周书涛, 孙强, 耿济世, 等. 2024. 亚临界水环境下川西糜棱岩水-热腐蚀效应研究[J]. 工程地质学报, 32(3): 851-861. doi: 10.13544/j.cnki.jeg.2024-0054.
    引用本文: 周书涛, 孙强, 耿济世, 等. 2024. 亚临界水环境下川西糜棱岩水-热腐蚀效应研究[J]. 工程地质学报, 32(3): 851-861. doi: 10.13544/j.cnki.jeg.2024-0054.
    Zhou Shutao, Sun Qiang, Geng Jishi, et al. 2024. Study on hydro-thermal corrosion effect of western Sichuan mylonite under subcritical water environment[J]. Journal of Engineering Geology, 32(3): 851-861. doi: 10.13544/j.cnki.jeg.2024-0054.
    Citation: Zhou Shutao, Sun Qiang, Geng Jishi, et al. 2024. Study on hydro-thermal corrosion effect of western Sichuan mylonite under subcritical water environment[J]. Journal of Engineering Geology, 32(3): 851-861. doi: 10.13544/j.cnki.jeg.2024-0054.

    亚临界水环境下川西糜棱岩水-热腐蚀效应研究

    STUDY ON HYDRO-THERMAL CORROSION EFFECT OF WESTERN SICHUAN MYLONITE UNDER SUBCRITICAL WATER ENVIRONMENT

    • 摘要: 位于青藏高原东部的川西构造带分布有高温地热资源,但同时也是地震活动多发区。为探究地热流体对断层岩石的腐蚀损伤,本文对川西金河-箐河断裂带上的糜棱岩开展100~350℃亚临界水环境(100~374℃,饱和蒸汽压0.1~22.1MPa)下的水-岩相互作用试验,通过电感耦合等离子体质谱仪(ICP-MS)和低温氮气吸附实验(LTNA)分析了反应后溶液成分和岩石孔隙结构随温度的变化规律。研究结果表明,川西糜棱岩Si的溶解速率在100~350℃范围内与水-岩作用温度呈正相关,350℃时溶解速率是100℃的10.97倍,而Na、Ca、K、Al和Mg等金属元素的溶解速率远低于Si。在长期水-热腐蚀下,糜棱岩Si元素的大量析出和硅酸盐矿物的分解会破坏岩石的孔隙结构,伴随微孔、中孔的萌生和发育,糜棱岩总孔体积由25℃时的0.00541cm3 ·g-1升高到350℃的0.00659cm3 ·g-1,且比表面积随热处理温度的升高呈上升趋势,这会加强水与糜棱岩的接触,从而导致岩石的进一步劣化。本项研究结果为探究糜棱岩在亚临界水环境下的水-热腐蚀机制和地热流体影响断层稳定性提供了一定的见解。

       

      Abstract: The West Sichuan tectonic belt,located in the eastern part of the Qinghai-Tibet Plateau,harbors high-temperature geothermal resources and experiences frequent seismic activities. To investigate the corrosion damage caused by geothermal fluids to fault rocks,this paper conducted water-rock interaction experiments under subcritical water environments(100~374℃,saturated vapor pressure 0.1~22.1MPa) at 100~350℃ on mylonite from the Jinhe-Qinghe fault in western Sichuan. The variation of solution composition and rock pore structure with temperature was analyzed by Inductively Coupled Plasma Mass Spectrometry(ICP-MS) and Low Temperature Nitrogen Adsorption(LTNA)experiments. The results demonstrated that the dissolution rate of Si in western Sichuan mylonite was positively correlated with the water-rock reaction temperature in the range of 100~350℃,and the dissolution rate at 350℃was 11.97 times higher than that at 100℃,while the dissolution rate of Na,Ca,K,Al,Mg,and other metal elements was much lower than that of Si. Under long-term hydrothermal corrosion,a large amount of Si in mylonite and the disintegration of silicate minerals will destroy the pore structure of the rock. With the initiation and development of micropores and mesopores,the total pore volume of mylonite increased from 0.00541cm3 ·g-1 at 25℃to 0.00659cm3 ·g-1 at 350℃. The specific surface area increased with the heat treatment temperature,which will enhance the contact between water and mylonite,resulting in further deterioration of the rock. This study provides insights into the mechanism of hydrothermal corrosion of mylonite in subcritical water environments and the influence of geothermal fluids on fault stability.

       

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