云南腾冲热海地热田特征及成因研究

【作者】 郭婷婷；

【导师】 徐世光；

【作者基本信息】 昆明理工大学 ， 地质工程， 2013， 博士

【摘要】 云南腾冲热海地热田位于腾冲县西南约12km,其地热流体温度高,表现形式复杂丰富,具有旅游、工农业、发电、医疗等方面开发的巨大潜力。因此,热海地热田特征及成因的研究具有重要的意义。腾冲地区构造运动活跃、断裂构造发育、岩浆活动频繁、火成岩分布广泛、新生代火山活动、现代水热活动异常强烈,温沸泉众多。热海热田是腾冲地热带热显示最强烈的热田之一,地热田地热显示范围为：北起硫磺塘、南至松木箐,东起忠孝寺,西抵芭蕉园的沟谷地带,面积约1.7km2。热海热田内不仅有各种不同温度的热泉,而且有冒汽地面、泉华、泉胶砂砾岩,喷气孔以及岩石水热蚀变等。区内共发现热泉25个,热水化学类型以HCO3·C1—Na型和C1·HCO3—Na型(包括C1·CO3—Na)为主,其它热水化学类型有：SO4—Na型、HCO3—Na, C1—Na型、SO4·C1—Na型、HCO3—Ca型、HCO3—Ca·Na·Mg型和HCO3·SO4—Na型。热泉水温度、流量、水的化学组份比较稳定,不随季节变化。热田处于腾冲—陇川水热活动带中北部,热源为地壳深部的岩浆,区内南北向、东西向断裂发育,近南北向的断裂是热田构造的主体,东西向断层是热田次级断层,往往是地表热显示最强烈的地方,大量热显示均沿断层带分布,并以高温热泉为主,其交叉部位是导热、导水的良好通道,大盈江断裂和忠孝寺—大寨断裂,是主要的控热构造。研究区地热水的氢氧同位素组成与雨水、地表水、常温地下水非常接近说明大气降水是地热水的主要补给来源。区内地下水的δD值相对于深部热流体的δD值高21‰,推断地下热水并不仅仅是由当地的降水补给,同时由地理位置较高的山区降水补给,且补给区很可能位于北东部较远山区的高黎贡山群变质岩区。因南林组(N1n)砂砾岩胶结较紧密,普遍高岭土化,渗透性差,是热田的良好盖层,其断层带构成浅层热储,下部的高黎贡山变质岩和燕山晚期花岗岩经多次构造运动影响,断裂、节理、裂隙发育,为热水的运移和储存提供了空间,形成深部脉状热储和局部层状热储。热田深部热流体C1—Na型热水在向上运移过程中,随着02含量的增加、岩石的溶滤和浅部冷水的不断混入形成不同的水化学类型。热水中,K、Na、C1、 HCO3、As、HBO2、SiO2、矿化度、PH值等与水温关系较密切,由于浓缩作用、混合作用和其它因素的影响,一般呈正相关关系,除SiO2外,其余均为对数函数关系。热田内存在“冷”、热水混合作用,冷水混合比例为60%到70%。地热水的化学组份主要来源于岩浆分异、岩石溶滤和常温地下水的带入。通过对周边瑞滇热田和邦腊掌温泉水化学类型的比拟推断热海热田地区热储岩性主要为燕山期花岗岩与概念模型中得出的结论相符合。研究区内的地质构造、地层岩性、水文地质条件、地震和岩浆活动等直接控制着地温场的变化。区内地温异常总体趋势北东高,南西低,大地热流值极高。根据能量守恒定律与傅里叶定律建立热传导数学关系式,对热储温度、地层厚度、岩浆侵入时间进行了计算,得出了与概念模型相吻合的结论,符合研究区水文地质与地热地质条件。文章利用石英温标和钾镁地热温标、氢氧同位素特征、氚法测年进行计算得出浅层热储为165℃,深层热储为250℃：热水循环深度为1461m；混合后热海热田区混合热水年龄大于15年。通过对地下热水的补给和径流条件分析并结合热水的温度和氘值,将腾冲热海热田地区划分混合型和深部流体型两种运移模式。本文在收集整理和综合分析前人资料的基础上,系统分析了区域地质条件、地热地质背景、地热显示特征、地球物理特征以及热流体物理化学特征。在此基础上,分别从地球物理综合分析、热源、热流体来源、热储条件、热通道及盖层等方面进行了深入研究建立了热海地热田的概念模型。文章为了更深入的研究热海地热田的成因模式,又分别对化学场和地温场进行了研究。通过对化学场的化学类型成因、分布规律、化学组份与水温的关系、化学组份的形成、混合模型的定量分析,建立了热流体化学模型,确定了热储岩性,为地温场的模拟奠定了条件并进一步验证了概念模型的正确性。后又从地温场的背景、异常特征、地温梯度特征、大地热流特征以及地温场的影响因素着手,建立了地温场解析模型,得到了与化学模型、概念模型基本吻合的结论。本文在综合分析研究概念模型、水化学场、地温场的基础上对热储温度、热水循环深度、热流体年龄及热流体的运移模式进行了计算、分析并建立了热海热田成因模型,以集中展示地热田的特征和成因机制,为本区的地热资源开发利用提供科学依据。更多还原

【Abstract】 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.更多还原