Thermal Properties and Geothermal Effects of Magmatic Rocks in Jiangsu Province, China

(1) Background: Geothermal resources are enriched in Jiangsu Province, particularly in its mid-deep geothermal reservoirs. The thermal properties and thermal effects of magmatic rocks, which are largely unknown in Jiangsu Province, are fundamental for analyzing the genetic mechanisms of geothermal resources and evaluating resource potential. (2) Methods: Representative magmatic rock samples from different geological periods and different tectonic settings are collected from the main tectonic units of Jiangsu Province. Key thermophysical parameters such as thermal conductivity, heat production rate, rock density, and porosity are systematically tested. (3) Results: The variation patterns of these thermal property parameters are analyzed, and the sources and spatiotemporal evolution characteristics of radiogenic heat production, and the thermal effects of magmatic rocks, are specifically explored. (4) Conclusions: Magmatic rock lithology from acidic to basic is negatively correlated with thermal conductivity, thermal diffusivity, and radiogenic heat production rate, and positively correlated with volumetric heat capacity. The radiogenic heat production of magmatic rocks is primarily controlled by the contents of U and Th, increasing with the increasing SiO2 content. The formation of geothermal anomalies in areas with thin or absent sedimentary cover is significantly influenced by the thermal effect of magmatic rocks, especially by the high heat-producing granites. The radioactive thermal contribution of the Taolin and Suzhou plutons was calculated.