1
|
Li J, Lin Y, Meier T, Liu Z, Yang W, Mao HK, Zhu S, Hu Q. Silica-water superstructure and one-dimensional superionic conduit in Earth's mantle. SCIENCE ADVANCES 2023; 9:eadh3784. [PMID: 37656794 PMCID: PMC10854424 DOI: 10.1126/sciadv.adh3784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 08/01/2023] [Indexed: 09/03/2023]
Abstract
Water in Earth's deep interior is predicted to be hydroxyl (OH-) stored in nominally anhydrous minerals, profoundly modulating both structure and dynamics of Earth's mantle. Here, we use a high-dimensional neuro-network potential and machine learning algorithm to investigate the weight percent water incorporation in stishovite, a main constituent of the subducted oceanic crust. We found that stishovite and water prefer forming medium- to long-range ordered superstructures, featuring one-dimensional (1D) water channels. Synthesizing single crystals of hydrous stishovite, we verified the ordering of OH- groups in the water channels through optical and nuclear magnetic resonance spectroscopy and found an average H-H distance of 2.05(3) Å, confirming simulation results. Upon heating, H atoms were predicted to behave fluid-like inside the channels, leading to an exotic 1D superionic state. Water-bearing stishovite could feature high ionic mobility and strong electrical anisotropy, manifesting as electrical heterogeneity in Earth's mantle.
Collapse
Affiliation(s)
- Junwei Li
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing 100193, China
| | - Yanhao Lin
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing 100193, China
| | - Thomas Meier
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing 100193, China
| | - Zhipan Liu
- Collaborative Innovation Center of Chemistry for Energy Material, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Key Laboratory of Computational Physical Science, Department of Chemistry, Fudan University, Shanghai 200433, China
| | - Wei Yang
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
| | - Ho-kwang Mao
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing 100193, China
| | - Shengcai Zhu
- School of Materials, Shenzhen Campus of Sun Yat-sen University, Shenzhen 518107, China
| | - Qingyang Hu
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing 100193, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| |
Collapse
|
2
|
Bajgain SK, Ashley AW, Mookherjee M, Ghosh DB, Karki BB. Insights into magma ocean dynamics from the transport properties of basaltic melt. Nat Commun 2022; 13:7590. [PMID: 36481757 PMCID: PMC9731987 DOI: 10.1038/s41467-022-35171-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 11/17/2022] [Indexed: 12/13/2022] Open
Abstract
The viscosity of magma plays a crucial role in the dynamics of the Earth: from the crystallization of a magma ocean during its initial stages to modern-day volcanic processes. However, the pressure-dependence behavior of viscosity at high pressure remains controversial. In this study, we report the results of first-principles molecular dynamics simulations of basaltic melt to show that the melt viscosity increases upon compression along each isotherm for the entire lower mantle after showing minima at ~6 GPa. However, elevated temperatures of the magma ocean translate to a narrow range of viscosity, i.e., 0.01-0.03 Pa.s. This low viscosity implies that the crystallization of the magma ocean could be complete within a few million years. These results also suggest that the crystallization of the magma ocean is likely to be fractional, thus supporting the hypothesis that present-day mantle heterogeneities could have been generated during the early crystallization of the primitive mantle.
Collapse
Affiliation(s)
- Suraj K Bajgain
- Earth Materials Laboratory, Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL, USA.
- Department of Geology, School of Natural Resources & Environment, Lake Superior State University, Sault Ste Marie, MI, USA.
| | - Aaron Wolfgang Ashley
- Earth Materials Laboratory, Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL, USA
| | - Mainak Mookherjee
- Earth Materials Laboratory, Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL, USA.
| | - Dipta B Ghosh
- School of Electrical Engineering and Computer Science, Department of Geology and Geophysics, Center for Computation and Technology, Louisiana State University, Baton Rouge, LA, USA
| | - Bijaya B Karki
- School of Electrical Engineering and Computer Science, Department of Geology and Geophysics, Center for Computation and Technology, Louisiana State University, Baton Rouge, LA, USA.
| |
Collapse
|
3
|
Zhang BH, Guo X, Yoshino T, Xia QK. Electrical conductivity of melts: implications for conductivity anomalies in the Earth's mantle. Natl Sci Rev 2021; 8:nwab064. [PMID: 34876992 PMCID: PMC8644999 DOI: 10.1093/nsr/nwab064] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/01/2021] [Accepted: 04/09/2021] [Indexed: 11/14/2022] Open
Abstract
Magmatic liquids, including silicate and carbonate melts, are principal agents of mass and heat transfer in the Earth and terrestrial planets, and they play a crucial role in various geodynamic processes and in Earth's evolution. Electrical conductivity data of these melts elucidate the cause of electrical anomalies in Earth's interior and shed light on the melt structure. With the improvement in high-pressure experimental techniques and theoretical simulations, major progress has been made on this front in the past several decades. This review aims to summarize recent advances in experimental and theoretical studies on the electrical conductivity of silicate and carbonate melts of different compositions and volatile contents under high temperature and pressure. The electrical conductivity of silicate melts depends strongly on temperature, pressure, water content and the ratio of non-bridging oxygens to tetrahedral cations (NBO/T). By contrast, the electrical conductivity of carbonate melts exhibits a weak dependence on temperature and pressure due to their fully depolymerized structure. The electrical conductivity of carbonate melts is higher than that of silicate melts by at least two orders of magnitude. Water can increase electrical conductivity significantly and reduce the activation energy of silicate melts. Conversely, this effect is weak for carbonate melts. In addition, the replacement of alkali-earth elements (Ca2+ or Mg2+) with alkali elements causes a significant decrease in the electrical conductivity of carbonate melts. A distinct compensation trend is revealed for the electrical conductivity of silicate and carbonate melts under anhydrous and hydrous conditions. Several important applications of laboratory-based melt conductivity are introduced in order to understand the origin of high-conductivity anomalies in the Earth's mantle. Perspectives for future studies are also provided.
Collapse
Affiliation(s)
- Bao-Hua Zhang
- Key Laboratory of Geoscience Big Data and Deep Resource of Zhejiang Province, School of Earth Sciences, Zhejiang University, Hangzhou 310027, China
| | - Xuan Guo
- CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Takashi Yoshino
- Institute for Planetary Materials, Okayama University, Misasa 682-0193, Japan
| | - Qun-Ke Xia
- Key Laboratory of Geoscience Big Data and Deep Resource of Zhejiang Province, School of Earth Sciences, Zhejiang University, Hangzhou 310027, China
| |
Collapse
|
4
|
Drewitt JWE. Liquid structure under extreme conditions: high-pressure x-ray diffraction studies. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:503004. [PMID: 34544063 DOI: 10.1088/1361-648x/ac2865] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 09/20/2021] [Indexed: 06/13/2023]
Abstract
Under extreme conditions of high pressure and temperature, liquids can undergo substantial structural transformations as their atoms rearrange to minimise energy within a more confined volume. Understanding the structural response of liquids under extreme conditions is important across a variety of disciplines, from fundamental physics and exotic chemistry to materials and planetary science.In situexperiments and atomistic simulations can provide crucial insight into the nature of liquid-liquid phase transitions and the complex phase diagrams and melting relations of high-pressure materials. Structural changes in natural magmas at the high-pressures experienced in deep planetary interiors can have a profound impact on their physical properties, knowledge of which is important to inform geochemical models of magmatic processes. Generating the extreme conditions required to melt samples at high-pressure, whilst simultaneously measuring their liquid structure, is a considerable challenge. The measurement, analysis, and interpretation of structural data is further complicated by the inherent disordered nature of liquids at the atomic-scale. However, recent advances in high-pressure technology mean that liquid diffraction measurements are becoming more routinely feasible at synchrotron facilities around the world. This topical review examines methods for high pressure synchrotron x-ray diffraction of liquids and the wide variety of systems which have been studied by them, from simple liquid metals and their remarkable complex behaviour at high-pressure, to molecular-polymeric liquid-liquid transitions in pnicogen and chalcogen liquids, and density-driven structural transformations in water and silicate melts.
Collapse
Affiliation(s)
- James W E Drewitt
- School of Physics, University of Bristol, H H Wills Physics Laboratory, Tyndall Avenue, Bristol, BS8 1TL, United Kingdom
| |
Collapse
|
5
|
Karki BB, Ghosh DB, Karato SI. Behavior and properties of water in silicate melts under deep mantle conditions. Sci Rep 2021; 11:10588. [PMID: 34012106 PMCID: PMC8134574 DOI: 10.1038/s41598-021-90124-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 05/06/2021] [Indexed: 11/17/2022] Open
Abstract
Water (H2O) as one of the most abundant fluids present in Earth plays crucial role in the generation and transport of magmas in the interior. Though hydrous silicate melts have been studied extensively, the experimental data are confined to relatively low pressures and the computational results are still rare. Moreover, these studies imply large differences in the way water influences the physical properties of silicate magmas, such as density and electrical conductivity. Here, we investigate the equation of state, speciation, and transport properties of water dissolved in Mg1-xFexSiO3 and Mg2(1-x)Fe2xSiO4 melts (for x = 0 and 0.25) as well as in its bulk (pure) fluid state over the entire mantle pressure regime at 2000-4000 K using first-principles molecular dynamics. The simulation results allow us to constrain the partial molar volume of the water component in melts along with the molar volume of pure water. The predicted volume of silicate melt + water solution is negative at low pressures and becomes almost zero above 15 GPa. Consequently, the hydrous component tends to lower the melt density to similar extent over much of the mantle pressure regime irrespective of composition. Our results also show that hydrogen diffuses fast in silicate melts and enhances the melt electrical conductivity in a way that differs from electrical conduction in the bulk water. The speciation of the water component varies considerably from the bulk water structure as well. Water is dissolved in melts mostly as hydroxyls at low pressure and as -O-H-O-, -O-H-O-H- and other extended species with increasing pressure. On the other hand, the pure water behaves as a molecular fluid below 15 GPa, gradually becoming a dissociated fluid with further compression. On the basis of modeled density and conductivity results, we suggest that partial melts containing a few percent of water may be gravitationally trapped both above and below the upper mantle-transition region. Moreover, such hydrous melts can give rise to detectable electrical conductance by means of electromagnetic sounding observations.
Collapse
Affiliation(s)
- Bijaya B Karki
- School of Electrical Engineering and Computer Science, Department of Geology and Geophysics, Center for Computation and Technology, Louisiana State University, Baton Rouge, LA, 70803, USA.
| | - Dipta B Ghosh
- School of Electrical Engineering and Computer Science, Department of Geology and Geophysics, Center for Computation and Technology, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Shun-Ichiro Karato
- Dpeartment of Earth and Planetary Sciences, Yale University, New Haven, CT, 06520, USA
| |
Collapse
|
6
|
Ghosh DB, Karki BB. Transport properties of carbonated silicate melt at high pressure. SCIENCE ADVANCES 2017; 3:e1701840. [PMID: 29226244 PMCID: PMC5718881 DOI: 10.1126/sciadv.1701840] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 11/03/2017] [Indexed: 06/07/2023]
Abstract
Carbon dioxide, generally considered as the second most abundant volatile component in silicate magmas, is expected to significantly influence various melt properties. In particular, our knowledge about its dynamical effects is lacking over most of Earth's mantle pressure regime. Here, we report the first-principles molecular dynamics results on the transport properties of carbonated MgSiO3 liquid under conditions of mantle relevance. They show that dissolved CO2 systematically enhances the diffusion rates of all elements and lowers the melt viscosity on average by factors of 1.5 to 3 over the pressure range considered. It is remarkable that CO2 has very little or no influence on the electrical conductivity of the silicate melt under most conditions. Simulations also predict anomalous dynamical behavior, increasing diffusivity and conductivity and decreasing viscosity with compression in the low-pressure regime. This anomaly and the concomitant increase of pressure and temperature with depth together make these transport coefficients vary modestly over extended portions of the mantle regime. It is possible that the melt electrical conductivity under conditions corresponding to the 410- and 660-km seismic discontinuities is at a detectable level by electromagnetic sounding observation. In addition, the low melt viscosity values of 0.2 to 0.5 Pa⋅s at these depths and near the core-mantle boundary may imply high mobility of possible melts in these regions.
Collapse
Affiliation(s)
- Dipta B. Ghosh
- School of Electrical Engineering and Computer Science, Department of Geology and Geophysics, Center for Computation and Technology, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Bijaya B. Karki
- School of Electrical Engineering and Computer Science, Department of Geology and Geophysics, Center for Computation and Technology, Louisiana State University, Baton Rouge, LA 70803, USA
| |
Collapse
|
7
|
Bajgain S, Ghosh DB, Karki BB. Structure and density of basaltic melts at mantle conditions from first-principles simulations. Nat Commun 2015; 6:8578. [PMID: 26450568 PMCID: PMC4633951 DOI: 10.1038/ncomms9578] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 09/06/2015] [Indexed: 11/11/2022] Open
Abstract
The origin and stability of deep-mantle melts, and the magmatic processes at different times of Earth's history are controlled by the physical properties of constituent silicate liquids. Here we report density functional theory-based simulations of model basalt, hydrous model basalt and near-MORB to assess the effects of iron and water on the melt structure and density, respectively. Our results suggest that as pressure increases, all types of coordination between major cations and anions strongly increase, and the water speciation changes from isolated species to extended forms. These structural changes are responsible for rapid initial melt densification on compression thereby making these basaltic melts possibly buoyantly stable at one or more depths. Our finding that the melt-water system is ideal (nearly zero volume of mixing) and miscible (negative enthalpy of mixing) over most of the mantle conditions strengthens the idea of potential water enrichment of deep-mantle melts and early magma ocean.
Collapse
Affiliation(s)
- Suraj Bajgain
- Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - Dipta B. Ghosh
- School of Electrical Engineering and Computer Science, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - Bijaya B. Karki
- Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803, USA
- School of Electrical Engineering and Computer Science, Louisiana State University, Baton Rouge, Louisiana 70803, USA
- Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| |
Collapse
|
8
|
Yang F, Kaplonski J, Unruh T, Mamontov E, Meyer A. A high temperature high pressure cell for quasielastic neutron scattering. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2011; 82:083903. [PMID: 21895254 DOI: 10.1063/1.3623796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present our recent development of a high temperature high pressure cell for neutron scattering. Combining a water cooled Nb1Zr pressure cell body with an internal heating furnace, the sample environment can reach temperatures of up to 1500 K at a pressure of up to 200 MPa at the sample position, with an available sample volume of about 700 mm(3). The cell material Nb1Zr is specifically chosen due to its reasonable mechanical strength at elevated temperatures and fairly small neutron absorption and incoherent scattering cross sections. With this design, an acceptable signal-to-noise ratio of about 10:1 can be achieved. This opens new possibilities for quasielastic neutron scattering studies on different types of neutron spectrometers under high temperature high pressure conditions, which is particularly interesting for geological research on, e.g., water dynamics in silicate melts.
Collapse
Affiliation(s)
- F Yang
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Köln, Germany
| | | | | | | | | |
Collapse
|