Static Compression of Hydrous Silicate Liquids

该项目的主要目标是确定高压下含水硅酸盐液体的密度和可压缩性。这将通过在活塞缸和多砧装置中进行静态压缩沉/浮实验来完成，压力从0.5到20 GPa。该小组在之前的研究中使用了下沉/浮子技术来确定无水液体的高压密度和可压缩性，包括橄榄岩、科马铁矿、陆地和月球玄武岩以及Fe2SiO4。这项研究将建立在这个数据库的基础上，并通过研究这些添加了H2O的相同液体，将其扩展到含水成分。提出的测量将为含水硅酸盐液体的结构和物理性质以及地幔中含水岩浆的流动性提供新的见解。含水硅酸盐液体等温体积模量（KT）和压力导数（K′）一旦通过这些实验建立，就可以应用于确定在地幔湿熔融过程中是否存在平衡晶体-液体密度反转。人们越来越认识到，无论是原始的还是近代的地幔岩浆活动，都可能经常发生在有水存在的情况下。这种现象可能影响地球内部的广泛过程，从地壳的浅层到地幔和地核交界处的深层。这项研究的主要焦点是确定地球上是否存在某些区域，在这些区域中，某些含有溶解水（也称为含水硅酸盐液体）的岩浆将被困住甚至下沉，而不是浮力上升到地表。我们从早期的实验研究中知道，一些没有水的岩浆在高压下会变得负浮力，并可能沉入地球和月球的深处，但这从未被确定为含水或“含水”岩浆。因此，这将是第一个系统的研究之一，以确定含水硅酸盐液体在高压和高温下的密度和可压缩性，在实验室中重建地幔岩浆活动的条件。本项目由以下项目共同资助：地球科学部（GEO）的岩石学和地球化学、地球物理项目以及EPSCoR项目（EHR）。

The primary goal of this project is to determine the density and compressibility of hydrous silicate liquids at high-pressure. This will be accomplished by performing static compression sink/float experiments in piston-cylinder and multi-anvil devices at pressures from 0.5 to 20 GPa. The sink/float technique has been used by this group in previous studies to determine high-pressure density and compressibility of anhydrous liquids that include peridotite, komatiite, terrestrial and lunar basalt, and Fe2SiO4. This study will build on this database and extend it to hydrous compositions by investigating these same liquids with added H2O. The proposed measurements will give new insight into the structure and physical properties of hydrous silicate liquids, and the mobility of water-bearing magmas in the Earth's mantle. Hydrous silicate liquid isothermal bulk moduli (KT) and the pressure derivative (K'), once established by these experiments, can then be applied to determine if equilibrium crystal-liquid density inversions exist during wet melting of the mantle.There is a growing realization that mantle magmatism, both primordial and recent, may frequently happen in the presence of water. This phenomenon could affect a wide range of the Earth's interior processes, from shallow crustal levels to the deep region at the boundary between the mantle and core. The main focus of this study is determine if there are regions in the Earth where certain magmas with dissolved water, also called hydrous silicate liquids, will become trapped or even sink, rather than rising buoyantly to the surface. We know from earlier experimental studies that some magmas, without water, become negatively buoyant at high pressure and can sink deep in the interiors of the Earth and the Moon, but this has never been determined for water-bearing or "hydrous" magmas. Therefore, this is to be one of the first systematic studies to determine the density and compressibility of hydrous silicate liquids at high pressures and temperatures in the laboratory that recreate conditions of magmatism in the Earth's mantle.This project is co-funded by the following programs: Petrology and Geochemistry, and Geophysics programs in the Division of Earth Sciences (GEO) together with the EPSCoR program (EHR).