Revealing fine-scale crustal structure and tectonic features in the Xiong’an New Area and its periphery using deep seismic reflection profiling

As an effective method to accurately reveal the deep geological structures and tectonic features of the Earth, deep seismic reflection profiling has been increasingly applied to the exploration of the continental and oceanic crusts, as well as the upper mantle of the lithosphere, making it internationally recognized pioneer technique for deep Earth exploration. This study examined the deep seismic reflection profile spanning across the Xiong’an New Area in Hebei Province, aiming to reveal the crustal structure and tectonic features of the study area. Key findings are as follows: (1) The crust in the study area can be divided into the upper and the lower crusts, with average thicknesses of approximately 18 km and 16 km, respectively and an average Moho depth of around 34 km. (2) In the upper crust, the sedimentary strata above the crystalline basement exhibit high stratification, strong reflected energy, and intricate structural characteristics. Faults are well-developed in the upper crust, exhibiting various morphologies and dislocation depths, with no deep-seated faults. The major faults encompass the Niudong, Niubei, Rongdong, Rongcheng, and Rongxi faults and the Taihang Mountain piedmont fault from southeast to northwest. (3) In the lower crust, the northwestern and southeastern portions of the deep seismic reflection profile are subjected to different tectonic stresses. Consequently, the northwestern and central segments manifest relatively simple seismic reflection features, reflecting relatively stable overall tectonics in the Xiong’an New Area. In contrast, the southeastern segment of the profile exhibits pronounced imbricate reflections, mirroring the lateral heterogeneity and local activity of the lower crust. These results will provide reliable data support for the overall planning and construction of the Xiong’an New Area and for the building of geological information platform Transparent Xiong’an, which involves survey depths of 10 000 m.