雷州半岛局部地热异常及其形成机制  

LOCAL GEOTHERMAL ANOMALIES AND THEIR FORMATION MECHANISMS ON LEIZHOU PENINSULA, SOUTH CHINA

作　　者：陈墨香[1] 夏斯高 杨淑贞[1] 

机构地区：[1]中国科学院地质研究所,北京100029

出　　处：《地质科学》1991年第4期369-383,共15页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金会;中国东南沿海地区地热研究和国家经委下达项目

摘　　要：雷州半岛地热场主要受基底构造格局的控制和地下水活动的影响,隐伏花岗岩体放射性元素生热对盖层地温的贡献不可忽视,第四纪更新世火山喷发活动的岩浆余热已几乎完全散失,岩浆体和围岩温度已趋于平衡。由火山喷发而形成的雷北螺岗岭和雷南石峁岭两个玄武岩台地,为半岛地下水的主要补给区,由于冷水流下渗的地温效应,新生界盖层浅部地温梯度<3℃/100m,呈现地热负异常。在以传导传热为主的区域,地热场特点与华北盆地相似,新生界盖层地温梯度与基底岩面的埋深密切相关。由于地壳深部较均一的热流在地壳表部再分配的结果,若干凸起区盖层地温梯度为4—5℃/100m,呈现地热正异常。某些控制凸起区的边界断裂,当深层热水沿其上涌,造成附加热源,和传导传热相叠加,盖层地温梯度可高达5—8℃/100m,形成更鲜明的地热正异常。Leizhou Peninsula as a land part of Beibuwan Basin is located on the northern continental shelf of South China Sea. According to the geologic structures, the basin is a stretch faul-ting-depression basin, most of the Cenozoic strata developed on the basement of the Paleozoic groups and the Yenshanian granites. The geohermal field is controlled mainly by the pattern of basement tectonics and influcened by ground water activity, but it cannot be ignored that the heat generation of radioactive elements in blind granites played a part here. The remained heat of the Pleistocene volcanic activities seems to be disappeared and thus a temperature balance is reached between magmatic rocks and their country rocks. The volcanic eruptions formed both the southern (Luogangling) and the northern (Shimoling) basaltic terraces, which are the intflow areas of groundwater. By the effect of downward cold water flow, the geothermal gradients are below 3℃/100m in the shallow part of the Conozoic cover, showing negative thermal anomalies. In the areas dominated by heat conduction, the geothermal field is similar to that in North China Basin, and the gradient of the Cenozoic cover is closely related to the depth of the bedrock roof. Because the uniform heat flow from the deeper crust was redistributed in the shallower Crust, the gradients in the cover on the several basement uplifts are in a range of 4-5℃/100m, showing positive thermal anomalies. In some fault zones bounded the uplifts, there are heat sources caused by upward hot water, which are superposed on the heat conduction, and the gradients are up to 5-8℃/100m, showing apparently positive thermal anomalies.

关 键 词：地热 异常 形成机制 雷州半岛 

分 类 号：P314[天文地球—固体地球物理学]