| 高温热泉中稀土元素的地球化学行为及其指示意义: 以西藏搭格架水热区为例 |
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| 引用本文： | 郭清海,张晓博.高温热泉中稀土元素的地球化学行为及其指示意义: 以西藏搭格架水热区为例[J].地质科技通报,2022,41(5):172-180. |
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| 作者姓名： | 郭清海 张晓博 |
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| 作者单位： | a.中国地质大学(武汉)自然资源部深部地热资源重点实验室，武汉 430078 |
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| 基金项目： | 国家自然科学基金项目42077278国家自然科学基金项目42111530023 |
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| 摘 要： | 西藏搭格架水热区位于拉萨-冈底斯地块南缘, 毗邻印度河-雅鲁藏布江缝合带中段, 区内出露酸性泉、中性泉和弱碱性泉, 为不同类型地热水中REE分布特征及其地球化学成因研究提供了理想场所。通过在搭格架采集不同类型热泉样品, 开展了样品REE浓度测试、配分模式分析和赋存形态计算, 旨在揭示高温地热环境中REE地球化学行为的指示意义。研究结果表明, 搭格架热泉中REE的地球化学行为呈非保守性, 其ΣREE浓度受热泉环境中富Fe, Al矿物(或无定形态固体)而非硫酸盐矿物的吸附过程的影响; 热泉REE配分模式和形态分布则主要受热储内氧化-还原条件及流体-岩石相互作用的控制, 是其地质成因和总体水化学特征的反映。虽然搭格架热泉中宏量组分水化学特征指示热储围岩应主要为长英质岩石, 但中、碱性热泉呈现的Ce负异常意味着热储中也可能存在碳酸盐岩。本研究为高温热泉稀土元素地球化学研究提供了典型范例。
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| 关 键 词： | 热泉 稀土元素 水-岩相互作用 氧化还原条件 搭格架 |
| 收稿时间： | 2022-09-08 |
Geochemical behavior of rare earth elements in high-temperature hot springs and its indications: A case study in the Daggyai hydrothermal area,Tibet |
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| Institution: | a.Key Laboratory of Deep Geothermal Resources, MNR, China University of Geosciences(Wuhan), Wuhan 430078, Chinab.School of Environmental Studies, China University of Geosciences(Wuhan), Wuhan 430078, China |
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| Abstract: | The Daggyai hydrothermal area (Tibet) is located on the southern margin of the Lhasa-Gangdise terrane and adjacent to the middle of the Indus-Tsangposuture. Acid, neutral, and weakly alkaline hot springs are ubiquitous in Daggyai, offering a peerless opportunity to study the distribution of rare earth elements (REE) in various geothermal waters as well as their geochemical origins. In this study, different types of the Daggyai hot springs were systematically collected to determine their REE concentrations, to discern the REE patterns and to calculate the REE speciation, which is helpful for revealing the indications of the geochemical behavior of REEs in high-temperature geothermal environments. The results of the study show that the REEs in the Daggyai hot springs behaved conservatively, with their concentrations being affected by the sorption of Fe-or Al-rich minerals or amorphous phases instead of sulfate minerals, and the REE patterns and speciation were controlled by the redox conditions and fluid-rock interactions in the reservoirs, capable of reflecting the geological genesis and the general hydrochemical characteristics of the hot springs. Although the major constituent hydrochemistry of the Daggyai hot springs demonstrates that the reservoir host rocks are primarily felsic rocks, the negative Ce anomaly of the neutral-to-alkaline hot springs implies that there are possibly carbonate rocks in the Daggyai reservoirs. This work is a typical example of relevant studies on REE geochemistry in high-temperature hot springs. |
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