Characteristics And Genesis Of Geothermal Field In Yunnan Tengchong Hot Haiti

The Rehai geothermal field lies about12km from the Tengchong Town, Southwestern Yunnan, China.The field is still very rich in active manifestations such as boiling spring, With tourism, agriculture and industry, power generation, medical, great potential for development.In this case,this paper focuses on the characteristics of the geothermal field and analyzing its formal modal of Rehai in Tengchong.In Tengchong region,,the structure movement is activity, the fault structure develops well,the magmatic activity is frequent and the igneous rock distributes extensively, the activity of cenozonic volcanoes and present-day hydrothermalactivity is intensive, the warm boiling spring is multitudinous.The Rehai geothermal has the heat-displaying which is one of most intense geothermal fields in Tengchong geothermal belt. The range of geothermal manifestation is:with Liuhuangtang and Songmuqing at its north and south ends respectively,with the Zhongxiao temple and Bajiao garden at its east and west ends.Not only there are many kinds of hot spring in the Rehai geothermal but also the steam ground, sinter, the spring rubber sandy conglomerate, fumarole as well as the hydrothermal alterations and so on.In the area it had been altogether discovered25hot springs, the hot water chemistry type by HCO3·Cl-Na and Cl·HCO3-Na (including Cl·CO3-Na) primarily, other hot water chemistry type includes:SO4-Na, HCO3-Na, Cl-Na, SO4·Cl-Na, HCO3-Ca, HCO3-Ca·Na·Mg and HCO3·SO4-Na.The hot water seepage temperature, the current capacity, the water chemistry component quite is stable, not along with seasonal variation.The geothermal field is in mid-north of the Tengchong-Longchuan hydrothermal activity belt, the heat source is the magma in the deep of earth’s crust, in the area the fault structure develops well in NS-trending and EW-trending,and the NS-trending structure is the main, the EW-trending fault is the secondary fault, which is often the most intense heat-displaying and distributes along the fault zonewith high temperature hot springs primarily. Its overlapping spot is the heat conduction and leads the water the good channel.Daying Jiang breaks and Zhongxiao temple-Dazhai breaks is the main heat-controlling structure.The isotope hydrogen content of hot water extremely closes the rain water, the surface water and the normal temperature ground water.It shows that atmosphere precipitation is the hot water main source of supply. The δD value of groundwater is higher than deep hot fluid21‰. So we infer the underground hot water not merely is supplied by the local precipitation military, simultaneously by the geographical position high mountainous area precipitation military supplies, also the military supplies area very possibly is located the far mountainous area granite area.Because thesandy conglomerateof Nanlin formation (N1n) which is the good cap rock of geothermal field cements closely, universal kaolinization, poor permeability, its fault zone constitutes the shallow heat reservoir.The inferior metamorphic rock of Gaoligong and LATE YANSHANIAN GRANITES are deep veinlike hot-reservoir and partial layered reservoir which develop the break, the jointing and the crevasse.They have provided the space for the hot water migration and the storage.With the C1-Na hot water of deep hot fluid in geothermal field in the upward, it forms the different hydrochemistry type along the O2content increases, rock lixiviation and the shallow cold water mixes in unceasingly.In the hot water, K, Na, Cl, HCO3, As, HBO2, SiO2, the hardness index, the PH value and so on have close relations of the water temperature, as a result of Inspissation, mixer action and other factor influence. It is a positive correlation, besides SiO2, other for logarithmic function relations.There is mixing with cold and hot water,the proportion of cold water is60%to70%. The chemistry components of hot water come from magmatic differentiation, rock lixiviation and normal temperature ground water drag-in.Through the Comparison of hydrochemistry type with Ruidian and Banglazhang geothermal field we know the lithology of reservoiris is LATE YANSHANIAN GRANITES.In the research area The geologic structure, formation lithology, hydro geological conditions, earthquake and magmatic activity and so on charge the geothermal fieldchanges.In area north ground temperature unusual overall tendency east high, south west low, the earth thermal current value is extremely high.According to the law of conservation of energy and the Fourier’s law we establish heat conduction mathematics relationship. The result of reservoir temperature, the stratum depth, the magmatic intrusion time is consistent with the conceptual modeland hydrology geology condition.Using the quartz temperature scale, K-Mg temperature scale,the isotope hydrogen characteristic, the tritium method,we get that the temperature of the shallow thermal reservoir is165℃and the deep thermal reservoir is250℃; The hot water depth of round is1461m; The mixed hot water age is bigger than for15years. Through analyzes the condition of the groundwater intake and runoff combined with the temperature and the deuterium value, the migration patternof Tengchong geothermal field is summarized mixed type and depth portion fluid.On the basis of the integration and summarization to previnus data, it was analyzed the regional geological condition,geothermy geology background, geothermy demonstration characteristic, geophysics characteristic as well as thermal fluid physical chemistry characteristic.In this foundation, this paper deep researches separately from the geophysics generalized analysis, the heat source, the hot liquid sources,the geothermal reservoir condition,, the hot channel, and aspects and so on to build conceptual model.This paper research the hydrogeochemistry and geothermal field in order to more powerful certificate the genetic models. The paper has studied the chemical type, the distribution law, the relationship between the chemical composition and temperature, chemical composition formation. It has been carried on the quantitative analysis to the thermal fluid mix model, established the thermal fluid chemistry model and determined the geothermal reservoir lithological character. All of these are the basic of establishing the condition for the ground temperature field and building the conceptual model. It has established the ground temperature field analytical model and has got the conclusion that the same as the hydrogrochemistry and genetic model form the geothermal field background, anomalous character,geothermal gradient characteristic, heat flow characteristic as well as ground temperature field influence factor. This paper calculated and analyzed the reservoir temperature, the thermal groundwater, the thermal fluid age,the thermal fluid migration model and established the genetic model in the foundation of the conceptual model, the hydrochemistry field, the ground temperature field.All of these provide scientific proof for the exploration and usage of the geothermal resources in the area.