鲁北平原阳信地区地热田地热地质特征及地热流体化学特征

Geothermal Geological Characteristics and Geothermal Fluid Chemical Characteristics of Geothermal Fields in Yangxin Area in Lubei Plain

山东省滨州市阳信地区在大地构造单元上位于惠民潜凹陷,北部边缘为无棣潜凸起,东部边缘为沾化潜凹陷,区内以沉降构造运动为主,形成巨厚的古近系、新近系和第四系沉积物地层,创造了地热资源形成的有利条件。阳信地区施工钻孔6眼,均揭露馆陶组热矿水,水温48~53℃,属于温热水型地热资源。地热流体化学研究显示,阳信地区地热流体为咸水,水化学类型为Cl-Na型,地热水中偏硅酸、锶、锂达到有医疗价值浓度标准,可用作理疗矿泉水。各样点的Na-K-Mg组离子分析显示,地热水属部分平衡水,溶解作用仍在进行。地热水同位素δ^(18)O和δ^(2)H接近大气降水线,表明区内地热水起源于大气降水。SiO_(2)温标对热储温度估算结果表明,T_(石英)=53.22~66.66℃,平均地温梯度为3.50℃/100 m,估算热循环深度为1146~1530 m。

Yangxin area in Shandong province is located in Huimin depression on the tectonic unit.Its northern edge is Wudi depression and the eastern edge is Zhanhua depression.The area is mainly characterized by subsidence tectonic movement,thick sedimentary strata of Paleogene,Neogene and Quaternary have been formed,and favorable conditions for the formation of geothermal resources have been created.6 construction boreholes have been drilled in Yangxin area,and all revealled hot mineral water of Guantao formation.The water temperature is 48~53℃,which belongs to warm water type geothermal resource.As showed by geothermal fluid chemistry,geothermal fluid in Yangxin area is saline water.Hydrochemical type is Cl-Na type.The concentration standards of metasilicic acid,strontium,and lithium in geothermal water can reach medical value.It can be used as therapeutic mineral water.Analysis of Na-K-Mg ions at various points shows that geothermal water belongs to partially equilibrium water,and dissolution is still ongoing.Geothermal isotopes of δ^(18)O and δ^(2)H are close to the atmospheric precipitation line.It is indicated that hot water in the area originates from atmospheric precipitation.The estimation results of SiO_(2) temperature scale for thermal storage temperature indicate that the temperature of quartz is 53.22~66.66℃,the average geothermal gradient is 3.50℃/100m,and the estimated depth of thermal cycle is 1146~1530 m.