| 中低温对流型地热系统中氢同位素的变化 |
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| 引用本文： | 林旭东,许建东.中低温对流型地热系统中氢同位素的变化[J].地震地质,2013,35(1):75-84. |
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| 作者姓名： | 林旭东 许建东 |
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| 作者单位： | 中国地震局地质研究所,活动构造与火山重点实验室 |
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| 基金项目： | 中国地震局地震行业科研专项(200708027)资助 |
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| 摘 要： | 中低温对流型地热系统在阐明地区构造活动性、地热资源形成与分布、水-岩相互作用以及有用元素富集成矿等方面具有十分重要的意义。而水作为地热系统的载体,研究其同位素变化机制是分析此系统中水-岩相互作用和地热水来源的必要前提。文中统计了中国大陆前人发表的167个温泉水与同一地区冷水的氢同位素(δD值)资料,并讨论了这些温泉水与区域活动构造的空间分布关系。结果表明,温泉水δD值均低于同一地区冷水,且91.11%的温泉发育于活动构造周边。文中还对造成温泉水δD值低于冷水的原因进行了分析: 主要是水由地表向地下渗透的过程中,水分子H-D同位素产生分馏作用(深循环作用),且分馏速率与温度相关,温度越高H-D分馏作用越明显; 其次,对于围岩中含高岭土矿物的地区,水与高岭土的H-D同位素也可能发生交换反应,从而降低温泉水中D同位素的含量。
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| 关 键 词： | 中低温对流型地热系统 氢同位素 地热水 δD |
| 收稿时间： | 2012-10-15 |
| 修稿时间： | 2012-12-14 |
THE EVOLUTION OF HYDROGEN ISOTOPE IN LOW-MEDIUM TEMPERATURE GEOTHERMAL SYSTEMS OF CONVECTIVE TYPE |
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| LIN Xudong,XU Jiandong.THE EVOLUTION OF HYDROGEN ISOTOPE IN LOW-MEDIUM TEMPERATURE GEOTHERMAL SYSTEMS OF CONVECTIVE TYPE[J].Seismology and Geology,2013,35(1):75-84. |
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| Authors: | LIN Xudong XU Jiandong |
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| Affiliation: | (Key Laboratory of Active Tectonics and Volcano,Institute of Geology, China Earthquake Administration, Beijing 100029,China) |
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| Abstract: | Low-medium temperature geothermal system of convective type has a very important significance in clarifying the regional tectonic activity,the formation of geothermal resource,as well as water-rock interaction and useful element enrichment mineralization. Water as a heat carrier,its isotopic variation is the premise for studying water-rock interaction and tracing the source of geothermal water. In this article,we have gathered 167 δD data in geothermal water and local cold spring water in China. Then,we overlay the location of geothermal field on the regional active fault system in order to figure out the spatial relationship between geothermal spring and regional active fault.The results show that 1) 91.11% of geothermal water locates near the Quaternary fault; 2) δD value of geothermal water is lower than local cold spring water. This δD variation is further studied in this article. According to kinetic fractionation theory,this phenomenon is caused by the H-D isotopic fraction in water during water recycle in the crust.The mechanism is a process that separates H-D isotopes from each other by their mass during unidirectional processes (water circulation),while the degree of fractionation is dependent on temperature and the routine length. For convection geothermal systems in active tectonic zones,there are plenty of fractures and fissures. In this way,water can make deep circulation in convection geothermal system. During the circulation,the H-D isotopes can gather enough heat quantity and enough routine to fraction. On the basis of above analysis,we have modeled the geothermal water H-D fraction in convection geothermal systems as raised by White (1968).As a secondary reason,the H-D isotopic exchange between water and kaoline/montmorillonite can also reduce the δD in geothermal water. |
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| Keywords: | low-medium temperature geothermal systems of convective type hydrogen and oxygen isotope geothermal water " target="_blank">δDzz')" href="#"> δD |
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