琼西南九所地热田水文地球化学特征及成因  

Hydrogeochemical characteristics and genesis of Jiusuo geothermal field in southwestern Hainan,China

作　　者：周艺颖 欧阳正平 徐子东 王文梅 杨勇昌 王江思 黄泽佼 马荣林 梁海艳 林毅 ZHOU Yiying;OUYANG Zhengping;XU Zidong;WANG Wenmei;YANG Yongchang;WANG Jiangsi;HUANG Zejiao;MA Ronglin;LIANG Haiyan;LIN Yi(Hainan Ecological Environmental Geological Survey Institute,Haikou 570206,China;Hainan Hydrogeological Engineering Geological Survey Institute,Haikou 570206,China)

机构地区：[1]海南省生态环境地质调查院,海口570206 [2]海南水文地质工程地质勘察院,海口570206

出　　处：《地质科技通报》2025年第1期216-228,共13页Bulletin of Geological Science and Technology

摘　　要：海南岛地热资源丰富,以往的地热勘查大多停留在生产层面,而对地热水化学成分的来源、水-岩作用、多方法评价热储温度和地热田成因机制等未深入研究。基于前人资料的深入分析,可以加深对成因机制的认识,为地热田开发提供参考。利用离子的比值及相关性、Piper图、F−浓度分布图、硅-焓图解与SiO_(2)混合模型和硅-焓方程法,探讨了九所地热田热水化学组分的来源、阳离子交换、F^(−)成因、热储温度和循环深度,提出了成因概念模型。结果显示:热水化学类型为SO_(4)·HCO_(3)-Na型;SO_(4)^(2-)主要源于安山岩、流纹岩区硫化物氧化;含F矿物溶解、离子交换是F−浓度的控制因素;热储温度99~169℃,冷水混合比例80%~93%,冷、热水混合前蒸汽损失的质量分数约10%;循环深度1.8~3.8 km。概念模型揭示:热水沿构造运移,从花岗岩区流向安山岩、流纹岩区,同时汲取热能,发生矿物溶滤和离子交换,导致F^(−)、SO_(4)^(2−)等组分浓度改变,引起水化学类型演化,在水力差和浮力差双重驱动下上升,于地下浅部与孔隙冷水混合存储于沉积盖层之下形成地热田。关于琼西南地热田的热源是否存在幔源热的问题目前没有充分证据,需进一步深入研究。Hainan Island harbors abundant geothermal resources.However,previous geothermal explorations have focused primarily on production,overlooking critical research areas such as the origins of geothermal water chemistry,water-rock interactions,methods for evaluating thermal reservoir temperatures,and mechanisms of geothermal field formation.[Objective]This study leverages existing exploration data to deepen our understanding of the genetic mechanism of geothermal fields and to offer valuable insights for their development.[Methods]We employed a range of analytical techniques,including major ion ratios and correlations,Piper diagrams,fluoride concentration maps,silicon-enthalpy and SiO_(2) mixing model graphs,silicon-enthalpy equations,and waterδD andδ^(18)O values.Focusing on the geothermal water of Jiusuo,we investigated the sources of chemical components,the cation exchange processes,the origin of F−events,the most likely reservoir temperatures,and the circulation depths of geothermal water,ultimately proposing a conceptual model explaining the genesis of the field.[Results]The results indicate that the hydrochemistry of geothermal water is mainly characterized by SO_(4)·HCO_(3)-Na type,with Ca^(2+)and Mg^(2+)replacing Na^(+)and K^(+)in the rock.The primary source of SO_(4)^(2-)is the sulfide oxidation of andesite and rhyolite.The fluoride concentration is regulated by the dissolution of minerals such as mica,amphibole,and fluorite,along with ion exchange and alkaline environments.The chemical composition is predominantly shaped by silicate mineral dissolution,ion exchange,and the degree of development of geological strata and structures.Most likely,when mixed with cold groundwater,the temperature range of geothermal water in this area falls to 99℃-169℃,with cold groundwater contributing 80%to 93%of the mix and approximately 10%steam loss prior to mixing.The circulation depth of geothermal water ranges from 1.8 to 3.8 km.[Conclusion]The proposed conceptual model suggests that the geothermal water in the Ji

关 键 词：九所地热田 地热水化学成分 离子交换 热储温度 热水成因模型 

分 类 号：P314.1[天文地球—固体地球物理学]