Magnetotelluric Evidence for Lithospheric Alteration Beneath the Wuyi?Yunkai Orogen: Implications for Thermal Structure of South China

The Wuyi-Yunkai Orogen experienced a polyphase tectonomagmatism and is key region for deciphering the alteration thermal structure of South China Block lithosphere. Herein, an electrical resistivity model lithosphere presented via three-dimensional inversion broadband (0.003–3600 s) magnetotelluric (MT) data collected along 380-km-long profile comprising 62 MT sites across Orogen, robustness this critically evaluated through series sensitivity tests. reveals that upper crust Cathaysia dominated by high-resistivity sedimentary cover interposed with low-resistivity features, mainly fault zones. High-resistivity bodies strong conductors in are interpreted as magmatic rocks tectonic mélanges, respectively. Another feature presence zones featuring enhanced conductivity (<30 ?m) extending from lower to mantle beneath Orogen. attributed saline fluids either dehydration subducting Paleo-Pacific slab or regional metamorphism-induced sandy argillaceous rocks. In contrast, 4%–7% partial melt, which corresponds analyses xenoliths China. These supply volatiles heat shallow geothermal systems. This work ultimately shows lithospheric thinning controlled upwelling caused retreat slab.