Lithologic mapping test for gravity and magnetic anomalies: A case study of gravity-magnetic anomaly profile in the eastern segment of the China–Mongolia border

2015 ◽  
Author(s):  
Wang Jian ◽  
Meng Xiaohong ◽  
Chen Zhaoxi ◽  
Wang Jun ◽  
Zhang Sheng ◽  
...  
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Gravity And Magnetic ◽  
Eastern Segment ◽  
Lithologic Mapping

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.

Lithologic mapping test for gravity and magnetic anomalies

2015 ◽  
Vol 117 ◽  
pp. 23-31
Author(s):  
Jian Wang ◽  
Xiaohong Meng ◽  
Zhaoxi Chen ◽  
Guofeng Liu ◽  
Yuanman Zheng ◽  
...  
Keyword(s):  
Magnetic Anomalies ◽  
Gravity And Magnetic ◽  
Lithologic Mapping

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.

A DIRECT COMPUTATION OF GRAVITY AND MAGNETIC ANOMALIES CAUSED BY 2- AND 3-DIMENSIONAL BODIES OF ARBITRARY SHAPE AND ARBITRARY MAGNETIC POLARIZATION BY EQUIVALENT‐POINT METHOD AND A SIMPLIFIED CUBIC SPLINE

Geophysics ◽  
1977 ◽  
Vol 42 (3) ◽  
pp. 610-622 ◽  
Author(s):  
Chao C. Ku
Keyword(s):  
Arbitrary Shape ◽  
Gaussian Quadrature ◽  
Magnetic Anomalies ◽  
Cubic Spline ◽  
The Body ◽  
Point Method ◽  
Magnetic Polarization ◽  
3 Dimensional ◽  
Equivalent Point ◽  
Gravity And Magnetic

A computational method, which combines the Gaussian quadrature formula for numerical integration and a cubic spline for interpolation in evaluating the limits of integration, is employed to compute directly the gravity and magnetic anomalies caused by 2-dimensional and 3-dimensional bodies of arbitrary shape and arbitrary magnetic polarization. The mathematics involved in this method is indeed old and well known. Furthermore, the physical concept of the Gaussian quadrature integration leads us back to the old concept of equivalent point masses or equivalent magnetic point dipoles: namely, the gravity or magnetic anomaly due to a body can be evaluated simply by a number of equivalent points which are distributed in the “Gaussian way” within the body. As an illustration, explicit formulas are given for dikes and prisms using 2 × 2 and 2 × 2 × 2 point Gaussian quadrature formulas. The basic limitation in the equivalent‐point method is that the distance between the point of observation and the equivalent points must be larger than the distance between the equivalent points within the body. By using a reasonable number of equivalent points or dividing the body into a number of smaller subbodies, the method might provide a useful alternative for computing in gravity and magnetic methods. The use of a simplified cubic spline enables us to compute the gravity and magnetic anomalies due to bodies of arbitrary shape and arbitrary magnetic polarization with ease and a certain degree of accuracy. This method also appears to be quite attractive for terrain corrections in gravity and possibly in magnetic surveys.

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