Phase-referenced static shift correction and Magnetotelluric inversion under strong static shift conditions: Assessment with synthetics and application to the Wanzhou–Yiyang profile, South China

Static shift is a pervasive near‑surface effect that degrades the reliability of Magnetotelluric (MT) imaging, particularly in structurally complex terrains with heterogeneous cover. We develop and test a three‑stage workflow for MT inversion under strong static shift: (i) construction of a prior‑constrained regional resistivity model; (ii) phase‑referenced correction in the apparent‑resistivity domain using reference curves; and (iii) joint inversion with explicit static‑shift parameterization. Synthetic tests based on finite‑difference forward modelling and nonlinear conjugate‑gradient inversion show that, in static‑shift‑free data, TE + TM with gradient regularization best recovers the target structure. Under strong static shift, the phase‑referenced correction combined with parameterized inversion markedly reduces artefacts and improves deep resolution relative to conventional inversion. Applied to an MT profile across the Wanzhou–Yiyang segment (central Jiangnan Orogen, South China), the preferred workflow yields a crustal model characterized by lateral compartmentalization and vertical layering above ∼ 40 km, with continuous deep conductors beneath the Qiyueshan faults (QYSF) and Zhangjiajie faults (ZJJF). These conductors agree with seismic constraints and, together with stream‑sediment and isotopic geochemistry, are interpreted as lithospheric‑scale pathways focusing ore‑forming fluids within the western Hunan–western Hubei metallogenic belt. The workflow provides a practical reference for MT imaging and metallogenic studies in regions affected by strong static shift.