The acidity of submarine hydrothermal solutions - an experimental study employing in-situ sampling techniques

海底热液的酸度——采用原位取样技术的实验研究

• 批准号: 314568258
• 负责人: Professor Dr. Christian Gerhard Ballhaus
• 金额: --
• 依托单位: Abteilung Geochemie/Petrologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/314568258?language=en
• 关键词: acidity; submarine; hydrothermal; solutions; experimental

Hydrothermal solutions at submarine vents can be quite acidic. In hydrothermal systems at mid-ocean ridges, pH values at 25°C (pH25) typically range around 3-5. In hydrothermal systems at back arcs the pH25 values appear to be more variable and are typically more acidic. The lowest reported pH25 values, all from back arc basins of the Western Pacific region, range between 1 and 3. Several reaction mechanisms are identified in being pH effective in hydrothermal systems, including the degassing of SO2 from sub-surface magma sources, the exchange of cations between hot seawater and lithologies of the oceanic lithosphere, and the precipitation of hydroxides and hydroxy-sulfates that may extract hydroxyl (OH) from seawater. A potentially important reaction is the hydrolysis of NaCl (to HCl and NaOH). When boiling occurs at high temperature, the two pH-active species (HCl and NaOH) may be separated physically from each other via liquid-vapor fractionation, since HCl is more volatile than NaOH. Because seawater is capable of precipitating upon heating several pH-active phases (portlandite, brucite, caminite), all with retrograde solubility, the extent of NaCl hydrolysis can only be quantified in the simple H2O-NaCl system. Novel experimental techniques are introduced here to study the extent of NaCl hydrolysis in H2O-NaCl solutions between 250 and 390°C. Aim is to assess the potential role of the equilibrium NaCl (liq) + H2O = HCl (vap) + NaOH (liq) in imposing acidic conditions on hydrothermal solutions.

潜艇喷口处的热液可能呈酸性。在洋中脊的热液系统中，25°C (pH25) 时的 pH 值通常在 3-5 左右。在弧后的热液系统中，pH25 值似乎变化更大，并且通常呈酸性。报告的最低 pH25 值全部来自西太平洋地区的弧后盆地，范围在 1 到 3 之间。在热液系统中，pH 有效的几种反应机制已被确定，包括地下岩浆源中 SO2 的脱气、热海水与海洋岩石圈岩性之间的阳离子交换，以及可提取羟基的氢氧化物和羟基硫酸盐的沉淀。 (OH) 来自海水。一个潜在的重要反应是 NaCl 的水解（生成 HCl 和 NaOH）。当在高温下发生沸腾时，两种 pH 活性物质（HCl 和 NaOH）可以通过液-气分馏而彼此物理分离，因为 HCl 比 NaOH 更容易挥发。由于海水在加热时能够沉淀多种 pH 活性相（波特兰石、水镁石、水镁石），所有这些都具有逆溶解度，因此 NaCl 水解的程度只能在简单的 H2O-NaCl 系统中进行量化。本文介绍了新的实验技术来研究 250 至 390°C 之间 H2O-NaCl 溶液中 NaCl 水解的程度。目的是评估平衡 NaCl (liq) + H2O = HCl (vap) + NaOH (liq) 在对热液施加酸性条件时的潜在作用。

项目成果

Spheroidal textures in igneous rocks – Textural consequences of H2O saturation in basaltic melts

• DOI: 10.1016/j.gca.2015.07.029
• 发表时间: 2015-10
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: C. Ballhaus;R. Fonseca;C. Münker;M. Kirchenbaur;Aurelia Zirner

Effect of boiling on the acidity of hydrothermal solutions

沸腾对热液酸度的影响

• DOI: 10.1007/s00410-018-1535-5
• 发表时间: 2019
• 期刊: Contributions to Mineralogy and Petrology
• 影响因子: 3.5
• 作者: Ballhaus C;Gäb F;Garbe-Schönberg D;Staubwasser M.
• 通讯作者: Staubwasser M.

Fingerprinting fluid sources in Troodos ophiolite complex orbicular glasses using high spatial resolution isotope and trace element geochemistry

使用高空间分辨率同位素和微量元素地球化学对特罗多斯蛇绿岩复合球状玻璃中的流体源进行指纹识别

• DOI: 10.1016/j.gca.2016.12.012
• 发表时间: 2017
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Fonseca R.O.C;Kirchenbaur M;Ballhaus C;Münker C;Zirner A;Gerdes A;Heuser A;Botcharnikov R;Lenting C.
• 通讯作者: Lenting C.