A Caradoc Failed-Rift within the Ordovician Marginal Basin of Wales

1988 ◽  
Vol 125 (3) ◽  
pp. 257-266 ◽  
Author(s):  
S. D. G. Campbell ◽  
M. F. Howells ◽  
M. Smith ◽  
A. J. Reedman
Keyword(s):  
Close Association ◽  
Basaltic Magma ◽  
Progressive Increase ◽  
Ocean Basin ◽  
Lithospheric Plate ◽  
Tectonic Structures ◽  
Extensional Stress ◽  
Lower Palaeozoic ◽  
Tectonic Framework ◽  
Volcanic Cycle

AbstractThe dolerite and basalt intrusions within the Lower Palaeozoic sequence of northwest Wales are largely restricted to the outcrop of Ordovician strata. Their distribution and close association with known volcano-tectonic structures were controlled by a tectonic framework of deep-seated fractures. In central and northern Snowdonia, volcanism during Caradoc times was related to the evolution of a fracture-controlled trough. An increase in the extensional stress across the trough with time is reflected in the progressive increase in basaltic magma movement during the volcanic cycle. The trough represents an attempted rift in the lithospheric plate, which failed to create an ocean basin and was subsequently aborted.

Crystallization of basaltic magma as recorded by variation of crystal-size in dikes

1949 ◽  
Vol 28 (205) ◽  
pp. 557-574 ◽  
Author(s):  
Helmut G. F. Winkler
Keyword(s):  
Grain Size ◽  
Quantitative Data ◽  
Crystal Size ◽  
Basaltic Magma ◽  
Size Variation ◽  
Progressive Increase ◽  
Lava Flows ◽  
The Individual

It is a familiar fact that in dikes, lava-flows, and sills the grain-size of the individual minerals normally varies according to the distance from the contacts. At or near the margins of the igneous body the grainsize is usually very much less than in the centre, and this phenomenon has been attributed to differences in the cooling-velocities at these spots. On the basis of measurements carried out by Queneau (8) the opinion seems to have been formed that the crystal-size always shows a progressive increase from the contacts towards the centre. This is not so, however, for as Lane (6) has shown, the crystal-size may increase to a maximum at a certain distance from the margin, and thereafter decrease again towards the centre of the intrusion. Apart from these investigations, carried out by Queneau and Lane, the only additioual quantitative data oil crystal-size variation known to the writer concerns a series of measurements made on an olivine-diabase by B. H. Dollen, under the direction of H. L. Alling.

Chemostratigraphic division of the Blake River Group, Rouyn–Noranda area, Abitibi, Quebec

1984 ◽  
Vol 21 (2) ◽  
pp. 220-231 ◽  
Author(s):  
Léopold Gélinas ◽  
Pierre Trudel ◽  
Claude Hubert
Keyword(s):  
Earth Element ◽  
Basaltic Magma ◽  
Volcanic Belt ◽  
Progressive Increase ◽  
Calc Alkaline ◽  
Significant Modification ◽  
Rhyolitic Magma ◽  
Tholeiitic Magma ◽  
Concentric Zone ◽  
Mafic Magmas

The effusive rocks of the Blake River Group in the Abitibi volcanic belt, Rouyn–Noranda region, belong to a bimodal sequence in which andesites and rhyolites clearly dominate. The identification of calc-alkaline and tholeiitic affinities is made upon examination of the major, trace, and rare earth element (REE) content. Thus, the andesites (58% normalized SiO2 value without volatiles) of the calc-alkaline units have average K (4800 ppm), Ba (160 ppm), and Rb (13 ppm) values that are greater than the average K (1800 ppm), Ba (130 ppm), and Rb (3 ppm) values for andésites (57% SiO2) that belong to associated tholeiitic units. Furthermore, tholeiitic andesites have distinctive average values of Ti (9600 ppm) and Y (40 ppm) that are higher than the average values of Ti (6700 ppm) and Y (25 ppm) of calc-alkaline andesites. An effective discrimination between the calc-alkaline and tholeiitic affinities is obtained using the Zr/Y and Ti/Zr ratios, which are, respectively, less than 4 and greater than 70 in andesites of the tholeiitic units.REE profiles of tholeiitic andesites are flat when compared with those of calc-alkaline andesites, which show an enrichment in light rare earths.The tholeiitic units of the Blake River Group are found in the proximity of the Porcupine-Destor and Larder Lake – Cadillac faults, the major faults of the region, and at the periphery of an ensemble of calc-alkaline units. Four of the five tholeiitic units are differentiated, showing an enrichment of iron passing from basalt to andesite. These units possess felsic variole-bearing flows, the result of an unmixing, which was probably responsible for the formation of minor associated quantities of porphyries and rhyolitic volcaniclastites.A progressive increase in the concentration of hygromagmatophile elements (REE, Zr, Nb) is observed in the tholeiitic units from the Pelletier unit beginning at the base and passing through the Trémoy, Destor, and Dufresnoy units, at the top of the Blake River Group. The calc-alkaline units are characterized by an alternation of rhyolitic complexes and calc-alkaline andesites. This cyclic repetition occurs without significant modification of the calc-alkaline andesite composition.It is proposed that the volcanism responsible for the formation of the Blake River Group was restricted to a concentric zone centring on a continental environment. Mafic magmas nourished the central reservoir where melting of the sialic crust took place. The rhyolitic magma occupying the upper part of this reservoir mixed with the basaltic magma, producing calc-alkaline andesites. Successive mantle melt products were also emplaced into subsidiary reservoirs peripheral to the central chamber. Injections of tholeiitic magma in the peripheral reservoirs underwent differentiation and unmixing during emplacement of a part of the magma at the surface.

Structural interpretations of the Southern Uplands Terrane

2000 ◽  
Vol 91 (3-4) ◽  
pp. 363-373 ◽  
Author(s):  
T. Bernard Anderson
Keyword(s):  
Accretionary Prism ◽  
Ocean Basin ◽  
Fault Reactivation ◽  
Geological History ◽  
Iapetus Ocean ◽  
Structural Fabric ◽  
History Of ◽  
Lateral Extent ◽  
Lower Palaeozoic ◽  
Prism Model

ABSTRACTBounded by sutures and demonstrating a unique geological history and structure, the Lower Palaeozoic rocks of the Southern Uplands–Down–Longford form a definitive Caledonian suspect terrane. The geological history of the final closure of Iapetus is encrypted in their structural fabric.Across the terrane, NW-younging turbidites predominate but graptolites invariably indicate the presence of younger sediments to the SSE. This fundamental Southern Upland paradox is soluble only by recognizing many strike-parallel faults, dividing the terrane into more than thirty tracts, each with its own variant of the stratigraphy and structure, and each having a lateral extent far in excess of what might be expected from the probable mechanical strength of the composing sediments. Structural interpretations of the terrane's unique tectonostratigraphic pattern are critically reviewed and the accretionary prism model, modified by strong sinistral transpression from the late Llandovery onward, is preferred. Transpression was apparently triggered when the converging continents of Laurentia and Avalonia made solid contact, so establishing a mechanically effective coupling of sialic crustal elements beneath and across the closing Iapetus ocean basin.The geometry of the terrane's internal structural fabric is analysed. Tentative area-balancing calculations indicate a crustal shortening from a basin width of at least 1,000 km to the current terrane width of 75 km. Continuing sinistral transpression was expressed in fault reactivation and the development of a major shear zone. Late Palaeozoic strike-parallel extension produced W-facing half-grabens and the associated rotation may account for the easterly plunge of most fold axes.

Immunocytochemical Localization of Amyloid Protein AA in the “Dense Fibrillar Inclusions” of the Reticuloendothelical Cells

1977 ◽  
Vol 35 ◽  
pp. 438-439
Author(s):  
T. Shirahama ◽  
M. Skinner ◽  
A.S. Cohen
Keyword(s):  
Amyloid Fibril ◽  
Close Association ◽  
Gel Filtration ◽  
Fibril Formation ◽  
Amyloid Protein ◽  
Electron Microscopic ◽  
Amyloid Deposits ◽  
Amyloid Fibril Formation ◽  
Electron Microscopic Technique ◽  
Lysosomal System

A1thought the mechanisms of amyloidogenesis have not been entirely clarified, proteolysis of the parent proteins may be one of the important steps in the amyloid fibril formation. Recently, we reported that "dense fibrillar inclusions" (DFI), which had the characteristics of lysosomes and contained organized fibrillar profiles as well, were observed in the reticuloendothelial cells in close association with the foci of new amyloid deposits. We considered the findings as evidence for the involvement of lysosomal system in amyloid fibril formation (l). In the present study, we attempted to determine the identity of the contents of the DFI by the use of antisera against the amyloid protein (AA) and an immuno-electron microscopic technique.Amyloidosis was induced in CBA/J mice by daily injections of casein (l). AA was isolated from amyloid-laden spleens by gel filtration and antibody to it was produced in rabbits (2). For immunocytochemistry, the unlabeled antibody enzyme method (3) was employed.

Linear Arrays of Helical Polyribosomes in Cells Exposed to Antitumor Drug Vincristine Sulfate

1969 ◽  
Vol 27 ◽  
pp. 358-359
Author(s):  
Awtar Krishan
Keyword(s):  
Close Association ◽  
Annulate Lamellae ◽  
Large Array ◽  
Vincristine Sulfate ◽  
Linear Arrays ◽  
Golgi Membranes ◽  
Related Drug ◽  
Drug Leads ◽  
Lethal Doses ◽  
Vinblastine Sulfate

Earle's L-929 fibroblasts treated with mitosis-arresting but sub-lethal doses of vinblastine sulfate (VLB) show hypertrophy of the granular endoplasmic reticulum and annulate lamellae. Exposure of the cells to heavier doses of vincristine sulfate (VCR), a VLB-related drug, leads to the accumulation of large amounts of helical polyribosomes, Golgi membranes and crystals in the cytoplasm. In many of these cells a large number of helical polyribosomes are arranged in prominent linear rows, some of which may be up to 5 micrometers in length. Figure 1 shows a large array of helical polyribosomes near a crystalline mass (CRS) in an Earle's L-929 fibroblast exposed to VCR (5ϒ/ml.) for 3 hours At a higher magnification, as seen in figure 2, the helical polyribosomes are seen arranged in parallel rows. In favorably cut sections, a prominent backbone like "stalk" of finely granular material, measuring approximately 300Å in width is seen in close association with the linear rows of helical polyribosomes.

SEM analysis of fish scale cross sections: A technique study

1992 ◽  
Vol 50 (1) ◽  
pp. 744-745
Author(s):  
M.E. Lee ◽  
A. Moller ◽  
P.S.O. Fouche ◽  
I.G Gaigher
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cross Sections ◽  
Soft Tissues ◽  
Close Association ◽  
Sem Analysis ◽  
Fish Scale ◽  
Fish Scales ◽  
Micro Structures ◽  
Scanning Electron

Scanning electron microscopy of fish scales has facilitated the application of micro-structures to systematics. Electron microscopy studies have added more information on the structure of the scale and the associated cells, many problems still remain unsolved, because of our incomplete knowledge of the process of calcification. One of the main purposes of these studies has been to study the histology, histochemistry, and ultrastructure of both calcified and decalcified scales, and associated cells, and to obtain more information on the mechanism of calcification in the scales. The study of a calcified scale with the electron microscope is complicated by the difficulty in sectioning this material because of the close association of very hard tissue with very soft tissues. Sections often shatter and blemishes are difficult to avoid. Therefore the aim of this study is firstly to develop techniques for the preparation of cross sections of fish scales for scanning electron microscopy and secondly the application of these techniques for the determination of the structures and calcification of fish scales.

PASTURE ESTABLISHMENT ON EAST COAST NORTH ISLAND HILL COUNTRY

1984 ◽  
pp. 216-218
Author(s):  
B.J. Arnst ◽  
O.L. Park
Keyword(s):  
White Clover ◽  
Carrying Capacity ◽  
Return On Investment ◽  
East Coast ◽  
Close Association ◽  
Development Programme ◽  
Low Fertility ◽  
Stock Management ◽  
Hill Country

Large areas of North Island hill country are producing below potential as a result of low fertility and poor pasture composition. Removal of undesirable species and replacement with a higher producing pasture is essential for increased productivity but is difficult to achieve. A development programme is described where the use of glyphosate in close association with oversowing and stock management has allowed rapid pasture establishment, marked increase in carrying capacity and a quick return on investment. Keywords: Pasture establishment, glyphosate, oversowing, white clover, subdivision, productivity.

Korea's Confucian Culture of Learning as a Gateway to Christianity: Protestant Missions in the Late Nineteenth and Early Twentieth Centuries

2016 ◽  
Vol 22 (1) ◽  
pp. 37-56
Author(s):  
K. Kale Yu
Keyword(s):  
Close Association ◽  
Cultural Value ◽  
Late Nineteenth Century ◽  
Confucian Culture ◽  
Korean Society ◽  
Culture Of Learning ◽  
The Bible ◽  
Christian Literature ◽  
Late Nineteenth ◽  
Protestant Missions

As Protestant missionaries landed on Korean shores in the late nineteenth century, a great deal of effort went into creating a Christian identity using literacy and literature as cornerstones of missional strategy that would become the benchmark of the Christian experience for Koreans. The relationship between the Protestant missions' emphasis on reading and Korea's Confucian culture of learning is of particular importance for an understanding of the growth of Christianity in Korea because Christianity's close association with literacy and sacred writings energised the Confucian imagination of Korean culture. Perceiving the reading of Christian literature, including the bible, as a salient way to salvation, Koreans turned to reading and memorising the scriptures to experience the manifestation of God's revelation. The high respect afforded to education and learning as a dominant cultural value constitutes an important, if overlooked, element in the replication of faith in Korean society that reproduced the gospel under their own familiar terms.

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