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0.5到20 Gpa的压力下在活塞-气缸和多砧座装置中进行静态压缩沉放/浮动实验来实现。该小组在以前的研究中使用了沉浮技术来确定无水液体的高压密度和可压缩性，这些液体包括橄榄岩、科马提岩、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的相同液体来将其扩展到含水成分。拟议的测量将为水合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。一旦这些实验建立了水合硅酸盐液体等温体积模数(KT)和压力导数(K‘)，就可以用来确定在地幔湿熔过程中是否存在平衡的晶液密度反转。人们越来越认识到，在水的存在下，地幔岩浆活动可能经常发生，无论是原始的还是现代的。这一现象可能会影响地球内部的广泛过程，从地壳浅层到地幔和地核交界处的深部。这项研究的主要重点是确定地球上是否有某些含有溶解水的岩浆，也被称为水合硅酸盐液体，会被困住甚至下沉，而不是漂浮到地表。我们从早期的实验研究中了解到，一些岩浆在没有水的情况下，在高压下会产生负浮力，并可能深入地球和月球的内部，但对于含水或含水的岩浆，这一点从未被确定。因此，这将是第一批在实验室中确定高压和高温下水合硅酸盐液体的密度和可压缩性的系统研究之一，该实验室再现了地球地幔的岩浆作用条件。该项目由以下项目共同资助：岩石学和地球化学，地球科学部(GEO)的地球物理项目以及EPSCoR计划(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).