Crustal structure of the Xuhuai Arc Tectonic Belt

The Xuhuai Arc Tectonic Belt (XHTB), located along the southeastern margin of the North China Craton (NCC) west of the Tan-Lu Fault Zone (TLFZ), remains poorly understood in terms of its formation mechanisms due to limited constraints on deep crustal architecture. In this study, we apply the receiver function method to teleseismic data recorded by 127 permanent broadband stations to estimate crustal thickness and average Vp/Vs ratios across the study region. Our results reveal a regional mean crustal thickness of 32.5 ± 2.0 km (range: 27.5–37.5 km) and an average Poisson’s ratio of 0.254 ± 0.018, with noticeable east-west structural heterogeneity across the TLFZ. The TLFZ is characterized by intermediate crustal thickness relative to adjacent blocks and the highest observed Poisson’s ratio (0.272 ± 0.011), supporting its interpretation as a trans-crustal, likely lithospheric-scale fault zone. The XHTB exhibits a distinctive combination of relatively thin crust and elevated Poisson’s ratio, plausibly consistent with lower crustal modification via mafic magma injection during Mesozoic tectonic activity. These findings provide new observational constraints on the deep structure of the TLFZ and the tectonic evolution of the XHTB.