Experimental investigation of deep fluids of the lower crust and subduction zones

下地壳及俯冲带深部流体实验研究

• 批准号: 2124650
• 负责人: Craig Manning
• 金额: $ 58.25万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-15 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2124650&HistoricalAwards=false
• 关键词: Experimental; investigation; deep; fluids; lower

Among the greatest geologic hazards we face as a society are the large earthquakes and volcanic eruptions associated with subduction zones, where two tectonic plates collide. Both hazard types are strongly influenced by the presence and movement of water-rich fluids at great depth. In the case of subduction-zone earthquakes, such fluids are liberated as rocks descend into the mantle, and they substantially modify the rates and style of the deformation that give rise to earthquakes. In the case of volcanic eruptions, the same fluids operate in the overriding plate to trigger melting, and ultimately to power massive, explosive eruptions at the surface. Yet the chemical properties of these fluids and the melts they produce remains very poorly understood, chiefly because the conditions at which they must be studied are quite challenging to generate in the laboratory. This project will exploit methods developed at UCLA for characterizing these deep fluids and melts, and how they dissolve and transport matter. The data and new models will provide unprecedented insights into the chemistry and properties of these deep fluids that figure so prominently in the hazards posed by subduction systems. Two graduate students will be mentored as part of this project, and the experimental laboratory at UCLA will host hands-on demonstrations during large UCLA science outreach events. All results of this work will be available to the rest of the geoscience community via incorporation in the Library for Experimental Phase Relations. The data and models produced will serve an international community of scientists investigating the role of fluids in high pressure geologic and geophysical processes.The work will involve three experimental investigations aimed at improving understanding of deep fluid-rock interaction. The first will be built around the system NaAlSi3O8-H2O, with and without NaCl. This chemical system is a useful model for silicate-rich fluids at depth. Experiments will focus on phase relations and thermodynamic data, allowing characterization of the stability of these fluids, their coexisting minerals, and what triggers their unmixing into separate fluids. The aim of the second project is to provide experimental constraints on the individual dissolved species found in deep fluids. We will use a new experimental design to investigate a wide compositional range of mineral saturation surfaces. The project will focus on dissolved Mg and Ca, which are most relevant to fluid-mantle interactions in subduction zones. The third project will combine experiments with new modeling to investigate aqueous silica in salty deep fluids. A modified model of quartz solubility based the densities of H2O-NaCl solutions will be extended to additional salt-H2O systems. New experiments on quartz solubility will be conducted along H2O-salt binaries, and in the H2O-NaCl-CO2 ternary. The data offers robust constraints on solution density, and can be used to constrain equations of state of salt-bearing deep fluids ranging from simple binaries with H2O, to more complex multicomponent systems expected in the deep crust and upper mantle. The end result of these investigations will be new data and models available to the broader geoscience community.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在我们整个社会面临的最大地质灾害中，与俯冲带有关的大地震和火山喷发是两个构造板块相撞的地方。这两种危险类型都受到深部富水流体的存在和运动的强烈影响。在俯冲带地震的情况下，当岩石下降到地幔中时，这种流体被释放出来，它们极大地改变了引发地震的变形的速度和方式。在火山喷发的情况下，同样的流体在覆盖的板块中运行，引发融化，并最终为地表大规模、爆炸性的喷发提供动力。然而，这些流体及其产生的熔体的化学性质仍然知之甚少，主要是因为在实验室中产生它们必须研究的条件相当具有挑战性。这个项目将利用加州大学洛杉矶分校开发的方法来表征这些深层流体和熔体，以及它们是如何溶解和运输物质的。这些数据和新模型将为这些深部流体的化学和性质提供前所未有的见解，这些深部流体在俯冲系统构成的危险中扮演着如此重要的角色。作为该项目的一部分，两名研究生将接受指导，加州大学洛杉矶分校的实验实验室将在加州大学洛杉矶分校的大型科学推广活动中举办动手演示。这项工作的所有成果将通过并入实验阶段关系图书馆向地球科学界的其他人员提供。产生的数据和模型将为研究流体在高压地质和地球物理过程中的作用的国际科学家社区服务。这项工作将涉及三项旨在提高对深层流体-岩石相互作用的理解的实验研究。第一个将围绕NaAlSi3O8-H2O体系建造，有无氯化钠。该化学体系是深部富含硅酸盐流体的有用模型。实验将集中在相关系和热力学数据上，从而能够表征这些流体的稳定性、它们共存的矿物，以及是什么触发它们分解成单独的流体。第二个项目的目的是为在深部流体中发现的个别溶解物种提供实验限制。我们将使用一种新的实验设计来研究矿物饱和表面的广泛成分范围。该项目将专注于溶解的镁和钙，这与俯冲带的流体-地幔相互作用最相关。第三个项目将把实验和新的模型结合起来，研究含盐深部流体中的二氧化硅水。修正的基于H2O-NaC l溶液密度的石英溶解度模型将推广到更多的盐-H2O体系。新的石英溶解度实验将在H2O-盐二元组和H2O-氯化钠-二氧化碳三元组中进行。这些数据对溶液密度提供了强有力的约束，并可用于约束含盐深部流体的状态方程，范围从简单的含水双星到预计在地壳和上地幔中的更复杂的多组分体系。这些调查的最终结果将是向更广泛的地球科学界提供新的数据和模型。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Experimental determination of quartz solubility in H2O-CaCl2 solutions at 600–900 °C and 0.6–1.4 GPa

600～900℃、0.6～1.4 GPa 下石英在 H2O-CaCl2 溶液中溶解度的实验测定

• DOI: 10.2138/am-2022-8387
• 发表时间: 2023
• 期刊: American Mineralogist
• 影响因子: 3.1
• 作者: Makhluf, Adam R.;Newton, Robert C.;Manning, Craig E.
• 通讯作者: Manning, Craig E.

Constraining the volatile evolution of mafic melts at Mt. Somma–Vesuvius, Italy, based on the composition of reheated melt inclusions and their olivine hosts

基于再加热熔体包裹体及其橄榄石基质的成分，限制意大利维苏威索马山镁铁质熔体的挥发演化

• DOI: 10.5194/ejm-35-921-2023
• 发表时间: 2023
• 期刊: European Journal of Mineralogy
• 影响因子: 2.1
• 作者: Esposito, Rosario;Redi, Daniele;Danyushevsky, Leonid V.;Gurenko, Andrey;De Vivo, Benedetto;Manning, Craig E.;Bodnar, Robert J.;Steele-MacInnis, Matthew;Frezzotti, Maria-Luce
• 通讯作者: Frezzotti, Maria-Luce