Mapping Basement Terranes in Eastern Arabian Basin Using 3D Inversion of Magnetic Data

Eastern Arabian Basin basement terranes are not exposed and poorly observed on seismic data due to the challenges presented by the thick Phanerozoic sedimentary cover. The identification of basement terranes has been done previously through qualitative interpretation of magnetic data. In this paper, a 3D inversion of magnetic data is used to estimate the lateral changes in magnetic susceptibilities on an interpreted depth to basement surface. The estimated magnetic susceptibilities are classified to represent the basement terranes. The top basement surface in Eastern Arabian Basin was mapped using 3D inversion of gravity data constrained by depth controls from wells and depth estimates from interpretation of magnetic data. Then another 3D inversion of magnetic data is utilized to estimate the intra-basement lateral susceptibility variations. The estimated susceptibility variations are linked directly to the magnetic mineral content of the basement layer, reflecting different terranes and being associated with significant changes in the basement composition. Phase and amplitude derivatives (tilt and theta), were applied to the estimated susceptibilities to allow for terrane boundary definition and mapping. The estimated susceptibilities were classified into 12 different unique groups based on the boundaries defined by the applied derivatives. The newly interpreted basement terranes are trending N-S, NW-SE, and NE-SW. Mean susceptibilities have been extracted for each terrane and possible rock composition have been highlighted. High susceptibility values are found in the eastern part of the basin, contradicting previous qualitative analysis. The new approach highlights possible insights for basement composition and thermal structure.