Deducing the Total Magnetic Intensity Field for Visualizing the Crustal Rocks Setting of Iraq from the World Magnetic Model 2023

This research includes the derivation of an updated total magnetic intensity map of Iraq given from the satellite data. The World Magnetic Model, (WMM) 2023, which was obtained from satellite orbitography adopted to determine the total magnetic intensity field (F) values for each grid point that covered the whole study region of Iraq. The WMM software was used to calculate the F value for 272 grid points that covers the whole study region. This region was gridded with suitable interstitial distances of 50 Km to cover such region representatively. The calculations of F were achieved in two steps. The first step represents the F calculation at sea level (altitude=0), whereas the second one calculated the F by considering the elevation meter value of altitude for each grid point. It was proposed to deduce the residual F by subtracting these values at altitude = 0 field from that altitude field. Then, the deduced residual surface was reflected the magnetic intensity variations across the study region for the rocks overlain the reference ellipsoid. Residual Fsurface was treated mathematically within the 2D domain by using the software. The results were provided a vision of the highest and lowest gradients of F and for interpreting their variations were shown to be coincided with the major tectonic boundaries of Iraq that been detected by previous studies. The given values of F were found to be mostly dependent on the magnetic susceptibility subsurface basement and / or crustal rocks depth. It was concluded that the increase of F values towards the N and NE direction is related to the increasing thickness of crustal rocks or the depth to the Moho discontinuity, and also such thickness or depth is found to be increased towards the E-W direction but with lesser values.