良乡地热田地热水化学特征及同位素分析.doc

良乡地热田地热水化学特征及同位素分析
摘要:通过对良乡地热田中地热地质条件、地热水化学资料及δD、δ18O、3H、14C同位素的研究,阐述了良乡地热田地热水的起源、地热水的变质与演化、同位素水文特征。研究表明:良乡地热田中地热水化学类型以HCO3?SO4Ca?Na?Mg型为主,同时地热水中含有***、偏硅酸等多种有医疗价值的特殊组分;通过对地热水离子浓度分析,良乡地热田中地热水具有入渗溶滤水特征,为初期变质水。从水岩平衡状态上看,地热田中地热水为未成熟水;依据主要离子浓度和同位素分析,良乡地热田中地热水为地热热源水和来自北京迭断陷西南方向现代循环水补给的混合型;依据放射性同位素3H与14C确定了良乡地热田中地热水年龄为38 960±630 a;依据氢氧稳定同位素计算了地热水补给高程为620~730 m,推断补给区来源于北京市西南房山区相对高程较小的中低山区。
关键词:地热水;水化学特征;同位素;良乡地热田
中图分类号:P314 文献标志码:A 文章编号:16721683(2015)05096305
Hydrochemical characteristics and isotope analysis of geothermal water in Liangxiang geothermal field
LIU Yingchao,LIU Kai,SUN Ying,LIU Jiurong,GUO Gaoxuan
(Beijing Institute of Hydrogeology and Engineering Geology,Beijing 100195,China)
Abstract:According to the geothermal settings,hydrochemical data,and research on the isotopes of δD,δ18O,3H,14C in geothermal water in the Liangxiang geothermal field,the origin,metamorphism and evolution,and hydrological characteristics of isotopes of geothermal water were results suggested that (1) the hydrochemistry type of geothermal water in the Liangxiang geothermal field is mainly HCO3?SO4Ca?Na?Mg,and the geothermal water contains ponents with medical benefits,especially chlorine and metasilicic acid;(2) according to the analysis of ion concentrations,the geothermal water is lixiviated and belongs to initially metamorphic water;(3) the geothermal water is immature based on the waterrock balance status;(4) the geothermal water is mainly formed by the mixing of geothermal heat source water and modern circulating water supply from the southwest of Beijing multiphase faultsubsidence;(5) the age of geothermal water is about 38 960±630 years based on the isotope analysis of 3H and 14C;and (6) the recharge elevation of the geothermal
water is about 620 to 730 m according to the stable isotope calculations of oxygen and hydrogen,and the recharge source is the mountain area with relatively lower elevations in the southwest of Beijing.
Key words:geothe