鄂东英山东河一带地下热水化学特征及成因

Hydrochemical characteristics and genesis of geothermal water in the area of Dong River in Yingshan,eastern Hubei

鄂东英山东河一带地热资源丰富,具有良好的地质成热条件和资源开发利用前景,但以往研究中对于地下热水来源及成因认识不足。以鄂东英山东河一带为研究区,采用Piper三线图解、矿物饱和指数计算、离子比例系数分析、反应路径模拟等方法,探究研究区地下热水演化特征,并利用氢氧同位素识别地下热水来源,综合多研究成果建立研究区地下热水成因的概念模型,分析研究区地下热水的成因机制。研究表明:研究区内地下热水水化学类型主要表现为SO_(4)-Na型,其次为HCO_(3)·SO_(4)-Na型;各地热田水化学演化过程相似,主要水-岩作用为石膏、长石类矿物的溶解以及阳离子交换作用;研究区地下热水成因的概念模型为研究区北部、东北部约800 m高程以上山区大气降水沿区内NNE或NE断裂径流,并在深循环加热条件下发生石膏、长石等矿物的溶解以及阳离子交换作用,地下热水在研究区中部及南部低处(草盘地、杨柳湾及温泉镇周边地区)沿断裂裂隙带上涌,形成鄂东地区一系列演化模式相似、空间上相对独立的地热系统。研究结果可为研究区地热资源进一步开发利用提供科学依据。

Dong River in Yingshan County in eastern Hubei Province is rich in geothermal resources,and has good geological heat generation conditions and resource development and utilization prospects.Taking Dong River as the research area,this paper explored the evolution characteristics of geothermal water by the Piper three-line diagram,saturation index calculation,ion ratio,and reaction path simulation method,identified sources of geothermal water using the hydrogen and oxygen isotopes,and established a concep-tual model of geothermal water in the study area based on more comprehensive research,which provides a scientific basis for further exploitation and utilization of geothermal resources in Yingshan Dong River area in eastern Hubei Province.The research shows that the chemical type of groundwater in the study area is mainly SO_(4)-Na type,followed by HCO_(3)·SO_(4)-Na type.The hydrochemical evolution process of thermal fields in various regions is similar,and the main water-rock interactions are the dissolution of gypsum and feldspar minerals and cation exchange.The conceptual model of the origin of groundwater in the study area is as follows:atmospheric precipitation over 800 m in the north and northeast of the study area flows along the NNE or NE faults in the area,and the dissolution of gypsum,feldspar and other minerals and cation exchange occur under deep cycle heating conditions.As a result,geothermal water rises along faults and fissures in the central and southern low places of the study area(Caopandi,Yangliuwan,and surrounding areas of Wenquan Town),forming a series of geothermal systems with similar evolution patterns and relatively spatial independence.The research results can provide scientific basis for the further development and utilization of geothermal resources in the study area.