To: “Gravity anomalies of 2-D bodies with variable density contrast,” J. Zhang, B. Zhong, X. Zhou, and Y. Dai (Geophysics 66, 809–813).

Geophysics ◽  
2002 ◽  
Vol 67 (1) ◽  
pp. 324-325 ◽  
Keyword(s):  
Gravity Anomalies ◽  
Variable Density ◽  
Density Contrast

Gravity anomalies of three-dimensional bodies with a variable density contrast

1989 ◽  
Vol 130 (4) ◽  
pp. 711-719 ◽  
Author(s):  
I. V. Radhakrishna Murthy ◽  
P. Rama Rao ◽  
P. Ramakrishna
Keyword(s):  
Three Dimensional ◽  
Gravity Anomalies ◽  
Variable Density ◽  
Density Contrast

Gravity anomalies of 2-D bodies with variable density contrast

Geophysics ◽  
2001 ◽  
Vol 66 (3) ◽  
pp. 809-813 ◽  
Author(s):  
Jianzhong Zhang ◽  
Benshan Zhong ◽  
Xixiang Zhou ◽  
Yun Dai
Keyword(s):  
Cross Section ◽  
Northeast China ◽  
Polynomial Function ◽  
Gravity Anomalies ◽  
Lateral Position ◽  
Variable Density ◽  
New Method ◽  
Density Contrast ◽  
Liaohe Basin ◽  
The Cross

A new method is presented to compute gravity anomalies that result from 2-D bodies with variable density contrast. The cross‐section of a body is approximated by a polygon. Density is assumed to vary as any order of polynomial function with depth and lateral position. Results calculated by the proposed method for models with variable density contrast compare well with other methods. Liaohe basin, northeast China, is modeled from field gravity anomalies using the formulas given, showing the method is valid and effective.

A versatile solution for the gravity anomaly of 3D prism-meshed bodies with depth-dependent density contrast

Geophysics ◽  
2017 ◽  
Vol 82 (4) ◽  
pp. G77-G86 ◽  
Author(s):  
Li Jiang ◽  
Jianzhong Zhang ◽  
Zhibing Feng
Keyword(s):  
Los Angeles ◽  
Half Space ◽  
Numerical Stability ◽  
Analytic Solution ◽  
Gravity Anomalies ◽  
Variable Density ◽  
Density Contrast ◽  
Contrast Variation ◽  
Stability Range ◽  
Limit Values

We have developed a generalized solution for computing the gravity anomalies of 3D irregular-mass bodies with complicated density-contrast variation. The 3D irregular-shaped bodies can be approximated flexibly by a collection of finite-juxtaposed right-rectangular prisms. The complicated density-contrast variation of each prism can be well-represented by a depth-dependent polynomial function. A novel analytic solution of gravity anomalies due to a right-rectangular prism with an arbitrary order of polynomial density-contrast function of depth is then derived. The solution is singularity free in the upper half-space over the prism, and its singularity in the lower half-space containing the prism is resolved by assigning their limit values to the singular terms. The numerical stability of the solution is also evaluated through numerical tests. Hence, the solution can be used to compute the gravity anomalies of 3D irregular bodies with variable density contrasts without singularities when computation points are within the numerical stability range. Based on synthetic models with variable density contrast, our solution is validated by using other solutions in the literature. We also simulated the gravity anomalies of the Los Angeles basin and compared them with the observed anomalies and with those computed using the analytic solutions of other workers. These tests confirm the accuracy and efficiency of our analytic solution.

Three‐dimensional Fourier gravity inversion with arbitrary density contrast

Geophysics ◽  
1992 ◽  
Vol 57 (1) ◽  
pp. 131-135 ◽  
Author(s):  
F. Guspí
Keyword(s):  
Frequency Domain ◽  
Three Dimensional ◽  
Gravity Anomalies ◽  
Sedimentary Basins ◽  
Variable Density ◽  
Density Contrast ◽  
Gravity Inversion ◽  
Linear Quadratic ◽  
Space Domain ◽  
Depth Functions

The use of variable‐density contrasts in gravity inversion has gained increasing importance in recent years due to the necessity of constructing more realistic models of geophysical structures such as sedimentary basins. Linear, quadratic, and exponential variations, either in the space or in the frequency domain, are the basis of several methods. See, among others, the papers by Granser (1987), Chai and Hinze (1988), Reamer and Ferguson (1989), and Rao et al. (1990). Guspí (1990) used polynomial density‐depth functions for inverting gravity anomalies into 2-D polygons in the space domain.

Gravity interpretation using Fourier transforms and simple geometrical models with exponential density contrast

Geophysics ◽  
1993 ◽  
Vol 58 (8) ◽  
pp. 1074-1083 ◽  
Author(s):  
D. Bhaskara Rao ◽  
M. J. Prakash ◽  
N. Ramesh Babu
Keyword(s):  
Los Angeles ◽  
Fourier Transforms ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Sedimentary Basins ◽  
Density Contrast ◽  
Model Parameters ◽  
Exponential Density ◽  
Exponential Density Contrast ◽  
Gravity Interpretation

The decrease of density contrast in sedimentary basins can often be approximated by an exponential function. Theoretical Fourier transforms are derived for symmetric trapezoidal, vertical fault, vertical prism, syncline, and anticline models. This is desirable because there are no equivalent closed form solutions in the space domain for these models combined with an exponential density contrast. These transforms exhibit characteristic minima, maxima, and zero values, and hence graphical methods have been developed for interpretation of model parameters. After applying end corrections to improve the discrete transforms of observed gravity data, the transforms are interpreted for model parameters. This method is first tested on two synthetic models, then applied to gravity anomalies over the San Jacinto graben and Los Angeles basin.

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