Sedimentology of Upper Ordovician – Silurian sequences on New World Island, Newfoundland: separate fault-controlled basins?

1983 ◽  
Vol 20 (3) ◽  
pp. 345-354 ◽  
Author(s):  
R. J. Arnott
Keyword(s):  
Debris Flow ◽  
Black Shale ◽  
New World ◽  
Upper Ordovician ◽  
Sedimentary Sequences ◽  
Narrow Belt ◽  
Two Stages ◽  
Fault Scarps

Remapping of northeast New World Island, Newfoundland demonstrates that two major faults separate three distinct sedimentary sequences, Paleontology and sedimentology indicate that these sequences are partly equivalent in age but were deposited in separate basins of deposition that were adjacent to each other. Active Silurian faults, the Boyds Island and Byrne Cove Faults (new names), bounded the margins of these basins and directly influenced sedimentation by uplifting Ordovician volcanics, limestone, and black shale, which are found both in situ and as blocks within Silurian sediments. Silurian sediments deposited adjacent to these faults are dominated by pebbly mudstones and chaotic bedding interpreted as debris flow deposits and slumped horizons. Away from the fault scarps sedimentation was predominantly axial; it comprises resedimented conglomerates and thick- and thin-bedded sandstone turbidites.West of New World Island, similar synsedimentary faults are confined to a narrow belt south of the Lukes Arm – Sops Head Fault. Two stages of Acadian deformation overprint all structures associated with the Silurian faulting.

Stratigraphy and graptolites of the Upper Ordovician Point Leamington Formation, central Newfoundland

1991 ◽  
Vol 28 (4) ◽  
pp. 581-600 ◽  
Author(s):  
S. Henry Williams
Keyword(s):  
Debris Flow ◽  
Black Shale ◽  
Strong Relationship ◽  
Late Ordovician ◽  
Black Shales ◽  
Upper Ordovician ◽  
Several Intervals

The Point Leamington Formation, as redefined herein, comprises a thick sequence of siliciclastic turbidites containing occasional Upper Ordovician graptolites and lies with the Exploits Subzone of the Dunnage Zone in central Newfoundland. The base of the unit is marked by the first coarse- to medium-grained sandstone, at a level that varies from the Dicranograptus clingani Zone to the Pleurograptus linearis Zone. Several intervals of interbedded black shales and siltstones higher in the formation yield assemblages characteristic of the P. linearis, Dicellograptus complanatus and Dicellograptus anceps zones. Debris-flow breccias occur at several levels within the Point Leamington Formation—some contain graptolitic, black shale clasts derived from the underlying Lawrence Harbour Formation—and range in age from Nemagraptus gracilis Zone to D. clingani Zone. Both the graptolite assemblages and lithostratigraphic succession of the Point Leamington Formation are similar to those of coeval rocks in southern Scotland, confirming a strong relationship between the two areas during the Late Ordovician.

Stratigraphy of eastern Bay of Exploits, Newfoundland

1981 ◽  
Vol 18 (4) ◽  
pp. 751-764 ◽  
Author(s):  
W. S. McKerrow ◽  
L. R. M. Cocks
Keyword(s):  
Debris Flow ◽  
New World ◽  
Upper Ordovician ◽  
Island Formation ◽  
Early Ordovician ◽  
New Name ◽  
Field Evidence ◽  
Continuous Sedimentation ◽  
Stratigraphic Sequences

Fossils from the Fanners Island Formation (new name) show that, southwest of New World Island, Newfoundland, a thick (over 3 km) sequence of late Llandeilo turbidites and basalts overlies the Dunnage mélange. These are overlain by a thicker (6 km) sequence of turbidites, conglomerates, and associated olistostromes assigned to the Sansom Formation. The recognition of olistostromes in the Upper Ordovician (Caradoc and Ashgill) Sansom Formation (some of which contain olistoliths with early Ordovician fossils) eliminates the necessity of postulating repeated stratigraphic sequences by major faults. The field evidence indicates that the olistoliths slipped into a basin with more or less continuous sedimentation of turbidites and debris-flow conglomerates. Major faults separate distinct sequences of turbidites and olistostromes, suggesting that some of the faulting may have been contemporaneous with sedimentation.

In-Situ Study of Ti/TiN Stability under Nitrogen Anneal

1999 ◽  
Vol 564 ◽  
Author(s):  
P. W. DeHaven ◽  
K. P. Rodbell ◽  
L. Gignac
Keyword(s):  
Annealing Temperature ◽  
Time Range ◽  
Second Phase ◽  
Transformation Rate ◽  
Transformation Mechanism ◽  
Second Stage ◽  
Transmission Electron ◽  
Reaction Proceeds ◽  
Two Stages

AbstractThe effectiveness of a TiN capping layer to prevent the conversion of α-titantium to titanium nitride when annealed in a nitrogen ambient has been studied over the temperature range 300–700°C using in-situ high temperature diffraction and transmission electron microscopy. Over the time range of interest (four hours), no evidence of Ti reaction was observed at 300°C. At 450°C. nitrogen was found to diffuse into the Ti to form a Ti(N) solid solution. Above 500°C the titanium is transformed to a second phase: however this reaction follows two different kinetic paths, depending on the annealing temperature. Below 600°C. the reaction proceeds in two stages, with the first stage consisting of Ti(N) formation, and the second stage consisting of the conversion of the Ti(N) with a transformation mechanism characteristic of short range diffusion (grain edge nucleation). Above 600°C, a simple linear transformation rate is observed.

Suitability of Natural Geomedia for Radwaste Storage

1982 ◽  
Vol 15 ◽  
Author(s):  
W. S. Fyfe
Keyword(s):  
Rock Properties ◽  
Fracture Flow ◽  
Time Prediction ◽  
Sedimentary Sequences ◽  
Rock Types ◽  
Direct Observations ◽  
Long Time ◽  
Mining Disturbance ◽  
Selection Of

ABSTRACTSelection of the best rock types for radwaste disposal will depend on their having minimal permeability, maximal flow dispersion, minimal chance of forming new wide aperture fractures, maximal ion retention, and minimal thermal and mining disturbance. While no rock is perfect, thinly bedded complex sedimentary sequences may have good properties, either as repository rocks, or as cover to a repository.Long time prediction of such favorable properties of a rock at a given site may be best modelled from studies of in situ rock properties. Fracture flow, dispersion history, and geological stability can be derived from direct observations of rocks themselves, and can provide the parameters needed for convincing demonstration of repository security for appropriate times.

scholarly journals Composition of dental plaque formed in the presence of sucrose and after its interruption

2003 ◽  
Vol 14 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Jaime Aparecido Cury ◽  
Aline Soler Marques ◽  
Cíntia Pereira Machado Tabchoury ◽  
Altair Antoninha Del Bel Cury
Keyword(s):  
Crossover Study ◽  
Dental Plaque ◽  
Sucrose Solution ◽  
Inorganic Phosphorus ◽  
Deionized Water ◽  
The Other ◽  
Low Concentration ◽  
Human Enamel ◽  
Two Stages

Since dental plaque reservoirs of fluoride (F), calcium (Ca) and inorganic phosphorus (Pi) are susceptible to decreases in pH, this in situ crossover study was conducted to test the hypothesis that the low concentration of these ions in plaque, formed in the presence of sucrose, could be attributed merely to the fermentation of this sugar. Eleven volunteers wore palatal appliances containing 6 human enamel blocks during two stages. In each stage, the treatments were either 20% sucrose solution or distilled deionized water, which were dripped onto the blocks 8 times a day. After 28 days, in each stage, the dental plaque formed on two blocks was collected, the treatment was inverted and after a further 24 and 48 h, the biofilm formed was collected from the other blocks. The concentration of acid-soluble F, Ca and Pi, and the concentration of insoluble polysaccharide (IP) were determined in the dental plaque. Statistically lower concentrations of F, Ca and Pi, and a higher concentration of IP were found in the 28-day biofilm formed in the presence of sucrose than in its absence; after the treatment inversion the change in F, Ca and Pi was not statistically significant, but the IP concentration changed significantly. The hypothesis was rejected because change in concentration of F, Ca and Pi is not due to fermentation of the sucrose.

Ruminal degradation characteristics of corn and corn–sunflower intercropped silages prepared at two stages of maturity

1992 ◽  
Vol 72 (4) ◽  
pp. 881-889 ◽  
Author(s):  
Z. Mir ◽  
P. S. Mir ◽  
S. Bittman ◽  
L. J. Fisher
Keyword(s):  
Dry Matter ◽  
Degradation Rate ◽  
Soluble Fraction ◽  
Corn Silage ◽  
Neutral Detergent Fiber ◽  
Acid Detergent Fiber ◽  
Ruminal Degradation ◽  
Whole Plants ◽  
Two Stages

The degradation characteristics of dry matter (DM), protein, neutral detergent fiber (NDF) and acid detergent fiber (ADF) of corn–sunflower intercrop silage (CSS) and monoculture corn silage (CS) prepared from whole plants, harvested at two stages of maturity, were compared using eight mature rumen-cannulated steers. The degradation characteristics were determined by incubating the silages in nylon bags for up to 72 h in the rumen of animals fed the respective silages. The degradation characteristics determined for the silages were the soluble fraction, the insoluble but degradable fractions, the rate of degradation of the degradable fractions of silage DM and protein, and the in situ disappearance of NDF and ADF after 0.5 and 72 h of incubation. The rate of particulate passage from the rumen was determined using chromium-mordanted NDF of the four silages. Values were used to estimate effectively degraded DM and protein. The rates of DM and protein degradation were highest for late-cut CSS (6.3 and 6.0% h−1, respectively) and the least for late-cut CS (2.5 and 0.8% h−1, respectively). Averaged across stages of maturity, more (P < 0.05) DM and protein were effectively degraded with CSS (57.4 and 70.1%, respectively) than with CS (48.8 and 48.7%). Degradation of NDF in early-cut CSS was lower (P < 0.05) than in CS after 72 h of incubation. ADF disappearance from all of the silages after 72 h of incubation was similar. Ruminal degradation of DM and protein in CSS was greater than in CS, which may affect efficiency of utilization of CSS. Key words: Degradation rate, effective degradability, corn silage, intercropped corn–sunflower, steers

Influence of maturity stage on in situ dry matter degradability of six maize varieties in fistulated sheep

2001 ◽  
Vol 2001 ◽  
pp. 89-89
Author(s):  
M. A. Akbar ◽  
P. Lebzien ◽  
G. Flachowsky
Keyword(s):  
Dry Matter ◽  
Nutritive Value ◽  
Climatic Conditions ◽  
Maturity Stage ◽  
Factors Affecting ◽  
Maize Varieties ◽  
Feed Value ◽  
Two Stages

The fresh weight, dry matter (DM) contents and nutritional quality in maize vary considerably with variation in varieties, stages at which harvested, climatic conditions and agronomic factors. Recently, agronomists, nutritionists, and dairy producers have placed increased emphasis on factors affecting the nutritive value of maize. However, very little information is available on quantitative variability of the feed value of maize fodder as affected by such factors. This study was, therefore, carried out to assess the effect of harvesting of six different maize varieties at two stages (dates) of grain maturity on quality of both the stover and cobs.

scholarly journals Pressure- and Temperature-Induced Insertion of N2, O2 and CH4 to Ag-Natrolite

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4096
Author(s):  
Donghoon Seoung ◽  
Hyeonsu Kim ◽  
Pyosang Kim ◽  
Yongmoon Lee
Keyword(s):  
Unit Cell Volume ◽  
Molecular Size ◽  
Unit Cell ◽  
Volume Changes ◽  
Volume Increase ◽  
X Ray ◽  
Onset Pressure ◽  
Two Stages ◽  
Cell Volumes

This paper aimed to investigate the structural and chemical changes of Ag-natrolite (Ag16Al16Si24O80·16H2O, Ag-NAT) in the presence of different pressure transmitting mediums (PTMs), such as N2, O2 and CH4, up to ~8 GPa and 250 °C using in situ synchrotron X-ray powder diffraction and Rietveld refinement. Pressure-induced insertion occurs in two stages in the case of N2 and O2 runs, as opposed to the CH4 run. First changes of the unit cell volume in N2, O2 and CH4 runs are observed at 0.88(5) GPa, 1.05(5) GPa and 1.84(5) GPa with increase of 5.7(1)%, 5.5(1)% and 5.7(1)%, respectively. Subsequent volume changes of Ag-natrolite in the presence of N2 and O2 appear at 2.15(5) GPa and 5.24(5) GPa with a volume increase of 0.8(1)% and a decrease of 3.0(1)%, respectively. The bulk moduli of the Ag-NAT change from 42(1) to 49(7), from 38(1) to 227(1) and from 49(3) to 79(2) in the case of N2, O2 and CH4 runs, respectively, revealing that the Ag-NAT becomes more incompressible after each insertion of PTM molecules. The shape of the channel window of the Ag-NAT changes from elliptical to more circular after the uptake of N2, O2 and CH4. Overall, the experimental results of Ag-NAT from our previous data and this work establish that the onset pressure exponentially increases with the molecular size. The unit cell volumes of the expanded (or contracted) phases of the Ag-NAT have a linear relationship and limit to maximally expand and contract upon pressure-induced insertion.

scholarly journals Zircon age of vaugnerite intrusives from the Central and Southern Vosges crystalline massif (E France): contribution to the geodynamics of the European Variscan belt

2020 ◽  
Vol 191 ◽  
pp. 26
Author(s):  
François Guillot ◽  
Olivier Averbuch ◽  
Michel Dubois ◽  
Cyril Durand ◽  
Pierre Lanari ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Granite Gneiss ◽  
Upper Ordovician ◽  
Inductively Coupled ◽  
Sedimentary Sequences ◽  
Magmatic Rocks ◽  
Continental Block ◽  
Plasma Mass Spectrometry ◽  
Granite Complex ◽  
Subduction System

To provide a better picture of the active geodynamics along the Variscan suture zones during the late collisional stage (particularly regarding the evolution of the orogenic system towards HT conditions), we focused here on vaugnerites, which consist of mafic ultra-potassic magmatic rocks, intrusive into the granite-gneiss sequences of the Variscan Vosges crystalline massif. Those rocks, though subordinate in volume, are frequently associated with late-collisional granites. In the Central-Southern Vosges, they appear either as (1) pluton margin of the Southern Vosges Ballons granite complex or (2) composite dykes intrusive into migmatite and metamorphic sequences classically referred to as granite-gneiss unit (Central Vosges). Both types correspond to melanocratic rocks with prominent, Mg-rich, biotite and hornblende (20–40% vol., 64 < mg# < 78), two-feldspar and quartz. Those Vosges vaugnerites display geochemical signatures characteristic of ultra-potassic mafic to intermediate, metaluminous to slightly peraluminous rocks. Zircon U-Pb ages were obtained by Laser Ablation Inductively Coupled Plasma Mass Spectrometry. Zircon grains were extracted from a sillimanite-bearing gneiss from the granite-gneiss unit hosting the Central Vosges vaugnerites. They yielded an age at 451 ± 9 Ma, indicating a pre-Variscan Upper Ordovician protolith for the host sequence. Zircon from the four vaugnerite intrusives display U-Pb ages (± 2σ) of 340 ± 2.5 Ma (Ballons), 340 ± 25 Ma, 340 ± 7 Ma and 336 ± 10 Ma (Central Vosges). Synchronous within uncertainty, vaugnerite age data suggest a relatively early emplacement during the Late Variscan collisional history (i.e. Middle Visean times). These results are in line with previously published ages from the Southern Vosges volcano-sedimentary sequences (Oderen-Markstein) and the nearby ultra-potassic granite complexes from the Central and Southern Vosges (Ballons, Crêtes) thereby arguing for a magmatic event of regional significance. Recent petrological studies on vaugnerites suggest that they derive from partial melting of a metasomatized mantle contaminated to some different degrees by elements of continental crust. We propose here that the major ultra-potassic magmatic pulse at 340–335 Ma is a consequence of a significant change into the dynamics of the Rhenohercynian subduction system below the Central-Southern Vosges. In the light of recent thermo-mechanical modelling experiments on mature continental collision, magmatism could result from a syn-collisional lithospheric delamination mechanism involving (1) first, continental subduction evolving towards (2) the underthrusting of the Avalonian continental margin lower crust and (3) the initiation of lithospheric delamination within the supra-subduction retro-wedge (Saxothuringian-Moldanubian continental block). This delamination would drive the emplacement of an asthenospheric upwelling, initially localized along the Variscan suture zones, and gradually propagating towards the southern front of the belt during the Late Carboniferous, as the delamination front migrated at the base of the crust.

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