Parameters related to seawater conditions and electrodeposition setting on the growth of formation of calcareous deposit: A review

2020 ◽  
Author(s):  
Li Mian Yeo ◽  
Denni Kurniawan
Keyword(s):  
Calcareous Deposit

XX. Researches on the foraminifera.—Part III. On the genera peneroplis, operculina , and amphistegina

1859 ◽  
Vol 9 ◽  
pp. 334-337
Keyword(s):  
Detailed Comparison ◽  
The Body ◽  
The Other ◽  
Considerable Degree ◽  
Composite Body ◽  
Calcareous Deposit ◽  
General Plan ◽  
Partition Walls ◽  
Adjacent Segments

In his preceding memoirs, the author has shown that two very dissimilar types of structure present themselves among Foraminifera, one characterized by its simplicity, the other by its complexity. In the former, of which Orbitolites, Orbiculina and Alveolina are typical examples, the calcareous skeleton does not present any definite indications of organization, but seems to have been formed by the simple calcification of a portion of the homogeneous sarcode-body of the animal; that sarcode-body is but very imperfectly divided into segments, the communications between the cavities occupied by these segments being very free and irregular; the form of the segments themselves, and the mode of their connexion, are alike inconstant; and even the plan of growth, on which the character of the organism as a whole depends, though preserving a general uniformity, is by no means invariably maintained. In the latter, to which Cycloclypeus and Heterostegina belong, the calcareous skeleton is found to present a very definite and elaborate organization. The several segments of the body are so completely separated from each other, that they remain connected only by delicate threads of sarcode. Each segment thus isolated has its own proper calcareous envelope, which seems to be moulded (as it were) upon it; and this envelope or shell is perforated with minute parallel tubuli closely resembling those of dentine, except in the absence of bifurcation; the partition-walls between adjacent segments are consequently double, and are strengthened by an intermediate calcareous deposit, which is traversed by a system of inosculating passages that seems properly to belong to it. The form of the segments, their mode of communication, and consequently the general plan of growth, have a very considerable degree of constancy; and altogether the tendency is strongly manifested in this type to the greater individualization of the parts of the composite body, which in the preceding must be looked upon rather as constituting one aggregate whole. In the present memoir this contrast is fully carried out by a detailed comparison of two characteristic examples from these types respectively, each of them having its own features of peculiar interest.

Kaolinite influence on calcareous deposit formation

2009 ◽  
Vol 55 (1) ◽  
pp. 196-203 ◽  
Author(s):  
C. Rousseau ◽  
F. Baraud ◽  
L. Leleyter ◽  
M. Jeannin ◽  
O. Gil
Keyword(s):  
Deposit Formation ◽  
Calcareous Deposit

I.—Notes on the Geology of the Nile Valley

1884 ◽  
Vol 1 (7) ◽  
pp. 289-292
Author(s):  
J. W. Dawson
Keyword(s):  
New Species ◽  
Red Sea ◽  
Nile Valley ◽  
Small Species ◽  
Mediterranean Species ◽  
Calcareous Deposit ◽  
Modern Species ◽  
Mode Of Occurrence ◽  
A New Species

Shortly after my arrival in Cairo, Dr. Schweinfurth, of that city, was so kind as to conduct me to a remarkable sea-terrace at the foot of the Mokattam hill, behind the tombs of the Caliphs, and stated, on the authority of Col. Ardagb, R.E., to be at an elevation of about 200 feet above the level of the sea, and which, I believe, was first described by Oscar Fraas. At this place a cliff of hard Eocene limestone, about 30 feet in height, has been perforated by Lithodomi, whose burrows are now filled with a grey calcareous deposit, and valves of a small species of oyster are also attached to the surface of the rock. The burrows resemble those of an ordinary Mediterranean species of Lithodomus, but I did not see the shells. The oyster has been described by Fuchs as a new species, under the name O. pseudo-cucullata; but, according to Dr. Schweinfurth, it does not seem distinguishable, except as a variety, from O. cucullata, Born. (=O. Forskali, Chemn.), of the Red Sea. Since the locality was observed by Fraas, Dr. Schweinfurth has discovered other shells in the crevices of the rock, more especially a Pecten, a Terebratula, and a Balanus, all modern species. The recent character of these shells and their mode of occurrence and state of preservation, oblige us, I think, to assign them to the Pleistocene, or at farthest the later Pliocene period, though I am aware that they have been regarded as Miocene.

scholarly journals V. Researches on the Foraminifera.—Fourth and concluding series

1860 ◽  
Vol 10 ◽  
pp. 506-510
Keyword(s):  
The Other ◽  
Great Care ◽  
Canal System ◽  
Calcareous Deposit ◽  
System A ◽  
Outer Whorl ◽  
Adjacent Segments ◽  
Physiological Characters

The author in this communication brings to a conclusion that series of inquiries into the structural and physiological characters of typical forms of Foraminifera, which he had been induced to work out for the sake of turning to the account of Zoological science the valuable collections made by Mr. Jukes in the Australian Seas and by Mr. Cuming in the Philippine. The first genus now treated of is Polystomella , the smaller and simpler forms of which have long been known, and of which the structure, so far as it can be elucidated by the examination of such specimens, has been already described with great care and accuracy by Professor W. C. Williamson. But in the comparatively gigantic and highly developed Polystomella of the Australian and Philippine series, a feature exists which is scarcely discernible in the humbler forms previously examined—that feature being the extraordinary development of the canal-system. A spiral canal runs along the inner margin of either surface of every whorl; from this canal a series of arches is given off, of which one passes down between every two adjacent segments, uniting it with the other spiral canal; whilst another set of straight branches passes directly towards the surface of the shell, through the thick calcareous deposit which covers in the depressed centre of the spire, and which extends as far as the last- formed spire . From the connecting arches, successive pairs of diverging branches proceed at frequent intervals; these, in the last whorl, make their way to the surface of the shell, and (when the shell is newly formed) open close on either side of the septal band; though, as the shell increases in thickness by subsequent deposit, the increased divergence of the branches separates their mouths from each other; and it very commonly happens that the two contiguous branches diverging from different arches meet and open by a single external pore half-way between the septal bands. When one whorl, however, has been surrounded by another, this radiating canal-system of the inner whorl does not usually continue itself directly into that of the outer (though such a continuation is not unfrequently seen), but the diverging canals for the most part terminate in the stolons of communication between the segments of sarcode that occupy the chambers of the outer whorl.

scholarly journals Havara on Cyprus - a surficial calcareous deposit

1998 ◽  
Vol 48 (1) ◽  
pp. 110-117
Author(s):  
Wolfgang Schirmer
Keyword(s):  
Calcareous Deposit

Abstract. Havara ist eine Lokalbezeichnung für ein gelblich-weißes, hoch kalkhaltiges, klastisches, quartärzeitliches Lockergestein mit weiter Verbreitung auf Zypern. Die Korngröße ist vorwiegend Silt, reicht aber bis Kiesgröße. Der Steinanteil wechselt örtlich bedingt. Regional ist Havara an den Ausstrich kalkig-mergeliger mariner Gesteine des Oberen Maastrichts bis zum Pliozän gebunden, die große Teile Zyperns einnehmen. Genetisch ist Havara Hangschutt mit Anhäufung am Hangfuß. Am Ausgang von Hanghohlformen, Hangrissen und Tälchen ist er zu Schuttkegeln angehäuft und enthält dann vermehrt gröbere Steinanteile. Ebene oder schwach geneigte Flächen werden von dünneren, eher feinkörnigen Kalkstaub- und Kalksanddecken überkleidet. Vorwiegender Transporttyp ist deluvial durch Abspülung am Hang. Ungeregelte Massen mit groben Gesteinsanteilen müssen auch solifluktiv bewegt worden sein. Unter anthropogenem Einfluß (Hangbearbeitung, Beweidung) gesellt sich kolluviale Bewegung hinzu. Sturzschutt und äolische Sedimentation sind sehr untergeordnet. Der Aufschluß Kalavaôs-Márcou (Abb. 1), eine Hangfußakkumulation, erschließt rhythmisch geschichteten Havara mit gradierter Schichtung von grob-unten zu fein-oben mit jeweiligem humosen Bodenabschluß (schwache Rendzina). Zwei solcher Böden ergaben ein 14C-Alter an Holzkohlen von 31.970 a BP im tieferen Profilteil und 27.440 a BP im höheren Profilteil (Abb. 2), also ein Alter des Mittelwürms 4 sensu Schirmer 1991 (Tab. 1). Die terrestrische Havara-Boden-Abfolge drängt zum Vergleich mit den Löß-Boden-Rhythmen im Mittelwürm des Schwalbenbergs am Mittelrhein, die ihrerseits weltweit mit Klimarhythmen aus Eiskernen und Tiefseesedimenten korrelierbar sind (Schirmer 1995: 531). Aus der Tatsache, daß Havara heute in viel geringerem Maße, und dann meist durch anthropogene Rodung bedingt, abgelagert wird, und aus der Wechselfolge von Havara und Interstadialböden in mächtigen Havarapaketen läßt sich für die Havara-Bildung eine vegetationsärmere Zeit folgern als die heutige in Zypern. Der weltweite Klimawechsel Stadial/Interstadial findet also auch im terrestrischen Bereich des östlichen Mittelmeerraumes seinen Niederschlag durch vermehrte Hangaktivität mit Schuttproduktion in den Stadialen und Bodenbildung in den Interstadialen. Im Unterschied zu Havara ist Kafkalla ein Ergebnis der Bodenbildung: Kalkkrusten, Caliche. Sie entstehen durch deszendente Kalkfällung als Kalkknollen und Kalkstangen (Cc-Horizont), vorwiegend aber durch aszendente Kalkverkrustung der Oberfläche und schließlich lateralen Kalktransport in seicht gelegenen Grobsedimenten.

Carbon Steel Corrosion and Cathodic Protection Data in Deep North Atlantic Ocean

CORROSION ◽  
10.5006/3552 ◽  
2020 ◽  
Vol 76 (11) ◽  
Author(s):  
Erwan Diler ◽  
Nicolas Larché ◽  
Dominique Thierry
Keyword(s):  
Carbon Steel ◽  
Atlantic Ocean ◽  
Cathodic Protection ◽  
Cold Water ◽  
Potential Temperature ◽  
Natural Seawater ◽  
Cathodic Current ◽  
Deposit Formation ◽  
X Ray ◽  
Calcareous Deposit

Many parameters may influence the corrosion and the cathodic protection current demand in natural seawater. These are potential, temperature, dissolved oxygen content, biofilm and fouling activity, hydrostatic pressure, and calcareous deposit formation. In this study, the influence of the exposure depth on the corrosion, cathodic protection current demand, and nature of the calcareous deposit formed on carbon steel was investigated at 1,020 m and 2,020 m depth. For this purpose, a set of coupons, cathodic protection, and environmental sensors were exposed in Azores in the Atlantic Ocean for 11 months. The higher corrosion rate and current density observed at 1,020 m can be explained by the higher temperature and oxygen diffusion. The cathodic current demand decrease with time can be attributed to the calcareous deposit formation. The current densities after 11 months are in agreement with the literature with 143 mA/m2 and 124 mA/m2 at 1,020 m and 2,020 m depth. Calcareous deposits formed, characterized by Raman spectroscopy, x-ray diffraction, and scanning electron microscopy/electron dispersive x-ray spectroscopy, highlight (i) the favored formation of calcite and hydrocalcite at the expense of aragonite in deep and cold water, (ii) the presence of a thin deposit after 11 months, (iii) the decrease of the Ca/Mg ratio with immersion depth, (iv) the presence of CaMgCO3 compounds, and (v) a higher decrease of the current demand with time in deep water, suggesting the formation of a more protective deposit. The capacity for aluminum-gallium and aluminum-indium galvanic anode were in agreement with the literature for long-term exposures.

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