Predicting Depth of Mineral Deposit using Gravity-Density Downward Correlation by Fourier Transform
Keywords:isostatic residual gravity anomaly, downward continuation, density log, attenuation, weighting density function
Residual gravity anomalies are the superposition of effects originating from several interfaces in the subsurface. In downward projection of the anomalies for the determination of the depth of the particular substructure which accounts for the bulk of the residual gravity anomalies on the plane can only be resolved with the aid of additional subsurface data such as density log. In this research, density log was used to determine the weighting density function, delineate the multiple layers and correlate with the gravity-density downward variation for predicting the mineral depth using the Fourier transform method.
The results show that the projected residual gravity anomaly at depth between 2015 m and 2170 m depicts all the gravity features that are clearly associated with that on the original plane and also show minimal distortion of the shape of the anomalies. The anomalous mass lies between these depths. The downward continuation depths obtained from the gravity model were compared with that obtained from reflection seismic observation from the study area and the relative error percent were 1.37 % and 0.46 % respectively.
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