惰性气体同位素确定地热流体循环深度

地热系统惰性气体同位素地球化学是地热成因研究的重要手段。许多惰性气体同位素都可用于地热系统的研究中，主要目的为揭示热田的热源性质、深-浅层地热流体的内在联系和循环深度等。本文从惰性气体理化特点、样品采集、测试技术及数据等若干方面介绍了惰性气体研究方法，重点探讨了在自由气和溶解气两种形态下，热泉、喷气孔、热水井不同环境下的惰性气体采样方法，还介绍了成熟的惰性气体同位素的测试方法，即利用磁偏转静态真空质谱计分析测试方法，最后基于世界各地典型地热系统的惰性气体测试数据，讨论地热系统的气体来源判别，不同气源的混合比例计算等，进而确定地热流体循环深度。

Noble gas isotopes to determine the depth of the geothermal fluid circulation

Isotope geochemistry of noble gases is an important method in genesis study of geothermal systems. Many noble gas isotopes may be applied to the analysis of the heat source,the relationship of deep and shallow geothermal fluids,as well as the depth of the geothermal fluid circulation. In this paper,firstly,we present methods on the noble gas study,including physical and chemical characteristics,sampling,testing technology and data of noble gases. The sampling process is critical due to the low concentration of the gases. Discussions are present on sampling methods for free and dissolved gases,and for hot springs,fumaroles and geothermal wells. We also introduce mature testing techniques for noble gas analysis,i.e magnetic deflection static vacuum mass spectrometer. Finally,data from several typical geothermal systems around world,together with our data on Xianyang geothermal system,are used to discuss the gas sources of the different geothermal systems,to calculate the mixing of gases with different sources and to determine the depth of the geothermal fluid circulation.