Estimation of Depth to Bottom of Magnetic Sources Using Spectral Methods: Application on Iran's Aeromagnetic Data

Abstract

The effect of window size while estimating the depth to bottom of magnetic sources (DBMS) is examined on the synthetic 2‐D magnetic field data. The data are generated for 3‐D fractal magnetization models assuming different combinations of depth to the top and bottom of magnetic sources. The depths are estimated assuming an uncorrelated and correlated random distribution of sources. The depths to the top estimated for fractal distribution of sources are found within 70% of the true values for all window sizes, whereas the values for the uncorrelated random distributions are far from the real depths. The DBMS for the correlated random distribution of sources are estimated within 70–80% of the true values for the window sizes of 5 times or more of the targeted depths. The modified centroid method is found to provide better estimations as compared to scaling‐spectral peak modeling. The modified centroid method is applied to the aeromagnetic data of Iran to estimate the DBMS using a window size of 200 × 200 km2. The shallow DBMS between 12 and 20 km are obtained for the Quaternary Sabalan and Sahand volcanoes to the NW of Iran, the central and NE of central Iran, the central Zagros, NW of Tabas block, and the south of the Lut Block. The deepest DBMS of the order of 40 km is found in the Makran. The rest of Iranian Plateau is characterized by DBMS of 20 to 30 km. The shallow DBMS are found in correlation with the depth of the Ophiolites.

Crustal structure of Sicily from modelling of gravity and magnetic anomalies

“…where ε o and ε t are the standard errors of the crystalline centroid and top depths, respectively 109,110 .…”

“…The standard error of the top and the centroid depths may be computed separately as 109 : where is the number of observations, and are the observed and estimated values of the corrected power spectrum, and are observed and mean values of the wavenumber considered for depth estimation.…”

“…The standard error of the depth to the Curie isothermal surface and Moho boundary may then be computed using: where and are the standard errors of the crystalline centroid and top depths, respectively 109 , 110 .…”

Crustal structure in the Campanian region (Southern Apennines, Italy) from potential field modelling

“…The standard error of the top and the centroid depths may be computed separately as 120 : where is the number of observations, and are the observed and estimated values of the corrected power spectrum, and are observed and mean values of the wavenumber considered for depth estimation. The standard error of the depth to the bottom of magnetic sources and Moho boundary may then be computed using: where and are the standard errors of the centroid and top/crystalline depths, respectively 120 , 121 .…”

Combined qualitative and quantitative regional interpretation of the thermal results of magnetic data in the Eastern Mediterranean Region

“…Alternatively, fractal magnetization parameter can be used for corrections on the power spectrum (Bouligand et al, 2009;Bansal et al, 2011;Li et al, 2013;Salem et al, 2014;Li et al, 2017;Martos et al, 2018;Kumar et al, 2020;Cruz et al, 2020). On the other hand, Ravat et al, (2007) suggested that the fractal model may yield overcorrection on the RAPS and unreliable results.…”