Stratigraphy of the Upper Ordovician upper Vaureal and Ellis Bay formations, eastern Anticosti Island, Quebec

1987 ◽  
Vol 24 (9) ◽  
pp. 1807-1820 ◽  
Author(s):  
D. G. F. Long ◽  
Paul Copper
Keyword(s):  
Late Ordovician ◽  
Eastern Coast ◽  
Upper Ordovician ◽  
New Members ◽  
Patch Reefs ◽  
Accurate Definition ◽  
Central Regions ◽  
Shallow Subtidal ◽  
Anticosti Island ◽  
Definition Of

Marked facies changes occur in Late Ordovician strata, assigned to the uppermost Vaureal and Ellis Bay formations (Ashgill: Rawtheyan–Hirnantian) on Anticosti Island, Quebec. Western Anticosti features shales and carbonates, whereas outcrops along the eastern coast contain prominent, discontinuous, mixed siliciclastic–carbonate units. Detailed section measurement along the northeast coast allows, for the first time, accurate definition of seven new members within this uninterrupted sequence. Sands present in the upper Vaureal and lower Ellis Bay formations in the east appear to have deterred the growth of muddy-bottom brachiopod communities comparable to those in the western and central regions of Anticosti. Sand units within the upper Vaureal Formation contain 1 m diameter colonies of Paleofavosites; coeval small coral patch reefs are found in the central part of the island, where sands are absent. The uppermost Ellis Bay Formation of northeast Anticosti is marked by a shallow, subtidal, coral–algal oncolite bed or by small (2–4 m across, 1–2 m thick) local coral patch reefs, the tops of which have been used to define the Ordovician – Silurian boundary. No supratidal or intertidal sediments and faunas are evident in the Anticosti succession, suggesting that Late Ordovician sea-level drawdown was insufficient to provide shelf-emergent conditions in this region.

scholarly journals Sedimentology and paleoecology of Upper Ordovician mounds of Anticosti Island, Quebec

1981 ◽  
Vol 18 (10) ◽  
pp. 1562-1571 ◽  
Author(s):  
John H. Lake
Keyword(s):  
Late Ordovician ◽  
Calcareous Algae ◽  
Upper Ordovician ◽  
Salmon River ◽  
Shallow Subtidal ◽  
Anticosti Island ◽  
Primary Porosity

Relatively thin organic buildups in the Ellis Bay Formation of Anticosti Island developed in a shallow subtidal regressive marine shelf environment during the Late Ordovician. The Ellis Bay Formation has been subdivided into six members by Bolton. Two buildups, one in each of members 4 and 6, were studied in detail. The member 6 mud mound on the Salmon River (8 m thick) is bound by calcareous algae, stromatoporoids, and corals, and consists of a micritic bafflestone core capped by crinoidal lime grainstone. Early marine cementation permeated nearly all of the primary porosity. Cathodoluminescence indicates at least five stages of cementation of the mound. Constructive mound development was terminated by progressively shallowing, agitated marine conditions.The member 4 mound is a small coral (ecological) reef exposed on the Vaureal River.

scholarly journals Late Ordovician (Hirnantian) diploporitan fauna of Anticosti Island, Quebec, Canada: implications for evolutionary and biogeographic patterns

2018 ◽  
Vol 55 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Sarah L. Sheffield ◽  
William I. Ausich ◽  
Colin D. Sumrall
Keyword(s):  
Evolutionary Dynamics ◽  
Late Ordovician ◽  
Upper Ordovician ◽  
Evolutionary Transitions ◽  
Biogeographic Patterns ◽  
Critical Data ◽  
New Localities ◽  
Reefal Facies ◽  
Anticosti Island ◽  
Fossil Data

Hirnantian (latest Ordovician) localities containing echinoderm fossils are rare; the few that have been discovered primarily contain disarticulated crinoid ossicles. Therefore, relatively little is known about echinoderm evolutionary dynamics across the Late Ordovician – early Silurian boundary, especially noncrinoid echinoderms. New diploporitan echinoderms, Holocystites salmoensis and an unidentified holocystitid, from reefal facies of the Upper Ordovician Ellis Bay Formation of Anticosti Island provide a critical data point concerning diploporitan biogeography and evolutionary pathways undertaken during the Ordovician and Silurian. These fossils also provide a crucial link in understanding the ancestry of the Silurian Holocystites Fauna, an unusual diploporitan fauna from the middle Silurian of North America, whose origination dates back at least 15 million years earlier than previously thought with the discovery of taxa described here. New fossil data such as these stress the importance of uncovering new localities from underrepresented times and places in Earth’s history, so that these evolutionary transitions can be better understood.

Late Ordovician - Early Silurian cryptospore occurrences on Anticosti Island (Île d'Anticosti), Quebec, Canada

2007 ◽  
Vol 44 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Jeffery G Richardson ◽  
William I Ausich
Keyword(s):  
North America ◽  
Late Ordovician ◽  
Land Plants ◽  
Eastern North America ◽  
Upper Ordovician ◽  
Lower Silurian ◽  
Low Diversity ◽  
Anticosti Island ◽  
Early Land

Residues from Hirnantian (Upper Ordovician) and Aeronian (Lower Silurian) strata of Anticosti Island, Quebec, Canada, have yielded the oldest occurrence of terrestrial-based palynomorphs (cryptospores) from eastern North America. A low-abundance, low-diversity cryptospore assemblage containing specimens of Pseudodyadospora, Velatitetras, and alete monads has been recovered from the Velleda Member of the Ellis Bay Formation (Upper Ordovician, Hirnantian). The Gun River Formation (Lower Silurian, Aeronian) contains a low-abundance, low-diversity assemblage composed of specimens of Velatitetras, Laevolcancis, and alete monads. The occurrence of these assemblages provides evidence for early land plants in this part of North America during the Late Ordovician and Early Silurian, and documents the existence of a terrestrial-based flora during and after the Saharan (Late Ordovician) glaciation.

Description and correlation of Late Ordovician conodonts from the D. ornatus and P. pacificus graptolite zones, Road River Group, northern Yukon Territory

1987 ◽  
Vol 24 (7) ◽  
pp. 1450-1464 ◽  
Author(s):  
Alexander D. McCracken
Keyword(s):  
New Species ◽  
New Genus ◽  
Late Ordovician ◽  
Yukon Territory ◽  
Upper Ordovician ◽  
The Road ◽  
Anticosti Island ◽  
Blackstone River ◽  
A New Species

Upper Ordovician carbonate beds within clastic strata of the Road River Group, northern Yukon Territory, have yielded 403 conodont elements representing 25 species; 19 of these are illustrated. Genera present are Amorphognathus, Belodina, Besselodus, Drepanoistodus, Eocarniodus?, Gamachignathus, Icriodella, Noixodontus, Oulodus, Panderodus s.l., Paroistodus?, Plectodina, Protopanderodus, Pseudobelodina s.l., Scabbardella, Strachanognathus, and Walliserodus. The apparatus of new genus A new species A includes a symmetrical and bifurrowed rastrate element.Sparse conodont faunas from Rock River occur in strata below a level bearing graptolites of the D. ornatus Zone and between this zone and the succeeding P. pacificus Zone. These conodonts have a range of "Trentonian" –Gamachian (upper Caradoc –Hirnantian).The fauna from Blackstone River is from a single bed that is 3 m below the G. persculptus Zone? and 13.7 m above the P. pacificus Zone. Although stratigraphically closer to the former, this fauna may be equivalent to a level within the P. pacificus Zone; the conodonts suggest correlation with the late Richmondian Fauna 12 and the lower G. ensifer Zone of Anticosti Island, Quebec. A similar fauna (G. ensifer Zone) occurs in one horizon within the P. pacificus Zone at upper Peel River. One metre above this is the informal D. cf. D. mirus graptolite biohorizon (P. pacificus Zone).The Blackstone and Peel faunas equate to a level within the Ordovician Anceps bands C and D of the Ordovician–Silurian boundary stratotype at Dob's Linn, Scotland. The interval of Fauna 13 and the Gamachian Stage may correspond to Anceps Band E and the C.? extraordinarius Band (and contiguous strata) at Dob's Linn. The base of the G. ensifer Zone and the higher base of the Gamachian are probably late Rawtheyan.

Continental-scale biogeographic variation: provinces versus gradients in the Upper Ordovician of Laurentia

Paleobiology ◽  
2016 ◽  
Vol 42 (3) ◽  
pp. 410-425 ◽  
Author(s):  
Chelsea E. Jenkins ◽  
Steven M. Holland
Keyword(s):  
Large Scale ◽  
Geographic Distance ◽  
Late Ordovician ◽  
Data Sets ◽  
Upper Ordovician ◽  
Jaccard Similarity ◽  
Faunal Composition ◽  
Continental Scale ◽  
Biogeographic Provinces ◽  
Shallow Subtidal

AbstractAlthough provinces are widely used to delimit large-scale variations in biotic composition, it is unknown to what extent such variations simply reflect large-scale gradients, much as has been shown at smaller scales for communities. We examine here whether four previously described Middle and Late Ordovician provinces on Laurentia are best described as distinct provinces or as biotic gradients through a combination of the Paleobiology Database and new field data. Both data sets indicate considerable overlap in faunal composition, with spatial patterns in Jaccard similarity, quantified Jaccard similarity, and nonmetric multidimensional scaling ordination structure that correspond to variations in substrate type, specifically from carbonate-dominated strata in western Laurentia to mixed carbonate–siliciclastic strata in the midcontinent to siliciclastic-dominated rocks in easternmost Laurentia. Because sampling was limited to shallow-subtidal settings, this gradient cannot be attributed to variations in water depth. Likewise, geographic distance accounts for only a quarter of the variation in faunal composition. This cross-continent faunal gradient increases in strength into the early Late Ordovician, and appears to represent increased siliciclastic influx into eastern Laurentia during the Taconic orogeny. These results raise the question of whether biogeographic provinces may be in general better interpreted and analyzed as biotic gradients rather than as discrete entities.

scholarly journals Late Ordovician (Hirnantian) diploporitan fauna of Anticosti Island, Quebec, Canada: implications for evolutionary and biogeographic patterns

2017 ◽  
Author(s):  
Sarah L. Sheffield
Keyword(s):  
Evolutionary Dynamics ◽  
Late Ordovician ◽  
Upper Ordovician ◽  
Evolutionary Transitions ◽  
Biogeographic Patterns ◽  
Critical Data ◽  
New Localities ◽  
Reefal Facies ◽  
Anticosti Island ◽  
Fossil Data

Abstract: Hirnantian (latest Ordovician) localities containing echinoderm fossils are rare; the few that have been discovered primarily contain disarticulated crinoid ossicles. Therefore, relatively little is known about echinoderm evolutionary dynamics across the Late Ordovician – early Silurian boundary, especially noncrinoid echinoderms. New diploporitan echinoderms, Holocystites salmoensis and an unidentified holocystitid, from reefal facies of the Upper Ordovician Ellis Bay Formation of Anticosti Island provide a critical data point concerning diploporitan biogeography and evolutionary pathways undertaken during the Ordovician and Silurian. These fossils also provide a crucial link in understanding the ancestry of the Silurian Holocystites Fauna, an unusual diploporitan fauna from the middle Silurian of North America, whose origination dates back atleast 15 million years earlier than previously thought with the discovery of taxa described here. New fossil data such as these stress the importance of uncovering new localities from underrepresented times and places in Earth’s history, so that these evolutionary transitions can be better understood.

Resolution and measurement in the scanning electron microscope

1987 ◽  
Vol 45 ◽  
pp. 534-537 ◽  
Author(s):  
Michael T. Postek
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Engineering Design ◽  
Resolving Power ◽  
Practical Applications ◽  
Instrument Resolution ◽  
Accurate Definition ◽  
Definition Of ◽  
Scanning Electron ◽  
Better Than

The term ultimate resolution or resolving power is the very best performance that can be obtained from a scanning electron microscope (SEM) given the optimum instrumental conditions and sample. However, as it relates to SEM users, the conventional definitions of this figure are ambiguous. The numbers quoted for the resolution of an instrument are not only theoretically derived, but are also verified through the direct measurement of images on micrographs. However, the samples commonly used for this purpose are specifically optimized for the measurement of instrument resolution and are most often not typical of the sample used in practical applications.SEM RESOLUTION. Some instruments resolve better than others either due to engineering design or other reasons. There is no definitively accurate definition of how to quantify instrument resolution and its measurement in the SEM.

Dasein, personeidad, intersubjetividad y persona-núcleo. El sujeto relacional después de Heidegger, en Zubiri, Apel y Polo. Dasein, Personhood, Inter-subjectivity and Nucleus-Person. The Relational Subject after Heidegger, in Zubiri, Apel and Polo

2017 ◽  
Author(s):  
Carlos Ortiz de Landázuri
Keyword(s):  
Heuristic Strategies ◽  
Accurate Definition ◽  
Being There ◽  
Definition Of

Heidegger, Zubiri, Apel y Polo habrían propuesto una definición más correcta de las respectivas nociones de sujeto relacional humano, a saber: “Dasein” o “ser-ahí”; “personeidad” o “esencia abierta”; “intersubjetividad” o “la llamada por parte de los entes a diversos interlocutores”; y, finalmente, “persona-núcleo” o “agente mediador entre los entes y el ser”. Se pretendía así evitar una vuelta a las paradojas del “sujeto transcendental” en Kant, del “yo absoluto” en Hegel o del “sujeto fenomenológico” en Husserl. Sin embargo en cada caso se siguieron estrategias heurísticas específicamente distintas a la hora de conceptualizar dicho sujeto relacional: Heidegger propuso una superación de la noción de “sujeto fenomenológico” en Husserl; Zubiri, en cambio, defendería una recuperación de la noción de “sujeto fenomenológico” en Husserl; por su parte, Apel propondría una reformulación semióticamente transformada del “Dasein” heideggeriano; finalmente, Polo propondría una reformulación gnoseológica de la noción de “Dasein” heideggeriano.Heidegger, Zubiri, Apel, and Polo have proposed a more accurate definition of the respective notions of human relational subject: “Dasein” or “being-there”; “Personhood” or “open essence”; “inter-subjectivity” or “entities’ appeal to diverse interlocutors”; and, finally, “nucleus-person” or “mediator between entities and being”. The aim is to avoid a return to Kant’s transcendental subject paradoxes and Hegel’s “absolute I” or Husserl´s “fenomenological subject”. But in each case specifically different heuristic strategies were followed when conceptualizing said relational subject: Heidegger proposed overcoming the notion of “phenomenological subject” in Husserl; Zubiri, however, defend the recovery of the notion of “phenomenological subject” in Husserl; meanwhile, Apel propose a transformed semiotically reformulation of Heidegger’s “Dasein”; finally, Polo propose a reformulation of the epistemological notion of Heidegger’s “Dasein”.

scholarly journals Advancing UK Regulatory Science Strategy in the Context of Global Regulation: a Stakeholder Survey

2021 ◽  
Author(s):  
Samantha Cruz Rivera ◽  
Barbara Torlinska ◽  
Eliot Marston ◽  
Alastair K. Denniston ◽  
Kathy Oliver ◽  
...  
Keyword(s):  
Pay For Performance ◽  
Regulatory Science ◽  
International Strategy ◽  
Free Text ◽  
The European Union ◽  
Accurate Definition ◽  
Definition Of ◽  
Healthcare Innovation ◽  
The Uk ◽  
Medium Enterprises

Abstract Background The UK’s transition from the European Union creates both an urgent need and key opportunity for the UK and its global collaborators to consider new approaches to the regulation of emerging technologies, underpinned by regulatory science. This survey aimed to identify the most accurate definition of regulatory science, to define strategic areas of the regulation of healthcare innovation which can be informed through regulatory science and to explore the training and infrastructure needed to advance UK and international regulatory science. Methods A survey was distributed to UK healthcare professionals, academics, patients, health technology assessment agencies, ethicists and trade associations, as well as international regulators, pharmaceutical companies and small or medium enterprises which have expertise in regulatory science and in developing or applying regulation in healthcare. Subsequently, a descriptive quantitative analyses of survey results and directed thematic analysis of free-text comments were applied. Results Priority areas for UK regulatory science identified by 145 participants included the following: flexibility: the capability of regulations to adapt to novel products and target patient outcomes; co-development: collaboration across sectors, e.g. patients, manufacturers, regulators, and educators working together to develop appropriate training for novel product deployment; responsiveness: the preparation of frameworks which enable timely innovation required by emerging events; speed: the rate at which new products can reach the market; reimbursement: developing effective tools to track and evaluate outcomes for “pay for performance” products; and education and professional development. Conclusions The UK has a time-critical opportunity to establish its national and international strategy for regulatory science leadership by harnessing broader academic input, developing strategic cross-sector collaborations, incorporating patients’ experiences and perspectives, and investing in a skilled workforce.

Katian (Late Ordovician) conodonts on the northwestern margin of the North China Craton

2021 ◽  
pp. 1-22
Author(s):  
Zhihua Yang ◽  
Xiuchun Jing ◽  
Hongrui Zhou ◽  
Xunlian Wang ◽  
Hui Ren ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Late Ordovician ◽  
Carbonate Platforms ◽  
Upper Ordovician ◽  
The North ◽  
Low Latitudes ◽  
Northwestern Margin ◽  
Conodont Fauna ◽  
Stratigraphic Range

Abstract Upper Ordovician strata exposed from the Baiyanhuashan section is the most representative Late Ordovician unit in the northwestern margin of the North China Craton (NCC). In total, 1,215 conodont specimens were obtained from 24 samples through the Wulanhudong and Baiyanhuashan formations at the Baiyanhuashan section. Thirty-six species belonging to 17 genera, including Tasmanognathus coronatus new species, are present. Based on this material, three conodont biozones—the Belodina confluens Biozone, the Yaoxianognathus neimengguensis Biozone, and the Yaoxianognathus yaoxianensis Biozone—have been documented, suggesting that the Baiyanhuashan conodont fauna has a stratigraphic range spanning the early to middle Katian. The Baiyanhuashan conodont fauna includes species both endemic to North China and widespread in tropical zones, allowing a reassessment of the previous correlations of the Katian conodont zonal successions proposed for North China with those established for shallow-water carbonate platforms at low latitudes. UUID: http://zoobank.org/7cedbd4a-4f7a-4be6-912f-a27fd041b586

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