The Depth of Magnetic Basement and Averaged Crustal MagneticSusceptibility of Afghanistan

In hydrocarbon explorations, knowledge of the depth and shape of sedimentary basins is of crucial importance. Calculating the depth of magnetic basement is capable of estimating the depth of sedimentary basins and their shapes provided that magnetic layers are not intercalated within the sedimentary cover. Calculating the averaged crustal magnetic susceptibility can detect presence of sedimentary basins with intercalated magnetic layers. Applying the fractal spectral method on the aeromagnetic data of Afghanistan, the depth of the magnetic basement and averaged crustal magnetic susceptibility are estimated. The choice of a suitable fractal parameter and an adequate window size is crucial for a reliable approximation of the depth of the magnetic basement and averaged crustal magnetic susceptibility. The calculated depth of the magnetic basement map of Afghanistan highlights the areal extent of the sedimentary basin belt of northern Afghanistan namely the Afghan Tajik, Amu Darya, Kushka and Tripul basins. The large susceptibility of the basins implies that the basins were formed by a volcanic rifting margin. In eastern Afghanistan, Katawaz basin is well detected with a large depth of magnetic basement of ~ ۱۶ km and a low averaged crustal magnetic susceptibility value very similar to Zagros (Iran) suggesting the igneous basement is related to an avolcanic passive margin. Helmand basin has a large depth range suggesting the presence of several sub-basins. The Farah and Rosgan basins show an overall shallow depth of magnetic basement but mean the basins show low averaged crustal magnetic susceptibility. This observation suggests the basin is covered by a thick sedimentary cover despite the presence of surface and interlayered igneous rocks.