| 赣南地热气体起源的同位素与地球化学证据 |
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| 引用本文： | 孙占学,高柏,张展适.赣南地热气体起源的同位素与地球化学证据[J].地质科学,2014,0(3):791-798. |
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| 作者姓名： | 孙占学 高柏 张展适 |
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| 作者单位： | 东华理工大学省部共建核资源与环境国家重点实验室培育基地 南昌 330013 |
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| 基金项目： | 国家自然科学基金项目(编号:40472147,40872165)资助 |
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| 摘 要： | 对取自赣南地区10个温泉的地热气体进行了气体化学成分及氦、碳、氖同位素组成的分析。该区地热气体可分为CO2型和N2型两种类型。CO2型地热气体分布在赣南东南部地区，主要成分是CO2，占总体积96.47%以上，二氧化碳气体的δ13C值为 -5.50‰～-3.49‰（PDB），平均为 -4.66‰，为幔源无机成因，其氦同位素组成为1.36～2.27 Ra，具有明显的幔源成因特征，最高约有28.2%的氦源于地幔，其N2-Ar-He关系研究表明，该型地热气体中的氮源于地幔-地壳-大气混合成因。研究揭示该区CO2型地热气体属幔源无机成因气，是地幔脱气作用的产物。N2型地热气体分布在赣南西部地区，N2含量占91.04%以上，其中二氧化碳气体的δ13C值为 -23.7‰～-12.6‰，平均为 -17.82‰，为壳源有机成因，其氦同位素组成为0.06～0.13 Ra，具有明显的壳源放射性成因特征，3He/4He 与 4He/20Ne关系和He-Ar-N2关系研究表明，N2型温泉气主要来源于大气，并有壳源气体的贡献。
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| 关 键 词： | 温泉 地热气体 稀有气体同位素 碳同位素 地球化学 赣南 |
| 收稿时间： | 2014-01-20 |
| 修稿时间： | 2014-01-20; |
Isotopic and geochemical evidence for origin of geothermal gases from hotsprings in southern Jiangxi Province,SE-China |
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| Sun Zhanxue,Gao Bai,Zhang Zhanshi.Isotopic and geochemical evidence for origin of geothermal gases from hotsprings in southern Jiangxi Province,SE-China[J].Chinese Journal of Geology,2014,0(3):791-798. |
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| Authors: | Sun Zhanxue Gao Bai Zhang Zhanshi |
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| Institution: | State Key Laboratory Breeding Base of Nuclear Resources and Environment, East China Institute of Technology, Nanchang 330013 |
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| Abstract: | Geothermal gases taken from 10 hotsprings in the southern Jiangxi Province,SE-China,were analyzed for gas chemistry and isotopic compositions of helium,neon and carbon. The hotspring gases can be categorized into two types: The CO2-dominated type with CO2 concentration greater than 96.47% distributed in the southeastern part of southern Jiangxi,and the N2-dominated type with nitrogen higher than 91.04% located in the western part of southern Jiangxi. The δ13 C values of CO2 for the CO2-dominant type geothermal gases are -5.50‰ to -3.49‰(PDB) with a mean value of -4.66‰(PDB) showing that the carbon dioxide of the gases are originated from magmatic inorganic sources. The helium isotopic compositions of this type geothermal gases range from 1.36 to 2.27 Ra,indicating that up to 28.2% of the total helium is derived from the mantle. Relative He,Ar and N2 contents reveal that the nitrogen of the type of gases is the mixture of mantle-derived,crustal and atmospheric N2. Evidences suggest that the CO2-dominated geothermal gases belong to the mantle-derived inorganic type resulted from degassing of the mantle. The δ13 C values of CO2 for the N2-dominant type geothermal gases are -23.7‰ to -12.6‰(PDB) with an average value of -17.82‰,suggesting that the CO2 come from crustal organic sources. The 3He/4He ratios of the N2-dominant gases are from 0.06 to 0.13 Ra,representing input of radiogenic 4He in the crust. The 4He/20Ne- 3He/4He as well as He-Ar-N2 relations of geothermal gases demonstrate that the N2-dominant gases are of atmospheric origin with some crustal contributions. |
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| Keywords: | Hotspring Geothermal gases Noble gas isotopes Carbon isotope Geochemistry Southern Jiangxi Province |
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