scholarly journals Shallow marine Paleodictyon from the Upper Ordovician Georgian Bay Formation of southern Ontario

10.4138/1994 ◽  
1993 ◽  
Vol 29 (2) ◽  
Author(s):  
D. C.A. Stanley ◽  
R. K. Pickerill
Keyword(s):  
Upper Ordovician ◽  
Southern Ontario ◽  
Shallow Marine ◽  
Georgian Bay

Pycnocrinus altilis, a new Late Ordovician channel-dwelling crinoid from southern Ontario

1987 ◽  
Vol 24 (5) ◽  
pp. 851-859 ◽  
Author(s):  
James D. Eckert
Keyword(s):  
Late Ordovician ◽  
Upper Ordovician ◽  
Submarine Channels ◽  
Southern Ontario ◽  
Georgian Bay

Pycnocrinus altilis n. sp. is described from the Upper Ordovician Georgian Bay Formation of Ontario. Closely related to P. dyeri (Meek), 1872, the cup of P. altilis is characterized by stellate ornamentation of plates comprising ridges bounded by deep subtriangular pits. Pycnocrinus altilis inhabited submarine channels in the prodeltaic regime of the Queenston deltaic complex and is inferred to have been anchored to the substrate by a distally coiled column.

Revised stratigraphy of the middle Simcoe Group (Ordovician, upper Sandbian–Katian) in its type area: an integrated approach

2020 ◽  
Vol 57 (1) ◽  
pp. 184-198 ◽  
Author(s):  
Timothy R. Paton ◽  
Carlton E. Brett
Keyword(s):  
New York ◽  
Integrated Approach ◽  
Early 20Th Century ◽  
Upper Ordovician ◽  
Southern Ontario ◽  
Lower Member ◽  
Type Area ◽  
Central United States ◽  
The Status ◽  
Uppermost Portion

The Upper Ordovician Bobcaygeon Formation of southern Ontario is a widespread unit that spans the Sandbian–Katian stage boundary and contains exceptionally preserved invertebrate fossil assemblages, including the famed ‘Kirkfield echinoderm fauna.’ However, the precise correlation of this interval remains poorly understood. This paper presents new data on high-resolution sequence and carbon isotope chemostratigraphy of the Bobcaygeon interval based on new quarry exposures and introduces refined definitions of unit boundaries based on allostratigraphic criteria. Sequence, chemo-, and biostratigraphic evidence indicate that the Bobcaygeon Formation represents a composite unit as it encompasses a major erosional unconformity. The Coboconk and Kirkfield formations, described in the early 20th century, were merged into a single unit, the Bobcaygeon, out of concern that the original lithostratigraphic divisions would be conflated with biostratigraphic zones of the same names. However, these biostratigraphic zones are no longer favoured, and the lower member of the Bobcaygeon is here elevated again to the status of formation (Coboconk Formation) and represents the uppermost portion of the Sandbian M4 sequence. The middle and upper members of the Bobcaygeon, herein reassigned to the Kirkfield Formation, represent the upper Sandbian to lower Katian M5A and M5B sequences recognized widely in the eastern and central United States. The term Bobcaygeon is retained and elevated to the rank of subgroup. The Kirkfield Formation is divided into three members and contacts are refined, placing a 1–2 m transgressive grainstone at the base of each sequence. These units are correlated with equivalent strata of New York and the Cincinnati Arch.

Sedimentology, Mineral Facies, and Petrofabric of the Meaford–Dundas Formation (Upper Ordovician) in Southern Ontario

1973 ◽  
Vol 10 (12) ◽  
pp. 1790-1804 ◽  
Author(s):  
K. Czurda ◽  
C. G. Winder ◽  
R. M. Quigley
Keyword(s):  
Clay Minerals ◽  
Heavy Minerals ◽  
Carbonate Content ◽  
The South ◽  
Upper Ordovician ◽  
Quartz Content ◽  
Southern Ontario ◽  
The North ◽  
Bedding Planes ◽  
Diffraction Patterns

The Meaford–Dundas Formation in southern Ontario is a medium gray shale with good fissility and resistant interbeds of gray fossiliferous limestones and siltstones. The hard layers are up to 20 cm in thickness and comprise 10 to 20% of the formation. The shale layers vary in thickness from 50 cm to 2 m.The clay minerals are principally illite, iron-chlorite, and small amounts of vermiculite and mixed-layer types. The carbonate content seems constant across the area at about 4 to 5% of the formation, except for the southwestern area where the carbonate increases to 20 or 25%. This increase is chiefly in dolomite content, a feature which reflects such factors as original conditions of deposition and possibly diagenesis subsequent to burial. The quartz content in the shale beds, and especially in the hard interbeds, increases towards the north to an average of 35 to 40% compared with 10 to 15% in the south. Framboids (aggregates of pyrite grains in spheroidal clusters) are a striking feature of the shale beds of the Meaford–Dundas Formation in the Meaford area.Fabric studies by means of X-ray diffraction patterns and scanning electron photomicrographs reveal, in most cases, high parallelism of clay platelets in the bedding planes, resulting in the good fissility of the shale.The principal source rock areas are the Appalachian orogen in the east (Taconic Mountains), which probably supplied most of the clay minerals and some quartz, and the Canadian Shield in the north, which provided the basin of sedimentation in the south with heavy minerals and additional quartz.

scholarly journals An unusual sponge – microbe – synsedimentary cement framework in a Late Ordovician reef, Southampton Island (Nunavut, Canada)

2016 ◽  
Vol 53 (8) ◽  
pp. 815-822 ◽  
Author(s):  
Ariane Castagner ◽  
André Desrochers ◽  
Denis Lavoie
Keyword(s):  
Spatial Relationship ◽  
Late Ordovician ◽  
Calcareous Algae ◽  
Upper Ordovician ◽  
Shallow Marine ◽  
Early Ordovician ◽  
Subaerial Exposure ◽  
Close Spatial Relationship ◽  
Diverse Community ◽  
Calcite Cement

A large, resistant buildup at the top of the Upper Ordovician (Hirnantian?) Red Head Rapids Formation on Southampton Island (Nunavut, Arctic Canada) is dominated by massive boundstone and cementstone facies. These massive facies have more in common with the sponge–microbial reefs that dominated worldwide in the Early Ordovician, including the following primary components: early calcified sponge material, microbial elements, and synsedimentary cement. A close spatial relationship between sponge and microbial framework elements suggests that a poorly preserved decaying sponge framework provided substrates for the attachment and development of microbes and that the microbes played essential roles as reef consolidators. Centimetre-scale colonial metazoans are present and locally intergrown with the sponge and microbial components. Other mound-dwelling invertebrates or calcareous algae are rare. Although altered now to calcite, cement fabrics suggest that aragonite was ubiquitous as seafloor precipitate. Prior to its subaerial exposure in the latest Ordovician, the Red Head Rapids Formation buildup developed on the margin of a shallow-marine evaporative epicratonic basin where a diverse community of reef-building metazoans was unable to flourish.

Occurrence and regional geological setting of Paleozoic rocks on the Grand Banks of Newfoundland

1986 ◽  
Vol 23 (4) ◽  
pp. 504-526 ◽  
Author(s):  
Lewis H. King ◽  
Gordon B. J. Fader ◽  
W. A. M. Jenkins ◽  
Edward L. King
Keyword(s):  
Oil And Gas ◽  
Black Shales ◽  
Source Rocks ◽  
Upper Ordovician ◽  
Acoustic Basement ◽  
Lower Paleozoic ◽  
Shallow Marine ◽  
Grand Banks ◽  
Younger Age ◽  
Seismic Reflection Profiles

Analyses of seismic reflection profiles supported by lithological and palynological studies of core samples from submarine outcrops indicate that the lower Paleozoic succession of the Avalon Terrane, southeast Newfoundland, is continuous offshore. The succession crops out over an area greater than 30 000 km2 and is approximately 8 km thick. The sequence is dominantly siltstone and is of Late Cambrian to ?Devonian or younger age. It is relatively unmetamorphosed, underlain by Hadrynian acoustic basement, and overlain along its eastern and southern margins by a Mesozoic–Cenozoic succession that is economically important from an oil and gas perspective.Lithofacies studies indicate that in Early Ordovician time restricted shallow-marine conditions probably prevailed over a vast area of the Avalon Terrane. Upper Ordovician and Silurian siltstones show evidence of deposition under more-dynamic and well-oxygenated conditions and probably represent a normal shallow-marine environment. Redbeds of possible Devonian or younger age are interpreted to be of continental origin. Black shales of Ordovician age are potential source rocks for the generation of hydrocarbons.

Sphenothallus-like fossils from the Martinsburg Formation (Upper Ordovician), Tennessee, USA

2011 ◽  
Vol 85 (2) ◽  
pp. 353-359 ◽  
Author(s):  
Maya Li Wei-Haas ◽  
Bosiljka Glumac ◽  
H. Allen Curran
Keyword(s):  
Marine Invertebrate ◽  
Limited Evidence ◽  
Upper Ordovician ◽  
Shallow Marine ◽  
Storm Waves ◽  
Waves And Currents

Tubular fossils, up to 2 mm in diameter and 60 mm in length, occur rarely in the upper Martinsburg Formation (Upper Ordovician), northeastern Tennessee Appalachians, U.S.A. The fossils are unbranched, straight or slightly bent, occasionally twisted and wrinkled, and not significantly tapered. Orientation of the fossils within shallow-marine tempestites suggests that they represent remains of organisms that were broken, transported, and deposited by storm waves and currents. The fossils are morphologically similar to many of the previously identified species belonging to the genus Sphenothallus, a relatively rare tube-dwelling Paleozoic marine invertebrate. Owing to the limited evidence for distal widening of the tubes, lack of holdfasts, and carbonaceous rather than phosphatic composition, the affinity of these fossils remains uncertain, and we refer to them as Sphenothallus-like.

scholarly journals Systematic ichnology of the Late Ordovician Georgian Bay formation of southern Ontario, eastern Canada /

1998 ◽  
Author(s):  
D. Christopher A. Stanley ◽  
R. K. Pickerill ◽  
Keyword(s):  
Late Ordovician ◽  
Eastern Canada ◽  
Southern Ontario ◽  
Georgian Bay

scholarly journals Early complex tiering pattern: Upper Ordovician, Barrandian area, the Czech Republic

2021 ◽  
Vol 77 (1) ◽  
pp. 17-35
Author(s):  
Pavel Bokr ◽  
Radek Mikuláš ◽  
Petr Budil ◽  
Petr Kraft
Keyword(s):  
Czech Republic ◽  
Trace Fossils ◽  
Preferred Orientation ◽  
Upper Ordovician ◽  
The Czech Republic ◽  
Shallow Marine ◽  
Fine Grained ◽  
Bedding Planes ◽  
Barrandian Area

Upper Ordovician shallow marine fine-grained sandstones and siltstones exposed in the Loděnice – vinice locality yielded a distinct and well-preserved tiering pattern of trace fossils. The two uppermost tiers are composed mainly of Bifungites and Nereites. Deeper in the sediment, tiers dominated by Thalassinoides, Zoophycos and Teichichnus occur. Most of the succession is completely bioturbated; however, several storm layers enabled study of a well-preserved frozen tiering pattern. Large portions of the bedding planes (ichnologic snapshots) showed a considerable patchiness of intensive surface bioturbation and a preferred orientation of Bifungites. The identified tiering pattern is one of the earliest examples of a well-documented complex tiering of burrows documented in detail.

Revision of the position of the Ordovician–Silurian boundary in southern Ontario: regional chronostratigraphic implications of δ13C chemostratigraphy of the Manitoulin Formation and associated strata

2011 ◽  
Vol 48 (11) ◽  
pp. 1447-1470 ◽  
Author(s):  
Stig M. Bergström ◽  
Mark Kleffner ◽  
Birger Schmitz ◽  
Bradley D. Cramer
Keyword(s):  
Middle Part ◽  
Adjacent Region ◽  
Geologic History ◽  
Southern Ontario ◽  
Georgian Bay ◽  
The North ◽  
Head Formation ◽  
Depositional Patterns ◽  
Baseline Values ◽  
Anticosti Island

δ13C values of 142 samples from the Manitoulin Formation and subjacent strata collected from 14 exposures and two drill-cores on Manitoulin Island, Bruce Peninsula, and the region south of Georgian Bay suggest that the Manitoulin Formation is latest Ordovician (Hirnantian) rather than earliest Silurian in age. A δ13C excursion identified as the Hirnantian isotope carbon excursion (HICE), which has a magnitude of nearly 2.5‰ above baseline values, is present in an interval from the upper Queenston Formation to the lower to middle part of the Manitoulin Formation in most of Bruce Peninsula and in the area south of Georgian Bay, whereas on Manitoulin Island the HICE appears to be absent. This indicates that a significant part of the Manitoulin Formation is older on the Bruce Peninsula and in its adjacent region than on Manitoulin Island. The chemostratigraphically based conclusions are consistent with biostratigraphic data from conodonts and brachiopods. The Hirnantian δ13C curve from Anticosti Island, Quebec is closely similar to those of southern Ontario. Traditionally, the Ordovician–Silurian boundary has been placed at the base of the Manitoulin Formation, but the new results suggest that it is more likely to be at, or near, the base of the overlying Cabot Head Formation. These new results have major implications for the interpretation of the geologic history and marine depositional patterns of the latest Ordovician of a large part of the North American Midcontinent.

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