The formation mechanism of geothermal salty water based on hydrochemistry and isotopes in Rudong geothermal field, Guangdong Province
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摘要:
地热咸水的形成机制是开发地热资源的重要参考，地热咸水中的化学组分可以揭示经历的水化学作用，同位素的示踪可以指示地下水的来源和水化学过程。因此，选用水化学和同位素来揭示广东儒洞地热咸水的来源和形成机制。研究表明，广东儒洞地热田发育高盐度地热水（TDS＞8000 mg/L），Cl−和Ca2+的含量分别高达5059.76 mg/L和1991.42 mg/L，为Cl−Ca·Na型水。K−Mg温标和玉髓温标估算热储温度88.13~121.42℃，循环深度1963~2790 m。水文地质条件和氢氧同位素结果证实，地热水来自于东部丘陵地区的大气降水补给，补给高程为260~315 m。通过离子比例系数和87Sr/86Sr分析，儒洞地热田地下水运移的环境较封闭，高温下发生了较充分的花岗岩矿物的溶解，同时围岩中蒸发成因盐岩的溶解提供了主要水化学组分，海水入侵的可能性较小，地热咸水和围岩存在一定的阳离子交换作用。因此，围岩中的蒸发成因盐岩的溶解和花岗岩矿物的溶解是地热咸水化学成分形成的主因。
Abstract:The formation mechanism of geothermal salty water is important scientific basis for the exploitation of geothermal resources. The chemical components in geothermal salty water can reveal the experienced hydrochemistry, and the isotopic tracing can indicate the source of groundwater and hydrochemical processes. Therefore, water chemistry and isotopes were chosen to reveal the source and formation mechanism of geothermal salt water in Rudong geothermal field, Guangdong. The hydrochemisty indicates that the Rudong geothermal field develops high salinity geothermal water (TDS > 8000 mg/L) with Cl− and Ca2+ contents as high as 5059.76 mg/L and 1991.42 mg/L, respectively, which is Cl-Ca·Na type water. The reservoir temperatures estimated with K−Mg geothermometer and chalcedony geothermometer are about 88.13~121.42℃, and the circulation depths are about 1963~2790 m. Hydrogeological conditions and hydrogen-oxygen isotope results confirm that the geothermal water comes from atmospheric precipitation recharge in the eastern hills with the recharge elevations of 260~315 m. Based on the ion ratio coefficient and 87Sr/86Sr, the environment for groundwater transport in the Rudong geothermal field is relatively closed, and the dissolution of granite minerals occurs more fully at high temperatures, while the dissolution of evaporative salt rock in the surrounding rocks provides the main water chemical components. The possibility of seawater intrusion is weak, and there is a certain cation exchange between the geothermal salty water and the surrounding rocks. Therefore, the dissolution of evaporative salt rock in the surrounding rocks and the dissolution of granite minerals are the main source of chemical composition for the geothermal salty water in Rudong geothermal field.
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表 1 广东儒洞地热田地热水化学和同位素测试结果
Table 1. Chemical and isotopic test results of geothermal water in Guangdong Rudong geothermal field
编号 温度/
℃pH TDS Ca2+ Na+ K+ Mg2+ HCO3− Cl− SO42− SiO2 Sr δ18O δD 水化学
类型mg·L−1 ‰ MM−1 79.2 6.8 9032.14 1886.92 1683.57 59.9 7.2 33.29 5026.07 255.96 93.8 2.07 −5.5 −43 Cl-Ca·Na MM−2 79 6.72 9129.25 1991.42 1679.71 28.2 12.8 30.17 5019.13 289.1 89.8 4 −6 −42 Cl-Ca·Na MM−3 77 6.85 9106.35 1908.59 1705.92 59.8 7.06 30.99 5051.6 256.42 99.4 2.06 −6 −43 Cl-Ca·Na MM−4 66.5 6.9 9012.64 1894.63 1731.38 35.8 4.28 32.11 4984.82 236.71 97.3 11.66 −5.9 −42 Cl-Ca·Na MM−5 76.5 6.74 8937.01 1863.9 1671.09 29.5 3.95 30.17 4995.91 261.7 84.6 11.27 −5.5 −43 Cl-Ca·Na MM−6 73.5 6.87 9048.51 1927.89 1666.27 37.3 2.09 30.17 5059.76 227.51 108.4 4.2 −5.5 −43 Cl-Ca·Na MM−7 74 6.76 8876.58 1952.02 1667.98 26.9 7.3 29.03 4896.26 236.9 69.7 5 −5.8 −43 Cl-Ca·Na MM−8 76 6.75 8900.17 1948.9 1687.27 23.1 6.56 28.89 4873.69 272.7 68.5 5 −6 −43 Cl-Ca·Na MM−9 77.5 6.75 8958.74 1911.86 1693.83 50.3 7.7 28.89 4952.68 203.56 108.9 15.46 −5.8 −43 Cl-Ca·Na 
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表 2 地热水深部热储温度估算值
Table 2. Temperature estimation of deep geothermal water reservoir
℃ 地热温标 Na−Li Na−K−Ca Na−K−Ca−Mg Na−K K−Mg 玉髓 K−Mg−玉髓 石英 MM−1 −19.12 404.07 118.50 108.94 117.03 106.57 111.80 133.65 MM−2 −25.63 373.77 110.41 63.92 88.13 103.94 96.04 131.27 MM−3 −18.89 403.54 118.36 107.94 117.27 110.12 113.70 136.86 MM−4 36.62 382.31 109.68 75.31 109.54 108.81 109.18 135.67 MM−5 36.90 375.98 106.79 66.59 105.16 100.41 102.79 128.06 MM−6 −7.33 384.79 106.62 79.85 121.42 115.55 118.49 141.75 MM−7 −22.28 372.33 107.61 61.81 94.23 89.37 91.80 117.97 MM−8 −24.54 366.59 105.36 53.47 91.62 88.41 90.02 117.09 MM−9 52.75 396.43 116.35 97.04 110.88 115.85 113.37 142.01
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表 3 研究区补给高程和循环深度评估值
Table 3. Circulation depth and recharge elevation of the study area
地下水样品 采样点高程/m 补给高程/m 循环深度/m MM−1 11 311 2596 MM−2 10 260 1927 MM−3 12 312 2651 MM−4 14 264 2520 MM−5 10 310 2334 MM−6 10 310 2790 MM−7 15 315 2015 MM−8 13 313 1963 MM−9 11 311 2641
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表 4 广东儒洞地热水离子比例系数值
Table 4. Ratio coefficient of hydrothermal water ions in Rudong, Guangdong Province
编号 rNa/rCl rSO4/rCl rCa/rMg rCa/rSr MM−1 0.335 0.019 262.07 911.56 MM−2 0.335 0.021 155.58 497.86 MM−3 0.338 0.019 270.34 926.50 MM−4 0.347 0.018 442.67 162.49 MM−5 0.334 0.019 471.87 165.39 MM−6 0.329 0.017 922.44 459.02 MM−7 0.341 0.018 267.40 390.40 MM−8 0.346 0.021 297.09 389.78 MM−9 0.342 0.015 248.29 123.66
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表 5 选取部分矿物的PHREEQC饱和指数值（SI）
Table 5. PHREEQC saturation index (SI) values of selected minerals
矿物 MM−1 MM−2 MM−3 MM−4 MM−5 MM−6 MM−7 MM−8 MM−9 方解石 0.63 0.38 0.64 0.63 0.45 0.68 0.35 0.32 0.52 文石 0.53 0.28 0.54 0.53 0.35 0.59 0.25 0.22 0.42 白云石 −1.21 −1.23 −1.23 −1.38 −1.66 −1.79 −1.45 −1.54 −1.42 石膏 −0.50 −0.50 −0.49 −0.54 −0.53 −0.52 −0.60 −0.54 −0.59 硬石膏 0.01 −0.12 0.04 −0.05 −0.09 0.05 −0.25 −0.21 −0.07 石英 0.21 0.34 0.22 0.25 0.25 0.21 0.27 0.28 0.26 玉髓 −0.01 0.09 0 0.02 0.01 0.01 0.01 0.01 0.04 萤石 — 1.96 — — — 0.89 1.63 1.97 — 天青石 −1.49 −1.24 −1.48 −0.78 −0.78 −1.19 −1.24 −1.19 −0.71 菱锶矿 −2.06 −2.02 −2.06 −1.31 −1.49 −1.72 −1.94 −1.97 −1.30 SiO2（a） −0.62 −0.56 −0.61 −0.59 −0.62 −0.59 −0.65 −0.64 −0.57 岩盐 −3.93 −3.91 −3.93 −3.92 −3.92 −3.94 −3.92 −3.92 −3.94 钾盐 −5.25 −5.52 −5.25 −5.47 −5.52 −5.48 −5.53 −5.59 −5.34
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表 6 研究区Sr元素及其同位素测试值
Table 6. Sr elements and their isotope values in the study area
编号 87Sr/86Sr Sr/(mg·L−1) MM−1 0.73646 2.070 MM−2 0.736294 4.000 MM−3 0.73628 2.060 MM−4 0.736116 11.660 MM−5 0.73619 11.270 MM−6 0.73619 4.200 MM−7 0.736223 5.000 MM−8 0.736211 5.000 MM−9 0.736275 15.460
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[1] Arnórsson S, Gunnlaugsson E, Svavarsson H. 1983. The chemistry of geothermal waters in Iceland. III. Chemical geothermometry in geothermal investigations[J]. Geochimica et Cosmochimica Acta, 47(3): 567−577.
[2] Aydin H, Karakuş H, Mutlu H. 2020. Hydrogeochemistry of geothermal waters in eastern Turkey: Geochemical and isotopic constraints on water-rock interaction[J]. Journal of Volcanology and Geothermal Research, 390: 106708.
[3] Battistel M, Hurwitz S, Evans W, et al. 2014. Multicomponent geothermometry applied to a medium-low enthalpy carbonate-evaporite geothermal reservoir[J]. Energy Procedia, 59: 359−365.
[4] Craig H. 1961a. Isotopic variations in meteoric waters[J]. Science, 133(3465): 1702−1703.
[5] Craig H. 1961b. Standard for reporting concentrations of deuterium and oxygen−18 in natural water[J]. Science, 133: 1833−1834.
[6] D'Amore F, Giusti D, Abdallah A. 1998. Geochemistry of the high-salinity geothermal field of Asal, Republic of Djibouti, Africa[J]. Geothermics, 27(2): 197−210.
[7] Delgado-Outeiriño I, Araujo-Nespereira P, Cid-Fernández J A, et al. 2009. Behaviour of thermal waters through granite rocks based on residence time and inorganic pattern[J]. Journal of Hydrology, 373(3/4): 329−336.
[8] Fouillac C, Michard G. 1981. Sodium/lithium ratio in water applied to geothermometry of geothermal reservoirs[J]. Geothermics, 10(1): 55−70.
[9] Fournier R O, Truesdell A H. 1973. An empirical Na−K−Ca geothermometer for natural waters[J]. Geochimica et Cosmochimica acta, 37(5): 1255−1275.
[10] Fournier R O. 1977. Chemical geothermometers and mixing models for geothermal systems[J]. Geothermics, 5(1/4): 41−50.
[11] Frape S K, Fritz P, McNutt R H. 1984. Water-rock interaction and chemistry of groundwaters from the Canadian Shield[J]. Geochimica et Cosmochimica Acta, 48(8): 1617−1627.
[12] Friedman I, Smith G I. 1970. Deuterium content of snow cores from Sierra Nevada area[J]. Science, 169(3944): 467−470.
[13] Gat J R. 1996. Oxygen and hydrogen isotopes in the hydrologic cycle[J]. Annual Review of Earth and Planetary Sciences, 24(1): 225−262.
[14] Ghabayen S M S, McKee M, Kemblowski M. 2006. Ionic and isotopic ratios for identification of salinity sources and missing data in the Gaza aquifer[J]. Journal of hydrology, 318(1/4): 360−373.
[15] Gibbs R J. 1970. Mechanisms controlling world water chemistry[J]. Science, 170(3962): 1088−1090.
[16] Giggenbach W F, Gonfiantini R, Jangi B L, et al. 1983. Isotopic and chemical composition of Parbati valley geothermal discharges, north-west Himalaya, India[J]. Geothermics, 12(2/3): 199−222.
[17] Giggenbach W F. 1988. Geothermal solute equilibria. derivation of Na−K−Mg−Ca geoindicators[J]. Geochimica et cosmochimica acta, 52(12): 2749−2765.
[18] Henley R W, Ellis A J. 1983. Geothermal systems ancient and modern: A geochemical review[J]. Earth-Science Reviews, 19(1): 1−50.
[19] Hiroshiro Y, Jinno K, Berndtsson R. 2006. Hydrogeochemical properties of a salinity-affected coastal aquifer in western Japan[J]. Hydrological Processes:An International Journal, 20(6): 1425−1435.
[20] Magri F, Akar T, Gemici U, et al. 2012. Numerical investigations of fault-induced seawater circulation in the Seferihisar-Balçova Geothermal system, western Turkey[J]. Hydrogeology Journal, 20(1): 103.
[21] Mao X, Wang Y, Zhan H, et al. 2015. Geochemical and isotopic characteristics of geothermal springs hosted by deep-seated faults in Dongguan Basin, Southern China[J]. Journal of Geochemical Exploration, 158: 112−121.
[22] Mao X, Zhu D, Ndikubwimana I, et al. 2021. The mechanism of high-salinity thermal groundwater in Xinzhou geothermal field, South China: Insight from water chemistry and stable isotopes[J]. Journal of Hydrology, 593: 125889.
[23] Mook W G. 2000. Environmental isotopes in the hydrological cycle: principles and applications[J]. International Hydrological Programme, 3(39): 1−98.
[24] Nieva D, Nieva R. 1987. Developments in geothermal energy in Mexico—part twelve: A cationic geothermometer for prospecting of geothermal resources[J]. Heat Recovery Systems and CHP, 7(3): 243−258.
[25] Wang S, Pang Z, Liu J, et al. 2013. Origin and evolution characteristics of geothermal water in the Niutuozhen geothermal field, North China Plain[J]. Journal of Earth Science, 24(6): 891−902.
[26] Wang X, Lu G, Hu B X. 2018. Hydrogeochemical characteristics and geothermometry applications of thermal waters in Coastal Xinzhou and Shenzao geothermal fields, Guangdong, China[J]. Geofluids, 2018: 1−24.
[27] Wang Y, Jiao J J. 2012. Origin of groundwater salinity and hydrogeochemical processes in the confined Quaternary aquifer of the Pearl River Delta, China[J]. Journal of Hydrology, 438: 112−124.
[28] Xi Y, Wang G, Liu S, et al. 2018. The formation of a geothermal anomaly and extensional structures in Guangdong, China: Evidence from gravity analyses[J]. Geothermics, 72: 225−231.
[29] Zhou Z M, Ma C Q, Qi S H, et al. 2020. Late Mesozoic high-heat-producing (HHP) and high-temperature geothermal reservoir granitoids: The most significant geothermal mechanism in South China[J]. Lithos, 366: 105568.
[30] 贺秀斌. 1997. 微量元素锶及其同位素的地球化学研究与应用前景[J]. 地球科学进展, 12(1): 15.
[31] 黄耀丽, 储茂东. 1995. 广东地质构造特征及其与地貌发育的关系[J]. 云南地理环境研究, 7(2): 85−89.
[32] 李向全, 余秋生, 侯新伟, 等. 2006. 宁南清水河盆地地下水循环特征与苦咸水成因[J]. 水文地质工程地质, (1): 46−51. doi: 10.3969/j.issn.1000-3665.2006.01.013
[33] 乃尉华, 王艺星, 韩玉杰. 2019. 喀什三角洲地下水锶元素的分布特征及其来源[J]. 西部探矿工程, 31(7): 144−146,153. doi: 10.3969/j.issn.1004-5716.2019.07.051
[34] 孙红丽, 王贵玲, 蔺文静. 2022. 西宁盆地地下热水的TDS分布特征及富集机理[J]. 地质科技通报, 41(1): 278−287,299.
[35] 汪啸. 2018. 广东沿海典型深大断裂带地热水系统形成条件及水文地球化学特征[D]. 中国地质大学(武汉)博士学位论文: 20−22.
[36] 汪洋, 张旭虎, 蒲丛林, 等. 2022. 河北廊坊南部地区地热水化学特征及成因机制[J]. 地质通报, 41(9): 1698−1706.
[37] 王恒纯, 1991. 同位素水文地质概论[M]. 北京: 地质出版社: 37−57.
[38] 肖荣阁, 张汉城, 陈卉泉, 等. 2001. 热水沉积岩及矿物岩石标志[J]. 地学前缘, 8(4): 379−385.
[39] 袁建飞. 2013. 广东沿海地热系统水文地球化学研究[D]. 中国地质大学(武汉)博士学位论文: 21−26.
[40] 袁星芳, 邢立亭, 贾群龙, 等. 2023. 威海市七里汤地热田特征及其成因机制[J]. 西北地质, 56(6): 209−218.
[41] 翟远征, 王金生, 左锐, 等. 2011. 北京平原区第四系含水层中水-岩作用的锶同位素示踪[J]. 科技导报, 29(6): 17−20.
[42] 张珂, 马浩明, 蔡剑波. 2002. 华南沿海温泉成因探讨[J]. 中山大学学报:自然科学版, 41(1): 82−86.
[43] 赵慈平, 冉华, 陈坤华. 2006. 由相对地热梯度推断的腾冲火山区现存岩浆囊[J]. 岩石学报, 22(6): 1517−1528.
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