Stratigraphy and tectono-sedimentary evolution of the Late Ordovician to Middle Devonian Gaspé Belt in northern New Brunswick: evidence from the Restigouche area

2004 ◽  
Vol 41 (5) ◽  
pp. 527-551 ◽  
Author(s):  
Reginald A Wilson ◽  
Elliott T Burden ◽  
Rudolf Bertrand ◽  
Esther Asselin ◽  
Alexander D McCracken
Keyword(s):  
Volcanic Rocks ◽  
Extended Period ◽  
West Point ◽  
Upper Ordovician ◽  
Early Devonian ◽  
Lower Silurian ◽  
Sedimentary Evolution ◽  
Indian Point ◽  
High Level ◽  
Late Emsian

The Gaspé Belt in the Restigouche area comprises three successions separated by a Late Silurian (Salinic) disconformity and an Early Devonian angular unconformity. The lower, Upper Ordovician to Lower Silurian sequence consists of siliciclastic turbidites of the Boland Brook and Whites Brook formations (Grog Brook Group), overlain by calcareous turbidites of the Pabos and White Head formations (Matapédia Group), and slope and shelf deposits of the Upsalquitch and Limestone Point formations (lower Chaleurs Group). Above the Salinic disconformity, the upper Chaleurs Group and the Dalhousie Group record a transgressive–regressive cycle. The former comprises Pridolian carbonate rocks of the West Point Formation and overlying Pridolian to Lochkovian sedimentary rocks of the Indian Point Formation. The Chaleurs Group is conformably overlain by Lochkovian to early Emsian subaerial volcanic rocks of the Dalhousie Group (Val d'Amour Formation), which is unconformably overlain by alluvial–lacustrine deposits of the late Emsian Campbellton Formation. Acadian orogenesis began during the Emsian and is characterized by open to closed folding, heterogenous cleavage development, and reverse and strike-slip faults. The Salinic orogeny is manifested in extensional block faulting, within-plate volcanism, and uplift and deep erosion of Early Silurian strata. Early Devonian high-level intrusion of the Matapédia Group, White Head clasts in Indian Point conglomerate, and thermal maturation data all indicate an extended period of Late Silurian – Early Devonian uplift in parts of the Restigouche area. Thermal maturities of West Point and Indian Point strata are within the oil and condensate windows and suggest potential for hydrocarbons in the study area.

scholarly journals Geochemical features and formation conditions of Early-Devonian cherty-argillaceous shales and the underlying basalts in the Ishkildino section (eastern slope of the Southern Urals)

LITOSFERA ◽  
2019 ◽  
pp. 30-47
Author(s):  
A. M. Fazliakhmetov
Keyword(s):  
Volcanic Rocks ◽  
Southern Urals ◽  
Geochemical Data ◽  
Upper Ordovician ◽  
The Southern Urals ◽  
Geochemical Composition ◽  
Early Devonian ◽  
Ocean Ridges ◽  
Clay Shales ◽  
Conodont Zone

Research subject.The West Magnitogorsk zone of the Southern Urals in the vicinity of the Ishkildino village features a subaerially exposed basaltic sequence superposed by cherts and siliceous-clay shales. The basalts and the overlying shales are assumed to have formed during the Ordovician and Silurian (?)–Early Devonian (up to the conodont zone excavates inclusive) periods, respectively. The aim of this research was to reconstruct, using geochemical data, the conditions under which the rocks present in this geological location were formed.Materials and methods. Five samples of the basalts (XRD and ICP-MS methods), 27 samples of the siliceous-clay shales and 10 samples of the cherts (XRD and ICP-AES methods) were analyzed.Results.According to the ratio of SiO2, Na2O and K2O, the volcanic rocks from the lower part of the section are represented by basalts and trachybasalts. Their geochemical composition corresponds to the N-MORB and is established to be similar to that of the basalts in the Polyakovskaya formation (the Middle–Upper Ordovician). In terms of main elements, the shales under study consist of quartz and illite with a slight admixture of organic matter, goethite, quartzfeldspar fragments, etc. The degree of the sedimentary material weathering according to the CIA, CIW and ICV index values is shown to be moderate. The values of Strakhov’s and Boström’s moduli correspond to sediments without the admixture of underwater hydrothermal vent products. The values of Cr/Al, V/Al and Zr/Al correspond to those characteristic of deposits in deep-water zones remote from the coasts of passive and active continental margins, basalt islands and areas adjacent to mid-ocean ridges. For most samples, the values of Ni/Co, V/Cr, Mo/Mn are typical of deposits formed under oxidative conditions. However, several samples from the upper part of the section, which is comparable to the kitabicus and excavatus conodont zones, demonstrate the Ni/Co, V/Cr, and Mo/Mn values corresponding to deposits formed under reducing atmospheres. An assumption is made that the existence of these deposits can be associated with the Bazal Zlichov event.Conclusion.The investigated pre-Emsian shales have shown no signs of volcanic activity in the adjacent areas. The studied deposits are established to correspond to the central part of the Ural Paleoocean.

Petrology of Upper Ordovician – Lower Silurian rocks of the Antigonish Highlands, Nova Scotia

1987 ◽  
Vol 24 (4) ◽  
pp. 752-759 ◽  
Author(s):  
J. B. Murphy
Keyword(s):  
Nova Scotia ◽  
Late Stage ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Late Ordovician ◽  
Geological History ◽  
Upper Ordovician ◽  
Marine Transgression ◽  
Lower Silurian ◽  
Clastic Rocks

Upper Ordovician to Lower Silurian rocks in the Antigonish Highlands consist of interlayered basalts, rhyodacites, arkoses, and conglomerates overlain by a thick sequence of marine clastic rocks and minor rhyolites. The stratigraphy documents a marine transgression. The volcanic rocks were deposited in a within-plate, continental, extensional environment. The basalts display alkalic and tholeiitic affinities, and the rhyodacites were formed by anatexis of the crust. The origin of the younger rhyolites is not clear: they are compositionally distinct from the rhyodacites but may be related to them as late-stage differentiates. At present, it is not possible to evaluate whether the tectonic setting and magmatic affinities are regionally or locally controlled.The geological history is very similar to that of Lower Silurian rocks immediately north of the Antigonish Highlands at Arisaig. In the simplest sense, this indicates these areas may have been juxtaposed prior to the Late Ordovician and limits cumulative post-Silurian movement on the boundary (Hollow) fault to about 40 km.

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.

The Salinic Orogeny in northern New Brunswick: geochronological constraints and implications for Silurian stratigraphic nomenclature1This article is one of a series of papers published in this CJES Special Issue: In honour of Ward Neale on the theme of Appalachian and Grenvillian geology.

2012 ◽  
Vol 49 (1) ◽  
pp. 222-238 ◽  
Author(s):  
Reginald A. Wilson ◽  
Sandra L. Kamo
Keyword(s):  
New Brunswick ◽  
Point Group ◽  
Volcanic Rocks ◽  
Upper Ordovician ◽  
Lower Silurian ◽  
Higher Rank ◽  
Upper Silurian ◽  
Radioisotopic Dating ◽  
Geochronological Constraints ◽  
Back Arc

The Salinic Orogeny is defined to encompass tectonic interactions that affect all elements of Ganderia involved in the closure of the Tetagouche–Exploits back-arc basin between the Late Ordovician and Early Devonian. Hence, the D1 and D2 deformations in the Miramichi Highlands and Elmtree Inlier of northern New Brunswick are Salinic events, and onlap of Lower Silurian rocks onto exhumed parts of the Brunswick Subduction Complex represents the earliest (Salinic A) of three Silurian unconformities in the region. Upper Ordovician to Lower Silurian rocks of the Matapédia successor basin contain widespread evidence of Middle Silurian tectonism (e.g., disconformities, angular unconformities, and fold interference patterns) created by Devonian overprinting of Silurian folds lacking axial planar cleavage (Salinic B). Recent U–Pb radioisotopic dating of chemically abraded zircon from rhyolite just above the Salinic B unconformity has yielded an age of 422.3 ± 0.3 Ma; combined with late Early Silurian fossil ages just below the unconformity, this indicates a ca. 5 million year Middle Silurian hiatus. Finally, Upper Silurian (Ludfordian) rocks are locally disconformably overlain by polymictic conglomerates that form the base of the Devonian section (Salinic C). All Silurian rocks in northeastern New Brunswick have historically been included in the Chaleurs Group; however, unconformities and local stratigraphic variations (especially compared with the type locality) support the introduction of new higher rank names in New Brunswick. Hence, the Quinn Point Group is introduced to incorporate Lower Silurian rocks, the Petit Rocher Group to include Upper Silurian sedimentary rocks in the Nigadoo River Syncline, and the Dickie Cove Group for Upper Silurian volcanic rocks in the Charlo – Jacquet River area. Upper Silurian rocks west of Campbellton that are contiguous with the Chaleurs Group in Quebec, will remain part of the Chaleurs Group.

scholarly journals Difference Analysis of Organic Matter Enrichment Mechanisms in Upper Ordovician-Lower Silurian Shale from the Yangtze Region of Southern China and Its Geological Significance in Shale Gas Exploration

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Ming Wen ◽  
Zhenxue Jiang ◽  
Kun Zhang ◽  
Yan Song ◽  
Shu Jiang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Shale Gas ◽  
Southern China ◽  
Sedimentary Organic Matter ◽  
Gas Content ◽  
Silicon Isotope ◽  
Upper Ordovician ◽  
Lower Silurian ◽  
Excess Silicon ◽  
Lower Yangtze

The upper Ordovician-lower Silurian shale has always been the main target of marine shale gas exploration in southern China. However, the shale gas content varies greatly across different regions. The organic matter content is one of the most important factors in determining gas content; therefore, determining the enrichment mechanisms of organic matter is an important problem that needs to be solved urgently. In this paper, upper Ordovician-lower Silurian shale samples from the X-1 and Y-1 wells that are located in the southern Sichuan area of the upper Yangtze region and the northwestern Jiangxi area of the lower Yangtze region, respectively, are selected for analysis. Based on the core sample description, well logging data analysis, mineral and elemental composition analysis, silicon isotope analysis, and TOC (total organic carbon) content analysis, the upper Ordovician-lower Silurian shale is studied to quantitatively calculate its content of excess silicon. Subsequently, the results of elemental analysis and silicon isotope analysis are used to determine the origin of excess silicon. Finally, we used U/Th to determine the characteristics of the redox environment and the relationship between excess barium and TOC content to judge paleoproductivity and further studied the mechanism underlying sedimentary organic matter enrichment in the study area. The results show that the excess silicon from the upper Ordovician-lower Silurian shale in the upper Yangtze area is derived from biogenesis. The sedimentary water body is divided into an oxygen-rich upper water layer that has higher paleoproductivity and a strongly reducing lower water that is conducive to the preservation of sedimentary organic matter. Thus, for the upper Ordovician-lower Silurian shale in the upper Yangtze region, exploration should be conducted in the center of the blocks with high TOC contents and strongly reducing water body. However, the excess silicon in the upper Ordovician-lower Silurian shale of the lower Yangtze area originates from hydrothermal activity that can enhance the reducibility of the bottom water and carry nutrients from the crust to improve paleoproductivity and enrich sedimentary organic matter. Therefore, for the upper Ordovician-lower Silurian shale in the lower Yangtze region, exploration should be conducted in the blocks near the junction of the two plates where hydrothermal activity was active.

scholarly journals Quality of colostral passive immunity and pattern of serum protein fluctuation in newborn calves

2003 ◽  
Vol 60 (3) ◽  
pp. 453-456 ◽  
Author(s):  
Patricia Pauletti ◽  
Raul Machado Neto ◽  
Irineu Umberto Packer ◽  
Raul Dantas D'Arce ◽  
Rosana Bessi
Keyword(s):  
Total Protein ◽  
Statistical Design ◽  
Extended Period ◽  
Experimental Period ◽  
Passive Immunity ◽  
Serum Total Protein ◽  
Non Linear ◽  
Medium Level ◽  
Group 2 ◽  
High Level

Immunity acquired by newborn animals is known as passive immunity, and for ruminants, antibody acquisition depends on the ingestion and absorption of adequate amounts of immunoglobulins from colostrum. This study relates different initial levels of acquired passive protection and serum total protein (TP) and immunoglobulin G (IgG). Serum immunoglobulin concentration and total protein were evaluated for female Holstein calves in the first sixty days of life. Animals were separated into three groups according to their initial level of passive immunity: group 1- animals with a low level of passive immunity (below 20 mg mL-1); group 2- animals with a medium level (between 20 and 30 mg mL-1), and group 3- animals with a high level (above 30 mg mL-1). Serum total protein was determined through the biuret method and IgG was determined by radial immunodiffusion. Data were analyzed as a completely randomized, split-plot statistical design. Fluctuation of the variables along the experimental period was determined through non-linear regression by the DUD method (PROC NLIN - Non Linear SAS). Animals with low antibody acquisition started to produce antibodies earlier, reflecting a compensatory synthesis. On the other hand, animals having adequate levels exhibited an extended period of immunoglobulin catabolism and the beginning of the endogenous phase was delayed. Regardless initial levels, the fluctuations in IgG contents occurred around adequate physiological concentrations, ranging from 20 to 25 mg mL-1.

New Early Devonian pteraspidids (Agnatha, Heterostraci) from Death Valley National Monument, southeastern California

1996 ◽  
Vol 70 (1) ◽  
pp. 152-161 ◽  
Author(s):  
David K. Elliott ◽  
Robert R. Ilyes
Keyword(s):  
Estuarine Environment ◽  
Death Valley ◽  
Early Devonian ◽  
National Monument ◽  
Bearing Unit ◽  
Late Emsian

Two species and genera of pteraspidids (Agnatha, Heterostraci), Blieckaspis priscillae n. gen., and Panamintaspis snowi n. gen. and n. sp., together with two undetermined species, are described from the lower part of the Lippincott Member of the Lost Burro Formation, southeastern California. The sharing of similar faunal elements with the Early Devonian assemblages of the Sevy Dolomite and Water Canyon Formation of Utah and Nevada, respectively, together with stratigraphic constraints on the age of the Death Valley fauna, suggest that these assemblages are age equivalent and have a late Emsian (inversus–serotinus Zones) age. The vertebrate-bearing unit of the Lippincott Member is interpreted as a channel-fill deposit laid down in an estuarine environment with low or fluctuating salinity.

scholarly journals Effect of Hydrothermal Activity on Organic Matter Enrichment of Shale: A Case Study of the Upper Ordovician and the Lower Silurian in the Lower Yangtze, South China

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 495 ◽  
Author(s):  
Yizhou Huang ◽  
Zhenxue Jiang ◽  
Kun Zhang ◽  
Yan Song ◽  
Shu Jiang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Oxygen Isotope ◽  
Shale Gas ◽  
Organic Matter Content ◽  
Hydrothermal Activity ◽  
Late Ordovician ◽  
Sedimentary Organic Matter ◽  
Upper Ordovician ◽  
Lower Silurian ◽  
Activity Intensity

The effect of organic matter on hydrocarbon potential, storage space, and gas content of shale is well-known. Additionally, present-day content of sedimentary organic matter in shale is controlled by depositional and preservation processes. Therefore, a study of the enrichment mechanisms of sedimentary organic matter provides a scientific basis for the determination of favorable areas of shale gas. In this study the Upper Ordovician Xinkailing Fm. and the first member of the Lower Silurian Lishuwo Fm. were examined. Stratigraphic sequences were identified through conventional logs and elemental capture spectrum data. Oxygen isotope analysis was applied to recover paleotemperature of seawater in the study area. The excess silicon content was calculated and the origin of the silica was determined by the Fe-Al-Mn ternary plot. The enrichment mechanism of organic matter was analyzed by two aspects: redox conditions and paleoproductivity. As a result, the stratigraphic interval was divided into two 3rd-order sequences. Through oxygen isotope, the paleotemperature of seawater was 62.7–79.2 °C, providing evidence of the development of hydrothermal activity. Analysis of excess siliceous minerals identified two siliceous mineral origins: terrigenous and hydrothermal. It also revealed an upwards decreasing tendency in hydrothermal activity intensity. Strong hydrothermal activity during the Late Ordovician, recognized as TST1, formed a weak-oxidizing to poor-oxygen environment with high paleoproductivity, which promoted organic matter enrichment. During the Late Ordovician to the Early Silurian, identified as RST1, TST2, and RST2, weakening hydrothermal activity caused the decline of paleoproductivity and increased oxidation of bottom waters, leading to a relative decrease of organic matter content in the shale. Therefore, favorable areas of shale gas accumulation in the Upper Ordovician and Lower Silurian are determined stratigraphically as the TST1, with a high total organic carbonate content. Geographically, the hydrothermally-active area near the plate connection of the Yangtze and the Cathaysian is most favorable.

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