Abstract:

The Bohai Bay Basin (BBB) is located in the Beijing-Tianjin-Hebei region, which is one of the most important areas of developing hydrothermal energy in China. According to the classification of basin types, the BBB belongs to a Mesozoic-Cenozoic superimposed fault basin. The extension of lithospheric controls the distribution of sags in the basin, and meanwhile leads to volcanic activities that affects the distribution of igneous rocks. The Cenozoic volcanic activities were closely related to rifting and depression in different regions of the BBB. In the Paleogene, the BBB entered the initial stage of rifting, and the tectonic volcanic activities were intense. The volcanic rocks erupted along large faults in the basin and were widely distributed. In the Neogene, the basin entered a depression stage, and the intensity of tectonic volcanic activities were obviously weakened. Since the Quaternary, volcanic activities in the BBB were weak and volcanic rocks were sporadic distribution. Volcanic activities of Paleogene to pre-Quaternary in the BBB can be divided into five stages, in which the volcanic apparatus and volcanic rocks formed by Quaternary volcanic activities are mainly distributed in the areas of vicinity of Cangzhou City and the coastal areas of Bohai Sea. The calculation results of radioactive heat generation rate of the latest basalt samples of volcanic apparatus found in Dashan and Xiaoshan are 1.62 to 2.07 μW/m³ and 1.87 μW/m³, which are higher than the average heat generation rate of Cenozoic rocks (0.80 μW/m³) in BBB, and also higher than that of basalt volcanic rocks of Cenozoic in other parts of China. The heat generation rate shows that the volcanic rocks formed during the Quaternary volcanic active period may be used as additional heat sources, forming geothermal anomaly areas and even potential areas for exploration of modern volcanic hot-dry rock resources.

Key words: Bohai Bay Basin (BBB), Cenozoic volcanic rocks, volcanic apparatus, geothermal explorationpotential