Deep structure of the Rongcheng geothermal field, Xiongan New Area: Constraints from resistivity data and boreholes

Abstract

The development of the Xiongan New Area is China's exploration into the future of urban design, with plentiful geothermal resources serving as a crucial component for building a green, ecological and habitable city. However, the region currently lacks high-precision geophysical exploration research. The boundaries of each sub-tectonic unit and the unclear distribution of deep strata impede further drilling and efficient geothermal resources development. Wide field electromagnetic method (WFEM) provides superior detection depth and high precision compared to the traditional electromagnetic methods. We obtained a high-precision resistivity model of Rongcheng geothermal field through two WFEM survey lines (343 stations) for the first time. This model distinctly illustrates the stratigraphic framework of the Quaternary-Neogene-Jixian system, and accurately reveals the spatial locations of the Rongcheng Bulge, Niutuozhen Bulge, Niubei Slope, and the Dahezhen Depression within the Xiongan New Area. Moreover, the model provided a more precise representation of the faults and strata structure, reinforced by two boreholes. The low resistivity area within the Rongcheng Bulge has a large potential for geothermal resources. Conversely, the low resistivity area at a depth of 4000 m in the Niubei Slope was formed by fractures and groundwater activities, and presumed to be a water-rich area, indicating a favorable area for future geothermal investigation. Thus, our study can provide fundamental data for the upcoming geological researches and geothermal development in the Xiongan New Area.