Numerical simulation and thermal control factor analysis of deep high-temperature geothermal energy in the Zhenghe-Dapu fault zone and its adjacent areas, Southeast China

Abstract

The coastal area of Southeast China, characterized by high heat flow and extensive magmatic activity, has long been a focus of geothermal research. However, the formation mechanisms and geological controls governing deep high-temperature geothermal resources in this region remain poorly constrained, posing challenges for accurate resource assessment. Here, we built a two-dimensional lithospheric geological model integrating geological, seismic, and magnetotelluric data to quantify key thermal controls. Simulations reveal significant high-temperature anomalies in the Wuyishan and Coastal terranes, with temperatures exceeding 180°C at 5 km depth and surface heat flow surpassing 80 mW/m². These anomalies result from asthenospheric upwelling, facilitated by a thinned lithosphere, which delivers 73–92 mW/m² of mantle-derived heat flow. Additionally, Late Mesozoic-Cenozoic magmatic intrusion elevate shallow crustal temperatures by 31–43 °C, while the Zhenghe-Dapu shear zone with anisotropic high thermal conductivity along mylonitic foliation, acts as a deep heat conduit, forming localized 205 °C anomalies. Overlying low-thermal-conductivity sedimentary cover further insulates the system, sustains elevated temperatures, and modulates surface heat flow variations by ∼30 %. This study provides new constraints on deep high-temperature geothermal formation and offers key indicators for identifying favorable geothermal targets and optimizing resource assessment.