A Synthesis of Geophysical Data in Southeastern North China Craton: Implications for the Formation of the Arcuate Xuhuai Thrust Belt

The Xuhuai fold thrust belt (XHTB) is a curved structure in the southeastern margin of the North China Craton (NCC) that has attracted great attentions due to its tectonic and petrological characteristics. However, few geophysical studies have focused on the deep structure of this belt. In this study, we carry out a systematic demonstration of the main geophysical features that characterize the XHTB and surrounding areas. The results reveal small negative gravity and magnetic anomalies, thin crust and lithosphere, lower shear velocity and shallower earthquake epicenters relative to other areas of the NCC, collectively indicating a lithospheric-scale rheological anomaly at this belt. The magnetic alignments show a trend similar to that of geological units in southeastern NCC and adjacent areas, although they differ from the SKS-splitting fast polarization directions, except in the Qinling-Dabie orogen where a vertical coherent deformation of the crust and mantle may be involved there. Based on the geophysical data, we propose a detachment-controlled model, which was caused by the different detachment depth/strength, for the formation of XHTB to explain its arcuate shape as well as the magnetic alignments, thus providing new insight into the deep processes of southeastern NCC.