Interpretation of Gravity Anomalies Over an Inclined Fault of Finite Strike Length With Quadratic Density Function

1990 ◽  
Vol 21 (3-4) ◽  
pp. 169-173 ◽  
Author(s):  
B. Bhaskara Rao ◽  
M. J. Prakash



Geophysics ◽  
1990 ◽  
Vol 55 (2) ◽  
pp. 226-231 ◽  
Author(s):  
D. Bhaskara Rao

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.





Geophysics ◽  
1970 ◽  
Vol 35 (4) ◽  
pp. 708-712 ◽  
Author(s):  
Bijon Sharma ◽  
Mahesh P. Vyas

The gravity anomaly due to a single horizontal semi‐infinite block terminated by a vertical or dipping fault has been discussed by several authors previously. Geldart, Gill, and Sharma (1966) gave a new and simple expression for calculating the gravity anomaly due to a block cut by an inclined fault at an arbitrary angle and used this expression to obtain the gravity anomaly due to a fault cutting a single bed. In their derivation the effects of both the upthrown and the downthrown blocks were taken into consideration. It is, however, only in the unusual situation that faults cut a single bed of uniform density. More often, faults cut a series of beds of different densities and thicknesses. If the densities and the thicknesses of the various beds differ greatly, an interpretation based upon replacement of the series of beds by a single bed of uniform density may be highly erroneous. Starting from the single block expression given by Geldart et al, an expression can be derived giving the gravity anomaly due to a fault cutting a series of beds having different densities and thicknesses.



Author(s):  
David Cockayne ◽  
David McKenzie

The technique of Electron Reduced Density Function (RDF) analysis has ben developed into a rapid analytical tool for the analysis of small volumes of amorphous or polycrystalline materials. The energy filtered electron diffraction pattern is collected to high scattering angles (currendy to s = 2 sinθ/λ = 6.5 Å-1) by scanning the selected area electron diffraction pattern across the entrance aperture to a GATAN parallel energy loss spectrometer. The diffraction pattern is then converted to a reduced density function, G(r), using mathematical procedures equivalent to those used in X-ray and neutron diffraction studies.Nearest neighbour distances accurate to 0.01 Å are obtained routinely, and bond distortions of molecules can be determined from the ratio of first to second nearest neighbour distances. The accuracy of coordination number determinations from polycrystalline monatomic materials (eg Pt) is high (5%). In amorphous systems (eg carbon, silicon) it is reasonable (10%), but in multi-element systems there are a number of problems to be overcome; to reduce the diffraction pattern to G(r), the approximation must be made that for all elements i,j in the system, fj(s) = Kji fi,(s) where Kji is independent of s.



2015 ◽  
Vol 47 (8) ◽  
pp. 24-40 ◽  
Author(s):  
Telman Abbas ogly Aliev ◽  
Naila F. Musaeva ◽  
Matanat Tair kyzy Suleymanova ◽  
Bahruz Ismail ogly Gazizade


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