大峡水电站坝址区岩性为前寒武系黑云母角门石英片岩，岩石节理、片理不甚发育，断裂构造规模不大；岩体呈弱～微风化，风化较浅，质地致密均匀、坚硬完整；地下水为第四系松散层中的潜水与基岩裂隙水，呈弱碱性，有硫酸盐侵蚀性。总体来说，大峡水电站坝址具有优良的工程地质 The lithology of the dam site of the Daxia Hydropower Station is the Precambrian biotite corner quartzite schist, which is not well-developed in the rock joints and is not well developed in scale. The rock mass is weak to slightly weathered and has a low degree of weathering, dense and uniform texture, Complete; Groundwater Quaternary loose layer of submersible and bedrock fissure water, was weakly alkaline, sulfate-aggressive. Overall, Daxia Hydropower Station dam site has excellent engineering geology