中国岩溶2026，Vol.45Issue(1)：128-139,12.DOI:10.11932/karst20260107
西藏间歇性高温喷泉水化学特征对其成因影响研究
Study on the influence of hydrochemical characteristics on the genesis of intermittent high-temperature geysers in Xizang
摘要
Abstract
This study systematically summarizes the hydrochemical characteristics of typical intermittent high-temperature hot springs in Xizang,aiming to clarify the consistent patterns of their fluid composition and the key factors controlling their eruption.Through comprehensive analysis of hydrochemical parameters and graphical classification methods,the results reveal the high degree of similarity in the hydrochemical properties of these hot springs.Specifically,the geothermal water temperature is close to the local boiling point,with weakly alkaline pH.The water exhibits relatively high silica(SiO2)content;cationically,it is dominated by sodium(Na+)and potassium(K+),while calcium(Ca2+)and magnesium(Mg2+)contents are extremely low.Anionically,chloride(Cl-)and bicarbonate(HCO3-)are the primary components,with a low sulfate(SO42-)content.Based on these consistent features,this type of geothermal fluid is formally defined as"high-silica alkaline hydrothermal fluid".Focusing on the main chemical components of the fluid in intermittent high-temperature fountains,this study particularly emphasizes the presence of colloidal silica particles in the hydrothermal fluid and their intrinsic correlation with the formation of silicified films. In terms of hydrochemical composition,the intermittent high-temperature fountains exhibit distinct regularity and uniqueness,which are prominently reflected in their ionic distribution and environmental parameters.From the perspective of cation composition,Na+and K+are the dominant species,with their combined proportion accounting for up to 98％of the total cations-establishing them as the absolute main cations.In stark contrast,the proportions of Ca2+and Mg2+,which are common cations in most geothermal systems,are negligible,typically less than 1％.This significant discrepancy in cation ratios constitutes one of the unique chemical signatures of these fountains.Beyond the aforementioned ionic characteristics,the high SiO2 content and weakly alkaline environment are indispensable properties of the intermittent high-temperature fountains in Xizang.These key factors interact synergistically to shape the unique,iconic hydrochemical composition of Xizang's intermittent high-temperature fountains,i.e.,the high-silica alkaline hydrothermal fluid system. To further verify the hydrochemical type and evolutionary stage of the fluid,two standard hydrogeochemical classification tools were employed.On the Piper trilinear diagram(a widely used tool for hydrochemical classification),the cations of this fluid type are concentrated in the Na++K+corner,while the anions are distributed along the base of the diagram,far from the SO42-axis,which is consistent with the low SO42-content observed in the chemical analysis.On the Na-K-Mg ternary diagram(a critical tool for evaluating geothermal fluid maturity),among the water samples collected from 12 intermittent high-temperature fountains,10 were classified as partially mature water and 2 as fully mature water;no immature water samples were detected.This result indicates that the geothermal fluid has undergone sufficient water-rock interaction in the subsurface and has not been significantly mixed with shallow,unreacted groundwater,further confirming the deep-origin nature of the fluid. Furthermore,researchers identified that the structure of the groundwater reservoir of intermittent high-temperature fountains is critical to their eruption.For the periodic eruption to occur,the reservoir must maintain excellent airtightness to prevent pressure leakage.This airtightness is primarily attributed to the deposition of the low-permeability coating on the inner surfaces of large fractures or cavities within the reservoir,and the formation of this coating is closely linked to the high SiO2 content in the geothermal water.During the sedimentation process of colloidal silica particles in the hydrothermal fluid,these particles effectively reduce the contents of Ca2+and Mg2+-likely through adsorption and co-precipitation.In contrast,alkali metal ions(e.g.,K+,Na+,Li+,Rb+)are less affected by this process and thus remain relatively enriched in the fluid.Additionally,the high SiO2 content in the hydrothermal fluid promotes the formation of silicified films on the inner surfaces of fluid-flow channels and cavities.These silicified films can repair small fractures generated in the groundwater reservoir,thereby enhancing the reservoir's airtightness and providing effective pressure retention to support the subsequent eruption process. In conclusion,this study clarifies the unique hydrochemical characteristics of intermittent high-temperature hot springs in Xizang and defines the"high-silica alkaline hydrothermal fluid"type,which enriches the classification system of geothermal fluids in high-altitude regions.The analysis of the relationship between colloidal silica,silicified films,and groundwater reservoir airtightness also provides a new mechanistic understanding of the eruption of intermittent high-temperature fountains.These findings can serve as a theoretical basis for further research on geothermal systems in Xizang and other tectonically active,high-altitude areas,as well as for the exploration and utilization of geothermal resources in related regions.关键词
间歇性高温喷泉/水化学特征/高硅碱性热液/二氧化硅/硅化膜Key words
intermittent high-temperature geyser/hydrochemical characteristics/high-silica alkaline hydrothermal fluid/SiO2/silicified film分类
天文与地球科学引用本文复制引用
刘高令,姜贞贞,李永林,卓玛曲西,李明礼..西藏间歇性高温喷泉水化学特征对其成因影响研究[J].中国岩溶,2026,45(1):128-139,12.基金项目
国家自然科学基金重点支持项目(U22A20575) （U22A20575）
西藏自治区自然科学基金重点项目(XZ202401ZR0065,XZ202001ZR0027G,XZ202501JD0015) （XZ202401ZR0065,XZ202001ZR0027G,XZ202501JD0015）
天津市科技计划项目(23JCQNJC00700) （23JCQNJC00700）
