京津冀基岩区地热资源远景的地球化学区划

Geochemical regional planning of geothermal resource prospect in Beijing-Tianjin-Hebei bedrock region

利用区域地球化学资料,结合区域地质条件圈定地热远景区,可以对地热资源的潜力做出评价。根据资料研究,京津冀地区不同成因类型地热产地As、Sb、Bi、Hg、F、Li、Sn、U、Th等的低缓异常,对不同类型的地热区可能具有相应指示作用。各种类型地热区地球化学标型指示元素为:火山岩型Li?F?As?U,侵入岩型Sn?Bi?Li?Th?As,变质岩型F?Th,沉积岩型Hg?Li?As?U。根据相关分析,在地热水温度T与水系沉积物元素含量之间可建立回归方程,结果表明碱性岩浆热液活动和钼、银成矿作用的伴生产物为产热、导热岩层,沉积岩为隔热保温层。根据指示元素地球化学异常组合空间分布,京津冀基岩区共圈定地热远景区50处,这些远景区呈NE、NW和EW向展布,与深大断裂、燕山期中—基性岩浆岩分布关系密切。近年来的地热勘查活动证实,这一成果具有重要的指导作用。

By using regional geochemical data in combination with regional geological conditions to determine geothermal prospect are?as,researchers can evaluate the potential of geothermal resources.Data research shows that geochemical characteristics of geothermal areas of different genetic types in Jingjinji are different.The lower mild anomalies of As,Sb,Bi,Hg,F,Li,Sn,U,Th and other ele?ments may have corresponding indication effects to different types of geothermal areas.Various types of geothermal geochemical indica?tor elements are as follows:Li?F?As?U for volcanic rock type,Sn?Bi?Li?Th?As for invasive rock type,F?Th for metamorphic rock type,and Hg?Li?As?U for sedimentary rock type.According to the correlation analysis,the regression equation can be established between the geothermal water temperature T and the sediment element content in the water system sediments.It is indicated that the alkaline mag?matic hydrothermal activities and the associated products of molybdenum and silver mineralization are heat?producing and thermal?con?ductive rock formations,whereas the metamorphic rocks and the sedimentary rocks constitute the insulation and heat preservation lay?ers.According to the spatial distribution of the combination of geochemical anomalies of the indicator elements,a total of 50 geopoten?tial or dry?hot rock prospect areas were delineated in bedrock areas of Jingjinji.These prospective areas show NE,NW and EW distri?butions,which are closely related to the deep huge faults and the Yanshanian medium?basic magmatic rocks.Meanwhile,they are con?sistent with the distributions of geothermal anomalies in the plain areas.In recent years,geothermal exploration activities show that this result has played an important guiding role.