New recumbent echinoderm genera from the Bois d'Arc Formation: Lower Devonian (Lochkovian) of Coal County, Oklahoma

2007 ◽  
Vol 81 (6) ◽  
pp. 1486-1493 ◽  
Author(s):  
Ronald L. Parsley ◽  
Colin D. Sumrall
Keyword(s):  
Great Britain ◽  
West Virginia ◽  
North American ◽  
Lower Devonian ◽  
Late Ordovician ◽  
Upper Ordovician ◽  
Early Devonian ◽  
Middle Ordovician

An echinoderm fauna from the Lower Devonian (Lochkovian) Cravatt Member of the Bois d'Arc Formation near Clarita, Oklahoma, has yielded specimens of recumbent, essentially bilaterally symmetrical taxa which are similar to Ordovician genera but absent or sparsely represented in Silurian strata. Claritacarpus smithi n. gen. and sp., is a dendrocystitid homoiostele with morphology similar to the Late Ordovician Dendrocystoides Jaekel, 1918; the anomalocystitid stylophoran Victoriacystis aff. holmesorum Ruta and Jell, 1999 shows strong affinities to Victoriacystis holmesorum Ruta and Jell, 1999, Humevale Formation, of Victoria, Australia; and the pleurocystitid rhombiferan, Turgidacystis graffhami n. gen. and sp., has close affinities to the Middle Ordovician Coopericystis Parsley, 1970 of West Virginia and Henicocystis Jell, 1983 of Victoria, Australia. Claritacarpus and Turgidacystis are North American range extensions for homoiosteles and pleurocystitids, respectively, being previously unknown from rocks younger than Upper Ordovician. Globally, Silurian homoiosteles and pleurocystitids are unknown although both occur in the Lower Devonian of Germany and Australia; additionally, Early Devonian pleurocystitids are known from Great Britain and Bohemia. These genera illustrate a pseudoextinction pattern suggesting a significant unsampled Silurian “homalozoan” and pleurocystitid history.

scholarly journals Upper Ordovician graptolites from the Cape Phillips Formation, Canadian Arctic Islands

1987 ◽  
Vol 35 ◽  
pp. 191-202
Author(s):  
M. J. Melchin
Keyword(s):  
Great Britain ◽  
Shallow Water ◽  
Depositional Environment ◽  
Canadian Arctic ◽  
Late Ordovician ◽  
Outer Shelf ◽  
Upper Ordovician ◽  
The World ◽  
Cape Phillips Formation ◽  
Varying Length

Ashgill age graptolites have been collected from seven sections of the Cape Phillips Formation across most of its outcrop belt. The earliest graptolite zone recognisable is that of Orthograptus fastigatus. It is correla­ted with the Dicellograptus ornatus · Zone of the northern Canadian Cordilllera and the Dicellograptus complexus Subzone of the Dicel/ograptus anceps Zone of Great Britain although no dicellograptids have been found at any of the present sections. The overlying zone is that of Paraorthograptus pacificus, an ea­sily recognisable zone around much of the world. Graptolites of the C/imacograptus extraordinarius and Glyptograptus persculptus zones appear to be en­tirely absent from this formation. This is attributed to the Late Ordovician glaciation which has induced regression and submarine erosion in many areas worldwide. The earliest recognisable Silurian zone varies from section to section due to buried or barren intervals and/or hiatuses of varying length. The Parakidograptus acuminatus Zone has been recognised at only one section. At the others, the Atavograptus atavus, the Lagarograptus acinaces-Coronograptus gregarius, the Monograptus convolutus or the Monograptus spiralis Zone (s.1.) are the earliest recognisable Silurian fau­nas. Relatively low fauna! diversities in the Ashgill and lowest Llandovery portion of the section and the to­tal lack of dicellograptids are interpreted to be due to relatively shallow water, outer shelf or carbonate ramp depositional environment.

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.

Biostratigraphy and paleobiogeography of Middle and Late Ordovician conodonts from the Langkawi Islands, northwestern peninsular Malaysia

2008 ◽  
Vol 82 (5) ◽  
pp. 957-973 ◽  
Author(s):  
Sachiko Agematsu ◽  
Katsuo Sashida ◽  
Amnan B. Ibrahim
Keyword(s):  
North Atlantic ◽  
Peninsular Malaysia ◽  
Late Ordovician ◽  
Upper Ordovician ◽  
Low Latitude ◽  
Cool Water ◽  
Middle Ordovician ◽  
Water Conditions ◽  
Unidentified Species ◽  
Assemblage Zone

The Middle and Upper Ordovician sequence of the Langkawi Islands, northwestern peninsular Malaysia, contains 20 species of conodonts belonging to 15 genera and four unidentified species, which are described and illustrated. The following four biostratigraphic zones are established for the study area: the Scolopodus striatus assemblage zone, the Periodon sp. A range zone, the Baltoniodus alobatus range zone, and the Hamarodus europaeus range zone, in ascending order. The Middle Ordovician fauna belongs to the low-latitude, warm-water Australian Province. Conodonts of the H. europaeus zone represent the HDS (Hamarodus europaeus-Dapsilodus mutatus-Scabbardella altipes) biofacies, which has been reported from the cool-water North Atlantic Faunal Region. The middle Arenigian limestones in the study area were deposited on a shallow-water shelf, whereas the late Arenigian to middle Darriwilian limestones formed in hemipelagic deeper-water conditions on an outer shelf or slope.

The location of the Iapetus Ocean suture in Newfoundland

1977 ◽  
Vol 14 (3) ◽  
pp. 488-495 ◽  
Author(s):  
W. S. McKerrow ◽  
L. R. M. Cocks
Keyword(s):  
Lower Devonian ◽  
New World ◽  
Late Ordovician ◽  
Calc Alkaline ◽  
The West ◽  
Early Devonian ◽  
Iapetus Ocean ◽  
Lower Palaeozoic ◽  
First Time ◽  
Avalon Peninsula

Brachiopod and trilobite faunal distributions indicate that the Iapetus Ocean was still wide enough to inhibit migration in the Middle and Late Ordovician. The presence of Silurian and Lower Devonian calc-alkaline rocks suggests that ocean crust was still being subducted long after the end of the Ordovician and that the Iapetus Ocean did not finally close in Newfoundland until the Acadian Orogeny. The Reach Fault divides successions containing different Lower Palaeozoic faunas; to the west, typical North American faunas occur in New World Island (Cobb's Arm Limestone), while to the east the rocks of the Gander region appear to have been attached to the Avalon Peninsula, with its European Lower Palaeozoic faunas, since the Early Ordovician. It is concluded that the Reach Fault marks the suture where the Iapetus Ocean closed at the end of the Early Devonian. This line probably extends across Newfoundland to the south of Buchans, and links up with the Cape Ray Fault in the southwest of the island. An Ordovician fauna from the Davidsville Group of the Gander area is illustrated for the first time; it is not clearly definitive of any faunal province.

scholarly journals Provenance and paleogeography of post-Middle Ordovician, pre-Devonian sedimentary basins on the Gander composite terrane, eastern and east-central Maine: implications for Silurian tectonics in the northern Appalachians

2017 ◽  
Vol 53 ◽  
pp. 063-085 ◽  
Author(s):  
Allan Ludman ◽  
John T. Hopeck ◽  
Henry N. Berry IV
Keyword(s):  
Sedimentary Basins ◽  
Late Ordovician ◽  
The West ◽  
East Central ◽  
Early Devonian ◽  
Middle Ordovician ◽  
Regional Correlation ◽  
Orogenic Wedge ◽  
Connecticut Valley ◽  
Seismic Reflection Profiles

Recent mapping in eastern and east-central Maine addresses long-standing regional correlation issues and permits reconstruction of post-Middle Ordovician, pre-Devonian paleogeography of sedimentary basins on the Ganderian composite terrane. Two major Late Ordovician-Silurian depocenters are recognized in eastern Maine and western New Brunswick separated by an emergent Miramichi terrane: the Fredericton trough to the southeast and a single basin comprising the Central Maine and Aroostook-Matapedia sequences to the northwest. This Central Maine/Aroostook-Matapedia (CMAM) basin received sediment from both the Miramichi highland to the east and highlands and islands to the west, including the pre-Late Ordovician Boundary Mountains, Munsungun-Pennington, and Weeksboro-Lunksoos terranes. Lithofacies in the Fredericton trough are truncated and telescoped by faulting along its flanks but suggest a similar basin that received sediment from highlands to the west (Miramichi) and east (St. Croix).Deposition ended in the Fredericton trough following burial and deformation in the Late Silurian, but continued in the CMAM basin until Early Devonian Acadian folding. A westward-migrating Acadian orogenic wedge provided a single eastern source of sediment for the composite CMAM basin after the Salinic/Early Acadian event, replacing the earlier, more local sources. The CMAM, Fredericton, and Connecticut Valley-Gaspé depocenters were active immediately following the Taconian orogeny and probably formed during extension related to post-Taconian plate adjustments. These basins thus predate Acadian foreland sedimentation.Structural analysis and seismic reflection profiles indicate a greater degree of post-depositional crustal shortening than previously interpreted. Late Acadian and post-Acadian strike-slip faulting on the Norumbega and Central Maine Boundary fault systems distorted basin geometries but did not disturb paleogeographic components drastically.

scholarly journals Primitive islandarc granitoids of the Schuchinskaya zone, the Polar Urals (SIMS U-Pb zircon dating)

2017 ◽  
pp. 22-32
Author(s):  
I. D. Sobolev ◽  
A. N. Shadrin ◽  
V. A. Rastorguev ◽  
D. A. Kozyreva
Keyword(s):  
Chemical Composition ◽  
Volcanic Rocks ◽  
Late Ordovician ◽  
Island Arc ◽  
Upper Ordovician ◽  
Early Devonian ◽  
Zircon Dating ◽  
Polar Urals ◽  
Devonian Age ◽  
The Polar Urals

In the Schuchinskaya Zone of the Polar Urals granitoids of the Rechnoy and Yalya-Pe paleovolcanoes have been studied. They were mapped as Khoimpeysky Complex of Silurian age. In addition, granitoids of the Nganotsky-1 and Nganotsky-2 plutons mapped as Yunyaginsky Complex of Early Devonian age have been investigated. It was found that based on the mineral and chemical composition the rocks of all plutons studied correspond to island arc I-type granitoids. U-Pb (SIMS) concordant ages of zircons from granitoids of the Rechnoy and Yalya-Pe paleovolcanoes, and of the Nganotsky-1 pluton are 456±6, 454±4 and 463±3 Ma, respectively, which implies the existence of an island arc in the Schuchinskaya Zone as early as the Middle-Late Ordovician. Establishing the age of granitoids allows to refer volcanic rocks cut by plutons to Syadayskaya Formation, and to clarify the upper stratigraphic limit of its sedimentation as Middle-Upper Ordovician.

Ordovician deformations in the Pyrenees: new insights into the significance of pre-Variscan (‘sardic’) tectonics

2010 ◽  
Vol 147 (5) ◽  
pp. 674-689 ◽  
Author(s):  
J. M. CASAS
Keyword(s):  
Large Volume ◽  
Volcanic Activity ◽  
Late Ordovician ◽  
Normal Faults ◽  
Upper Ordovician ◽  
Middle Ordovician ◽  
Early Ordovician ◽  
Gondwana Margin ◽  
Magmatic Event ◽  
European Variscides

AbstractTwo deformational events which developed prior to the Variscan structures can be characterized in the Palaeozoic rocks of the Pyrenees: a Middle (?) Ordovician folding event and a Late Ordovician fracture episode. The Middle (?) Ordovician folding event gives rise to NW–SE- to N–S-oriented, metric- to hectometric-sized folds, without cleavage formation or related metamorphism. These folds can account for the deformation and uplift of the pre-Upper Ordovician (Cambro-Ordovician) sequence and for the formation of the Upper Ordovician unconformity. Ordovician folds control the orientation of the Variscan main-folding-phase minor structures, fold axes and intersection lineation in the Cambro-Ordovician sediments. The Late Ordovician fracture episode gave rise to normal faults affecting the lower part of the Upper Ordovician series, the basal unconformity and the underlying Cambro-Ordovician metasediments. Displacement of some of these faults diminishes progressively upwards of the series and tapers off in the upper part of the Upper Ordovician rocks, indicating that the faults became inactive during Late Ordovician times before deposition of the Ashgillian metasediments. Normal faults can be linked to the Upper Ordovician volcanic activity, which has been extensively described in the Pyrenees. The aforementioned deformation episodes took place after the Early Ordovician magmatic event, which gave rise to a large volume of plutonic rocks in the Pyrenees as in other segments of the European Variscides. This Middle Ordovician contractional event separated two extensional events in the Pyrenees from Early Ordovician to Silurian times. This event prevents us from assuming the existence of a continuous extensional regime through Ordovician and Silurian times, and suggests a more complex evolution of this segment of the northern Gondwana margin during the Ordovician.

Biogeography of Ordovician sponges

1999 ◽  
Vol 73 (1) ◽  
pp. 26-37 ◽  
Author(s):  
Marcelo G. Carrera ◽  
J. Keith Rigby
Keyword(s):  
North American ◽  
New South ◽  
New South Wales ◽  
Late Ordovician ◽  
Published Data ◽  
Middle Ordovician ◽  
Biogeographic Patterns ◽  
Early Ordovician ◽  
South Wales ◽  
Argentine Precordillera

Sponges have an unrealized potential importance in biogeographic analysis. Biogeographic patterns determined from our analysis of all published data on distribution of Ordovician genera indicate Early Ordovician sponge faunas have relatively low diversity and are completely dominated by demosponges. Early Ordovician (Ibexian) faunas are characterized by the widespread co-occurrence ofArchaeoscyphiaand the problematicCalathium.This association is commonly found in biohermal structures. Middle Ordovician faunas show an increase in diversity, and two broad associations are differentiated: Appalachian faunas (including Southern China and the Argentine Precordillera) and Great Basin faunas.Late Ordovician faunas show important changes in diversity and provincialism. Hexactinellid and calcareous sponges became important and new demosponge families appeared. Four Mohawkian-Cincinnatian associations are recognized here, including: 1) Midcontinent faunas; 2) Baltic faunas; 3) New South Wales faunas; and 4) Western North American (California and Alaska) faunas. However, two separate biogeographic associations are differentiated based on faunal differences. These are a Pacific association (western North American and New South Wales) and an Atlantic association (Midcontinent Laurentia and Baltica).Distribution of sponge genera and migration patterns are utilized to consider paleogeographic dispositions of the different continental plates, climatic features, and oceanic currents. Such an analysis points to close paleogeographic affinities between the Argentine Precordillera and Laurentian Appalachian faunas. However, significant endemicity and the occurrence of extra-Laurentian genera suggest a relative isolation of the Precordillera terrane during the Late Ibexian-Whiterockian. The study also shows a faunal migration from the Appalachian region to South China during the Middle Ordovician and the migration of faunas from Baltica to Laurentia in the Late Ordovician. The occurrence of Laurentian migrants in New South Wales during the Late Ordovician could be related to inferred oceanic current circulation between these two areas, although other paleogeographic features may be involved.

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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