Geological structure imaging from airborne electromagnetic and magnetic data, a case study in Kalat-e-Reshm area, Iran

In this paper, a set of airborne magnetic data and helicopter-borne frequency domain electromagnetic data are used in order to retrieve a joint model of magnetic susceptibility and electrical conductivity. The study area called Kalat-e-Reshm located in Semnan province of Iran consists of an arc-shaped porphyry andesite covered by sedimentary units which has high potential of mineral occurrences especially porphyry copper. Based upon Occam approach assuming a multilayered earth model with fixed thicknesses, a conductivity-depth plot from airborne electromagnetic data is generated to image the desired porphyry type geological structure. The 3D visualization of the 1D conductivity models along all flight lines provided a resistive geological unit which corresponds to the desired porphyry andesite. A multi-constraint method is also applied on the airborne magnetic data to recover a 3D distribution of magnetic susceptibility model which reveals extension of an arc-shaped porphyry andesite at depth. The high susceptibility, low conductivity porphyry andesite shows a thicker structure than what is shown on the geological map and extends to depth.