Strain controls the electrical conductivity distribution in the lithosphere

Abstract Magnetotellurics (MT) utilize measurements of electromagnetic fields at Earth's surface to image the electrical conductivity distribution at depths from a few meters to ~200 km. MT is especially powerful for mapping mineralized fluid pathways, as it is sensitive to interconnected minor conductive phases such as fluids, melts, or sulfides. However, conductivity anomalies documented by lithosphere-scale MT surveys do not necessarily capture the geometry of conductivity structures at depth and are often hard to interpret. To address this limitation, we developed a new approach that integrates laboratory-based conductivity with 3-D thermomechanical modeling. Our aim was to test the relationship between strain and conductivity in the case of a pull-apart basin. We show that networks of high-strain zones, which largely govern fluid transfer across the lithosphere, exert a first-order control on spatial distribution of conductivity anomalies. When compared to real MT data from the Marmara pull-apart basin along the North Anatolian fault (northwestern Türkiye), our synthetic survey shows good agreement with observed conductivity anomalies. This relationship suggests that strain plays a key role in controlling electrical conductivity distribution in the lithosphere by facilitating the interconnectivity of conductive phases.