| 水化学温度计估算粤西沿海深部地热系统热交换温度 |
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| 引用本文： | 郭静,毛绪美,童晟,冯亮.水化学温度计估算粤西沿海深部地热系统热交换温度[J].地球科学,2016,41(12):2075-2087. |
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| 作者姓名： | 郭静 毛绪美 童晟 冯亮 |
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| 作者单位： | 中国地质大学环境学院，湖北武汉 430074 |
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| 基金项目： | 国家自然科学基金项目40602031国家自然科学基金项目41440027 |
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| 摘 要： | 在实际案例分析中，采用传统地球化学温标计算的温度与实测温度往往有一定的差距，研究系统中矿物-流体的平衡状态、判断作为估算热交换温度的地热温标是否使用、选出最合适的计算结果非常重要.在讨论热水与矿物的平衡状态时，采用Na-K-Mg三角图解法和PHREEQCI程度模拟计算矿物饱和指数的方法进行研究，结果表明:(1) 粤西沿海地热系统采集的23组水样的分析发现其热水水化学特征为热水呈中低温弱碱性、氟含量较高源于热水与花岗岩的水岩相互作用、由内陆至沿海地区水化学类型由HCO3·Cl-Ca·Na型向Cl-Na型转化；(2) 浅层水的混合使得硅温标的估算值低于实测温度；只有21号水样适合用阳离子温标，其热交换平衡温度为150~170 ℃；1号和19号样可用K-Mg温标计算其热交换温度下限值，分别为136.2和151.6 ℃，其余水样则适合用log(Q/K)-T平衡法估算，深部热水在经历深循环后上升至地表，在浅层受到冷水混合.
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| 关 键 词： | 热交换温度 水化学温度计 Na-K-Mg三角图 矿物饱和指数 热泉 环境地质 地球化学 |
| 收稿时间： | 2016-01-22 |
Using Hydrochemical Geothermometers Calculate Exchange Temperature of Deep Geothermal System in West Coastal Area of Guangdong Province |
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| Abstract: | The estimated temperatures by traditional geochemical geothermometers and borehole temperatures are always different in practice. It is important to decide the equilibrium between minerals and fluids, determine the application of geothermometers for calculating heat exchanging temperatures, and choose the most suitable results. In this study, both Na-K-Mg triangular diagram and PHREEQCI code that simulate minerals saturation indexes were used to judge the equilibrium state between hot waters and minerals. The results show that: (1) the 23 water samples collected from the deep geothermal system in west coastal area of Guangdong Province are characterized by middle-low temperatures with weak alkalinity, high content of fluoride derived from the water-rock interaction between underground water and granite, and the transition of hydrochemical type from HCO3·Cl-Ca·Na to Cl-Na in groundwater from inland to coastal area; (2) Hydrochemical geothermometer temperature estimations show that the mixture of shallow water with deep water leads to the lower silica geothermometer temperatures than the actual ones. Only sample 21 with a subsurface equilibrium temperature at 150-170 ℃ can be calculated by cation geothermometers. K-Mg geothermometers yield minimum temperatures of heat exchange for samples 1 and 19 at 136.2 and 151.6 ℃, respectively. log(Q/K)-T plot proves better for other samples. The mixing (with cold water) process occurs when thermal waters ascend to the surface after a deep circle. |
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