Sub-basalt imaging in the Southeast Anatolian Orogenic Belt using three-dimensional magnetotellurics

Abstract

The Southeast Anatolian Orogenic Belt, including the Bitlis–Zagros fold-and-thrust system, is a major collisional domain formed by intense compressional tectonics. In this setting, the Karacada? Volcanic Complex, the largest basaltic province in the region, overlies deformed Mesozoic–Cenozoic successions and masks potential hydrocarbon-bearing strata. To image the concealed subsurface, broad-band magnetotelluric (MT) data from 63 sites were used to construct the first three-dimensional (3D) resistivity model of the area. The model delineates the resistivity distribution associated with the main lithological units and identifies thick (~3 km) sedimentary sequences beneath a highly resistive volcanic cover. The low resistivity (<10 Ωm) Lower Maastrichtian Kastel Formation likely acts as a regional cap rock, whereas the moderately resistive Aptian–Cenomanian Mardin Group carbonates, overlying the organic-rich Silurian–Lower Devonian Dada? Formation, may represent potential reservoir units. The resistivity distribution exhibits gently varying resistivity geometries compatible with fold-and-thrust-related deformation, which could favor the development of structural closures. This study highlights the effectiveness of 3D MT inversion for imaging sedimentary architectures beneath volcanic cover and demonstrates its value as an exploration tool in fold-and-thrust and volcanic-dominated settings where seismic methods are limited.