Mandula−Tongchuan−Fuling ultra-long seismic profile: undulating crystalline basement of basins-mountain coupling chains and mineral resources

The Mandula-Tongchuan-Fuling ultra-long seismic profile spans a total length of 1700 km, traversing from north to south through the Yin Mountains Orogenic Belt, the Ordos Basin, the Qinling Orogenic Belt, and extending to the southern edge of the Sichuan Basin near Fuling, with a diverse interlacing of basin and mountain systems. Based on the upper crustal velocity structure image using the refraction seismic data of this profile, our study has confirmed that: (1) The Qinling-Daba Orogenic Belt belongs to the same crystalline basement. The basin-mountain zone basement is highly undulating and orderly, forming a coupled chain of diverse basin-mountain sequences; (2) The two major basins have thick depressions cut by faults, with the crystalline basement layers whose depth reaching 4.0 ~ 6.0 km (Ordos Basin) and 6.0 ~ 10.0 km (Sichuan Basin); (3) Along the profile, the southern two orogenic belts are metallogenic belts, while the two sedimentary basins are areas for the accumulation and storage of oil and gas (or enrichment areas).