广东惠州黄沙洞地区地热资源地球化学勘探方法研究

Geochemical exploration of geothermal resources in the Huangshadong Area,Huizhou,Guangdong:A methodological study

地热地球化学探查技术是地热探测技术的一种,其勘探方法包括各种土壤化学元素(Hg、As等)测量法、气体(Rn、H_(2)、CH_(4)等)测量法、地温测量法等。利用热释汞、地温、氢(H_(2))、氡(Rn)等方法和指标对广东惠州黄沙洞地区进行地热资源勘探,结果表明:研究区内热释汞、地温等指标的高值点具有很好叠合性,呈北西、北东向近似交叉“十”字型展布特征,它们与区域内北东向潼湖大断裂带(地热通道)中北北西向隐伏花岗闪长岩岩株(地热源)分布走势相一致,它们有效地指示了地热水沿断裂通道(断裂破碎带、大的裂缝及裂隙)向上迁移泄漏特征,地热水(地热载体)沿北东向主断裂带及大的北西向裂缝、裂隙泄漏是上述指标高值异常成因。lgH_(2)指标局部高值呈北西向分布于中部,它与热释汞、地温在此处有高度重叠;lgRn指标值与地热源(岩浆岩体是Rn物质源)、垂向渗漏方式、地热水携带迁移散失作用等因素相关,lgRn指标与lgH_(2)指标相关分析值为负值。热释汞、地温、Rn、H_(2)等地化指标为黄沙洞地区地热资源勘探提供了良好的地球化学应用依据。

As one of geothermal exploration technologies,geothermal geochemical exploration technology includes a variety of soil chemical element survey methods(Hg,As,etc.),gasometry(Rn,H_(2),CH_(4),etc.),geothermometry,etc.Geothermal resources in the Huangshadong area of Huizhou,Guangdong Province were explored by means of thermally released mercury,geothermal temperature,hydrogen(H_(2)),radon(Rn)and other methods and indicators.The results show that the high values of mercury release and geothermal indexes in the study area have a good overlap,showing an approximate"cross"pattern in the direction of NW and NE,which is consistent with the extension of the concealed granodiorite stock(geothermal source)in the regional northeast-trending Tonghu major fault zone(geothermal channel),effectively indicating the upward migration and leakage characteristics of geothermal water along the fracture channel(fracture zone,large crack and fissure).Geothermal water(geothermal carrier)leakage along the northeasterly major fault zone and large northwesterly crack and fissure is the cause of high abnormal values of the above indexes.The local high values of lgH_(2) index were distributed in the middle of the region in a NW direction,and they overlapped with mercury release and geothermal indicators.The lgRn index value is related to such factors as geothermal source(magmatic rock mass is material source of Rn),vertical leakage mode,and carrying,migration and dissipation of hydrothermal water.The correlation analysis value of lgRn index and lgH_(2) index is negative.Mercury release,geothermal temperature,Rn,H_(2) and other geochemical indexes provide good geochemical basis for geothermal resource exploration in the Huangshadong area.