同仁地区地下热水水化学特征及演化过程分析

Analysis of hydrochemical characteristics and evolution process of thermal groundwater in Tongren

为了查明同仁地区地下热水的形成机理及演化规律,本文在同仁地区采集81组天然温泉地热流体样品,进行水化学组分分析、同位素测年及水-岩平衡研究,以Na-K-Mg三角图法、多矿物平衡法等方法计算分析其热储温度,并通过管道模型初步计算地下热水循环深度。结果表明:同仁地区地下热水水化学类型以SO_(4)-Na型为主;该区地下热水未达到水岩平衡状态,地热流体处于不断地补给—径流—排泄过程中。在浅部循环冷水向深部循环热水的演变过程中,主要发生离子交换作用,引起Na^(+)含量增加,Ca^(2+)、HCO_(3)^(-)含量降低;深层地下热水补给区绝对海拔为2420-3510 m,年龄为11770-20280 a。

81 samples of natural hot spring geothermal fluid are collected and analyzed for hydrochemistry component analysis,isotope dating and water-rock balance in order to investigate the formation mechanism and evolution law of thermal groundwater in Tongren.The thermal storage temperature is calculated by using Na-K-Mg triangular method and multi-mineral balance method.The circulation depth of thermal groundwater is calculated by using pipeline model.The results show that the hydrochemistry of thermal groundwater in Tongren is mainly SO_(4)-Na;the thermal groundwater in the area has not reached the state of water rock equilibrium.The geothermal fluid is in the process of constant supply-runoff-discharge.Ion exchange mainly occurs during the evolution from shallow circulating cold water to deep circulating hot water,which causes the increase o Na^(+) content and the decrease of Ca^(2+) and HCO_(3)^(-)content.The absolute elevation of deep groundwater supply area is 2420-3510 m,and the age is 11770-20280 year.