scholarly journals Chemical composition, stratigraphy, and depositional environments of the Black River Group (Middle Ordovician), southwestern Ohio

1981 ◽  
Vol 92 (9) ◽  
pp. 629
Author(s):  
DAVID A. STITH
Keyword(s):  
Chemical Composition ◽  
Depositional Environments ◽  
Middle Ordovician ◽  
Black River Group

Middle Ordovician Fish-bearing Beds from the St. Lawrence Lowlands of Quebec

1973 ◽  
Vol 10 (6) ◽  
pp. 954-960 ◽  
Author(s):  
Leslie S. Eliuk
Keyword(s):  
Lower Portion ◽  
Quebec City ◽  
Marine Environments ◽  
European Standard ◽  
Shallow Marine ◽  
Vertebrate Fauna ◽  
Middle Ordovician ◽  
Fish Remains ◽  
Black River Group

Ostracoderm tubercles were recovered from the lower portion of two Black River Group sections between Montreal and Quebec City. Some of these fish remains seem identical to tubercles of Astraspis desiderata from the Harding Sandstone of Colorado. The age of the Quebec remains is questionably earliest Blackriveran or basal Caradocian of the European standard. The remains were found in sandy carbonates probably laid down in the supratidal to shallow marine environments. It is concluded that these remains may represent part of a continent-wide, biostratigraphically useful vertebrate fauna and that bulk sampling and acid residuing might be a technique whereby sparse, fragmentary, earliest Paleozoic fish remains could be found.

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.

Regional microfabric analysis and insoluble residues of Black River Group (Middle Ordovician) in southern Ontario

1970 ◽  
Vol 7 (6) ◽  
pp. 1437-1448 ◽  
Author(s):  
K. K. Mukherji ◽  
C. G. Winder
Keyword(s):  
Rock Mass ◽  
Source Area ◽  
Mineral Species ◽  
Southern Ontario ◽  
Middle Ordovician ◽  
The North ◽  
Longshore Currents ◽  
Wide Range ◽  
Shallow Basin ◽  
Black River Group

Carbonates of the Middle Ordovician Black River Group across the outcrop in southern Ontario have a fabric of elongate particles trending consistently in NW–SE and NE–SW directions. The origin of the fabric is considered primarily resulting from longshore currents in a shallow basin influenced by tidal activity. Insoluble residues constitute a small portion of the rock mass, but contain a wide range of mineral species. Although their distribution is sporadic, suites of minerals east and west of Marmora contain distinctive species. Generally, the detrital minerals seem to reflect the Precambrian source area to the north of the Paleozoic outcrop. A higher concentration of anhydrite to the east is interpreted as indicative of an area of more restricted marine conditions.

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
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