Influence of the Hainan Plume on the Deep Thermal Structure and Shallow Geothermal Field of Southeastern Coastal China

Thermal anomalies within the lithosphere are an important manifestation of mantle plume–lithosphere interaction. Early studies primarily concentrated on the presence of the Hainan plume and its surface responses, with comparatively little research devoted to its hotspot track and lithospheric-scale thermal responses. Based on high-resolution seismic data, we reveal that, although a low-velocity anomaly caused by the plume exists in the asthenospheric mantle beneath Hainan Island (>70 km), no such anomaly is observed in the lithospheric mantle (40~70 km). In comparison, within the same depth slice, a low-velocity body in the lithospheric mantle (40~70 km) is observed beneath the Jiangxi–Fujian boundary, accompanied by high-surface heat flow, and its location is shifted approximately 1300 km to the northeast relative to the low-velocity anomaly in the asthenosphere located under Hainan Island. To explain the spatial offset of the low-velocity anomalies, we constructed a three-dimensional geodynamic model aimed at investigating the lithospheric thermal evolution during interaction between the stationary Hainan plume and the moving South China Plate. The findings indicate that the lithospheric low-velocity zone beneath the Jiangxi-Fujian region may be a consequence of the migration of the lithospheric thermal anomaly caused by the Hainan plume with the South China Plate.