LITHOSTRATIGRAPHY AND DEPOSITIONAL ENVIRONMENTS OF THE ANCELL GROUP IN CENTRAL ILLINOIS: A MIDDLE ORDOVICIAN CARBONATE-SILICICLASTIC TRANSITION

1991 ◽  
pp. 309-351
Author(s):  
T. H. SHAW ◽  
B. C. SCHREIBER
Keyword(s):  
Depositional Environments ◽  
Middle Ordovician ◽  
Central Illinois

Middle Ordovician Echinoderms from Northern Illinois and Southern Wisconsin

1975 ◽  
Vol 49 (S7) ◽  
pp. 1-74 ◽  
Author(s):  
Dennis R. Kolata
Keyword(s):  
New Species ◽  
New Genus ◽  
Carbonate Sediments ◽  
North Central ◽  
Middle Ordovician ◽  
South Central ◽  
The Family ◽  
Central Illinois ◽  
First Time ◽  
One New Species

Echinoderms of the Middle Ordovician Platteville and lower Galena Groups of north-central Illinois and south-central Wisconsin are represented by at least seven classes including the Homoiostelea, Cystoidea, Crinoidea, Stelleroidea, Edrioasteroidea, Cyclocystoidea, Echinoidea, and possibly Holothuroidea. The most abundant and diverse echinoderms are monocyclic and dicyclic inadunate and camerate crinoids, of which the cupulocrinids and glyptocrinids are best represented. Thirteen new species and one new genus of crinoids are described:Cremacrinus guttenbergensis, Anulocrinus forrestonensis, Isotomocrinus minutus, Carabocrinus oogyi, Dendrocrinus? springeri, Merocrinus britonensis, Cupulocrinus plattevillensis, C. molanderi, Reteocrinus rocktonensis, R. spinosus, Traskocrinus mahlburgi(n. gen. et sp.),Rhaphanocrinus buckleyi, Glyptocrinus charltoni, andG. pustulosis.One new species of rhombiferan cystoid,Coronocystis durandensis, is also described. Echinoids of the family Bothriocidaridae (Bothriocidaris solemin. sp. andNeobothriocidaris templetonin. sp.) are reported for the first time from North America and appear to be the earliest recorded occurrence. Remains of a third bothriocidarid characterized by coalesced podial pores have also been discovered. Light and scanning electron microscopy of well preserved cyclocystoid specimens reveal a number of previously undescribed morphologic features of the central disc and submarginal ring that may shed some light on their functional morphology.Cupulocrinus gracilisRamsbottom from the Upper Drummuck Group Starfish Bed at Thraive Glen near Girvan, Scotland, is here reassigned toC. drummuckensisn. sp.Echinoderms are associated with an abundant and diverse fauna consisting largely of suspension feeders, primarily strophomenid and orthid brachiopods and trepostome and cryptostome bryozoans. Other common groups include corals, trilobites, sponges, and mollusks. Filamentous brown, foliose red and siphonaceous green algae are associated with the fauna at some localities.Carbonate rocks of both the limestone and dolostone facies of the Platteville (Briton, Walgreen and Forreston Members) and lower Galene Groups in the study area consist primarily of abundant shelly invertebrates occurring as whole and broken, unabraded, commonly articulated remains “floating” in a calcisiltite matrix that is highly bioturbated. Carbonate sediments appear to have been deposited in a near-to below wave base, highly stable, open marine environment characterized by low depositional slopes, good circulation and low terrigenous influx.

Trace fossils and depositional environments in the Hawaz Formation, Middle Ordovician, western Libya

2011 ◽  
Vol 60 (1-2) ◽  
pp. 28-37 ◽  
Author(s):  
Jordi M. de Gibert ◽  
Emilio Ramos ◽  
Mariano Marzo
Keyword(s):  
Trace Fossils ◽  
Depositional Environments ◽  
Middle Ordovician

Revision and correlation of late Middle Ordovician stratigraphy northeast of Quebec City

1979 ◽  
Vol 16 (7) ◽  
pp. 1467-1483 ◽  
Author(s):  
Edward S. Belt ◽  
John Riva ◽  
Louise Bussières
Keyword(s):  
Slight Modification ◽  
Depositional Environments ◽  
Quebec City ◽  
Submarine Fan ◽  
Marine Transgression ◽  
Steep Gradient ◽  
Utica Shale ◽  
Middle Ordovician ◽  
Submarine Fans ◽  
South West

Autochthonous late Middle Ordovician rock units between Neuville (near Quebec City) and La Malbaie (160 km to the northeast) have been revised lithologically and correlated by means of graptolites. The following rock units have either had a slight modification of their lithologic definition or have been found to extend into a region where they were not previously recognized: Cap-à-l'Aigle Formation, Saint-Irénée Formation, Utica Shale, and Lotbinière Formation. In addition, two new rock units have been named: Beaupré Formation and Moulin River facies (an informal term) of the Trenton Group.The depositional environments of each of the late Middle Ordovician rock units have been briefly identified (although the bulk of evidence is reserved for a later report). Thus, when the various facies are correlated, some important facts emerge about the southern margin of the Laurentian Platform and the rise of the Taconic Orogen to the southeast of Logan's Line. The Deschambault limestone and underlying Cap-à-l'Aigle sandstone were deposited during a marine transgression, after which a structural feature (Montmorency Promontory) developed in the Quebec City to Beaupré area. The promontory was asymmetrical, with a gentle gradient to the southwest, and a steep gradient and a basin to the northeast. Sedimentary thicknesses increased three- to fourfold in the basin northeast of the promontory, and the facies within the basin are markedly different from those over the promontory and southwest. Within the basin there developed deep-water limestone (Moulin River facies), and submarine-fan facies (Saint-Irénée Formation and 'new facies') with interfan microflysch (Lotbinière Formation). Trenton limestone facies on the promontory were deposited in a carbonate bank environment. No Utica Shale is found northeast of the Montmorency Promontory. In contrast, the 'typical' succession of Trenton–Utica–Lotbinière–Lorraine was developed in the region of the promontory and south-west in the St. Lawrence Lowland. An exception is the Beaupré submarine fan that developed over the promontory. All three submarine fans were shed by the rising Taconic Orogen which can be shown by graptolites and the presence of Mg-rich chromite to have been deeply eroded as early as ruedemanni zone time. No Lorraine Group facies are known from the area of our investigation.

scholarly journals Middle Ordovician Aparchitidae and Schmidtellidae: the significance of ‘featureless’ ostracods

1995 ◽  
Vol 14 (1) ◽  
pp. 7-24 ◽  
Author(s):  
Mark Williams ◽  
Jean M. C. Vannier
Keyword(s):  
North America ◽  
Depositional Environments ◽  
Common Element ◽  
Ventral Valve ◽  
Stratigraphic Correlation ◽  
Diagnostic Features ◽  
Middle Ordovician ◽  
Depositional Settings ◽  
Root Stock ◽  
Valve Overlap

Abstract. Schmidtellidae and Aparchitidae form a common element of North American middle Ordovician ostracod faunas. Characterized by relatively simple morphology with few obvious diagnostic features they are conventionally assigned to the Leiocopa. Their simple morphology has led to numerous species being referred to as ‘bag gencra’ such as Aparchites or Schmidtella. Aparchitids differ markedly from schmidtellids in the nature and degree of valve overlap, shell thickness and development of dorsal and ventral valve modifications. Schmidtellids may be more closely related to leperditellaceans. Kayina, previously assigned to the leiocope Family Jaanussoniidae and recorded from the middle Ordovician of North America, does not conform to leiocope morphology and is probably a leperditellacean. Aparchitaceans (Aparchitidae and Jaanussoniidae) may represent the root-stock from which the Paraparchitacea evolved later in the Palaeozoic. In North America schmidtellids and aparchitids have potential for middle Ordovician stratigraphic correlation. They co-occur in normal marine shelf depositional environments but were absent from marginal marine depositional settings.

Upper Middle Ordovician submarine fans and associated facies, northeast of Quebec City

1981 ◽  
Vol 18 (6) ◽  
pp. 981-994 ◽  
Author(s):  
Edward S. Belt ◽  
Louise Bussières
Keyword(s):  
Source Region ◽  
Depositional Environments ◽  
Turbidity Currents ◽  
Quebec City ◽  
Submarine Fan ◽  
Bottom Currents ◽  
Middle Ordovician ◽  
Submarine Fans ◽  
Facies Associations ◽  
Carbonate Bank

Autochthonous upper Middle Ordovician strata northwest of Logan's Line and northeast of Quebec City have been subdivided into six facies types. One or more facies type characterizes the revised formations of our previous report (Belt et al.). These facies were deposited in the following depositional environments: moderately shallow carbonate bank; deeper carbonate slope and foot of slope; submarine fan; and basin plain. The submarine fan facies (Beaupré and Saint-Irénée Formations) contain the only facies with appreciable sandstone. The source region of the sandstones (determined by petrography and paleocurrents) lay to the southeast of Logan's Line. This source was uplifted and eroded during the early phases of the Taconic Orogeny. Turbidity currents and debris flows brought sand into a foredeep trough that lay between the mobile Taconic Orogen and the more stable Canadian Shield. During Trenton time, a carbonate bank developed on the margin of the shield, northwest of the trough axis. Olistostromes, produced by bank-edge collapse, slid southeast into the trough and intercalated with the Saint-Irénée sandy fan lobes derived from the other side of the foredeep basin. Bottom currents, reworking the sand, flowed southwest along the axis of the trough. Later, after regional foundering of the carbonate bank, a larger (Beaupré Formation) submarine fan developed in the foredeep basin. Bottom currents continued reworking the sands down the trough to the southwest.The submarine fans found in this region never developed some of the facies associations commonly expected of suprafan lobes. The initial fan facies consists of lenticular coarse and pebbly sandstone and shale that are only rarely organized into coarsening-up successions. No definite feeder channel deposits are found in the Saint-Irénée Formation although three are recognized in the middle Beaupré Formation at the type section. The presence of these channels plus the geometry of all Beaupré facies and the paleocurrent divergence show that these facies are not disorganized base-of-slope or basin-plain deposits, but best fit a submarine fan model.

Diversity and paleobiogeographic distribution patterns of early and Middle Ordovician graptolites in distinct depositional environments of South China

2010 ◽  
Vol 53 (12) ◽  
pp. 1811-1827 ◽  
Author(s):  
YuanDong Zhang ◽  
Xu Chen ◽  
Goldman Dan ◽  
Ju Zhang ◽  
JunFeng Cheng ◽  
...  
Keyword(s):  
South China ◽  
Distribution Patterns ◽  
Depositional Environments ◽  
Middle Ordovician

scholarly journals The development of Early Paleozoic shell concentrations: evidence from the Cambrian and Ordovician of the Great Basin

1992 ◽  
Vol 6 ◽  
pp. 183-183 ◽  
Author(s):  
Xing Li ◽  
Mary Droser
Keyword(s):  
Great Basin ◽  
Critical Time ◽  
Depositional Environments ◽  
Early Cambrian ◽  
Early Paleozoic ◽  
Lower Paleozoic ◽  
Middle Ordovician ◽  
Physical Scale ◽  
Shell Beds ◽  
Shell Concentrations

Shell concentrations have constituted an important and conspicuous part of the stratigraphic record since the Early Cambrian. The paleontological and stratigraphic significance of shell beds is well understood, primarily from Mesozoic and Cenozoic examples. Lower Paleozoic fossil concentrations, however, have not received much attention. The Cambrian and Ordovician evolutionary radiations were two of the most significant events in the history of life and established the Cambrian and Paleozoic faunas respectively. In order to determine the effect of these radiations on the development of fossil accumulations, a systematic study of early Paleozoic shell beds was conducted in the Great Basin areas of California, Nevada, and Utah.In order to minimize taphonomic variations in original chemical and physical conditions, shell beds were compared from strata deposited in similar depositional environments from similar tectonic settings. Preliminary analysis of the shell beds from relatively pure carbonate facies and mixed carbonate and siliciclastic facies shows: 1) that shell concentrations became a significant stratigraphic feature in the later Early Cambrian; 2) the thickness and lateral extent of the shell beds increase from Early Cambrian to Middle Ordovician; 3) the abundance and internal complexity of the shell beds increase from Early Cambrian to Middle Ordovician; and 4) the Cambrian and Early Ordovician shell beds are primarily, if not exclusively, dominated by trilobites whereas the Middle Ordovician shell beds are dominated by brachiopods and ostracodes.These data show a temporal trend in the development of the early Paleozoic shell beds. The nature of the Cambrian and Ordovician shell beds differs qualitatively and quantitatively. There is an increase in physical scale, abundance, and internal complexity through time. The thickness and abundance of the trilobite beds increase through the Cambrian. Interestingly, although trilobites were still diverse and abundant, they did not commonly generate thick trilobite beds after the Late Cambrian. The early Middle Ordovician is a critical time in the development of early Paleozoic shell beds. A variety of monotaxic and polytaxic shell beds, including 6m thick composite beds, first appeared at this time. While the brachiopods and ostracodes generate laterally extensive, commonly monotaxic, shell beds, the gastropods and bryozoans only formed lenticular concentrations.

Sign in / Sign up

Export Citation Format

Share Document