Magnetic anomaly of a circular lamina

Geophysics ◽  
1979 ◽  
Vol 44 (1) ◽  
pp. 102-107 ◽  
Author(s):  
S. K. Singh ◽  
R. Castro E. ◽  
M. Guzman S.
Keyword(s):  
Circular Cylinder ◽  
Closed Form ◽  
Gravity Anomaly ◽  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Hankel Transform ◽  
Poisson’S Equation ◽  
Poisson's Equation ◽  
Gravity And Magnetic

Closed form expressions for the gravity anomaly of a circular lamina and the gravity and magnetic anomalies due to a vertical right circular cylinder have been obtained previously (Singh, 1977a; Singh, 1977b; Singh and Sabina, 1978) by a method which avoids complicated integrations commonly used in deriving such solutions (e.g., Nabighian, 1962; Rao and Radhakrishnamurty, 1966). The method involves use of the Fourier‐Hankel transform of Poisson’s equation. The final expressions are obtained in closed form by employing certain tabulated integrals.

Gravity and magnetic anomalies of the Sutton Mountains region, Quebec and Vermont: expressions of rift volcanics related to the opening of Iapetus

1981 ◽  
Vol 18 (4) ◽  
pp. 680-692 ◽  
Author(s):  
P. S. Kumarapeli ◽  
A. K. Goodacre ◽  
M. D. Thomas
Keyword(s):  
Gravity Anomaly ◽  
Magnetic Anomaly ◽  
Triple Junction ◽  
Three Dimensional ◽  
Surface Expression ◽  
Magnetic Anomalies ◽  
Iapetus Ocean ◽  
Metavolcanic Rocks ◽  
Gravity And Magnetic ◽  
Narrow Belt

Prominent, nearly coincident, positive gravity and magnetic anomalies occur in the Sutton Mountains region, centered about 100 km east of Montreal, Quebec. Several lines of evidence indicate that the gravity anomaly stems from two principal sources: a deep (mid and lower crustal) source of speculative origin and a shallow source identifiable with a narrow belt of late Precambrian – early Cambrian metavolcanic rocks, the Tibbit Hill volcanics. The magnetic anomaly seems to be produced mainly by the metavolcanic rocks. Three-dimensional modelling of a residual gravity anomaly, supplemented by two-dimensional modelling of the magnetic anomaly, shows that the seemingly minor belt of metavolcanic rocks constitutes the surface expression of a thick (maximum thickness ~8 km) pile of dominantly mafic volcanics, which are only slightly exposed at the present level of erosion.The Tibbit Hill volcanics are regarded as products of rift-related volcanism that occurred at an rrr triple junction developed during the early stages of the opening of the Iapetus Ocean. The Ottawa graben is probably the failed arm of this triple junction. The emplacement of the Grenville dike swarm whose trend is nearly coincident with that of the Ottawa graben was probably coeval with the volcanism in the Sutton Mountains region. The present work shows that the volcanism in the region was on a much larger scale than hitherto recognized.

On: “Geophysical Analysis in Central Indiana using Potential Field Continuation,” by A. J. Rudman, Judson Mead, Joseph F. Whaley, and Robert F. Blakely (GEOPHYSICS, October 1971, p. 878–890)

Geophysics ◽  
1972 ◽  
Vol 37 (6) ◽  
pp. 1047-1047
Author(s):  
Douglas J. Guion
Keyword(s):  
Gravity Anomaly ◽  
Magnetic Anomaly ◽  
Potential Field ◽  
Downward Continuation ◽  
Gravity Effect ◽  
Gravity And Magnetic ◽  
Gravity And Magnetic Anomaly ◽  
Field Continuation ◽  
Hamilton County

I read with interest the article concerning modeling the Hamilton County, Indiana, gravity and magnetic anomaly. The authors’ method for outlining the igneous body by downward continuation aroused my curiosity to the point that I decided to study the results in detail. My investigation revealed that the calculated gravity effect of the model did not satisfy the observed gravity anomaly. In fact, the amount of mismatch is quite serious.

North American Gravity and Magnetic Anomaly Workshops

Geophysics ◽  
1981 ◽  
Vol 46 (11) ◽  
pp. 1611-1617
Author(s):  
W. J. Hinze ◽  
N. W. O’Hara ◽  
M. S. Reford ◽  
J. G. Tanner
Keyword(s):  
Gravity Anomaly ◽  
Magnetic Anomaly ◽  
North American ◽  
North American Continent ◽  
The North ◽  
Terrain Effects ◽  
Gravity And Magnetic ◽  
Anomaly Map ◽  
Map Series ◽  
Gravity And Magnetic Anomaly

The North American Gravity and Magnetic Anomaly Map Workshops, realizing the importance of regional gravity and magnetic anomalies to investigating the structure and composition of the earth, enthusiastically support the preparation of North American gravity and magnetic anomaly maps. Sufficient magnetic and gravity anomaly data are available over the North American continent, the Caribbean, and adjacent marine areas to produce geologically meaningful maps. These maps will be published within the decade at a scale of 1:5 million on the same map base being used by a variety of organizations to produce other geologic/geochemical/geophysical maps in cooperation with the Geological Society of America’s Centennial Map Series. The anomaly maps will be published in color with transparent overlays also available. The gravity anomaly map will be contoured at a 10 mgal interval using Bouguer anomalies onshore corrected wherever possible and necessary for terrain effects and free‐air anomalies offshore. Existing or soon to be completed magnetic and gravity anomaly maps of Canada, the U.S., and Mexico will provide the nuclei for preparing the North American maps. Programs for producing these maps in a timely manner are organized based upon a series of committees and the cooperation of agencies of the involved North American nations.

Spectral analysis of gravity and magnetic anomalies due to a vertical circular cylinder

Geophysics ◽  
1983 ◽  
Vol 48 (2) ◽  
pp. 224-228 ◽  
Author(s):  
A. Soto ◽  
S. K. Singh ◽  
C. Flores
Keyword(s):  
Spectral Analysis ◽  
Circular Cylinder ◽  
Bessel Function ◽  
Magnetic Anomalies ◽  
Gravity And Magnetic ◽  
Amplitude Spectra ◽  
Phase Spectra ◽  
Magnetic Case

Expressions for the spectra of gravity and magnetic anomalies due to a vertical right circular cylinder can be written in terms of a Bessel function and the sum of two exponentials. From the zeros of the amplitude spectra, which are the zeros of the Bessel function, an estimate of the radius of the cylinder can be obtained. The depths to the top and to the bottom enter as exponents of the exponential terms and can be evaluated by taking ratios of the spectra at several frequencies. The density or the intensity of magnetization can then be easily estimated. For the magnetic case the epicenter of the cylinder can be obtained from the slope of the phase spectra. The method has been tested on anomalies of various cylinders and was found to give good results.

Gravimagnetic similarity in anomaly formulas for uniform polyhedra

Geophysics ◽  
2002 ◽  
Vol 67 (4) ◽  
pp. 1126-1133 ◽  
Author(s):  
Horst Holstein
Keyword(s):  
Gravity Field ◽  
Magnetic Anomaly ◽  
Vector Function ◽  
Magnetic Anomalies ◽  
Magnetic Potential ◽  
Tensor Form ◽  
Linear Combinations ◽  
Differential Relation ◽  
Gravity And Magnetic ◽  
Gravity And Magnetic Anomaly

Gravitational and magnetic anomalies of an arbitrary target body are linked through Poisson's differential relation. For a uniform polyhedral target, Poisson's relation reduces to an algebraic link between gravity and magnetic anomaly formulas. The derivation is given in tensor form. It identifies for each target facet edge a vector function, in terms of which the gravitational and magnetic potential and field anomaly formulas are similarly expressed as appropriately weighted linear combinations. This similarity unifies the theory of uniform polyhedral anomalies. It benefits analysis and construction of software that naturally embraces all anomalies in a single code. The analysis is exemplified by a discussion of singularities and by the adaptation of three gravity‐field algorithms to the remaining gravitational and magnetic cases, while retaining the respective computational advantages of the former gravity‐field algorithms.

scholarly journals Analyzing Gravity and Magnetic Data for the Detection of Deep-Seated Faults and Faults within the Sedimentary Cover Near Habbanieyah and Razzaza Lakes in the Middle of Iraq

2021 ◽  
Vol 54 (2C) ◽  
pp. 29-38
Author(s):  
Wadhah Mahmood Shakir AL-Khafaji
Keyword(s):  
Gravity Anomaly ◽  
Sedimentary Cover ◽  
Magnetic Anomalies ◽  
Tectonic Activity ◽  
Magnetic Data ◽  
Quantitative Interpretation ◽  
Residual Gravity ◽  
Basement Rocks ◽  
Gravity And Magnetic ◽  
Residual Gravity Anomaly

This research deals with the processing and analyzing of magnetic and gravitational data for an area covering the region of Habbanieyah - Razzaza Lakes and its adjacent areas. The study includes data processing and mapping of the total gravity and magnetic anomalies for only the concerned region, then separating the residual anomalies by adopting the polynomial regression graphical method. The residual gravity anomaly reflects the variations of rock densities within the sedimentary cover. The horizontal gradient filter has been applied to the residual gravity anomaly in order to conduct the locations of fault planes within the sedimentary cover where sudden variations of gravity field take place. The quantitative interpretation for both gravity and magnetic anomalies yielded a preliminary determination for the depth to the center of major faults within the sedimentary cover. By constructing a gravity model along a profile which directed NE-SW and passing through the middle part of the study region, depth to the center of the effective faults found. This depth variation is due to the effect of tectonic activity which produced a set of faults, such faults caused the upward and downward structural motions and were responsible for positioning the deep high density causative slabs of bedrock. The residual magnetic field quantitative interpretation along two profiles crosses over anomalies at the NE and SW parts of the region yielded the depth to the top of magnetized basement rocks. The difference in depth of the basement rocks and the shifted anomaly locations reflects the effect of tectonic activity which may relate to a strike slip faulting in the higher depths.

MAGNETIC ANOMALY DUE TO A VERTICAL RIGHT CIRCULAR CYLINDER WITH ARBITRARY POLARIZATION

Geophysics ◽  
1978 ◽  
Vol 43 (1) ◽  
pp. 173-178 ◽  
Author(s):  
Shri Krishna Singh ◽  
Federico J. Sabina
Keyword(s):  
Magnetic Field ◽  
Circular Cylinder ◽  
Closed Form ◽  
Magnetic Anomaly ◽  
Closed Form Solution ◽  
Form Solution ◽  
Arbitrary Polarization ◽  
Shaped Body ◽  
Anomalous Magnetic Field

A closed form solution for the total anomalous magnetic field due to a vertical right circular cylinder with arbitrary polarization is derived under the assumption that the magnetization is uniform. As expected, the computed field is similar to the field due to a “similar” prism‐shaped body.

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