通过对良乡地热田中地热地质条件、地热水化学资料及DD、D18O、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 # SO42 Ca# Na# Mg 型为主, 同时地热水中含有氟、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2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14 C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2低山区。

Acco rding to the g eo thermal settings, hydrochemical dat a, and research o n the iso topes of DD, D18O, 3H, 14 C in geo ther2 mal water in the Liangx iang geo thermal field, the or igin, metamo rphism and evo lutio n, and hydro lo gical character istics o f iso2 to pes o f geot hermal water w ere investig ated. The results sugg ested that ( 1) the hydrochemistr y type o f g eothermal w ater in the Liang x iang g eothermal field is mainly H CO3 # SO42Ca# Na# M g, and the geo thermal w ater co nta ins miner al com ponents with medical benefits, especially chlo rine and metasilicic acid; ( 2) accor ding to the ana lysis o f ion concentrat ions, the geo thermal w a2 ter is lixiviated and belong s t o initially metamo rphic water ; ( 3) t he g eothermal water is immature based o n the w ater2r ock bal2 ance status; ( 4) the geothermal w ater is mainly fo rmed by t he mix ing o f g eo thermal heat source w ater and modern cir culating water supply fr om the southwest of Beijing multiphase fault2subsidence; ( 5) the age of g eothermal w ater is about 38 960? 630 years based on the iso tope analysis of 3H and 14 C; and ( 6) the recharg e elevatio n o f the geo thermal w ater is abo ut 620 to 730 m acco rding to the stable iso tope calculations o f ox yg en and hydrog en, and the r echar ge source is t he mountain ar ea w ith relativ ely low er elevatio ns in the southwest of Beijing.

中国地质调查局/ 全国地热资源调查评价) 北京市地热资源现状调查评价与区划0 项目( 水[ 2013] 0120292006)