Crustal structure and tectonic inheritance in the eastern Yangtze Craton: Reworking history of a buried Paleoproterozoic orogenic belt

After subduction of the oceanic plate and continental collision, ancient orogenic belts could be reactivated as intracontinental orogens or rift zones. These intracontinental weak zones often experienced multiphase deformation, magmatism, erosion and sedimentation, which raise ambiguity in interpretation of geological records. The Xuefengshan belt in central South China is generally regarded as the Early Neoproterozoic collision zone between the Yangtze and Cathaysia blocks, and behaved as the western boundary of the widespread Mesozoic deformation and magmatism in South China. However, recent study found SE-dipping mantle reflections beneath the eastern Yangtze Craton, suggesting a fossil subduction zone during the assembly of the Yangtze Craton. Here we combined a 2400-m-deep borehole in the Xuefengshan belt, high-resolution deep seismic and electrical structures, rock physics, and geological data to investigate the crustal structure of the eastern Yangtze Craton. Our results confirm the buried Paleoproterozoic orogen beneath Neoproterozoic strata of the eastern Yangtze Craton. The variations of the Moho depth and the lithospheric thickness, distribution of seismic reflections, low velocity anomalies and high conductivity anomalies in the Xuefengshan belt reveal multiple reworking events, including the Neoproterozoic intracontinental rifting and crustal thinning, the Triassic thrusting, magma underplating and granite intrusion, the basement-involved fold-and-thrust belt in the Mid-Late Jurassic, as well as crustal extension and graben development in the Cretaceous. Therefore, the Xuefengshan belt provides a unique example how tectonic inheritance controlled crustal reworking of an intracontinental orogenic belt.