scholarly journals Late Ordovician brachiopods from east-central Alaska, northwestern margin of Laurentia

2020 ◽  
Vol 94 (4) ◽  
pp. 637-652
Author(s):  
Jisuo Jin ◽  
Robert B. Blodgett
Keyword(s):  
Cluster Analysis ◽  
Late Ordovician ◽  
Similar Species ◽  
East Central ◽  
Tectonic Plates ◽  
Northwestern Margin ◽  
Mackenzie Mountains ◽  
Brachiopod Fauna ◽  
Anticosti Island

AbstractA Late Ordovician brachiopod fauna from the Black River quadrangle (D-1 1:63,360 scale) of east-central Alaska comprises taxa typical of the Late Ordovician brachiopod fauna in the pericratonic epeiric seas of Laurentia, including Hesperorthis pyramidalis (Twenhofel, 1928), Plaesiomys occidentalis (Okulitch, 1943), Eoplectodonta sp., Holtehdalina sp., Leptaena sp., Brevilamnulella minuta n. sp., Tcherskidium tenuicostatum n. sp., Rhynchotrema iowense Wang, 1949, and Whitfieldella sp. The presence of Plaesiomys occidentalis and Tcherskidium tenuicostata n. sp. indicates a latest Katian age by correlation with similar species in the Mackenzie Mountains, southern Manitoba, Anticosti Island, the American midcontinent, Kolyma, and Siberia. Cluster analysis based on 20 well-studied late Katian brachiopod faunas from various regions within Laurentia and elsewhere in other tectonic plates suggests that the small brachiopod faunule from Alaska has the strongest paleobiogeographic affinity with Laurentia, confirming that the Black River quadrangle of Alaska was part of Laurentia during the Late Ordovician.UUID: http://zoobank.org/6b387856-61d5-4685-a592-faf5287c1e0f

New cheirurinid trilobites from the lower Whittaker Formation (Ordovician), southern Mackenzie Mountains

1976 ◽  
Vol 13 (7) ◽  
pp. 947-959 ◽  
Author(s):  
Rolf Ludvigsen
Keyword(s):  
New Species ◽  
Late Ordovician ◽  
New Genera ◽  
Monotypic Genus ◽  
Northern Canada ◽  
Mackenzie Mountains ◽  
Anticosti Island ◽  
Early Late

Two new genera of cheirurinid trilobites are described from the lower Whittaker Formation (?Rocklandian to Edenian; late Middle and early Late Ordovician) of the southern Mackenzie Mountains. The monotypic genus, Whittakerites n. gen., is a probable descendant of Ceraurus and is presently known only from northern Canada. Borealaspis n. gen. is established for two species from northern Canada, one of which possibly occurs in northern Greenland, and includes B. numitor (Billings) from Anticosti Island. New species described are Whittakerites planatus, Borealaspis whittakerensis, and B. biformis.

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

Anticostia, a distinctive new Late Ordovician "glyptograptid" (Diplograptacea, Graptoloidea) based on three-dimensionally preserved specimens from Anticosti Island, Quebec

1997 ◽  
Vol 34 (2) ◽  
pp. 215-228 ◽  
Author(s):  
Scott Stewart ◽  
Charles E. Mitchell
Keyword(s):  
Late Ordovician ◽  
Type Specimens ◽  
Anticosti Island ◽  
First Time

Three-dimensionally preserved specimens of Late Ordovician graptolites have been isolated from Vauréal Formation limestone samples collected from Anticosti Island, Quebec. The morphology, astogeny, and systematics of Anticostia macgregorae n.gen., n.sp. are described. These specimens show a new astogenetic pattern (pattern K) described for the first time. The similar glyptograptid species Glyptograptus hudsoni Jackson, Glyptograptus tenuissimus Ross and Berry, and Orthograptus fastigatus Davies all possess a pattern K astogeny. These species, along with Glyptograptus lorrainensis, which possesses the less-derived pattern G astogeny, are included within Anticostia n.gen. Anticostia tenuissima (Ross and Berry) is redescribed and Normalograptus? occidentalis (Ruedemann) is refigured based on their type specimens from coeval rocks in Nevada and Idaho.

Late Ordovician sand-wave complexes on Anticosti Island, Quebec: a marine tidal embayment?

1987 ◽  
Vol 24 (9) ◽  
pp. 1821-1832 ◽  
Author(s):  
D. G. F. Long ◽  
Paul Copper
Keyword(s):  
Local Community ◽  
Late Ordovician ◽  
Sand Wave ◽  
Sand Waves ◽  
The North ◽  
Sand Ridges ◽  
Tidal Embayment ◽  
Tidal Modification ◽  
Global Sea Level ◽  
Anticosti Island

Laterally discontinuous, mixed carbonate–siliciclastic sandstones in the upper Vaureal and lower Ellis Bay formations of Anticosti Island were deposited on an equatorial carbonate ramp with a slope of less than 1°. The 10–18 m thick sandstones are interpreted as subaqueous sand-wave complexes analogous to detached parts of modern shoreface-connected sand ridges. These record storm-enhanced, tidal modification of a northerly derived shoal retreat massif that may have formed in response to recovery from global sea-level lowstands in the Late Ordovician (Ashgill: late Rawtheyan – Hirnantian). The sand-wave complexes formed within a tidal embayment that was confined by the Precambrian Shield to the north and northwest by rising tectonic highlands of the Humber Zone in Newfoundland to the east, and by active tectonic highlands in the Quebec Appalachians (Gaspésie) to the south. Paleocurrent distributions, parallel to the western margins of the Strait of Belle Isle, suggest that the north end of the embayment was closed in Late Ordovician time. Low-diversity faunas within the sand units consist mostly of sowerbyellid, strophomenid, and rhynchonellid brachiopods, bivalves, gastropods, large aulacerid stromatoporoids, and large, domed favositid corals. These "sandy fades" faunas belong to communities significantly different from those found in the laterally interfingering and overlying carbonates and shales, suggesting that the sand waves played an important role in local community modification.

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.

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