福建沿海地区是我国东南丘陵-沿海地带重要的地热异常区,其成因机制、热源构成一直是我国地热学界关注的重要课题。本文利用热、震、磁、重资料分析了该区地热异常的成因及热量来源。结果表明:福建沿海地区剪切波“低速走廊”与政和—大埔断裂带和滨海断裂带在深部形成的铲形逆冲断层相关,其东端向下至环太平洋地热带高温热源区,西端向上至漳州、福州地表地热异常区。居里面至莫霍面之间,地温增温平缓,不具备形成现代侵入岩体异常热源的条件。花岗岩放射性生热是地表热异常的重要组成部分,放射性元素热源深度小于5 km,地下水沿导热构造“汲取”围岩放射性生热量,向热田中心汇集形成高温区。我们认为:福建沿海地热异常区的热能由深、浅两种来源组成,深部热能来源于环太平洋高温岩浆,浅部热能来源于花岗岩放射性元素生热。深部热源的热量顺铲形逆冲断层向上传输到地表,浅部热源的热量由地下水汇集到地热田中心。

The Fujian geothermal anomaly area represents a significant geothermal anomaly region located in the southeastern coastal zone of China. The formation mechanism and composition of heat sources in this area have long been a focal point of theoretical and applied geothermal research. By utilizing thermal, seismic, magnetic, and gravity data, this study examines the heat source composition and genesis of the geothermal anomaly in the Fujian region. The analysis reveals the presence of a shear wave “low-velocity corridor” in the upper crust of the Fujian coastal area, which is associated with a regional listric thrust fault comprising the Zhenghe-Dabu fault zone and the Binhai fault zone. The eastern end of the listric thrust fault connects to the high-temperature zone in the Pacific, while the western end links to the geothermal anomaly area along the Fujian coast. The temperature gradient from the Curie depth to the Moho suggests a lack of conditions for abnormal heat source formation from modern intrusive rock masses. Notably, the radioactive heat generation from granite plays a crucial role in the thermal anomaly observed in this region, with the depth of the radioactive element heat source being less than 5 km. Groundwater acts as a conduit for absorbing radioactive heat from the surrounding rock along thermal conductivity structures, leading to the accumulation of heat and the formation of high-temperature centers. It is proposed that the geothermal anomaly area in the Fujian coastal region is influenced by both deep-seated and shallow heat sources. The deep heat source originates from the high-temperature magma in the Pacific Ocean, transmitted to the surface along the listric thrust fault. In contrast, the shallow heat source arises from the radioactive elements present in granite, with groundwater facilitating its transport to the geothermal field center. In summary, the heat in the Fujian coastal geothermal anomaly area is a result of the combined effects of deep-seated high-temperature magma and shallow radioactive heat sources. The upward transfer of heat from the deep source along the thrust fault, coupled with the collection of shallow heat by groundwater, contributes to the thermal dynamics of the region.