An experimental investigation of high-temperature interactions between seawater and rhyolite, andesite, basalt and peridotite
An experimental investigation of high-temperature interactions between seawater and rhyolite, andesite, basalt and peridotite
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海水与流纹岩、安山岩、玄武岩和橄榄岩之间高温相互作用的实验研究
DOI：
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发表时间：
1982
期刊：
影响因子：
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通讯作者：
G. W. Chandler
中科院分区：
文献类型：
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作者：
A. Hajash;G. W. Chandler
天然海水与流纹岩、安山岩、玄武岩和橄榄岩在 200°–500°C、1000 巴、水/岩质量比为 5 和 50 的条件下发生反应，以研究岩石类型、水/岩比和温度对溶液化学和蚀变矿物学的影响。结果表明，海水与各种火成岩的相互作用在水合硅酸镁和硬石膏作为主要蚀变产物的产生中是相似的。参与相互作用的流体在蚀变相中失去镁，同时从岩石中浸出铁、锰和硅。溶液的 pH 值主要由 Mg-OH-硅酸盐的形成控制，因此随系统的 Mg 和 Si 浓度而变化。其他涉及 Mg 的反应（例如 Mg-Ca 交换）或产生游离 H+ 的反应，会导致不同海水/岩石系统之间的流体化学发生重大差异。高水/岩石比系统 (50/1) 通常比低比系统 (5/1) 酸性更强，浸出效率更高，因为可用于硅酸镁生产的海水镁相对较多。实验表明，大规模的海水/岩石相互作用可以对海水的化学成分产生相当大的控制，并产生大量的蚀变岩和伴生矿床。由于火成岩活动、构造作用和附近水库（海水或原生水）的同时存在，活动板块的辐合或发散边缘是热液系统的适宜环境。实验数据表明，海水与火成岩的相互作用可以产生许多矿床特征，例如日本的黑子矿床、秘鲁的劳尔矿床、摩洛哥的布莱达矿床以及与蛇绿岩有关的矿床。橄榄岩的蛇纹石化和与板块边缘相关的火成岩杂岩的蚀变也可以通过海水与冷却岩石的相互作用来解释。通过开发化学、温度和压力控制系统来最大限度地延长热液流的寿命，地热能生产可以受益于热水/岩石系统的实验研究。
Natural seawater was allowed to react with rhyolite, andesite, basalt, and peridotite at 200°–500° C, and 1,000 bars at water/rock mass ratios of 5 and 50 in order to investigate the effects of rock type, water/rock ratio, and temperature on solution chemistry and alteration mineralogy. The results indicate that interactions of seawater with various igneous rocks are similar in the production of a hydrous Mg-silicate and anhydrite as major alteration products. Fluids involved in the interactions lose Mg to alteration phases while leaching Fe, Mn, and Si from the rocks. The pH of the solutions is primarily controlled by Mg-OH-silicate formation and therefore varies with Mg and Si concentration of the system. Other reactions which involve Mg (such as Mg-Ca exchange) or which produce free H+, cause major differences in fluid chemistry between different seawater/ rock systems. High water/rock ratio systems (50/1) are generally more acidic and more efficient in leaching than low ratio systems (5/1), due to relatively more seawater Mg available for Mgsilicate production. The experiments show that large-scale seawater/rock interaction could exert considerable control on the chemistry of seawater, as well as producing large bodies of altered rock with associated ore-deposits.Active plate margins of convergence or divergence are suitable environments for hydrothermal systems due to the concurrence of igneous activity, tectonism, and a nearby water reservoir (seawater or connate water). The experimental data indicate that seawater interactions with igneous host rocks could generate many of the features of ore-deposits such as the Kuroko deposits of Japan, the Raul Mine of Peru, the Bleida deposit of Morocco, and deposits associated with ophiolites. Serpentinization of peridotite and alteration of igneous complexes associated with plate margins can also be explained by seawater interaction with the cooling rock. Geothermal energy production could benefit from experimental investigations of hot water/rock systems by development of chemical, temperature, and pressure control systems to maximize the lifetime of hydrothermal flow.