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.

Designation of a neotype and paraneotype for Conularina triangulata (Raymond, 1905) (Upper Ordovician, eastern North America)

2020 ◽  
Vol 94 (4) ◽  
pp. 796-797
Author(s):  
Heyo Van Iten ◽  
Mario E. Cournoyer ◽  
Michelle Coyne
Keyword(s):  
New York ◽  
North America ◽  
Late Ordovician ◽  
Quebec City ◽  
Eastern North America ◽  
Upper Ordovician ◽  
Thrust Sheet ◽  
City Formation ◽  
Early Late

Conularina triangulata (Raymond, 1905), the genotype of Conularina Sinclair, 1942, is a rare, early Late Ordovician conulariid (Cnidaria, Scyphozoa; Van Iten et al., 2006) having three sides or faces instead of four (Sinclair, 1942, fig. 9; Van Iten, 1992, text-fig. 3E). Originally described from the Valcour Formation (early Sandbian; Dix et al., 2013) on Valcour Island, New York (Sinclair, 1942), C. triangulata has since been found in laterally equivalent strata of the upper Laval Formation (‘Upper Chazy’; Sinclair, 1942) in Laval, Québec, Canada (Sinclair, 1942). From this same unit and area, Sinclair (1942) erected three new, four-sided species of Conularina (C. irrasa, C. raymondi, and C. undosa), and he erected a single four-sided species (C. narrawayi) from the Ottawa Formation (now the Sandbian–Katian Ottawa Group; Dix et al., 2013) at Tétreauville (now Gatineau), Québec. Subsequently, Jerre (1994) reported the occurrence of two species of Conularina in the Upper Ordovician of Sweden. Jerre (1994) also proposed that Eoconularia? forensis Sinclair, 1946 from the Upper Ordovician Citadelle Formation (‘Quebec City’ Formation; Sinclair, 1946) in Québec City, Québec (Promontoire de Québec thrust sheet, Appalachian Humber Zone, Allochtonous Domain; Castonguay et al., 2002) is a species of Conularina.

Graptolites with Multiple Genicular Spines from the Upper Ordovician of Western North America

1974 ◽  
Vol 11 (10) ◽  
pp. 1455-1460
Author(s):  
John Riva
Keyword(s):  
North America ◽  
Distinct Species ◽  
Late Ordovician ◽  
Western North America ◽  
Upper Ordovician ◽  
Lower Silurian ◽  
The Pacific

A careful restudy has been made of the types of Climacograptus innotatus var. pacificus Ruedemann from the topmost Ordovician of western North America and of topotype material of Climacograptus innotatus Nicholson from the Lower Silurian of Scotland. The study shows that these two forms are morphologically unrelated, the former being represented by short, stubby individuals with complex spinose growths, including double genicular spines, and the latter by slender, lanceolate individuals apparently provided with genicular flanges. Var. pacificus is here recognized as a distinct species, Climacograptus pacificus, and typifies and is restricted to Late Ordovician graptolite faunas of western North America and the Pacific Faunal Province.A deformed individual from Idaho characterized by three or four genicular spines is distinguished as Climacograptus pacificus pilosus, subspec. nov.

Parastrophinella (Brachiopoda): Its paleogeographic significance at the Ordovician/Silurian boundary

1997 ◽  
Vol 71 (3) ◽  
pp. 369-380 ◽  
Author(s):  
Jisuo Jin ◽  
Paul Copper
Keyword(s):  
North America ◽  
Type Species ◽  
Late Ordovician ◽  
Eastern North America ◽  
Hudson Bay ◽  
Morphologic Change ◽  
Baffin Island ◽  
Median Septum ◽  
Lamellar Layer ◽  
Anticosti Island

The type species of Parastrophinella, P. reversa, a pentamerid brachiopod from the uppermost Ordovician (Hirnantian) Ellis Bay Formation of Anticosti Island, Quebec, shows that the genus is characterized by three features: 1) a ventral median septum apically buried in a thickened valve floor, but anteriorly rising above valve floor; 2) prominent alate plates, which are homologous to brachial processes; and, 3) a pseudocruralium consisting of a dorsal median septum, which is largely buried in the valve floor posteriorly, and outer plates that are connected to the median septum via prismatic substance (with poorly developed lamellar layer at the junctions) at, or slightly above, the valve floor. These constitute criteria by which many species previously assigned to Parastrophinella are excluded from the genus. Late Ordovician species that fit the redefinition of Parastrophinella are now confined to eastern North America. The genus crosses the Ordovician/Silurian boundary without major morphologic change, and Early Silurian species of Parastrophinella occur in both eastern North America and Great Britain. In the Late Ordovician, the pentamerid fauna of North America (Laurentia) contrasted sharply with that of Baltica and Kazakhstan, where the Holorhynchus fauna was dominant. Typical elements of the Holorhynchus fauna, such as the large-shelled Holorhynchus and Proconchidium, are known only in the northern parts of Laurentia (Baffin Island, Greenland, and Kolyma), and are absent in the Hudson Bay and Williston basins and southwards.

DID EARLY LAND PLANTS PRODUCE A STEPWISE-CHANGE IN ATMOSPHERIC OXYGEN DURING THE LATE ORDOVICIAN (SANDBIAN ~ 458 MA)?

2019 ◽  
Author(s):  
Y. Datu Adiatma ◽  
◽  
Matthew R. Saltzman ◽  
Seth A. Young ◽  
Elizabeth M. Griffith ◽  
...  
Keyword(s):  
Atmospheric Oxygen ◽  
Late Ordovician ◽  
Land Plants ◽  
Stepwise Change ◽  
Early Land

scholarly journals Effect of Hydrothermal Activity on Organic Matter Enrichment of Shale: A Case Study of the Upper Ordovician and the Lower Silurian in the Lower Yangtze, South China

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 495 ◽  
Author(s):  
Yizhou Huang ◽  
Zhenxue Jiang ◽  
Kun Zhang ◽  
Yan Song ◽  
Shu Jiang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Oxygen Isotope ◽  
Shale Gas ◽  
Organic Matter Content ◽  
Hydrothermal Activity ◽  
Late Ordovician ◽  
Sedimentary Organic Matter ◽  
Upper Ordovician ◽  
Lower Silurian ◽  
Activity Intensity

The effect of organic matter on hydrocarbon potential, storage space, and gas content of shale is well-known. Additionally, present-day content of sedimentary organic matter in shale is controlled by depositional and preservation processes. Therefore, a study of the enrichment mechanisms of sedimentary organic matter provides a scientific basis for the determination of favorable areas of shale gas. In this study the Upper Ordovician Xinkailing Fm. and the first member of the Lower Silurian Lishuwo Fm. were examined. Stratigraphic sequences were identified through conventional logs and elemental capture spectrum data. Oxygen isotope analysis was applied to recover paleotemperature of seawater in the study area. The excess silicon content was calculated and the origin of the silica was determined by the Fe-Al-Mn ternary plot. The enrichment mechanism of organic matter was analyzed by two aspects: redox conditions and paleoproductivity. As a result, the stratigraphic interval was divided into two 3rd-order sequences. Through oxygen isotope, the paleotemperature of seawater was 62.7–79.2 °C, providing evidence of the development of hydrothermal activity. Analysis of excess siliceous minerals identified two siliceous mineral origins: terrigenous and hydrothermal. It also revealed an upwards decreasing tendency in hydrothermal activity intensity. Strong hydrothermal activity during the Late Ordovician, recognized as TST1, formed a weak-oxidizing to poor-oxygen environment with high paleoproductivity, which promoted organic matter enrichment. During the Late Ordovician to the Early Silurian, identified as RST1, TST2, and RST2, weakening hydrothermal activity caused the decline of paleoproductivity and increased oxidation of bottom waters, leading to a relative decrease of organic matter content in the shale. Therefore, favorable areas of shale gas accumulation in the Upper Ordovician and Lower Silurian are determined stratigraphically as the TST1, with a high total organic carbonate content. Geographically, the hydrothermally-active area near the plate connection of the Yangtze and the Cathaysian is most favorable.

Upper Ordovician ostracods from the Cautley district, northern England: Baltic and Laurentian affinities

2001 ◽  
Vol 138 (5) ◽  
pp. 589-607 ◽  
Author(s):  
MARK WILLIAMS ◽  
PHILIP STONE ◽  
DAVID J. SIVETER ◽  
PAULINE TAYLOR
Keyword(s):  
North America ◽  
Significant Extent ◽  
Baltic Region ◽  
Upper Ordovician ◽  
Northern Germany ◽  
Iapetus Ocean ◽  
Windermere Supergroup ◽  
Distributional Patterns ◽  
Anticosti Island ◽  
The Baltic

The Cautley Mudstone Formation and Cystoid Limestone Member of the Ashgill Formation (Windermere Supergroup; Ashgill Series), from the Cautley district of northern England, has yielded an ostracod fauna of more than 30 species. Many of these have short ranges, permitting recognition of stratigraphically successive Pusgillian–lower Cautleyan, middle–upper Cautleyan, and Rawtheyan ostracod faunas. Several species are also known from the upper Ordovician of North America (Anticosti Island), Scotland (Girvan district) and the Baltic region (Estonia, glacial erratic boulders of northern Germany), providing evidence to correlate upper Ordovician successions in these areas. The ostracods include abundant podocopes, at some horizons accounting for more than 80% of the fauna. Binodicopes are also common, but palaeocopes are rare. Assemblages are typical of a clastic dominated open marine shelf setting. Diversity at most horizons is low (c. 3–5 species), but reaches a peak of between 13–14 species in middle Cautleyan horizons. Lower diversity at Pusgillian and Rawtheyan horizons coincides with the encroachment of deeper marine-shelf facies which were probably hostile to Ordovician benthonic ostracods. Some of the ostracods (particularly Aechmina) have distributions suggesting tolerance of a range of mid- to deep shelf benthonic palaeoenvironments, but none were pelagic. During Ashgill times the Cautley district (part of palaeocontinental Avalonia) was replete with ostracod genera and species which also occur in the Baltic region (palaeocontinental Baltica; more than 90% generic similarity) and to a lesser, but nonetheless significant extent in North America and Scotland (parts of palaeocontinental Laurentia). Such trans-Tornquist Sea and Iapetus Ocean distributional patterns add to previous ostracod data that support models which show palaeogeographical proximity of Avalonia and Baltica, and Avalonia and Laurentia, by Ashgill times. The widely cited observation, that trans-Iapetus ostracod faunas remained strictly provincial until the mid-or late Silurian, cannot be sustained.

Flexible crinoids from the Upper Ordovician Maquoketa Formation of the northern midcontinent and the evolution of early flexible crinoids

2001 ◽  
Vol 75 (2) ◽  
pp. 370-382 ◽  
Author(s):  
James C. Brower
Keyword(s):  
New Species ◽  
North America ◽  
Late Ordovician ◽  
Upper Ordovician ◽  
Middle Ordovician

Three flexible crinoids occur in the Upper Ordovician Maquoketa Formation of Illinois, Iowa, and Minnesota:Protaxocrinus girvanensisRamsbottom, 1961,Clidochirus anebosnew species, andProanisocrinus oswegoensis(Miller and Gurley, 1894).Protaxocrinus girvanensisis also found in the Upper Ordovician of Scotland which indicates that the ocean was narrow enough to allow at least one crinoid species to cross the barrier. The Upper Ordovician of North America and Scotland also share many common crinoid genera. Both phenetic and cladistic methods result in similar phylogenies of flexible crinoids.Protaxocrinuswas derived from a cupulocrinid ancestor during the Middle Ordovician.Clidochirusevolved fromProtaxocrinusor its ancestral stock prior to the Richmondian of the Late Ordovician. The RichmondianProanisocrinusand later anisocrinids are most closely related toClidochirusor its immediate predecessor. Thus, three major lineages of flexible crinoids,Protaxocrinus(taxocrinid group),Clidochirus(icthyocrinid), andProanisocrinus(anisocrinids and homalocrinids), appeared during the Ordovician. Despite their rarity during the Ordovician, all three flexible lineages survived the Latest Ordovician extinction, whereas their more abundant and successful cupulocrinid ancestors were eliminated.

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.

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 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.

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