Dissertations / Theses: 'Stratigraphic Ordovician'

1

Dresbach, Russell Ivan. "Early ordovician conodonts and biostratigraphy of the Arbuckle group in Oklahoma /." free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9901233.

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2

Krueger, Diane M. "Conodont biostratigraphy of middle and upper Ordovician rocks in the Ouachita Mountains of Arkansas and Oklahoma /." free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3052190.

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3

Quintavalle, Marco. "Lower to Middle Ordovician palynomorphs of the Canning Basin, Western Australia /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18370.pdf.

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4

Montañez, Isabel Patricia. "Regional dolomitization of Early Ordovician, Upper Knox Group, Appalachians." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54248.

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The Early Ordovician, Upper Knox Group consists of meter-scale shallowing-upward cycles that were deposited on a low-sloping ramp. Cycles formed in response to short term (<100 k.y.) eustatic sea-level fluctuations and typically have well developed tidal flat caps. Cycles are bundled into five transgressive-regressive sequences which correspond to third order (1-10 m.y.) sea-level fluctuations defined by Fischer plots. The Upper Knox Group is 90% dolomite of which greater than 75% predates Middle Ordovician, Knox Unconformity development. Early dolomitization occurred penecontemporaneously with tidal flat progradation during fifth-order (up to 100 k.y.) sea-level falls as indicated by: abundant dolomite in cycles with well-developed tidal flat caps and scarce dolomite in cycles with no or thin laminite caps; decrease in dolomite abundance with distance below tidal flat caps; dolomitized cycles decrease basinward; and dolomite clasts veneer cycle tops and the Knox Unconformity surface. Third-order sea-level fluctuations also strongly controlled early dolomitization as indicated by Fischer plots; limestone, subtidal-dominated cycles correspond to third-order sea level rises and completely dolomitized, peritidal-dominated cycles correspond to third-order sea level falls. "Early" dolomite was metastable and its geochemical composition was modified during initial stabilization by marine brines during progradation of each cycle, and by mixed fresh/marine waters of the Knox aquifer associated with unconformity development. Much "early" dolomite however, remained metastable into the deep burial environment where it was replaced and overgrown by burial fluids as suggested by: covariant trends between crystal size, mole % CaCO₃, Sr²⁺, Mn²⁺ and δ¹⁸O; similar regional trends defined by stable isotope values of "early" dolomites and burial dolomites; and water-rock modeling of trace element and stable isotopic trends. Trace element and stable isotope compositions of least-altered "early" dolomite however, record a memory of a precursor evaporative dolomite. Cathodoluminescent dolomite stratigraphy defines five generations of burial dolomite that can be correlated over 100,000 km². Burial dolomites postdate a regional dissolution event attributed to migration of organic acid-rich fluids through the Knox carbonates. Regional dolomitization occurred coeval with Late Paleozoic deformation and was closely associated with MVT mineralization and hydrocarbon migration. The δ¹⁸O values and trace element contents of burial dolomites in conjunction with fluid inclusions, suggest that burial fluids were warm (135 to 200°C), saline (13 to 22 wt. % NaCl equiv.), ¹⁸O-enriched (+2 to +9 % SMOW) fluids with geochemical compositions similar to present day basinal brines. Mn²⁺ and Fe²⁺ contents of the dolomites suggest a redox control over Mn and Fe fluid chemistry, and in conjunction with regional δ¹³C trends, likely record precipitation from organic acid-rich fluids. Regional trace element and δ¹⁸O trends record a basinal fluid source and regional northwestward flow. Stable isotope values of burial dolomites and fluid inclusions from dolomites and associated minerals, define a prograderetrograde sequence that formed during basinwide, gravity-driven fluid flow which developed in response to Late Paleozoic thrusting and uplift.
Ph. D.

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Hall, Lindsay Anne Forsyth. "Ordovician tectonic evolution of the southern Long Range Mountains, Newfoundland /." Internet access available to MUN users only, 1998. http://collections.mun.ca/u?/theses,39263.

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MCLAUGHLIN, PATRICK IAN. "LATE ORDOVICIAN SEISMITES OF KENTUCKY AND OHIO: A SEDIMENTOLOGICAL AND SEQUENCE STRATIGRAPHIC APPROACH." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1028144697.

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McLaughlin, Patrick I. "Late Ordovician seismites of Kentucky and Ohio a sedimentological and sequence stratigraphic approach /." Cincinnati, Ohio : University of Cincinnati, 2002. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1028144697.

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8

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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9

Malhame, Pierre. "Quartz arenites of the uppermost Cambrian-lowermost Ordovician Kamouraska Formation, Québec, Canada : gravity flow deposits of eolian sand in the deep sea." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101868.

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The uppermost Cambrian-Lower Ordovician Kamouraska Formation in the external Humber Zone of the Quebec Appalachians consists of dominant thick massive to graded quartz arenite beds, subordinate pebble conglomerate and intercalated thin shale and siltstone beds. It was deposited by hyperconcentrated to concentrated density flows in a meandering submarine canyon on the continental slope bordering the Iapetus Ocean. Turbidity currents deposited beds with turbidite structure divisions. The sandstones consist of well sorted, well rounded quartz sand with frosted grains. Scanning electron microscopy reveals the presence of textures supporting eolian transport before redeposition in the deep sea. The Kamouraska quartz arenites are considered an ancient equivalent of Pleistocene eolian-sand turbidites on an abyssal plain off West Africa consisting of Sahara sand. Sand provenance is attributed to eolian equivalents of the Cairnside Formation of the Potsdam Group. The quartz arenites of the Kamouraska Formation provide a variant to tectonic sandstone provenance proposed in the scheme of Dickinson and Suczek (1979).

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Baar, Eric Edward. "Determining the regional-scale detrital zircon provenance of the middle-late Ordovician Kinnikinic (Eureka) Quartzite, east-central Idaho, U.S." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Spring2009/e_baar_050609.pdf.

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Thesis (M.S. in geology)--Washington State University, May 2009.
Title from PDF title page (viewed on July 15, 2009). "School of Earth and Environmental Sciences." Includes bibliographical references (p. 76-83).

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Blue, Christina Renee. "Stratigraphic Architecture and Paleogeography of the Juniata Formation, Central Appalachians." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31683.

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Late Ordovician (Cincinnatian) strata of the central Appalachians provide an opportunity to study the effects of both tectonics and eustasy within a foreland-basin setting. The Juniata Formation consists of red sandstones, siltstones, and shales that were deposited as part of an extensive siliciclastic basin-fill that resulted from the Taconic Orogeny. This study attempts to resolve some of the questions regarding tectonic and eustatic influences on sedimentation by (1) reconstructing the paleogeographic environment of the Juniata Formation and (2) examining the stratigraphic architecture of the Juniata Formation. A combination of both outcrop and subsurface data was analyzed.

Seven facies were identified in this study, including: (1) â proto-vertisolsâ , (2) red shale/mudstone, (3) siltstone/silty mudstone with interbedded sandstones, (4) quartz arenite and sublithic arenite, (5) argillaceous sandstone, (6) hummocky-bedded sandstones and siltstones, and (7) lithic sandstones and conglomerates. These facies are grouped into four facies associations (Aâ D), which are interpreted to be deposited from the inner shelf to the upper shoreface. Isopach and paleocurrent data suggest the shoreline was oriented NEâ SW and detrital sediment was dispersed west and southwest across the basin.

Tectonics controlled the 2nd-Order basin-fill pattern, and these patterns vary along the strike of the basin. Eustatic changes are expressed in two 3rd-Order sequences that were identified in the formation, and possibly in the 4th-Order (?) cycles of Facies Association A. The Ordovicianâ Silurian boundary is expressed as an unconformity throughout the study area, and along-strike variations in the structural setting of the basin were important in its development.
Master of Science

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12

Blue, Christina R. "Stratigraphic Architecture and Paleogeography of the Juniata Formation, Central Appalachians." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/31683.

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Late Ordovician (Cincinnatian) strata of the central Appalachians provide an opportunity to study the effects of both tectonics and eustasy within a foreland-basin setting. The Juniata Formation consists of red sandstones, siltstones, and shales that were deposited as part of an extensive siliciclastic basin-fill that resulted from the Taconic Orogeny. This study attempts to resolve some of the questions regarding tectonic and eustatic influences on sedimentation by (1) reconstructing the paleogeographic environment of the Juniata Formation and (2) examining the stratigraphic architecture of the Juniata Formation. A combination of both outcrop and subsurface data was analyzed.

Seven facies were identified in this study, including: (1) â proto-vertisolsâ , (2) red shale/mudstone, (3) siltstone/silty mudstone with interbedded sandstones, (4) quartz arenite and sublithic arenite, (5) argillaceous sandstone, (6) hummocky-bedded sandstones and siltstones, and (7) lithic sandstones and conglomerates. These facies are grouped into four facies associations (Aâ D), which are interpreted to be deposited from the inner shelf to the upper shoreface. Isopach and paleocurrent data suggest the shoreline was oriented NEâ SW and detrital sediment was dispersed west and southwest across the basin.

Tectonics controlled the 2nd-Order basin-fill pattern, and these patterns vary along the strike of the basin. Eustatic changes are expressed in two 3rd-Order sequences that were identified in the formation, and possibly in the 4th-Order (?) cycles of Facies Association A. The Ordovicianâ Silurian boundary is expressed as an unconformity throughout the study area, and along-strike variations in the structural setting of the basin were important in its development.
Master of Science

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13

Ganis, George Robert. "Ordovician graptolite faunas and stratigraphic construction of the Martinsburg/Hamburg foreland segment, central Appalachians, North America." Thesis, University of Leicester, 2004. http://hdl.handle.net/2381/30455.

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Graptolite fossils provide a means for separating Late Ordovician autochthonous Martinsburg foreland basin strata (Appalachians, Pennsylvania, USA) from tectonically emplaced allochthonous Hamburg succession rocks. The youngest allochthonous rocks (Dauphin Formation) are Middle Ordovician, late Darriwilian 3 to 4a age, approximately two graptolite zones older than the foreland strata. Nineteen taxa described from the Dauphin Formation include Archiclimacograptus cf. A. riddellenis (Harris), Cryptographs schaeferi Lapworth, Normalograptus antiquus (Ge), Pterograptus elegans Holm, Hustedograptus teretiusculus (Hisinger)?, Pseudophyllograptus augustifolius s.l. (J. Hall), Haddingograptus oliveri (Boucek), Bergstroemograptus crawfordi (Harris), Tetragraptus cf. T. erectus Mu, Geh & Yin, and Kalpinograptus spp. (nov?). Newly described taxa are Pseudotrigonograptus ? ricardo sp. nov., and two (possibly more) reteograptids. The initial allochthonous incursion (Unit H-1; = Cocalico Formation ?) into the foreland carried a synorogenic piggyback basin of mid-to-late Nemagraptus gracilis Zone turbidites (Unit M-1). Emplacement was upon the Hershey/Myerstown Formation deposited during earliest regional foreland subsidence. Emplacement of allochthonous Unit H-2 followed which was covered by foreland Unit M-2 (late Climacograptus bicornis Zone), containing allochthonous fragments. The foreland basin then spread laterally over the Jacksonburg Formation and equivalent "basal limestones" as Unit M-3 (Martinsburg Formation. s.s.) during Dicranograptus clingani time. The Hamburg succession (= Dauphin Formation) contains basin sediments deposited within the Octoraro Sea adjacent to the northern fringe of the microcontinent "Baltimoria". Late Cambrian through Early Ordovician age rocks are composed of quartzfeldspathic, micaceous strata overlain by phosphorites, and covered by a black shale and quartzose-ribbon limestone package; lower to middle Arenig rocks are mostly starved clastic hemipelagites. After a biostratigraphic gap of 3-4 graptolite zones those rocks were incorporated into a Middle Ordovician, trench-origin olistostrome, formed as the Octoraro Sea closed, and co-occur with turbidites, distal pelagites and extrusive/intrusive volcanics.

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Xu, Jingqi. "Facies and sequence stratigraphic analyses of the Upper Ordovician shales in northeast Indiana and northwest Ohio." Thesis, Indiana University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10142334.

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The Upper Ordovician Maquoketa Group equivalent strata in Indiana and Ohio were part of a westward-thinning shale-dominant succession. Large amounts of fine-grained siliciclastics were shed from the eastern highlands during the Taconic Orogeny.

The detailed lithofacies analysis of the Upper Ordovician shales has yielded recognition of a series of genetically related sequences in a seemingly homogenous succession. The lower succession is pyritic laminated/banded organic-rich mudstone that accumulated after the onset of a major flooding event. Cryptobioturbation, bottom current ripples, graded silt/clay couplets and well preserved benthic fossils indicate an oxygen-depleted dysoxic condition. In addition, layers enriched in phosphatic fossils, phosphate and pyritic grains appear to mark flooding surfaces and sediment starvation. The maximum organic-matter enrichment mainly occurred within black homogenized mudstone in the middle succession. Upsection, more extensive bioturbation and carbonate production are observed. The intermittent yet frequent wave and current activity, suggested by cross-lamination, wavy-lenticular stratification and hummocky cross stratification, indicate a shallower and proximal settings with enhanced sediment influx.

The deposition of the Upper Ordovician shales in the Maquoketa Group reflects a complex interplay between storms, sediment supply, and eustatic sea-level changes. Nonetheless, with distinct characteristics of lithofacies, wireline logs, and organic carbon isotope data, a high-resolution sequence stratigraphic framework of the Upper Ordovician shales can be compiled for the study area. The whole studied interval comprises an entire 3rd order sequence, wherein the lower part appears to be a transgressive systems tract and the remaining overlying strata represent a highstand systems tract. This project is an example how integration of sedimentological observations, geophysical data, petrographical and geochemical data enable a better understanding of the accumulation of this mudstone succession in a regional sequence stratigraphic context.

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Chhun, Eath. "Ordovician igneous rocks of the central Lachlan Fold Belt : geochemical signatures of ore-related magmas /." University of Sydney. Geosciences, 2004. http://hdl.handle.net/2123/610.

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The majority of economic gold deposits in NSW are associated with Ordovician-aged igneous rocks and are examples of the Cu-Au porphyry-skarn-epithermal association commonly developed in convergent margin to orogenic settings. They are among the oldest porphyry Cu-Au deposits in the Pacific Rim region. They are similar to younger deposits in terms of tectonic setting and structure, but the largest are chemically distinct, being associated with shoshonite magmas (Cadia, Ridgeway and Northparkes). The Lachlan Fold Belt (LFB) porphyries are subdivided into four sub-groups based mainly on their age relative to development of the Lachlan Transverse Zone (LTZ) structure. Two subgroups pre-date the LTZ, one group is syn�LTZ and one group post-dates the LTZ. No mineralisation has been found or reported among pre-I.TZ porphyries. but it is common in post- . l Z_ porphyries. Petrographic analysis and microprobe results establish a wide range of primary and secondary features within the Ordovician rocks examined in this study. Cale alkaline to shoshonitic affinities are supported by the variable abundance of primary K-feldspars. Primary mineral phases such as pyroxenes and igneous magnetite provide an indication of fractioning mineral assemblages responsible for igneous trends in magma chemistry. The hydrothermal mineral assemblages documented in these LFB study areas are characteristic of younger Cu-Au Porphyry style mineralisation. As expected, the most pervasive alteration is associated with highly mineralised shoshonitic Ordovician rocks at Ridgeway, and Cadia. the less strongly mineralised calc alkaline Ordovician rocks at Cargo. Copper Ilill and Fairholme. are correspondingly less strongly altered overall. although secondary mineral assemblages are locally abundant. Many varieties of oxides and carbonates are observed at the different study localities. Most of the studied samples conform to igneous chemical trends because they are weakly altered, although post magmatic processes, such as veining, are detectable in certain trends. The K2O enrichment of the studied samples is consistent with subductionmoditied mantle wedge sources. A few effects, such as the high Fe203 contents of some Ridgeway samples, probably reflect porphyry-style hydrothermal alteration processes. Host rocks at the Cadia and Ridgeway are entirely alkalic on the K2O versus SiO2 plot and shoshonitic on the Total Alkalies versus SiO2 plot. Igneous rocks at the other deposits display a range of compositions between low K tholeiites to shoshonites that in some cases reflects multiple igneous suites. The LREE and L1LE enrichments, and HFSE depletions (Nb, Ta and Ti) of the magmas associated with these deposits are characteristics of a subduction-related tectonic setting. They all fall in the volcanic-arc granite and syn-collisional granite field of the Nb-Y tectonic discrimination diagram. Several magma types are identified by differences in the HFSE and REE trends. Differences in the extent and style of magma fractionation are evident in the trace element data. The Ridgeway samples define a wider range of trace element concentrations than the Cadia samples that may indicate a greater extent of fractionation during emplacement of the Ridgeway magmas. Fairholme samples display a high Nh and /If trends that are distinct from the main fields on Zr variation diagrams. Compositional differences between larger Cu-Au deposits, Cadia-Ridgeway and smaller deposits, Copper Ifill, Cargo and Fairholme are evident in terms of Nb-Ta depletion and variation. The smaller deposits show constant Nb/Ta or negative Nb/Ta trends that extend to high Nb. The larger deposits display positive Nb/Ta trends that do not extend to high Nb. This distinction reflects a difference of preferential incorporation of Nb in a mineral phase (magnetite). Comparisons between Cadia-Ridgeway and other shoshonite (altered samples of Bajo de la Alumbrera, Argentina), calc alkaline magmas from New Zealand and rocks from other areas indicate that Nb/Ta is not directly correlated with the shoshonitic classification, K2O vs. SiO2, and that the Cadia-Ridgeway Nb and Ta variation is not the result of alteration. The fact that the weakly altered LFB Capertee shoshonites exhibit a narrow range of Nb and low Nb/Ta suggest the shoshonite trend for the LFB as a whole is a steep one on the Nb/Ta versus Nb plot. The results of this study could provide important information for exploration within the LFB. Only the Cadia and Ridgeway deposits display a wide range of Nb/Ta values and lack the near-horizontal trend seen for other localities associated with smaller deposits. The tectonic evolution of the LFB is a major factor contributing to occurrence of large porphyry Cu-Au deposits. The sequence of important events, however, commences with sub-crustal generation of oxidised magma and finishes with efficient Cu-Au accumulation by hydrothermal processes at favourable structural sites. The increase in Au-Cu deposit size from small (Copper Hill-Cargo) to world class (Cadia-Ridgeway) indicates the importance of magma composition during this process. The most obvious differences between the Cadia-Ridgeway and New Zealand rocks is that the latter are volcanic in origin and associated with an arc-back arc system. Therefore, they did not form in a tectonic regime suitable for the evolution of porphyries and the focussed movement of hydrothermal fluids during dilatant episodes. As a result, they are not linked to mineralisation despite having Nb-Ta and Nb/Ta variations that are typical of the high oxidation states in Au-prospective magmas of the LFB.

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Carter, James Edward. "Structure, stratigraphy, and geochemistry of the Upper Ordovician Lawrence Harbour Formation, Exploits Subzone, Newfoundland." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0028/MQ36103.pdf.

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Paquette, Jeanne. "Sedimentology and diagenesis of the Levis slope conglomerates, near Québec City : remnants of a Cambro-Ordovician carbonate platform margin." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66096.

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Scarpone, Gregory S. "The subsurface geology of the Fort Atkinson formation in Indiana." Virtual Press, 1997. http://liblink.bsu.edu/uhtbin/catkey/1041920.

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The purpose of this study was to define the lithofacies and areal extent of the Fort Atkinson Formation (Maquoketa Group, Upper Ordovician) in the subsurface in Indiana. Two distinct lithologic facies (Members) of the Fort Atkinson Formation can be distinguished in the subsurface. The upper Shoaling Member consists of coarse grained crinoid-bryzoan grainstone deposited in a high energy depositional environment. Beneath the Shoaling Member is the Transition Member of the Fort Atkinson. This Member consists of alternating beds of shale and limestone which were deposited in depositional environments that varied from high to low energy. The Fort Atkinson is an important stratigraphic marker used to define four depositional provinces within the Maquoketa Group in Indiana. The four depositional provinces include the Maquoketa Shelf, the Overlap Ramp. the Cincinnati Shelf, and Michigan Shelf.
Department of Geology

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Lowe, David. "Sedimentology, Stratigraphic Evolution and Provenance of the Cambrian – Lower Ordovician Potsdam Group in the Ottawa Embayment and Quebec Basin." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35303.

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The Cambrian – Lower Ordovician Potsdam Group is a mostly siliciclastic unit that provides important insight into the paleoenvironmental, geologic and tectonic history of Early Paleozoic Laurentia. Nevertheless, in spite of 178 years of study the Potsdam in the Ottawa Embayment and Quebec Basin remains poorly understood. Also poorly understood is how the Potsdam relates with coeval strata regionally. In this work six siliciclastic paleoenvironments are recognized: (a) braided fluvial, (b) ephemeral fluvial, (c) aeolian, (d) coastal sabkha, (e) tide-dominated marine and (f) open-coast tidal flat. Fluvial strata were examined in particular detail and interpreted to consist of two end-member kinds. Braided fluvial deposits are dominated by low-relief bars formed in wide, shallow channels; however where basement structures limited the lateral growth of channels, flows were deeper and bar deposits thicker and higher angle. In contrast, ephemeral fluvial strata are dominated by sheetflood splay sedimentation with rare preservation of scour-filling supercritical bedform strata – all later subjected to aeolian reworking. In the upper Potsdam, alternating ephemeral and braided fluvial strata provide a record of climate change, which, respectively, correlate with documented global cool (arid) and warm (humid) periods during the Late Cambrian and Early Ordovician. Three allounits are recognized in Potsdam strata, recording regional episodes of sedimentation and facilitating correlation with coeval strata throughout eastern North America. These correlations, aided with provenance data from detrital zircons, show that changes in the areal distribution of sediment supply, accommodation and deposition/erosion were principally controlled by episodic reactivation of the Neoproterozoic Ottawa graben, which then periodically modified the stratigraphic expression of the ongoing Sauk transgression. Specifically, episodes of tectonic reactivation occurred during late Early to Middle Cambrian (allounit 1), late Middle to early Late Cambrian (allounits 2 – 3 unconformity), and Earliest Ordovician (allounits 3 – 4 unconformity). The earliest episode is correlated to regional extension of southern Laurentia, whereas the latter two are linked to peri-Laurentian accretion events that triggered reactivation of the Ottawa graben via the Missisquoi oceanic fracture zone.

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Young, Seth Allen. "A chemostratigraphic investigation of the late Ordovician greenhouse to icehouse transition oceanographic, climatic, and tectonic implications /." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1201628490.

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MacLachlan, Kate. "The Wild Bight Group, Newfoundland Appalachians : a composite early to middle-Ordovician ensimatic arc and continental margin arc-arc rift basin /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0011/NQ36208.pdf.

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Farley, Claude. "Sediment dynamics and stratigraphic architecture of a mixed carbonate-siliciclastic ramp: The Upper Ordovician (Hirnantian) Ellis Bay Formation, Anticosti Island, Quebec, Canada." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27629.

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The Upper Ordovician (Hirnantian) Ellis Bay Formation on Anticosti Island, Quebec, Canada provides a unique opportunity to study the stratigraphic architecture of mixed carbonate-siliciclastic deposits that formed during a period of major glaciation on a storm-influenced, slowly subsiding tropical ramp. The west-east-trending Ellis Bay outcrop belt is ∼180 km long, slightly oblique to the paleoshoreline, and offers superb coastal exposure at both ends of the island. The western sections (90 m thick) consist of stacked cycles of mid- to outer-ramp, storm-dominated carbonates with argillaceous mudstones. Inner-ramp oncolitic and reefal carbonates are also present in the uppermost part of the formation. The thinner eastern sections (45 m thick) are composed of basal sandstone and argillaceous mudstone units forming a continuous succession from (1) incised-valley fill to (2) storm-influenced delta to (3) storm-dominated strandplain deposits. Overlying these basal sandstones are mid- to outer-ramp, mixed carbonate-siliciclastic tempestites capped by pure carbonate tempestites and, finally, oncolitic and reefal units that correlate with those in the western section. The gradual upward decrease in siliciclastic content in the eastern sections is attributed to the incremental migration (avulsion) of a siliciclastic-supplying delta confined to the eastern Anticosti Platform. Alternatively, it could result from river avulsion coupled with a gradual shift from relatively humid to more arid climatic conditions. Despite these important lateral facies changes, the recognition of four major transgressive-regressive sequences allows a precise correlation between the western and eastern sections. These sequences (or cycles) are likely driven by glacio-eustasy in association with the end-Ordovician Gondwanan glaciation.

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Tomescu, Iulia. "The Ordovician : a window toward understanding abundance and migration patterns of biogenic chert and implications for paleoclimate /." Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1103302033.

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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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Young, Timothy Peter. "The stratigraphy of the upper Ordovician of central Portugal." Thesis, University of Sheffield, 1985. http://etheses.whiterose.ac.uk/6043/.

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The project has involved the revision of the stratigraphy of the upper part of the Ordovician succession in central Portugal. Using evidence derived principally from the study of measured sections, with some limited geological mapping, this thesis first considers a new lithostratigraphy of the upper Ordovician deposits. The scheme presented includes four groups, twelve formations and eleven members. Most of the elements of the scheme are described here for the first time. The sedimentology of the deposits has been studied to allow an interpretation of the depositional environment. The history of sedimentation in the upper Ordovician is divided into three broad phases. In the first of these (phase A) storm-dominated deposition of detrital clastics took place on a wide, flat, shallow shelf. During the second phase (B) a localised area of igneous activity developed in the area of highest subsidence seen in the preceding phase. This igneous activity was accompanied by the deposition of some carbonate sediments. The third phase of deposition (C) is linked to the effects of the upper Ordovician glaciation. A review of most of the macrofauna recovered 1s given. The faunas of Portugal form a highly distinct and homogeneous "province" with those of Armorica, Spain, Sardinia. The palaeoecology of the faunas Montagne Noire and collected during this study are discussed. Thirteen broad associations (sensu Lockley 1983) are identified. Factors other than latitude-related influences play an important role in controlling the diversity, abundance and taxonomic constitution of the palaeocommunities. Twelve biozones are erected to cover the range of fossiliferous Ordovician strata examined in this project. The correlation between the biostratigraphie scheme erected herein and the international standard is discussed. An overview attempts to place the study area within the context of the peri-Gondwana shelf, and within the Variscan fold-belt.

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Meddour, Amira. "Les séries de l'Ordovicien moyen et supérieur de l'Anti-Atlas oriental (Maroc) : stratigraphie, sédimentologie et paléogéographie des systèmes de plate-forme silico-clastique." Thesis, Bordeaux 3, 2016. http://www.theses.fr/2016BOR30061.

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L’étude de l’Ordovicien de l’Anti-Atlas oriental s’intègre dans un vaste projet celui de l’étude de la plate-forme nord-gondwanienne qui se caractérise par une sédimentation essentiellement silico-clastique avec une polarité globale qui est Sud-Nord. Cette étude, basée sur les principes de la stratigraphie séquentielle et de la sédimentologie, met en évidence l’existence de deux systèmes de dépôts sur la marge nord-ouest de la plate-forme nord-gondwanienne. A l’Ordovicien moyen et supérieur préglaciaire, à l’emplacement de l’Anti-Atlas oriental, coexistent un système deltaïque (lato sensu) et un système de plate-forme dominée par l’action de la houle et des tempêtes. Ces deux systèmes de dépôts ont une certaine répartition spatiale et temporelle. Le système deltaïque domine le nord-est de l’Anti-Atlas oriental où il prend naissance à l’Est du Tafilalt. Ce système deltaïque est à dominance fluviale, il est actif lors des périodes de régression. Pendant les maximums de régression, il incise le haut du plateau continental en créant d’importantes structures érosives dont le remplissage se fait par des faciès de haute énergie à composante unidirectionnelle. Le système de haute énergie influencé par l’action de la houle et des tempêtes domine le secteur sud de l’Anti-Atlas oriental et se répand au nord au cours des périodes transgressives. La sédimentation durant l’Ordovicien préglaciaire sur la marge nord-ouest du Gondwana a un contrôle tectonique et eustatique avec une polarité des systèmes, dans le Tafilalt-Maïder qui diffère de celle de la plate-forme nord-gondwanienne et est Nord Est-Sud-Ouest. Le profil de dépôt est quasi plat où les clinoformes sont de faible amplitudes et se dessinent à l’intérieur des séquences de 3ème ordre. Le Darriwillien se caractérise par des une subsidence différentielle entre le domaine nord et le domaine sud en raison d’une tectonique active. Alors que, le Sandbien-Katien montre un taux de subsidence faible (x 10m/Ma) en adéquation avec un contexte intracratonique. L’Hirnantien dans le Tafilalt, décrit comme étant discontinu voir absent, est très bien développé il se caractérise par la mise en place d’une sédimentation mixte gréso-carbonaté à bryozoaires de type littoral et ce à l’extrémité oriental de l’Anti-Atlas et d’une épaisse série conglomératique (conglomérat d’Amessoui et d’Imzizoui) et flyschoïde qui peut atteindre les 500m dans le Tafilalt
The Ordovician Anti-Atlas study is part of a larger project of comprehension the sedimentary system of the north Gondwana platform. This sedimentary area is characterized by essentially terrigenous sediments that come from the south from de West African Craton. This study based on sequence stratigraphy and sedimentology principles highlights two systems juxtaposed during the preglacial Ordovician period (before hirnantian). These two deposits systems have a spatial and temporal distribution. One deltaic occurs on north-eastern Tafilalt (east Anti-Atlas) and widespread during regressive periods. The second is storm dominate system which is developed in the south-western part of eastern Anti-Atlas and transgressive periods. The deltaic system is river dominant, it incise the continental shelf by creating a significant erosive structure whose filling is done by high energy facies unidirectional component. During the Ordovician, the sedimentation was controlled by tectonic and eustatic variation. The polarity of the system in the Tafilalt-Maïder is different from that of the northern Gondwana platform and it is given North East- South West. The Darriwilian characterized by differential subsidence, between the north and the south of the oriental Anti-Atlas, due to active tectonics, while, Sandbian-Katian show a low subsidence rates (x10m/Ma) in the line of intracratonic basin. The Hirnantian, in Tafilalt, is largely well developed and characterized by huge conglomeratic series, flysch deposits and Bryozoan limestone at the northeastern

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Moreau, Julien. "Architecture stratigraphique et dynamique des dépots glacières ordoviciens du bassin de Murzuq (Libye)." Université Louis Pasteur (Strasbourg) (1971-2008), 2005. http://www.theses.fr/2005STR1GE13.

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La glaciation ordovicienne est considérée comme un événement majeur et singulier dans l'histoire de la Terre. Ce manuscrit présente les résultats d'une thèse effectuée sur la série glaciaire ordovicienne, particulièrement bien préservée dans le Bassin de Murzuq (Libye). Cette étude est en premier lieu basée sur un travail de terrain associé aux outils de télédétection dans la zone de Ghat-Tikiumit (bordure Ouest du bassin) et à des méthodes d'investigations pétrolières comme la modélisation stratigraphique des affleurements et l'interprétation de blocs sismiques 3D (Nord du bassin). L'utilisation conjointe de ces techniques a conduit à des résultats sur les relations entre la dynamique de l'inlandsis ordovicien, l'architecture stratigraphique et la reconstitution des systèmes de dépôt et ce, à différentes échelles de temps et d'espace. Ainsi, au sein de la série glaciaire de Libye, sont reconnus deux grands cycles glaciaires, chacun se terminant par un retrait complet de la glace du bassin. Chaque cycle comprend plusieurs phases glaciaires (avancée puis retrait de la glace). Chaque retrait glaciaire est suivi du dépôt d'une séquence de dépôt glaciaire dont l'évolution sédimentaire a été analysée en terme de stratigraphie séquentielle. Lors des phases d'avancée, la zone d'étude est plusieurs fois sous l'influence de grands fleuves de glaces. La séquence de déglaciation finale, effectuée par paliers, est à l'origine d'une imbrication le long du profil de dépôt de fan-deltas proglaciaires. La transgression postglaciaire finale utilise la forte topographie résiduelle liée à cette déglaciation, localisant ainsi les réservoirs ordoviciens et la roche mère silurienne. La synthèse des différents résultats a conduit à proposer une courbe d'évolution eustatique ainsi que d'une reconstitution des événements sédimentaires et glaciologiques à l'échelle du Bassin de Murzuq au cours de la glaciation ordovicienne
The Late Ordovician glaciation is considered as an outstanding event of Earth history. Preservation of Ordovician glacial deposits is exceptional into the Murzuq Basin (Libya) and the aim of this PhD thesis is to study this succession. This work is principally based on field work study in the Ghat-Tikiumit area (west rim of the basin) associated with remote sensing analysis and petroleum investigation methods (stratigraphical modelling and interpretation of 3D seismic surveys). Results consist in relationships between ice-sheet dynamic, stratigraphical architecture and depositional system reconstructions at various space and time scales. Thus, two major glacial cycles are recognized into the Libyan glacial succession. Both terminate by a complete ice-sheet retreat and associated postglacial transgression at basin scale. Each cycle comprise several glacial phases (ice-sheet advance then retreat). Ice retreat is followed by the deposition of a glacial depositional sequence. During ice-sheet advances, the study area is repeatedly covered by ice streams. The final deglaciation sequence creates landward stepwise imbricate proglacial fan-deltas and associated ice fronts. Final postglacial transgression is driven by strong remnant topography and is responsible for the localisation of the Ordovician reservoir rocks and Silurian "hot-shale". Results consist in, into the Murzuq Basin, sequence stratigraphy interpretation of the glacial succession, eustatic evolution as well as ice-sheet and sedimentary reconstruction through the different glacial cycles and phases

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Stockfors, Martin. "Cambro-Ordovician microorganisms: acritarchs and endoliths." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5726.

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Organic-walled microfossils are abundant and taxonomically diverse in Cambrian-Ordovician strata; some are important for biostratigraphy and for the correlation of geological successions. New assemblages of Cambrian-Ordovician acritarchs from Kolguev Island, Arctic Russia and Middle Cambrian ichnofossils of endoliths from Peary Land, North Greenland are studied. Twenty-seven acritarch species are described in detail and 10 taxa are left under open nomenclature. The diagnosis of one genus is restricted, and two other are emended. New combinations are proposed for three species and one new species is recognised. The studied acritarch assemblages are taxonomically rich and age-diagnostic and used to recognise Upper Cambrian and Tremadoc strata on Kolguev Island. The sedimentologically continuous successions provide for the first time palaeontological evidence of Cambrian strata in the north-eastern sector of Europe. The exact level of the Cambrian-Ordovician boundary was distinguished together with stratigraphic intervals equivalent to the Peltura and Acerocare zones of the Upper Cambrian of Baltica. The newly established relative age of the lowermost sedimentary succession overlying the Timanian unconformity allows verification of the minimum age of the Timanian deformation and the time-span of the hiatus bound to this unconformity. Endoliths occur in the fossil record from the Early Archean and they played an important role in the formation of stromatolites and the process of bioerosion and biodegradation. Endoliths that have actively bored into brachiopod shells or carbonate grains (euendoliths), and some that inhabited the cavities inside brachiopod shells (cryptoendoliths) are described. Borings within the carbonate grains extended with a dentritic pattern, whereas those within the brachiopod shells were formed by a multifilamentous euendolith which produced characteristic longitudinally ridged galleries. The cryptoendolithic morphologies include indeterminate coccoid masses and at least two filamentous forms. However, considerable variation in the dimensions of the currently phosphatised diagenetic crusts of the cryptoendoliths hinders discrimination.

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Fitzgerald, Devin R. "Clay Mineralogy, Provenance, and Sequence Stratigraphy of Upper Ordovician Shales in Eastern Ohio." Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1449489305.

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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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Edwards, Cole T. "Carbon, sulfur, and strontium isotope stratigraphy of the Lower-Middle Ordovician, Great Basin, USA: Implications for oxygenation and causes of global biodiversification." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1405797089.

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MacDonald, Carole Anne K. "Stratigraphy, volcanology and environments of the Ordovician Nepisiguit Falls Formation, Bathurst Camp, New Brunswick." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61280.pdf.

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Pope, Michael C. "High Resolution Stratigraphy of Ordovician Carbonates, Kentucky: Evidence for a Greenhouse to Glacial Transition." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-05202008-111414/.

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Denalle, Heloisa Pasetto. "Geoquímica do alogrupo Guaritas (Ordoviciano da Bacia do Camaquã, RS)." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/76139.

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O Alogrupo Guaritas, inserido na fase final de preenchimento da Bacia do Camaquã, é composto por arenitos castanho avermelhados de origem aluvial, lacustre, fluvial e eólica e é subdividido em duas sequências deposicionais nomeadas Pedra Pintada e Varzinha. Este estudo envolveu a realização de análises químicas em rocha total de vinte e seis amostras selecionadas do Alogrupo Guaritas e a consequente aplicação desses dados geoquímicos para fins de caracterização geoquímica, quimioestratigráfica e isotópica desta unidade, além da tentativa de restringir sua proveniência e intemperismo das suas rochas fontes. Os arenitos são composicionalmente uniformes e apresentam similaridade com a Crosta Continental Superior, indicando derivação de fontes mais diferenciadas. Entretanto, enquanto que os arenitos da Aloformação Pedra Pintada mostram-se depletados em praticamente todos os elementos terras raras, os arenitos da Aloformação Varzinha são depletados apenas em Sc, V, Sr, Y, Zr, Ni e enriquecidos em Ba e Rb em relação à Crosta Continental Superior. Os padrões de Elementos Terras Raras mostram enriquecimento em Elementos Terras Raras Leves, com razões La(N)/Sm(N) entre 3,7 e 6,1 e padrões mais suaves para Elementos Terras Raras Pesados, com razões Gd(N)/Yb(N) entre 1,0 e 2,7; acoplados a presença de anomalias de Eu moderadas. O Índice Químico de Alteração (CIA: 55-64) revelam protólitos pouco a moderadamente intemperizados para os arenitos estudados indicando predomínio de intemperismo físico de desagregação das rochas fonte. Considerações geoquímicas apresentadas pelas razões SiO2/Al2O3 e K2O/Na2O indicam a possibilidade de áreas fontes mais diferenciadas ou com maior retrabalhamento sedimentar na Aloformação Pedra Pintada, com aporte de fontes menos diferenciadas na Aloformação Varzinha. Uma indicação de proveniência compatível com áreas fonte dominadas predominantemente por rochas ígneas graníticas é sugerida para o Alogrupo Guaritas através das elevadas razões Th/Sc e Zr/Sc apresentadas pelas amostras e pela composição isotópica Nd-Sr utilizada como traçadora de proveniência.
The final phase of the Camaquã Basin sedimentary filling is represented by the Guaritas Alogroup. Reddish and brownish sandstones of alluvial, lacustrine, fluvial and eolic origin are the main litology, subdivided into two units named Pedra Pintada and Varzinha. This research presents twenty six chemical analyses of selected whole rock samples of the Guaritas Alogroup and the application of these data concerning the chemical characterization, chemical and isotopic stratigraphy and also indications of provenance and weathering of their source rocks. Guaritas sandstones are homogeneous in relation to the composition and very similar to the SCC (Superior Continental Crust) thus indicating derivation of more differentiated sources. Although the sandstones of the Pedra Pintada Aloformation are depleted in relation to the rare earth elements, the sandstones of the Varzinha Aloformation are only depleted in Sc, V, Sr, Y, Zr Ni and enriched in Ba and Rb (related to the SCC). The patterns of the Rare Earth Elements (REE) indicate enrichment in the Light Rare Earth Elements (LREE) with ratios La(N)/Sm(N) between 3,7 e 6,1 and slightly patterns to the Heavy Rare Earth Elements (HREE), with ratios Gd(N)/Yb(N) between 1,0 e 2,7; and a visible Eu anomaly. The index CIA calculated to the studied sandstones is around 55 to 64 and can be correlated with protolites slightly to moderately weathered, associated with a predominance of physical processes. Ratios SiO2/Al2O3 and K2O/Na2O are indicative of source areas more differentiated or with better reworking in the Pedra Pintada and arriving of detritus associated with source slightly enriched in the Varzinha Aloformation. High ratios Th/Sc and Zr/Sc and Nd-Sr isotopic compositions indicates a provenance of source areas dominated by granitic igneous rocks to the Guaritas Alogroup.

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Cornell, Sean Richard. "Sequence Stratigraphy and Event Correlations of Upper Black River and Lower Trenton Group Carbonates of Northern New York State and Southern Ontario, Canada." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin997444936.

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MCLAUGHLIN, SUSANNAH. "SEQUENCE STRATIGRAPHY AND FAUNAL PATTERNS OF THE MIDDLE LEXINGTON LIMESTONE (UPPER ORDOVICIAN) IN CENTRAL KENTUCKY." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1141314237.

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Umholtz, Nicholas Moehle. "Middle to Late Ordovician δ¹³C and ⁸⁷Sr/⁸⁶Sr stratigraphy in Virginia and West Virginia: implications for the timing of the Knox unconformity." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1400681920.

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Aucoin, Christopher D. "Revised Correlations of the Ordovician (Katian, Richmondian) Waynesville Formation of Ohio, Indiana and Kentucky." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1418909609.

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El, Gadi Muftah Saleh. "Sedimentology and sequence stratigraphy of the Ordovician Black River and lower Trenton Groups, Lake Simcoe area, Ontario." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61975.pdf.

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Davis, Colter R. "Sequence Stratigraphy, Chemostratigraphy, and Biostratigraphy of Lower Ordovician units in Northeastern and Western Central Utah: Regional Implications." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5879.

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The Lower to Middle Ordovician Garden City Formation and Pogonip Group are coeval successions of mixed carbonate and siliciclastic rocks deposited under normal marine conditions on a shallow carbonate ramp on the western margin of Laurentia. The Garden City Formation was deposited in the Northern Utah Basin and the Pogonip Group was deposited in the Ibex Basin. These two basins experienced different rates of thermal subsidence following Neoproterozoic rifting along the western margin of Laurentia resulting in significant thickness differences between rock units and varying lithologic expressions of eustatic change. This study provides a unique opportunity to examine the lithologic, geochemical, and paleontological responses to eustatic oscillations of two coeval sedimentary basins in Utah that formed under different tectonic settings and subsidence rates. The Garden City Formation is composed of fourteen lithotypes and the Pogonip Group is composed of eleven lithotypes. These lithotypes mainly represent depositional environments ranging from inner ramp and middle ramp with minor outer ramp deposits. Many lithologies appear to be storm influenced due to the presence of abundant rip-up clasts (intraclasts), fragmented bioclasts, and occasional mega-ripples. Other lithologies have been extensively bioturbated and burrowed. Nine stratigraphic sequences have previously been identified within the Pogonip Group. Eight equivalent, albeit compressed, sequences within the Garden City Formation were located using biostratigraphic and chemostratigraphic correlations, and increases in insoluble residues often found at the bases of sequence boundaries. Sequences are expressed as deepening-upward packages containing silty/sandy lowstand deposits that transition into wackestones and lime mudstone-rich highstand deposits. Several sequence boundaries appear to coincide with conodont and/or trilobite extinction events. Important sequence boundaries mark the Sauk III-m and Sauk IV-m transition and the Ibexian- Whiterockian Series boundary. Meter-scale cycles are common and likely related to Milankovitch cyclicity. Insoluble residue increases upsection at each location which may indicate a gradual overall drop in sea level due to the onset of the regressive upper portion of the Sauk III supersequence. Insoluble residue from the Pogonip Group ranges from 1.2 to 84.7 wt. % with an average of 16.0 wt. % ± 0.7 wt. %. Insoluble residue from the Garden City Formation ranges from 1.5 to 63.8 wt. % with an average of 13.4 wt. % ± 1.0 wt. %. New stable carbon isotope data (δ13C) from the Garden City Formation and the Pogonip Group range from -2.92 to 1.23 ‰ V-PDB and -2.19 to 0.56 ‰ V-PDB, respectively. Four distinct δ13C trends are recognized in both sections: 1) a drop in δ13C from positive values between 0.2-1.0 ‰ to negative values approaching -1.0 ‰ near the base of the Ordovician, 2) a 0.5 to 1.0 ‰ positive δ13C excursion near the top of the Rossodus manitouensis Zone, 3) a drop in δ13C values to near -2.0 ‰ through most of the Acodus deltatus –Oneotodus costatus Zone, and 4) a gradual increase in δ13C from - 2.0 ‰ to -1.0 ‰ throughout the remainder of the sections. δ13C of the Garden City Formation and the Pogonip Group appear to be correlative based on these distinct trends. This correlative relationship was verified by the lowest occurrence of conodont species Scolopodus filosus and Scalpellodus n. sp. A of the Low Diversity Interval which coincides with the positive δ13C excursion in both the Garden City Formation and the Pogonip Group. New δ13C data likely represent global primary seawater chemistry based on the correlation of similar δ13C trends from the Argentine Precordillera and western Newfoundland.

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Raine, Robert James. "The Durness Group of NW Scotland : a stratigraphical and sedimentological study of a Cambro-Ordovician passive margin succession." Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/586/.

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The Cambrian to Ordovician Durness Group was deposited on the Scottish sector of the passively-subsiding, continental margin of the Laurentian craton, and now forms part of the Hebridean terrane, lying to the west of the Moine Thrust zone. It represents c. 920 m of shallow marine, peritidal carbonates with minor siliciclastic and evaporitic strata. Facies analysis shows that the carbonates represent deposition within coastal sabkha, intertidal and shallow subtidal to shelfal environments and sedimentary logging of all available sections has revised the thicknesses of the lithostratigraphic formations within the Durness Group. A diverse array of microbialites is documented, and their application for interpreting the sea-level and palaeoenvironmental history is discussed. The enigmatic ‘leopard rock’ texture is here concluded to represent a thrombolite, thus significantly increasing the abundance of microbial facies within the section. A revised conodont biostratigraphy for the Ordovician upper five formations of the Durness Group allows more precise correlation with the once contiguous sections in western Newfoundland and Greenland and dating of the lithostratigraphical and sequence stratigraphical subdivisions for the first time. Based upon the new conodont biostratigraphy, a sequence stratigraphical model for the Cambro-Ordovician strata in Scotland is proposed, comprising four depositional megasequences, which correlate well with the Sauk sea level sequence recognised across Laurentia. This study allows for further correlation with Laurentian margin sections and the global sea-level record.

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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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Schramm, Thomas J. "Sequence Stratigraphy of the Late Ordovician (Katian), Maysvillian Stage of the Cincinnati Arch, Indiana, Kentucky, and Ohio, U.S.A." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1322052575.

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44

Adiatma, Yoseph Datu. "Did early land plants produce a step-change in atmospheric oxygen centered on the Late Ordovician Sandbian Age ~458 Ma?" The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1546386257035643.

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45

Poey, Jean-Luc. "Stratigraphy and depositional environments of an Upper Ordovician to Lower Devonian shelf-to-basin transition, Svendsen Peninsula, Ellesmere Island, N.W.T." Thesis, University of Ottawa (Canada), 1988. http://hdl.handle.net/10393/5354.

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46

Barbour, Susan Leigh. "Microstratigraphic Analysis of an Amalgamated Horizon in the Type Cincinnatian:Implications for Spatio-Temporal Resolution in the Fossil Record." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1030643781.

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47

Moros, León Josè Saul. "Reservoir geometry and architecture in Ordovican fluvio-marine sandstones : P3B unit, Pacoota formation, Amadeus Basin, Central Australia." Thesis, Queensland University of Technology, 1998. https://eprints.qut.edu.au/37017/1/37017_Moros%20Leon_1998_v1.pdf.

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Abstract:

Detailed facies analysis and sequence stratigraphic principles applied to outcrop and subsurface data have aided in the development of a reservoir geological model for the Pacoota P3B Unit at the Mereenie Field, Central Australia. Mereenie is a linear Northwest/southeast trending oil and gas field 4 km wide and 35 km long, and covers an area of approximately 130 km2. In this field, oil and gas are produced from some of the oldest known petroleum reservoirs in the word: reservoirs approximately 500Ma. The Ordovician Pacoota P3B Unit, is part of an overall transgressive succession which records the transition from non-marine to marine environments in the northeastern margin of the Amadeus Basin. This transgression was punctuated by episodic events of rapid sea level rise and periods of sea level fall. The resulting vertical succession consists of three Fourth-order deltaic sequences formed by the regular alternation of sand-prone, non-marine sediments with marine mud/sand-prone deposits that prograded northeast as the basin subsided. Unlike previous investigations, this study recognizes four distinct types of sandstone facies associations within the broad braid delta system that characterizes the Pacoota P3B Unit. Facies Association 1 records the depositional characteristics of a distal braid plain that was dominated by episodic sheetflood events. Facies Association 2 reflects a sudden change in fluvial style from fine-grained sheetflood lobes to a coarse to pebbly-grained braid-delta system during a short-lived regressive phase. With time, this basal braid-delta system evolved into a tide-influenced braid plain indicating a transgressive phase. Facies Association 3 records the abrupt change from fluvial to tidal processes. This association is interpreted as the product of a tide-dominated delta front that prograded northeast. The palaeoenvironment of Facies Association 4 is interpreted as the fill of a wide incised fluvial valley system, which marked the end of fluvial sedimentation at the margin of the Amadeus Basin during the Ordovician. This association is capped by the transgressive marine deposits of the Pacoota P3A Unit. These four facies associations represent a complex network of depositional environments that results from the deposition of superimposed sandy, deltaic systems affected by tidal currents. The vertical facies evolution is punctuated by erosional sequence boundaries. The development of a detailed stratigraphic framework allows the Pacoota P3B Unit to be subdivided into five correlative intervals that define reservoir compartments in the Mereenie Field. These reservoir compartments are bounded by key stratigraphic surfaces and represent the lowstand (LST), transgressive (I'ST) and highstand (HST) systems tracts of the Fourth-order sequences defined within the P3B Unit. Maximum reservoir quality is associated with amalgamated fluvial sandstones that define the LST of each sequence. Marginal to impermeable reservoir characteristics occur within the tidally-influenced TST and HST. From base to top reservoir intervals are: P3-250, P3-230, P3-190, P3-150 and P3-120/130. Of these, the lowstand P3-120/130, P3-230 and P3-250 Reservoir Intervals are the most prolific producers. The transgressive to highstand P3-150 and P3-190 Reservoir Intervals are considered as not economically profitable for hydrocarbon exploitation. Petrophysical characterization of lithofacies types observed in the succession indicate that within each compartment, depositional facies exert the primary control on reservoir properties. Flow units are associated with tabular, cross-bedded sandstones. Permeability barriers are associated with bidirectional cross-beds, parallellaminated sandstones, soft-sediment deformed sandstones and bioturbated beds. During transgression the upper part of the lowstand fluvial system was sheared off resulting in a transgressive surface capping the fluvial deposits. Reworked fluvial sediments were redeposited as reversing tidal flows above the lowstand intervals. These deposits, interpreted as neap-spring tidal cycles, consist of alternating sand and silt/mud and bioturbated beds. In this setting, intense bioturbation generate sediment mixing destroying the reservoir properties of this interval. Additionally the areally continuous and impermeable silt/shale intervals of the tidal deposits contributed to the vertical barriers to flow in the reservoir. This study illustrates how facies analysis and high resolution sequence stratigraphy can be applied to improve reservoir characterization in fluvio-marine successions deposited before the existence of land vegetation. In the Mereenie Field, these concepts have been successfully applied to: i) recognize with confidence all correlative reservoir intervals and ·ii) identify, orientate and map the LST of the Fourth-order sequences which represent the major reservoir intervals of the P3B Unit.

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de, Freitas Tim A. "Stratigraphy, mud buildups, and carbonate platform development of the Upper Ordovician to Lower Devonian sequence, Ellesmere, Hans, and Devon Islands, Arctic Canada." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7937.

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The Upper Ordovician to Lower Devonian platform in the Canadian Arctic twice evolved from a ramp to a rimmed shelf profile. Platform backstepping occurred in the fastigatus, acuminatus, cyphus?, sakmaricus (in North Greenland only) and linearis graptolite zones. Two major phases of pinnacle reef development followed platform backstepping, the first beginning in the lower Llandovery (cyphus Zone) and the second in the Ludlow (linearis Zone). Pinnacles of the first phase are uncommon, occur in the vicinity of Baumann Fiord, and show a vertical succession of lime mudstone, poorly exposed microbial carbonate, and coralgal biolithite, representing upward shallowing. The last named lithofacies is newly interpreted as representing a high-energy, wave-stressed environment that excluded stromatoporoid growth but favoured a sparse skeletal metazoan fauna, thickly encrusted by microbes. Paleo-surface area of these structures was apparently important for the accumulation of extensive ooids, which are associated with the upper parts of some pinnacle reefs. Three large mud buildups on central Ellesmere Island were established on the shelf margin subsequent to Upper Ordovician (fastigatus Zone) platform drowning. These structures show a vertical lithofacies succession: bioturbated lime mudstone is overlain by microbial carbonate then by mudstone-rich stromatoporoid floatstone and bindstone. The succession records overall upward shallowing. The olive green shale unit, well exposed in the vicinity of Trold Fiord, is an areally extensive and mappable middle Ludlow unit of the Cape Phillips Formation that postdates diachronous, middle Ludlow platform backstepping in the vicinity of Baumann Fiord. After backstepping, condensed sequences occurred over paleotopographic highs and expanded sections over lows, and a subsequent second major phase of platform rimming occurred. Stratigraphy known in the southern Arctic Islands is generally applicable to northeastern Ellesmere Island, but local lithological variations occur. The upper part of the Allen Bay Formation at Darling Peninsula, in particular, is unusually thick, and subtidal, perhaps resulting from greater subsidence, related to lithospheric flexure and deep marine clastic sedimentation that drowned the contiguous platform on North Greenland. Other formations recognized in this area include the Cape Storm, Douro, and Goose Fiord formations, although these, too, show minor lithological differences from type sequences. A thick grey siltstone unit in the vicinity of Bay and Vesle fiords is suggested to be a distal facies of the Red Canyon River Formation. This sequence is a progradational clastic wedge that likely represents the first, largest phase of the tripartite Caledonian Inglefield Uplift which profoundly affected carbonate deposition in the areas of southern and central Ellesmere Island during the late Silurian and early Devonian time. The base of this unit is diachronous and likely late Silurian in age. (Abstract shortened by UMI.)

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Fortin, Danielle. "Contact Beekmantown-Chazy dans les basses-terres du St-Laurent : évaluation des effets de la discordance (ordovicien inférieur)." Master's thesis, Université Laval, 1987. http://hdl.handle.net/20.500.11794/57120.

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Dans la séquence stratigraphique des Basses-Terres du St-Laurent, la discordance la plus importante serait celle qui existe entre les dolomies de Beekmantown (Ordovicien inférieur) et les calcaires de Chazy (Ordovicien moyen). Notre étude s'est intéressée à ce contact et aux carbonates adjacents, compte tenu de l'implication possible sur la métallogénie des Basses-Terres. De façon générale, les empilements de carbonates sous-jacents à des discordances forment des cibles de prédilection pour l'emplacement de gisements de plomb et de zinc. Les dolomies de Beauhamois présentent des lithofaciès à dominance intertidale et supratidale, témoignant d'environnements de platier de carbonates accumulés en milieu aride. Des corrélations effectuées sur six coupes montrant le contact dans la région de Montréal n'ont pas permis de mettre en évidence une surface d'érosion ou d'exposition aérienne au sommet du Beekmantown, et ce même à grande échelle. L'étude diagénétique de ces mêmes dolomies n'indique pas de dissolution de carbonates en profondeur susceptible d'exprimer une karstification en télodiagenèse. La dédolomitisation, seul phénomène pouvant réfléter une altération par des eaux météoriques superficielles, semble plutôt reliée à la diagenèse d'enfouissement, et plus spécifiquement à l'épisode de carbonatisation de sulfates. Suite à nos travaux, nous croyons que la discordance du Beekmantown dans les Basses-Terres du St-Laurent serait inexistante ou de faible magnitude dans la région étudiée.

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50

KIRCHNER, BRIAN T. "AN INTEGRATED ANALYSIS OF LATERAL TRENDS IN THE FAUNAL AND SEDIMENTOLOGIC CHARACTER OF METER-SCALE LIMESTONE-MUDROCK CYCLES IN THE KOPE FORMATION OF THE CINCINNATI REGION." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1116272427.

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Dissertations / Theses on the topic 'Stratigraphic Ordovician'

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