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- Volume 6, Issue 1, 1958
Geophysical Prospecting - Volume 6, Issue 1, 1958
Volume 6, Issue 1, 1958
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THE ESTIMATION OF THE LIMITING DEPTH OF GRAVITATING BODIES
Authors M. H. P. BOTT and R. A. SMITHAbstractSome new formulae for the rapid estimation from the gravity field of the maximum possible depth to the top surface of gravitating bodies of positive mass are stated, discussed and proved.
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MANGANESE ORE OF SOUTH‐INDIA AND ITS MAGNETIC PROPERTIES *)
Authors V. L. S. BHIMASANKARAM and B. S. R. RAOAbstractThe Kodur Manganese belt has been surveyed with a vertical magnetometer. It was generally observed that both high positive and negative anomalies were associated with some of the existing ore bodies. Other large manganese ore deposits gave little or no magnetic anomalies. Further it was observed that both types of manganese ore deposits giving rise to large and little magnetic anomalies, contained similar percentages of manganese and iron. In view of these discrepancies, an extensive study of the magnetic properties of these manganese ores was taken up. The results of these measurements showed that the susceptibilities of the manganese ore samples collected vary over a wide range.
It was observed that the high susceptibilities are associated with samples containing manganmagnetite and vredenburgite, whereas samples rich in psilomelane and pyrolusite possess low susceptibilities. From the chemical analysis, normative values of manganmagnetite and vredenburgite–with a general formula of (Mn.Fe)3O4– were calculated and a linear relationship could be established between these normative values and susceptibilities.
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RADON MEASUREMENTS AS A GEOPHYSICAL METHOD *)
By E. BUDDEAbstractFaults or Uranium‐bearing veins are often to be found by measuring the Radon‐content of the air in the ground through a layer of porous material, even over some distance.
It is shown by measurements in the laboratory and in the field, that this distance depends on the character of the porous material (composition of grains with different diameters and water content).
A quantitative relation between the composition of grains with different diameters and the coefficient of diffusion of Radon is obtained by comparing the practical measurements with theoretical results.
The result of the investigations is, that Uranium‐bearing veins or faults do not cause any measurable anomaly even over a distance of only 5 cm, if they are hidden under fine‐grained material with its natural water content.
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RICHTCHARAKTERISTIKEN VON GEOPHONGRUPPEN MIT BERÜCKSICHTIGUNG DER EINZELCHARAKTERISTIKEN*
Authors JOST SCHILLEMEIT and AIVARS CELMINŠAbstractThe directional sensitivities of an array of geophones depend as much on the size of the array as on the directional sensitivities of the single geophones forming the array. In a former paper (Celminš 1956) the effect of the size of the array was investigated. In addition to this the influence of the directional sensitivities of the individual geophones on the sensitivities of an array of geophones is investigated here.
In δ 2 some general formulae for the directional sensitivities are derived. In addition the directional sensitivities of a single geophone according to P‐ and S‐waves are investigated (δ3 and δ4). In δ5 the'directional sensitivities for the most important cases of arrays of parallel geophones are computed. The results of the computation (shown in fig. 4 and 5) give an idea of the types of directional sensitivities which occur in the use of geophone arrays.
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QUELQUES RECENTS ASPECTS DU FORAGE SISMIQUE*
Authors J. DUFOUR and A. DEGORSEABSTRACTThe shothole drilling industry has had new developments and its evolution is tied to several causes. First, more and more difficult and varied formations have to be drilled. Second, new procedures have to be used in desert regions recently open to prospecting. Finally, modifications of the seismic methods themselves (multiplication of the charges, shallow holes, etc.) lead the driller to use more economical and lighter tools. In this paper the following types of drilling equipment are described: the Mouton Delmag for spudding through pebbles and loose gravels; a mud mixing water truck and an extensible mast used for drilling multiple medium depth holes through caving sands; a compressed air‐drill for regions where the water supply is practically nil; rock drills, such as a Wagon‐Jack and the Warsop hammer, for multiple shallow holes in various formations.
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ÉTUDE DE DÖMES DE SEL AU GABON *)
Authors D. REYRE and J. M. VALLETAbstractThe present development of exploration in Gabon and the latest successes obtained by drilling have led the authors to publish a historical account of the geological and geophysical research concerning two particularly typical salt domes: those of N'Daminzé and Ozouri.
Both of them are located in the western basin of Gabon: the first one in the zone of the savannahs, the second being a part of a series of salt domes in the delta of Ogooué.
The western basin of Gabon forms, as a whole, a huge westward‐inclined monocline and is characterized by a general phenomenon of diapirism the type of which, in the delta of Ogooué, greatly differs from that of the savannahs zone.
Because of the scarcity of outcrops in these zones geophysical exploration has been of valuable help.
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BOOK REVIEWS
Book reviewed in this articles:
Elastic Waves in Layered Media by W. Maurice Ewing, Wenceslas S. Jardetski, and Frank Press
Geology of Petroleum by A. I. Levorsen
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Volumes & issues
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Volume 72 (2023 - 2024)
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Volume 71 (2022 - 2023)
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Volume 70 (2021 - 2022)
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Volume 69 (2021)
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Volume 68 (2020)
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Volume 67 (2019)
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Volume 66 (2018)
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Volume 65 (2017)
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Volume 64 (2015 - 2016)
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Volume 63 (2015)
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Volume 62 (2014)
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Volume 61 (2013)
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Volume 60 (2012)
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Volume 59 (2011)
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Volume 58 (2010)
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Volume 57 (2009)
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Volume 56 (2008)
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Volume 55 (2007)
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Volume 54 (2006)
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Volume 53 (2005)
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Volume 52 (2004)
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Volume 51 (2003)
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Volume 50 (2002)
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Volume 49 (2001)
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Volume 48 (2000)
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Volume 47 (1999)
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Volume 46 (1998)
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Volume 45 (1997)
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Volume 44 (1996)
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Volume 43 (1995)
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Volume 42 (1994)
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Volume 41 (1993)
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Volume 40 (1992)
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Volume 39 (1991)
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Volume 38 (1990)
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Volume 37 (1989)
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Volume 36 (1988)
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Volume 35 (1987)
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Volume 34 (1986)
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Volume 33 (1985)
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Volume 32 (1984)
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Volume 31 (1983)
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Volume 30 (1982)
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Volume 29 (1981)
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Volume 28 (1980)
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Volume 27 (1979)
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Volume 26 (1978)
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Volume 25 (1977)
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Volume 24 (1976)
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Volume 23 (1975)
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Volume 22 (1974)
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Volume 21 (1973)
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Volume 20 (1972)
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Volume 19 (1971)
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Volume 18 (1970)
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Volume 17 (1969)
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Volume 16 (1968)
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Volume 15 (1967)
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Volume 14 (1966)
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Volume 13 (1965)
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Volume 12 (1964)
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Volume 11 (1963)
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Volume 10 (1962)
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Volume 9 (1961)
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Volume 8 (1960)
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Volume 7 (1959)
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Volume 6 (1958)
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Volume 5 (1957)
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Volume 4 (1956)
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Volume 3 (1955)
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Volume 2 (1954)
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Volume 1 (1953)