滇东南楔形构造区典型地热流体地球化学特征研究*

(1.中国地震局地球物理研究所,北京 100081; 2.云南省地震局,云南 昆明 650224; 3.中国地震局地壳应力研究所,地壳动力学重点实验室,北京 100085)

地热流体; 地球化学特征; 水岩反应; 热储温度; 滇东南

Study on Geochemical Characteristics of Geothermal Fluid in the Wedge-shaped Tectonics,Southeast Yunnan
WANG Yun1,2,3,ZHAO Ciping2,LI Qilin2,LIU Yaowei3

(1. Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)(2. Yunnan Earthquake Agency,Kunming 650224,Chin)(3. Key Laboratory of Crustal Dynamics,Institute of Crustal Dynamics,China Earthquake Administration,Beijing 100085,China)

geothermal fluid; geochemical characteristics; water-rock interaction; thermal reservoir temperature; Southeast Yunnan

备注

对滇东南楔形构造区内4个地震宏观观测点地热流体取样分析及地球化学特征进行研究,水化学特征表明,4个泉点中的主量离子组分主要来自地表水对围岩地层中方解石、白云石和石膏等矿物的溶滤,表明主要离子具有浅层成因。除曲江温泉水岩作用达到部分平衡外,其余3个泉点均未达到平衡。结合硅焓模型判断,4个泉点具有不同程度的冷水混入。估算曲江温泉、热水塘火车站温泉及海口温泉的循环深度为5~10 km,属于断裂深循型地热系统; 气体地球化学特征表明,曲江温泉逸出气主要是大气源、有机源和壳源的混染,喷珠池的逸出气的成因主要是地壳无机变质,其余2个泉点的气体均不具有幔源特征。

In this study,geothermal fluid sampling analysis and geochemical characteristics of four seismic macroscopic-observed sites have been conducted in the wedge-shaped tectonics,Southeast Yunnan. The feature of water chemistry shows that the main ions of four springs have shallow formation characteristics,because they are derived from the leaching of minerals such as calcite,dolomite and gypsum in the host rock strata. Except for the Qujiang Hot Spring,where water-rock interaction reached the partial equilibrium,the remaining three springs did not reach the partial equilibrium. Combination with estimation of silica-enthalpy model,four springs are mixed by surface cold water in some degrees. The Qujiang Hot Springs,Railway Station Hot Spring and Haikou Thermal Spring are the deep-circulation type geothermal system in the light of their circulation depth between 5 km and 10 km. Gas geochemical characteristics show that free gas from the Qujiang Hot Spring is the mixture of atmosphere,organic source and crust-derived,while free gas form the Penzhu spring is mainly the origin of the crustal inorganic metamorphism. Both of the spring gases did not show mantle-derived characteristics.