The age and upper boundary of the Nepean Formation in its type section near Ottawa, Ontario

1977 ◽  
Vol 14 (9) ◽  
pp. 2002-2006 ◽  
Author(s):  
Uwe Brand ◽  
Brian R. Rust
Keyword(s):  
North America ◽  
Carbonate Content ◽  
Marine Transgression ◽  
Type Section ◽  
Lower Ordovician ◽  
Conodont Fauna ◽  
Upper Boundary

A sharp but conformable boundary with the overlying March Formation is present at the top of a section of the Nepean Formation near Ottawa, here proposed as the type section. The basal March unit can be recognized by its consistent and distinctly higher carbonate content (calcite and dolomite) than the underlying Nepean sandstones. The March and upper Nepean strata in this section contain a lower Arenigian conodont fauna, which can be correlated with similar faunas elsewhere in North America, and in Europe, Asia, and Australia. The Nepean–March contact is younger near Ottawa than around Brockville, indicating that the lower Ordovician succession represents a marine transgression, which progressed northward with time.

New echinoderms from the Early Ordovician of west Texas

1994 ◽  
Vol 68 (2) ◽  
pp. 324-338 ◽  
Author(s):  
James Sprinkle ◽  
Gregory P. Wahlman
Keyword(s):  
North America ◽  
El Paso ◽  
Middle Ordovician ◽  
Early Ordovician ◽  
West Texas ◽  
Lower Ordovician ◽  
Single Well ◽  
Thecal Plate ◽  
Stem Segments

Four specimens of blastozoan and crinozoan echinoderms are described from the Lower Ordovician El Paso Group in the southern Franklin Mountains just north of El Paso, west Texas.Cuniculocystis flowerin. gen. and sp., based on two partial specimens, appears to be a typical rhombiferan in most of its morphologic features except that it lacks pectinirhombs and instead has covered epispires (otherwise known only from Middle Ordovician eocrinoids) opening on most of the thecal plate sutures. The covered epispires inCuniculocystisindicate that some early rhombiferans had alternate respiratory structures and had not yet standardized on pectinirhombs, a feature previously used as diagnostic for the class Rhombifera.Bockia?elpasoensisn. sp. is a new eocrinoid based on one poorly preserved specimen that has a small ellipsoidal theca and unbranched brachioles attached to a flat-topped spoutlike summit. It is the earliest known questionable representative of this genus and the only one that has been described from North America.Elpasocrinus radiatusn. gen. and sp. is an early cladid inadunate crinoid based on a single well-preserved calyx. It fits into a lineage of early cladids leading to the dendrocrinids and toCarabocrinus.Several additional separate plates, stem segments, and a holdfast of these and other echinoderms are also described.

Arenig (Lower Ordovician) conodonts and biozonation in the eastern Siljan district, central Sweden

1994 ◽  
Vol 68 (6) ◽  
pp. 1350-1368 ◽  
Author(s):  
Anita M. Löfgren
Keyword(s):  
North America ◽  
The Other ◽  
South Central ◽  
Lower Ordovician ◽  
Conodont Zone ◽  
Local Base ◽  
Reference Section ◽  
Zones And Subzones

Based on biostratigraphic investigations in the eastern Siljan district, central Sweden, and combined with earlier studies at Hunneberg, south-central Sweden, it is shown that the early post-Tremadoc-age Paroistodus proteus conodont Zone can be divided into four successive subzones. These are, in ascending order: the Drepanoistodus aff. D. amoenus Subzone; the Tripodus Subzone; the Paracordylodus gracilis Subzone; and the Oelandodus elongatus-Acodus deltatus deltatus Subzone. The lowermost of the subzones is a concurrent range zone, with its reference section at Storeklev, Hunneberg, and the other three interval zones with the reference section at Sjurberg in the eastern Siljan district. Correlations between these two areas, as well as with the Flåsjö area, Jämtland, the Finngrundet core, and some other areas, are discussed, and it is concluded that the Drepanoistodus aff. D. amoenus Subzone and the Tripodus Subzone together correspond to the Megistaspis (Ekeraspis) armata trilobite Zone, and occur below the Hunnegraptus copiosus graptolite Zone. The Paracordylodus gracilis Subzone is equivalent with the lower part of the Megistaspis (Varvaspis) planilimbata trilobite Zone, and may correspond to the Hunnegraptus copiosus Zone. The uppermost subzone, the Oelandodus elongatus-Acodus deltatus deltatus Subzone, equals the upper part of the M. (V.) planilimbata Zone, and the local base of the Tetragraptus phyllograptoides graptolite Zone is close to the base of this conodont subzone. The last occurrences of T. phyllograptoides are close to the top of this conodont subzone. Also included in the investigation are the uppermost part of the uppermost Tremadoc Paltodus deltifer Zone and the conodont zones overlying the P. proteus Zone in the eastern Siljan district, the Prioniodus elegans Zone and the Oepikodus evae Zone; the latter zone corresponds to the trilobite zones of Megalaspides (M.) dalecarlicus and Megistaspis (Varvaspis) estonica. A few samples from the superimposed Baltoniodus triangularis, B. navis, and Paroistodus originalis Zones have been investigated and are described as well. The correlation of these conodont zones and subzones with those of areas outside Baltoscandia, particularly North America, is also discussed.

Age et position des calcaires de Saint-Jean-de-la-Riviere dans le Cambrien des Moitiers d'Allonne (Manche)

1963 ◽  
Vol S7-V (5) ◽  
pp. 722-729
Author(s):  
Francis Dore
Keyword(s):  
Lower Cambrian ◽  
Early Precambrian ◽  
Red Sandstone ◽  
Type Section ◽  
Lower Ordovician ◽  
Sandy Shale ◽  
Sandstone Facies

Abstract The type section for the Saint-Jean-de-la-Riviere limestone outcrops on the Moitiers d'Allonne anticline in the Douits valley north of Carteret and east of Moitiers (France). The limestones are younger than the sandy shale of the Cap Carteret series and between Moitiers and Bosquet the sequence is overlain by shales and red sandstones separating it from the Armorican sandstones. The lower Cambrian of the area presents a complete sedimentary section ending with a red sandstone facies of a regressing sea. A significant hiatus is evident before lower Ordovician transgression and continued deposition. Hyolothides and sponges, believed to be Azoic (early Precambrian) and older than Archaeocyathidae and Bigotina, are found in calcareous sandstone nodules on the beach at Carteret.

Hexactinellid and associated sponges from the upper Reef Trail Member of the Bell Canyon Formation, southern Guadalupe Mountains National Park, Texas

2007 ◽  
Vol 81 (6) ◽  
pp. 1241-1256 ◽  
Author(s):  
J. Keith Rigby ◽  
Gorden L. Bell ◽  
Kirsten Thompson
Keyword(s):  
North America ◽  
National Park ◽  
Southwestern Part ◽  
Type Section ◽  
Different Types ◽  
Guadalupe Mountains National Park ◽  
Hexactinellid Sponges

A small faunule of silicified hexactinellid sponges and root tufts has been recovered from the upper Guadalupian Reef Trail Member of the Bell Canyon Formation, from the Patterson Hills, in the southwestern part of the Guadalupe Mountains National Park in western Texas. Some demosponges from the type section of the Reef Trail Member, near the mouth of McKittrick Canyon on the front of the Guadalupe Mountains in the park, have also been documented. Included in the faunule from the Patterson Hills localities are the new amphidiscosid hexactinellid pelicasponge Trailospongia reischi n. gen. and sp., the questionable pelicaspongiid Hexirregularia nana n. gen. and sp., and the dictyospongiid hexactinellids Microstaura doliolum Finks, 1960, and Microstaurella minima n. gen. and sp., and Microstaurella parva n. gen. and sp. They are associated with specimens of the lyssacinosid brachiosponges Toomeyospongiella gigantia Rigby and Bell, 2005, Toomeyospongia modica n. sp., and Toomeyospongia minuta n. gen. and sp., and fragments of three different types of root tufts, termed Tufts 1, 3, and 4. Two specimens of the new cylindrical demosponge Mckittrickella pratti n. gen. and sp. are associated with Tuft 2 in the collection from the type section of the Reef Trail Member, and a third specimen was collected from the member in the Patterson Hills. These sponges from Localities 1-7 are the youngest Permian sponges known from the region, and possibly from North America.

Deciphering the geology of some Darriwilian–Sandbian (Ordovician) ‘ghost’ formations in the UK and North America using olistoliths in marine debris flows

2017 ◽  
Vol 155 (7) ◽  
pp. 1507-1522 ◽  
Author(s):  
STIG M. BERGSTRÖM ◽  
ANNALISA FERRETTI
Keyword(s):  
North America ◽  
Marine Debris ◽  
Carbonate Sediments ◽  
Ouachita Mountains ◽  
Depositional History ◽  
West Texas ◽  
History Of ◽  
Conodont Fauna ◽  
The Uk ◽  
Nw Europe

AbstractOlistostromes with calcareous olistoliths are rare components in the Ordovician successions in NW Europe and North America, having been described from only a small number of localities. One of the best exposed, but least known, is in the Garn Formation in coastal outcrops in Anglesey in northwestern Wales. Here, in the graptolite-bearing shales of the Garn Formation, there are numerous limestone olistoliths that are derived from an otherwise unknown ‘ghost’ formation whose original depositional site remains an enigma. These olistoliths contain a Baltoscandian type of conodont fauna that is otherwise unknown in Wales and England. It represents the Baltoniodus variabilis Subzone of the Amorphognathus tvaerensis Zone. Similar, but slightly older, conodont faunas are recorded from olistoliths in the Tweeddale Member of the Shinnel Formation in southern Scotland and in probable olistoliths of the Cobbs Arm Limestone in northeasternmost Newfoundland. Approximately coeval conodont faunas are present in calcareous olistoliths in the Woods Hollow Shale of West Texas and the Womble Shale in the Ouachita Mountains of Arkansas, USA. Lithological and conodont evidence indicates that the calcareous olistoliths were derived from carbonate sediments deposited in relatively shallow water. It is concluded that the study of ‘ghost’ formation olistoliths may provide otherwise unavailable but important data bearing on the marine depositional history of a particular region.

REFERENCE SECTION FOR THE MAJEAU LAKE FORMATION

1967 ◽  
Vol 4 (5) ◽  
pp. 873-876
Author(s):  
C. A. Pollock
Keyword(s):  
Type Section ◽  
Lake Formation ◽  
Standard Section ◽  
Conodont Fauna ◽  
Northeastern Alberta ◽  
Reference Section

A cored section in the Imperial Westlock No. 14–24 well (Lsd. 14, Sec.24, Tp.59, Rge.26, W.4th Meridian) in northeastern Alberta is proposed as a type reference section for the Majeau Lake Formation, and it is proposed that Texaco McColl Majeau No. 1 (Lsd. 12, Sec. 1, Tp. 57, Rge. 3, W. 5th Meridian) be formally adopted as the type section well. The formation is 216 ft thick in the reference well. The conodont fauna suggests that the Majeau Lake Formation lies within the middle Polygnathus asymmetrica (to Iα) Zone of the German Devonian standard section.

Conodonts from the Upper Olentangy Shale (Upper Devonian, central Ohio) and stratigraphy across the Frasnian-Famennian Boundary

2000 ◽  
Vol 74 (1) ◽  
pp. 101-112
Author(s):  
D. Jeffrey Over ◽  
Meredith K. Rhodes
Keyword(s):  
Middle Devonian ◽  
Appalachian Basin ◽  
Upper Devonian ◽  
Distal Margin ◽  
Type Section ◽  
Conodont Fauna

The Upper Olentangy Shale of Ohio, a green pyritic shale interbedded with thin dark gray shale beds, disconformably overlies the lithologically similar Middle Devonian Lower Olentangy Shale. The muds were deposited in a quiet offshore environment on the distal margin of the Appalachian Basin during the Late Frasnian through Early Famennian. The Upper Olentangy Shale contains abundant and diverse conodonts of MN Zone 13 and the Middle triangularis Zone. The Frasnian-Famennian boundary is 4-8 cm below the base of the Huron Shale at the Olentangy Shale type section in Delaware, Ohio. The boundary interval is a green shale containing a mixed highest Frasnian (e.g., Palmatolepis bogartensis, P. linguiformis) and lowest Famennian (e.g., P. delicatula, P. subperlobata, P. triangularis) conodont fauna. An ash horizon, pyritic bed, finely laminated dark shale, and a thin green-blue shale comprise the upper 3 cm of the Olentangy, and contain a conodont fauna indicative of the Middle triangularis Zone.

Conodonts from a platform-to-basin transect, lower Ordovician to lower Silurian, northeastern British Columbia, Canada

2003 ◽  
Vol 77 (1) ◽  
pp. 146-171 ◽  
Author(s):  
Leanne J. Pyle ◽  
Christopher R. Barnes
Keyword(s):  
British Columbia ◽  
New Species ◽  
New Genus ◽  
Early Ordovician ◽  
The Road ◽  
Lower Silurian ◽  
Lower Ordovician ◽  
Conodont Fauna

The conodont fauna from nine sections across a platform-to-basin transect in northeastern British Columbia includes species of Early Ordovician (Tremadocian) to Early Silurian (Llandovery) age. A collection of 9,110 conodont elements was recovered from 205 samples taken from nine stratigraphic sections that preserve the platform succession of the Kechika, Skoki, Beaverfoot, McCusker and Nonda Formations and their off-shelf equivalents, the Ospika, Robb, Kenny and Laurier Formations of the Road River Group. The fauna is assigned to 106 species representing 67 genera; the Ordovician species are representative of two faunal realms. One new genus, left in open nomenclature, is described. Five new species include Drepanoistodus latus and four new species left in open nomenclature assigned to the following genera: Walliserodus, Multioistodus?, Pseudooneotodus, and Belodina. The Midcontinent Realm zones recognized include, in ascending order, the Acodus kechikaensis, Oepikodus communis, Jumudontus gananda, Tripodus laevis to Plectodina aculeata zones, Phragmodus undatus and Gamachignathus ensifer? zones. Zonal species of the Atlantic Realm are Microzarkodina flabellum, Eoplacognathus suecicus, Baltoniodus variabilis, Pygodus anserinus, and Amorphognathus tvaerensis. The Silurian fauna, of lower diversity than the Ordovician fauna, is representative of the Distomodus staurognathoides and Pterospathodus amorphognathoides zones.

A Sagitta Zone Conodont Fauna from the Wenlockian of the Usk Inlier, Monmouthshire

1967 ◽  
Vol 104 (3) ◽  
pp. 274-283 ◽  
Author(s):  
R. L. Austin ◽  
M. G. Bassett
Keyword(s):  
North America ◽  
Conodont Zone ◽  
Conodont Fauna

AbstractA conodont fauna from a thin limestone bed, considered to be of Wenlockian age, in the Usk inlier, Monmouthshire, is described. Ninety-seven specimens are assigned to four genera and eight species. The fauna is referable to the sagitta conodont zone and suggested correlations are made with the upper part of the Ostra-coden-Kalkes in Germany, with part of the Aulacopleura Schichten and Kok-Kalk in Austria, and with part of the Lockport Dolomite and Rochester Shale in North America.

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