurognathoides Zone lies within the Pesika Formation (middle
Llandovery).
The conodont faunas therefore provide detailed temporal constraints for the
stratigraphic framework. Some evolutionary remarks are made for selected species
involved in radiations, especially in the Tremadoc and Arenig, that are useful in further
refining the standard Midcontinent Realm zonation. The Midcontinent Realm conodont
faunas are used for regional correlations within North America and those of the Atlantic
Realm provide calibration on an interregional scale, for example, with Baltica.Graduate
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Abre, Paulina. "Provenance of ordovician to silurian clastic rocks of the Argentinean precordillera and its geotectonic implications." Thesis, 2009. http://hdl.handle.net/10210/2344.
Full textAbstract:
D. Phil.A Mesoproterozoic basement and a Cambrian-Ordovician carbonate platform characterize the Precordillera terrane. These characteristics and its distinct geologic history mark a difference between this suspected exotic-to-Gondwana terrane and the Gondwanan autochthonous, leading to speculation that the Precordillera was derived from Laurentia. The surprising similarities of the carbonate sequences between the Precordillera and certain parts of southeast Laurentia suggest a common geological history. However, other models interpret the origin of the Precordillera terrane as being para-autochthonous with respect to Gondwana. All these models are still controversial. A combination of several methodologies including petrography and heavy minerals analysis, geochemistry, Sm-Nd and Pb-Pb isotopes and zircon dating were applied to several Ordovician and Ordovician to Silurian units of the Precordillera terrane. Geochemistry and petrography indicates that all the Formations studied have similar characteristics, with at least two sources providing detritus to the basin. The dominant source has an unrecycled upper continental crust composition whereas the other component is more depleted. The study of detrital chromian spinels suggests that mid-ocean ridge basalts, continental intraplate flood basalts and ocean island basaltrelated rocks were among the sources for the detrital record of the Precordillera terrane. Nevertheless, the mafic sources and their ages remain unknown. Nd isotopes account for negative εNd values and TDM ages in a range of variation found elsewhere within Gondwana and basement rocks of the Precordillera. The Sm/Nd ratios of certain samples indicate fractionation of LREE. Pb isotopes indicate that a source with high 207Pb/204Pb was important, and point to Gondwanan sources. Detrital zircon dating constrain the sources as being dominantly of Mesoproterozoic age (but with a main peak in the range 1.0 to 1.3 Ga), with less abundant populations of Neoproterozoic (with a main peak in the range 0.9 to 1.0 Ga), Palaeoproterozoic, Cambrian and Ordovician ages in order of abundance. i The uniformity shown by the provenance proxies indicate that there were no important changes in the provenance from the Lower Ordovician until the Early Silurian. Several areas are evaluated as sources for the Precordillera terrane. The rocks that fit best all the provenance constraints are found within the basement of the Precordillera terrane and the Western Pampeanas Ranges. Basement rocks from the Arequipa-Antofalla area (Central Andes) also match the isotopic characteristics, but a northern source is less probable, except for the Western tectofacies. On the other hand, areas such as Antarctica, Falklands/Malvinas Microplate, the Natal-Namaqua Metamorphic belt and the Grenville Province of Laurentia can be neglected as sources. The proposal of these areas as sources is in agreement with palaeocurrents and facies analyses and suggests proximity between them and the Precordillera since at least the Late Arenig to Early Llanvirn. This has important implications for the proposed models regarding the geotectonic evolution of the Precordillera terrane. The models would need to be adjusted to the here proposed youngest timing of collision.
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Stuart-Smith, Peter Gordon. "Structure and tectonics of the Tumut region, Lachlan Fold Belt, Southeastern Australia." Phd thesis, 1990. http://hdl.handle.net/1885/140636.
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Underwood, Chad A. "Stratigraphic controls on vertical fracture patterns within the Silurian dolomite of Door County, Wisconsin and implications for groundwater flow." 1999. http://catalog.hathitrust.org/api/volumes/oclc/42013233.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 1999.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 183-192).
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Platts, William David. "A study of the base-metal, gold and barite mineralization in the Silurian volcanosedimentary belts of the Canberra region." Master's thesis, 1988. http://hdl.handle.net/1885/109808.
Full textAbstract:
The Silurian volcano sedimentary belts of the Canberra region contain numerous small deposits of base-metal sulphides, iron oxides, barite and gold. Many different styles of
mineralization are present including: veins, stockworks, massive stratiform bodies, and
stratabound veins and disseminations. Primary features in the deposits and the host rocks are
commonly masked by the development of greenschist facies mineral assemblages and a
metamorphic foliation. The foliation in some rocks is domainal so that some premetamorphic
minerals and textures are preserved and it is possible to infer premetamorphic alteration
assemblages and textures.
The distribution of volcanic and sedimentary facies in the Canberra region suggests that the
Late Silurian palaeogeography consisted of a meridionally trending. deep-marine trough bounded
on its western side by a broad shallow-marine shelf with local subaerial areas. The trough was
bounded on its eastern side initially by a shallow-marine shelf and later by a belt of subaerial
volcanics. Numerous zones of mineralization, including the Woodlawn and Captains Flat massive
sulphide deposits, occur in rocks deposited in the trough. The shallow-marine and terrestrial
sequences along both sides of the trough contain only minor, small vein deposits.
The Late Silurian sequence in the Bredbo-Bunyan area consists of basal shallow-marine
sedimentary rocks overlain by subaerial volcanic rocks with rare sedimentary rocks followed by a
transgressive sequence overlain by interbedded mudstones and volcanic rocks deposited in a
deep-marine environment. A number of zones of mineralization, including the Cosgrove Hill,
Billilingra, Barite, Driscolls Hill, Hamett and Stonehenge Prospects, form a mineralized horizon
along the top of the subaerial volcanic sequence and in the transgressive sequence. Mineralization
consists of disseminations and veins of pyrite, base-metal sulphides and gold-rich sulphidic
barite associated with zones of sericitic, K-feldspar, advanced argillic and propylitic alteration. In
parts of the volcanics below this horizon, including at the Picasso and Stonehenge Prospects, there
are narrow zones of sericite, pyrite, ±kaolinite alteration surrounded by broad zones of propylitic
alteration. In the basal sedimentary sequence at the Gillans Prospect sericite, pyrite alteration zones
are surrounded by propylitic zones which contain pyrrhotite and pyrite. Above the mineralized
horizon there are a few jasper zones.
There is no obvious difference in the primary geochemical composition of the volcanic rocks
above and below the mineralized horizon in the Bredbo-Bunyan area. The sericitic rocks in the
mineralized horizon have gained K and Rb and lost Fe, Mg, Ca, Na and Sr whereas chloritic rocks
have gained Fe, Mg, K, Rb, and V and lost Ca, Na, and Sr. The rare earth element (REE) patterns
of the volcanic rocks were preserved during low-grade alteration and metamorphism except for
zones of intense sericite alteration where the heavy REE were lost during the destruction of
hornblende. The sulphur isotope composition of sulphides from below the mineralized horizon
form a tight cluster around 𝛅³⁴S=+5%o whereas those from the mineralized horizon range from
-14.9 to +3.5%o. Barites from the main horizon range from +20.5 to +26.0 which is lighter than
Late Silurian seawater sulphate (+26%o). The results suggest that seawater cannot have been the only source of sulphur in the system and are consistent with the equilibrium oxidation of the sulphide in the hydrothermal fluid, possibly by mixing with seawater. The mineralization in the Bredbo-Bunyan area formed in an epithermal system operated in a mixed subaerial and submarine setting. The Peak View
massive sulphide deposit occurs a small outlier of Silurian volcanic and sedimentary rocks 53 km
south of Captains Flat. Footwall rocks include volcanic rocks (deposited at least in part as
lavas), volcaniclastic rocks and biogenic limestones. There is a broad zone of propylitic
alteration with sulphides in veins and disseminations in the footwall beneath the sulphide lens.
The mineralized horizon consists of a stratiform massive sulphide lens, fine-grained volcaniclastic
rocks and carbonate bodies. The sulphide lens is composed of massive sulphides (pyrite, sericite
and chlorite with minor sphalerite, galena, chalcopyrite, quartz and rare tennantite-tetrahedrite
and arsenopyrite) with minor pyritic chert and veins of quartz and chalcopyrite. The hangingwall
rocks are volcanic rocks, deposited partly as lavas, which contain zones of chloritic, albitic
(originally zeolitic?) and sericitic alteration. The hangingwall rocks have a different primary
geochemical composition to the footwall volcanic rocks. The Peak View deposit is of the volcanic
associated, massive sulphide style and may have formed by convective circulation of seawater below
the seafloor.
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Ickert, Ryan Ben. "U-Pb, Lu-Hf, and O isotope systematics of zircon from southeastern Australian Siluro-Devonian granites." Phd thesis, 2010. http://hdl.handle.net/1885/147724.
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Morávek, Radek. "Společenstva Chitinozoí na vybraných silurských profilech v Barrandienu (Pražská pánev, ČR)." Doctoral thesis, 2010. http://www.nusl.cz/ntk/nusl-286849.
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McAuley, Robert J. "Uppermost Ordovician and lowermost Silurian stratigraphy and solitary rugose corals of the east-central United States." 1985. http://hdl.handle.net/1993/28787.
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