近日，荷兰乌得勒支大学Oliver Plümper团队揭示了纳米约束改变岩石圈含水流体的地球化学。相关论文于2025年2月10日发表在《自然—地球科学》杂志上。
水是地球流体的主要成分，其与岩石的相互作用决定了岩石圈的地球化学和地球动力学过程。水岩相互作用在社会相关资源管理中至关重要，包括地下能源开采和储存、深层碳循环和产生关键金属矿床。主流观点认为，流体在岩石圈中流动，不受纳米级物质所产生的独特性质的影响。
研究组使用电子显微镜和中子散射数据表明，包括砂岩、橄榄岩和蛇纹岩在内的各种岩石圈岩石始终显示出纳米孔隙度，主要为孔径<100纳米。通过分子动力学模拟证明了水的介电常数（一种支配其地球化学行为的基本特性）在从环境温度到700°C和5GPa的极端条件下，在纳米约束中与块体对应物不同。其地球化学模拟表明，由于限制而导致的水介电常数变化将降低矿物的溶解度，这一过程目前在流体-岩石相互作用模型中尚未被考虑。鉴于介电常数也与离子形态密切相关，预计孔径依赖性特性将对岩石反应性和流体-岩石相互作用过程中流体的地球化学演化产生主要影响。
附：英文原文
Title: Geochemistry of lithospheric aqueous fluids modified by nanoconfinement
Author: Chogani, Alireza, King, Helen E., Tutolo, Benjamin, ivkovi, Aleksandar, Plmper, Oliver
Issue&Volume: 2025-02-10
Abstract: Water is a principal component of Earth’s fluids, and its interaction with rocks governs lithospheric geochemical and geodynamic processes. Water–rock interactions are crucial in societally relevant resource management, including subsurface extraction and storage of energy, the deep carbon cycle and generating critical metal deposits. The prevailing view is that fluids navigate through the lithosphere without being influenced by the distinct properties that arise from matter confined at the nanoscale. Here we use electron microscopy and neutron scattering data to show that a diverse range of lithospheric rocks, including sandstones, peridotites and serpentinites, consistently show nanoporosity, predominantly with pore sizes<100 nanometres. Using molecular dynamics simulations, we demonstrate that water’s dielectric permittivity—a fundamental property that governs its geochemical behaviour—diverges in nanoconfinement from its bulk counterpart under conditions ranging from ambient to extremes of 700°C and 5GPa. Our geochemical simulations suggest that changes in water permittivity due to confinement will decrease mineral solubility, a process that is not currently considered in models of fluid–rock interactions. Given that permittivity is also intimately linked to ion speciation, pore-size-dependent properties should be expected to exert a primary influence on rock reactivity and the geochemical evolution of fluids during fluid–rock interactions.
DOI: 10.1038/s41561-024-01629-5
Source: https://www.nature.com/articles/s41561-024-01629-5