Analysis of gravity anomalies of sedimentary basins by an asymmetrical trapezoidal model with quadratic density function

Geophysics ◽  
1990 ◽  
Vol 55 (2) ◽  
pp. 226-231 ◽  
Author(s):  
D. Bhaskara Rao
Keyword(s):  
Density Function ◽  
Quadratic Function ◽  
Gravity Anomalies ◽  
Sedimentary Basins ◽  
Variable Density ◽  
Constant Density ◽  
Quadratic Density Function ◽  
Marquardt Algorithm ◽  
Damping Parameter ◽  
Godavari Basin

The decrease of density contrast with depth in many sedimentary basins can be approximated by a quadratic function. The interpretation of gravity anomalies over sedimentary strata can be more realistic if variable density contrasts, rather than constant density contrasts, are assumed. I derive the equation for the gravity anomaly of an asymmetrical trapezoidal model, assuming a quadratic density function, and I develop methods of interpretation, using the Marquardt algorithm. While interpreting a synthetic anomaly profile, the convergence of the algorithm is shown by plotting the values of the objective function, damping parameter, and various parameters of the model with respect to iteration number; the results are superior to those obtained when using constant density contrasts. In addition, I apply the method in the interpretation of gravity anomalies over the San Jacinto graben and the lower Godavari basin.

Fourier forward modeling of vector and tensor gravity fields due to prismatic bodies with variable density contrast

Geophysics ◽  
2016 ◽  
Vol 81 (1) ◽  
pp. G13-G26 ◽  
Author(s):  
Leyuan Wu ◽  
Longwei Chen
Keyword(s):  
Fourier Transform ◽  
Numerical Stability ◽  
Numerical Solutions ◽  
Gravity Anomalies ◽  
Variable Density ◽  
Model Parameters ◽  
Constant Density ◽  
Density Functions ◽  
Prismatic Bodies ◽  
2D And 3D

Prismatic bodies with variable density contrasts are very useful in modeling and inversion of gravity anomalies for sedimentary basins, in which some simple mathematical functions offer better approximations for the density-depth relationship of the basin fill than a constant density model. We have explored Fourier-domain modeling of vector and tensor gravity anomalies due to 2D and 3D prismatic bodies following a wide class of variable density functions. We placed the emphasis on general polynomial models because they provided a flexible way to approximate arbitrary density functions. The recently proposed Gauss-fast Fourier transform method was applied to improve the accuracy of inverse Fourier transform. The numerical performance of the presented method was examined by comparing with space-domain analytical, seminumerical, or completely numerical solutions. Singularity and numerical stability of the algorithm were also analyzed with ranges of numerical stability for polynomial density models of different orders specified. Truncation errors of Fourier forward methods were estimated quantitatively using relevant model parameters, and the behavior was observed through theoretical analysis and model tests. Synthetic models, of 2D and 3D prisms with variable density contrasts, found the accuracy, efficiency, and flexibility of the method. We also interpreted a real data example of the gravity profile across the San Jacinto graben.

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.

A new sedimentary cover model for the southern area of the East European Platform and the Pre-Caucasus based on decompensation gravity anomalies data

2021 ◽  
Author(s):  
Mikhail Kaban ◽  
Alexei Gvishiani ◽  
Roman Sidorov ◽  
Alexei Oshchenko ◽  
Roman Krasnoperov
Keyword(s):  
East European Platform ◽  
Sedimentary Cover ◽  
Gravity Anomalies ◽  
Sedimentary Basins ◽  
The Caucasus ◽  
Near Surface ◽  
New Model ◽  
Origin And Evolution ◽  
East European ◽  
Bouguer Anomalies

<p><span>A new model has been developed for the density and thickness of the sedimentary cover in a vast region at the junction of the southern part of the East European Platform, the Pre-Caucasus and some structures adjacent to the south, including the Caucasus. Structure and density of sedimentary basins was studied by employing the approach based on decompensation of gravity anomalies. Decompensative correction for gravity anomalies reduces the effect of deep masses providing compensation of near-surface density anomalies, in contrast to the conventional isostatic or Bouguer anomalies. . The new model of sediments, which implies their thickness and density, gives a more detailed description of the sedimentary thickness and density and reveals new features which were not or differently imaged by previous studies. It helps in better understanding of the origin and evolution of the basins and provides a background for further detailed geological and geophysical studies of the region.</span></p>

Sign in / Sign up

Export Citation Format

Share Document