The ongoing India‐Asia collision since the Paleogene created the Tibetan Plateau, the most prominent elevated plateau on our planet. This convergence also contributed to the formation of two distinct types of active surface deformation of the plateau, namely, north–south trending normal fault systems and “conjugate” strike‐slip fault systems. The tectonics and geodynamic mechanism(s) behind this curious combination are still unclear, despite numerous theories proposed over past decades. Here we present a new three‐dimensional, lithospheric‐scale, electrical conductivity model with unprecedented resolution of the central part of Tibetan Plateau derived from the SINOPROBE magnetotelluric array data set and discuss its inferences related to this question. Our model reveals contrasting conductivity structures corresponding to the surface deformation patterns, namely, highly conductive lower crustal anomalies beneath the graben systems in the Lhasa and Qiangtang terranes and moderately resistive crustal features in the strike‐slip region near Bangong‐Nujiang Suture Zone. With the help of experimentally calibrated constraints between conductivity and melt fraction, the conductivity model and the inferred lateral viscosity distribution together suggest a weak lower crust beneath the graben regions, compared to a stronger crustal rheology associated with the strike‐slip zone. Here we expand the previously proposed “extensional extrusion” tectonic model in central Tibet to interpret our conductivity model and other geophysical/geodesic observations. The weak rheology under a N‐S directed primary stress may have caused the east–west extension of the graben regions, which further aides the eastward extrusion of the conjugate strike‐slip zone and eventually shapes the surface deformation of central Tibetan Plateau into its current, complex pattern.

A weak middle crust induced by fluid phases is generally considered to exist beneath the Himalayan‐Tibetan orogen; however, there remains controversy regarding the interpretation of high‐conductivity and low‐velocity regions imaged in various geophysical studies. To better understand middle crustal rheological behaviors and associated triggering mechanisms beneath southern Tibet, we present a geoelectrical model derived from a three‐dimensional magnetotelluric inversion in this study. An effective conductivity of 0.3 S/m at depths of 10–28 km indicates a high melt fraction of ∼35 vol% in the Lhasa terrane. In the Tethyan Himalayan orogen, an effective conductivity of <0.2 S/m corresponds to a melt fraction <15 vol%, which is lower than previous estimations. We obtain very low viscosities either from laboratory data (10¹⁰–10¹² Pa s) or empirical models (10¹⁶–10¹⁸ Pa s). A combination of radiogenic heat and strain heating may account for the weakened middle crust. We prefer a weak coupling between crustal east‐west extensions and mantle lithospheric deformations.

In the southern Tibetan plateau, which is considered to be the ongoing India–Eurasia continental collision zone, tracing of the Indian crustal front beneath Tibet is still controversial. We conducted deep subsurface electrical modeling in southern Tibet and discuss the geometry of the front of the Indian crust. Three areas along the Yarlung-Zangbo river zone for which previous magnetotelluric (MT) data are available were inverted independently using a three-dimensional MT inversion algorithm ModEM. Electrical horizontal slices at different depths and north–south oriented cross sections at different longitudes were obtained to provide a geoelectrical perspective for deep processes beneath the Tethyan Himalaya and Lhasa terrane. Horizontal slices at depths greater than − 15 km show that the upper crust is covered with resistive layers. Below a depth of − 20 km, discontinuous conductive distributions are primarily concentrated north of the Yarlung-Zangbo sutures (YZS) and could be imaged from mid- to lower crust. The results show that the maximum depth to which the resistive layers extend is over − 20 km, while the mid- to lower crustal conductive zones extend to depths greater than − 50 km. The results indicate that the conductive region in the mid- to lower crust can be imaged primarily from the YZS to south of the Bangong-Nujiang sutures in western Tibet and to ~ 31°N in eastern Tibet. The northern front of the conductive zones appears as an irregular barrier to the Indian crust from west to east. We suggest that a relatively less conductive subsurface in the northern portion of the barrier indicates a relatively cold and strong crust and that the front of the Indian crust might be halted in the south of the barrier. We suggest that the Indian crustal front varies from west to east and has at least reached: ~ 33.5°N at ~ 80°E, ~ 31°N at ~ 85°E, and ~ 30.5°N at ~ 87°E and ~ 92°E.

In development over 70 years, magnetotelluric (MT) sounding, a high-resolution technique for subsurface electrical resistivity imaging, has been widely applied in resource exploration in the Earth. The key factors of the metallogenic system of metallic mineral deposits can be closely correlated to the electrical anomalies of the lithosphere. In this paper, we review the relationship between the electrical resistivity model of the lithosphere and the metallogenic system. At the beginning, we indicate why the electrical parameters relate to the metallogenic system in all geophysical parameters. The advantage of MT sounding in sketching an electrical resistivity model of the lithosphere is subsequently discussed, and some methods of data processing, analysis and inversion are also introduced. Furthermore, we summarize how to bridge the relationship between the electrical resistivity model of the lithosphere and metallogenic system, and analyze the influence of the rheological variation estimated from conductivity in the lithosphere on mineralization. In the end, we list some typical cases of the application of MT sounding in mineral exploration, and also give some suggestions for future work. This study is aimed at providing guidance in discussing the metallogenic system using an electrical resistivity model.

Deep underground laboratories offer advantages for conducting high-precision observations of weak geophysical signals, benefiting from a low background noise level. Enhancing strong, noisy ground electromagnetic (EM) field data using synchronously recorded underground EM signals, which typically exhibit a high signal-to-noise ratio, is both valuable and feasible. In this study, we propose an EM field reconstruction method employing a Long Short-Term Memory (LSTM) recurrent neural network with referenced deep underground EM observations. Initially, a deep learning model was developed to capture the time-varying features of underground multi-component EM fields using the LSTM recurrent neural network. Subsequently, this model was applied to process synchronously observed strong, noisy data from other conventional observation systems, such as those at the surface, to achieve noise suppression through signal reconstructions. Both the theoretical analysis and the practical observational data suggest that the proposed method effectively suppresses noise and reconstructs clean EM signals. This method is efficient and time-saving, representing an effective approach to fully utilizing the advantages of deep underground observation data. Furthermore, this method could be extended to the processing and analysis of other geophysical data.