1
|
Mijit E, Durandurdu M, Rodrigues JEFS, Trapananti A, Rezvani SJ, Rosa AD, Mathon O, Irifune T, Di Cicco A. Structural and electronic transformations of GeSe 2 glass under high pressures studied by X-ray absorption spectroscopy. Proc Natl Acad Sci U S A 2024; 121:e2318978121. [PMID: 38536755 PMCID: PMC10998580 DOI: 10.1073/pnas.2318978121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 02/20/2024] [Indexed: 04/08/2024] Open
Abstract
Pressure-induced transformations in an archetypal chalcogenide glass (GeSe2) have been investigated up to 157 GPa by X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations. Ge and Se K-edge XAS data allowed simultaneous tracking of the correlated local structural and electronic changes at both Ge and Se sites. Thanks to the simultaneous analysis of extended X-ray absorption fine structure (EXAFS) signals of both edges, reliable quantitative information about the evolution of the first neighbor Ge-Se distribution could be obtained. It also allowed to account for contributions of the Ge-Ge and Se-Se bond distributions (chemical disorder). The low-density to high-density amorphous-amorphous transformation was found to occur within 10 to 30 GPa pressure range, but the conversion from tetrahedral to octahedral coordination of the Ge sites is completed above [Formula: see text] 80 GPa. No convincing evidence of another high-density amorphous state with coordination number larger than six was found within the investigated pressure range. The number of short Ge-Ge and Se-Se "wrong" bonds was found to increase upon pressurization. Experimental XAS results are confirmed by MD simulations, indicating the increase of chemical disorder under high pressure.
Collapse
Affiliation(s)
- Emin Mijit
- Physics Division, School of Science and Technology, University of Camerino, CamerinoI-62032, Italy
- European Synchrotron Radiation Facility, Grenoble Cedex 938043, France
| | - Murat Durandurdu
- Department of Nanotechnology Engineering, Abdullah Gül University, Kayseri38080, Turkey
| | | | - Angela Trapananti
- Physics Division, School of Science and Technology, University of Camerino, CamerinoI-62032, Italy
| | - S. Javad Rezvani
- Physics Division, School of Science and Technology, University of Camerino, CamerinoI-62032, Italy
| | | | - Olivier Mathon
- European Synchrotron Radiation Facility, Grenoble Cedex 938043, France
| | - Tetsuo Irifune
- Geodynamics Research Center, Ehime University, Matsuyama790-8577, Japan
| | - Andrea Di Cicco
- Physics Division, School of Science and Technology, University of Camerino, CamerinoI-62032, Italy
| |
Collapse
|
2
|
He Y, Kim DY, Struzhkin VV, Geballe ZM, Prakapenka V, Mao HK. The stability of FeH x and hydrogen transport at Earth's core mantle boundary. Sci Bull (Beijing) 2023:S2095-9273(23)00382-1. [PMID: 37355390 DOI: 10.1016/j.scib.2023.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 05/29/2023] [Accepted: 05/31/2023] [Indexed: 06/26/2023]
Abstract
Iron hydride in Earth's interior can be formed by the reaction between hydrous minerals (water) and iron. Studying iron hydride improves our understanding of hydrogen transportation in Earth's interior. Our high-pressure experiments found that face-centered cubic (fcc) FeHx (x ≤ 1) is stable up to 165 GPa, and our ab initio molecular dynamics simulations predicted that fcc FeHx transforms to a superionic state under lower mantle conditions. In the superionic state, H-ions in fcc FeH become highly diffusive-like fluids with a high diffusion coefficient of ∼3.7 × 10-4 cm2 s-1, which is comparable to that in the liquid Fe-H phase. The densities and melting temperatures of fcc FeHx were systematically calculated. Similar to superionic ice, the extra entropy of diffusive H-ions increases the melting temperature of fcc FeH. The wide stability field of fcc FeH enables hydrogen transport into the outer core to create a potential hydrogen reservoir in Earth's interior, leaving oxygen-rich patches (ORP) above the core mantle boundary (CMB).
Collapse
Affiliation(s)
- Yu He
- Key Laboratory of High-Temperature and High-Pressure Study of the Earth's Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
| | - Duck Young Kim
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China; Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.
| | - Viktor V Struzhkin
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
| | - Zachary M Geballe
- Geophysical Laboratory, Carnegie Institution, Washington DC 20015, USA
| | - Vitali Prakapenka
- Center for Advanced Radiation Sources, University of Chicago, Chicago IL 60637, USA
| | - Ho-Kwang Mao
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
| |
Collapse
|
3
|
Hansen SE, Garnero EJ, Li M, Shim SH, Rost S. Globally distributed subducted materials along the Earth's core-mantle boundary: Implications for ultralow velocity zones. SCIENCE ADVANCES 2023; 9:eadd4838. [PMID: 37018398 PMCID: PMC10075969 DOI: 10.1126/sciadv.add4838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 03/02/2023] [Indexed: 06/19/2023]
Abstract
Ultralow velocity zones (ULVZs) are the most anomalous structures within the Earth's interior; however, given the wide range of associated characteristics (thickness and composition) reported by previous studies, the origins of ULVZs have been debated for decades. Using a recently developed seismic analysis approach, we find widespread, variable ULVZs along the core-mantle boundary (CMB) beneath a largely unsampled portion of the Southern Hemisphere. Our study region is not beneath current or recent subduction zones, but our mantle convection simulations demonstrate how heterogeneous accumulations of previously subducted materials could form on the CMB and explain our seismic observations. We further show that subducted materials can be globally distributed throughout the lowermost mantle with variable concentrations. These subducted materials, advected along the CMB, can provide an explanation for the distribution and range of reported ULVZ properties.
Collapse
Affiliation(s)
- Samantha E. Hansen
- Department of Geological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Edward J. Garnero
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281, USA
| | - Mingming Li
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281, USA
| | - Sang-Heon Shim
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281, USA
| | - Sebastian Rost
- School of Earth and Environment, The University of Leeds, Leeds LS2 9JT, UK
| |
Collapse
|
4
|
Pierru R, Andrault D, Manthilake G, Monteux J, Devidal JL, Guignot N, King A, Henry L. Deep mantle origin of large igneous provinces and komatiites. SCIENCE ADVANCES 2022; 8:eabo1036. [PMID: 36322665 PMCID: PMC9629742 DOI: 10.1126/sciadv.abo1036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 08/17/2022] [Indexed: 06/16/2023]
Abstract
Large igneous provinces (LIPs) resulted from intraplate magmatic events mobilizing volumes of magma up to several million cubic kilometers. LIPs and lavas with deep mantle sources have compositions ranging from komatiites found in Archean greenstone belts to basalts and picrites in Phanerozoic flood basalt and recent oceanic islands. In this study, we identify the mantle conditions appropriate to each type of lava based on an experimental study of the melting of pyrolite. The depth of the mantle source decreases from 600 to 700 km for the oldest komatiites to 100 to 300 km for picrites and basalts, and the extent of mantle melting ranges from 10 to 50%. We develop a geodynamical model that explains the origin of the hot mantle plumes capable of generating these melting P-T conditions. Within a superadiabatic temperature gradient persisting in the deep mantle, the ascent of hot mantle plumes creates excess temperatures up to 250 to 300 K by adiabatic decompression.
Collapse
Affiliation(s)
- Rémy Pierru
- Université Clermont Auvergne, CNRS, IRD, OPGC, LMV, F-63000 Clermont-Ferrand, France
| | - Denis Andrault
- Université Clermont Auvergne, CNRS, IRD, OPGC, LMV, F-63000 Clermont-Ferrand, France
| | - Geeth Manthilake
- Université Clermont Auvergne, CNRS, IRD, OPGC, LMV, F-63000 Clermont-Ferrand, France
| | - Julien Monteux
- Université Clermont Auvergne, CNRS, IRD, OPGC, LMV, F-63000 Clermont-Ferrand, France
| | - Jean Luc Devidal
- Université Clermont Auvergne, CNRS, IRD, OPGC, LMV, F-63000 Clermont-Ferrand, France
| | | | | | | |
Collapse
|
5
|
Liu S, Gao P, Hermann A, Yang G, Lü J, Ma Y, Mao HK, Wang Y. Stabilization of S 3O 4 at high pressure: implications for the sulfur-excess paradox. Sci Bull (Beijing) 2022; 67:971-976. [PMID: 36546032 DOI: 10.1016/j.scib.2022.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 12/19/2021] [Accepted: 12/20/2021] [Indexed: 01/06/2023]
Abstract
The amount of sulfur in SO2 discharged in volcanic eruptions exceeds that available for degassing from the erupted magma. This geological conundrum, known as the "sulfur excess", has been the subject of considerable interests but remains an open question. Here, in a systematic computational investigation of sulfur-oxygen compounds under pressure, a hitherto unknown S3O4 compound containing a mixture of sulfur oxidation states +II and +IV is predicted to be stable at pressures above 79 GPa. We speculate that S3O4 may be produced via redox reactions involving subducted S-bearing minerals (e.g., sulfates and sulfides) with iron and goethite under high-pressure conditions of the deep lower mantle, decomposing to SO2 and S at shallow depths. S3O4 may thus be a key intermediate in promoting decomposition of sulfates to release SO2, offering an alternative source of excess sulfur released during explosive eruptions. These findings provide a possible resolution of the "excess sulfur degassing" paradox and a viable mechanism for the exchange of S between Earth's surface and the lower mantle in the deep sulfur cycle.
Collapse
Affiliation(s)
- Siyu Liu
- State Key Laboratory of Superhard Materials & International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
| | - Pengyue Gao
- State Key Laboratory of Superhard Materials & International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
| | - Andreas Hermann
- Centre for Science at Extreme Conditions and Scottish Universities Physics Alliance, School of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3FD, UK
| | - Guochun Yang
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China
| | - Jian Lü
- State Key Laboratory of Superhard Materials & International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China.
| | - Yanming Ma
- State Key Laboratory of Superhard Materials & International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China; International Center of Future Science, Jilin University, Changchun 130012, China
| | - Ho-Kwang Mao
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China.
| | - Yanchao Wang
- State Key Laboratory of Superhard Materials & International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China.
| |
Collapse
|
6
|
Lobanov SS, Speziale S, Winkler B, Milman V, Refson K, Schifferle L. Electronic, Structural, and Mechanical Properties of SiO_{2} Glass at High Pressure Inferred from its Refractive Index. PHYSICAL REVIEW LETTERS 2022; 128:077403. [PMID: 35244414 DOI: 10.1103/physrevlett.128.077403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 11/29/2021] [Accepted: 12/23/2021] [Indexed: 06/14/2023]
Abstract
We report the first direct measurements of the refractive index of silica glass up to 145 GPa that allowed quantifying its density, bulk modulus, Lorenz-Lorentz polarizability, and band gap. These properties show two major anomalies at ∼10 and ∼40 GPa. The anomaly at ∼10 GPa signals the onset of the increase in Si coordination, and the anomaly at ∼40 GPa corresponds to a nearly complete vanishing of fourfold Si. More generally, we show that the compressibility and density of noncrystalline solids can be accurately measured in simple optical experiments up to at least 110 GPa.
Collapse
Affiliation(s)
- Sergey S Lobanov
- Deutsches GeoForschungsZentrum GFZ, Telegrafenberg, 14473 Potsdam, Germany
- Institut für Geowissenschaften, Universität Potsdam, Karl-Liebknecht-Str. 24-25, Golm 14476, Germany
| | - Sergio Speziale
- Deutsches GeoForschungsZentrum GFZ, Telegrafenberg, 14473 Potsdam, Germany
| | - Björn Winkler
- Institut für Geowissenschaften, Goethe-Universität Frankfurt, Altenhöferallee 1, 60438 Frankfurt am Main, Germany
| | - Victor Milman
- Dassault Systèmes BIOVIA, 334 Science Park, Cambridge CB4 0WN, United Kingdom
| | - Keith Refson
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Lukas Schifferle
- Deutsches GeoForschungsZentrum GFZ, Telegrafenberg, 14473 Potsdam, Germany
- Institut für Geowissenschaften, Universität Potsdam, Karl-Liebknecht-Str. 24-25, Golm 14476, Germany
| |
Collapse
|
7
|
Yokoo S, Hirose K, Tagawa S, Morard G, Ohishi Y. Stratification in planetary cores by liquid immiscibility in Fe-S-H. Nat Commun 2022; 13:644. [PMID: 35115522 PMCID: PMC8813981 DOI: 10.1038/s41467-022-28274-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/10/2022] [Indexed: 11/09/2022] Open
Abstract
Liquid-liquid immiscibility has been widely observed in iron alloy systems at ambient pressure and is important for the structure and dynamics in iron cores of rocky planets. While such previously known liquid immiscibility has been demonstrated to disappear at relatively low pressures, here we report immiscible S(±Si,O)-rich liquid and H(±C)-rich liquid above ~20 GPa, corresponding to conditions of the Martian core. Mars’ cosmochemically estimated core composition is likely in the miscibility gap, and the separation of two immiscible liquids could have driven core convection and stable stratification, which explains the formation and termination of the Martian planetary magnetic field. In addition, we observed liquid immiscibility in Fe-S-H(±Si,O,C) at least to 118 GPa, suggesting that it can occur in the Earth’s topmost outer core and form a low-velocity layer below the core-mantle boundary. Yokoo et al. find the liquid immiscibility between H-rich and S-rich liquids Fe above 20 GPa. The separation of immiscible liquids could explain the disappearance of Mars’ magnetic field and the formation of low-velocity layer atop the Earth’s core.
Collapse
Affiliation(s)
- Shunpei Yokoo
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan.
| | - Kei Hirose
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan.,Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
| | - Shoh Tagawa
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan.,Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
| | - Guillaume Morard
- Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, Université Gustave-Eiffel, ISTerre, 38000 Grenoble, France
| | - Yasuo Ohishi
- Japan Synchrotron Radiation Research Institute, SPring-8, Sayo, Japan
| |
Collapse
|
8
|
Gottschalk M. Evaluation of numerous J-, K-, L-, M-, and N-integrals used in perturbation theory. Mol Phys 2021. [DOI: 10.1080/00268976.2021.2000652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Matthias Gottschalk
- Section 3. 6: Chemistry and Physics of Earth Materials Telegrafenberg, GFZ German Research Centre for Geosciences, Potsdam, Germany
| |
Collapse
|
9
|
Xie L, Chanyshev A, Ishii T, Bondar D, Nishida K, Chen Z, Bhat S, Farla R, Higo Y, Tange Y, Su X, Yan B, Ma S, Katsura T. Simultaneous generation of ultrahigh pressure and temperature to 50 GPa and 3300 K in multi-anvil apparatus. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:103902. [PMID: 34717412 DOI: 10.1063/5.0059279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 09/10/2021] [Indexed: 06/13/2023]
Abstract
We attempted to generate ultrahigh pressure and temperature simultaneously using a multi-anvil apparatus by combining the technologies of ultrahigh-pressure generation using sintered diamond (SD) anvils, which can reach 120 GPa, and ultrahigh-temperature generation using a boron-doped diamond (BDD) heater, which can reach 4000 K. Along with this strategy, we successfully generated a temperature of 3300 K and a pressure of above 50 GPa simultaneously. Although the high hardness of BDD significantly prevents high-pressure generation at low temperatures, its high-temperature softening allows for effective pressure generation at temperatures above 1200 K. High temperature also enhances high-pressure generation because of the thermal pressure. We expect to generate even higher pressure in the future by combining SD anvils and a BDD heater with advanced multi-anvil technology.
Collapse
Affiliation(s)
- Longjian Xie
- Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany
| | - Artem Chanyshev
- Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany
| | - Takayuki Ishii
- Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany
| | - Dmitry Bondar
- Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany
| | - Keisuke Nishida
- Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany
| | - Zhen Chen
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China
| | - Shrikant Bhat
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Robert Farla
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Yuji Higo
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 689-5198, Japan
| | - Yoshinori Tange
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 689-5198, Japan
| | - Xiaowan Su
- School of Earth and Space Sciences, Peking University, Beijing 100871, China
| | - BingMin Yan
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China
| | - Shuailin Ma
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Tomoo Katsura
- Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany
| |
Collapse
|
10
|
Behavior of light elements in iron-silicate-water-sulfur system during early Earth's evolution. Sci Rep 2021; 11:12632. [PMID: 34168164 PMCID: PMC8225640 DOI: 10.1038/s41598-021-91801-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 05/27/2021] [Indexed: 11/30/2022] Open
Abstract
Hydrogen (H) is considered to be one of the candidates for light elements in the Earth’s core, but the amount and timing of delivery have been unknown. We investigated the effects of sulfur (S), another candidate element in the core, on deuteration of iron (Fe) in iron–silicate–water system up to 6–12 GPa, ~ 1200 K using in situ neutron diffraction measurements. The sample initially contained saturated water (D2O) as Mg(OD)2 in the ideal composition (Fe–MgSiO3–D2O) of the primitive Earth. In the existence of water and sulfur, phase transitions of Fe, dehydration of Mg(OD)2, and formation of iron sulfide (FeS) and silicates occurred with increasing temperature. The deuterium (D) solubility (x) in iron deuterides (FeDx) increased with temperature and pressure, resulting in a maximum of x = 0.33(4) for the hydrous sample without S at 11.2 GPa and 1067 K. FeS was hardly deuterated until Fe deuteration had completed. The lower D concentrations in the S-containing system do not exceed the miscibility gap (x < ~ 0.4). Both H and S can be incorporated into solid Fe and other light elements could have dissolved into molten iron hydride and/or FeS during the later process of Earth’s evolution.
Collapse
|
11
|
Reversal of carbonate-silicate cation exchange in cold slabs in Earth's lower mantle. Nat Commun 2021; 12:1712. [PMID: 33731704 PMCID: PMC7969735 DOI: 10.1038/s41467-021-21761-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 02/04/2021] [Indexed: 01/31/2023] Open
Abstract
The stable forms of carbon in Earth's deep interior control storage and fluxes of carbon through the planet over geologic time, impacting the surface climate as well as carrying records of geologic processes in the form of diamond inclusions. However, current estimates of the distribution of carbon in Earth's mantle are uncertain, due in part to limited understanding of the fate of carbonates through subduction, the main mechanism that transports carbon from Earth's surface to its interior. Oxidized carbon carried by subduction has been found to reside in MgCO3 throughout much of the mantle. Experiments in this study demonstrate that at deep mantle conditions MgCO3 reacts with silicates to form CaCO3. In combination with previous work indicating that CaCO3 is more stable than MgCO3 under reducing conditions of Earth's lowermost mantle, these observations allow us to predict that the signature of surface carbon reaching Earth's lowermost mantle may include CaCO3.
Collapse
|
12
|
Ohta K, Wakamatsu T, Kodama M, Kawamura K, Hirai S. Laboratory-based x-ray computed tomography for 3D imaging of samples in a diamond anvil cell in situ at high pressures. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:093703. [PMID: 33003770 DOI: 10.1063/5.0014486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/30/2020] [Indexed: 06/11/2023]
Abstract
Three-dimensional (3D) visualization of a material under pressure can provide a great deal of information about its physical and chemical properties. We developed a technique combining in-house x-ray computed tomography (XCT) and a diamond anvil cell to observe the 3D geometry of a sample in situ at high pressure with a spatial resolution of about 610 nm. We realized observations of the 3D morphology and its evolution in minerals up to a pressure of 55.6 GPa, which is comparable to the pressure conditions reported in a previous synchrotron XCT study. The new technique developed here can be applied to a variety of materials under high pressures and has the potential to provide new insights for high-pressure science and technology.
Collapse
Affiliation(s)
- Kenji Ohta
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
| | - Tatsuya Wakamatsu
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
| | - Manabu Kodama
- School of Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
| | - Katsuyuki Kawamura
- School of Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
| | - Shuichiro Hirai
- School of Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
| |
Collapse
|
13
|
Lobanov SS, Schifferle L, Schulz R. Gated detection of supercontinuum pulses enables optical probing of solid and molten silicates at extreme pressure-temperature conditions. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:053103. [PMID: 32486715 DOI: 10.1063/5.0004590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 05/02/2020] [Indexed: 06/11/2023]
Abstract
Optical studies of materials at high pressure-temperature (P-T) conditions provide insights into their physical properties that may be inaccessible to direct determination at extreme conditions. Incandescent light sources, however, are insufficiently bright to optically probe samples with radiative temperatures above ∼1000 K. Here we report on a system to perform optical absorption experiments in a laser-heated diamond anvil cell at T up to at least 4000 K. This setup is based on a pulsed supercontinuum (broadband) light probe and a gated CCD detector. Precise and tight synchronization of the detector gates (3 ns) to the bright probe pulses (1 ns) diminishes the recorded thermal background and preserves an excellent probe signal at high temperature. We demonstrate the efficiency of this spectroscopic setup by measuring the optical absorbance of solid and molten (Mg,Fe)SiO3, an important constituent of planetary mantles, at P ∼30 GPa and T ∼1200 K to 4150 K. Optical absorbance of the hot solid (Mg,Fe)SiO3 is moderately sensitive to temperature but increases abruptly upon melting and acquires a strong temperature dependence. Our results enable quantitative estimates of the opacity of planetary mantles with implications to their thermal and electrical conductivities, all of which have never been constrained at representative P-T conditions, and call for an optical detection of melting in silicate-bearing systems to resolve the extant ambiguity in their high-pressure melting curves.
Collapse
Affiliation(s)
- Sergey S Lobanov
- GFZ German Research Centre for Geosciences, Section 3.6, Telegrafenberg, 14473 Potsdam, Germany
| | - Lukas Schifferle
- GFZ German Research Centre for Geosciences, Section 3.6, Telegrafenberg, 14473 Potsdam, Germany
| | - Reiner Schulz
- GFZ German Research Centre for Geosciences, Section 3.6, Telegrafenberg, 14473 Potsdam, Germany
| |
Collapse
|
14
|
Intraplate volcanism originating from upwelling hydrous mantle transition zone. Nature 2020; 579:88-91. [PMID: 32103183 DOI: 10.1038/s41586-020-2045-y] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 12/02/2019] [Indexed: 11/08/2022]
Abstract
Most magmatism occurring on Earth is conventionally attributed to passive mantle upwelling at mid-ocean ridges, to slab devolatilization at subduction zones, or to mantle plumes. However, the widespread Cenozoic intraplate volcanism in northeast China1-3 and the young petit-spot volcanoes4-7 offshore of the Japan Trench cannot readily be associated with any of these mechanisms. In addition, the mantle beneath these types of volcanism is characterized by zones of anomalously low seismic velocity above and below the transition zone8-12 (a mantle level located at depths between 410 and 660 kilometres). A comprehensive interpretation of these phenomena is lacking. Here we show that most (or possibly all) of the intraplate and petit-spot volcanism and low-velocity zones around the Japanese subduction zone can be explained by the Cenozoic interaction of the subducting Pacific slab with a hydrous mantle transition zone. Numerical modelling indicates that 0.2 to 0.3 weight per cent of water dissolved in mantle minerals that are driven out from the transition zone in response to subduction and retreat of a tectonic plate is sufficient to reproduce the observations. This suggests that a critical amount of water may have accumulated in the transition zone around this subduction zone, as well as in others of the Tethyan tectonic belt13 that are characterized by intraplate or petit-spot volcanism and low-velocity zones in the underlying mantle.
Collapse
|
15
|
Abstract
The earth’s core is thought to be composed of Fe-Ni alloy including substantially large amounts of light elements. Although oxygen, silicon, carbon, nitrogen, sulfur, and hydrogen have been proposed as candidates for the light elements, little is known about the amount and the species so far, primarily because of the difficulties in measurements of liquid properties under the outer core pressure and temperature condition. Here, we carry out massive ab initio computations of liquid Fe-Ni-light element alloys with various compositions under the whole outer core P, T condition in order to quantitatively evaluate their thermoelasticity. Calculated results indicate that Si and S have larger effects on the density of liquid iron than O and H, but the seismological reference values of the outer core can be reproduced simultaneously by any light elements except for C. In order to place further constraints on the outer core chemistry, other information, in particular melting phase relations of iron light elements alloys at the inner core-outer core boundary, are necessary. The optimized best-fit compositions demonstrate that the major element composition of the bulk earth is expected to be CI chondritic for the Si-rich core with the pyrolytic mantle or for the Si-poor core and the (Mg,Fe)SiO3-dominant mantle. But the H-rich core likely causes a distinct Fe depletion for the bulk Earth composition.
Collapse
|
16
|
Solomatova N, Caracas R. Pressure-Induced Coordination Changes in a Pyrolitic Silicate Melt From Ab Initio Molecular Dynamics Simulations. JOURNAL OF GEOPHYSICAL RESEARCH. SOLID EARTH 2019; 124:11232-11250. [PMID: 32025456 PMCID: PMC6988478 DOI: 10.1029/2019jb018238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/04/2019] [Accepted: 10/29/2019] [Indexed: 06/10/2023]
Abstract
With ab initio molecular dynamics simulations on a Na-, Ca-, Fe-, Mg-, and Al-bearing silicate melt of pyrolite composition, we examine the detailed changes in elemental coordination as a function of pressure and temperature. We consider the average coordination as well as the proportion and distribution of coordination environments at pressures and temperatures encompassing the conditions at which molten silicates may exist in present-day Earth and those of the Early Earth's magma ocean. At ambient pressure and 2,000 K, we find that the average coordination of cations with respect to oxygen is 4.0 for Si-O, 4.0 for Al-O, 3.7 for Fe-O, 4.6 for Mg-O, 5.9 for Na-O, and 6.2 for Ca-O. Although the coordination for iron with respect to oxygen may be underestimated, the coordination number for all other cations are consistent with experiments. By 15 GPa (2,000 K), the average coordination for Si-O remains at 4.0 but increases to 4.1 for Al-O, 4.2 for Fe-O, 4.9 for Mg-O, 8.0 for Na-O, and 6.8 for Ca-O. The coordination environment for Na-O remains approximately constant up to core-mantle boundary conditions (135 GPa and 4000 K) but increases to about 6 for Si-O, 6.5 for Al-O, 6.5 for Fe-O, 8 for Mg-O, and 9.5 for Ca-O. We discuss our results in the context of the metal-silicate partitioning behavior of siderophile elements and the viscosity changes of silicate melts at upper mantle conditions. Our results have implications for melt properties, such as viscosity, transport coefficients, thermal conductivities, and electrical conductivities, and will help interpret experimental results on silicate glasses.
Collapse
Affiliation(s)
- N.V. Solomatova
- CNRS, École Normale Supérieure de LyonLaboratoire de Géologie de Lyon, CNRS UMR 5276LyonFrance
| | - R. Caracas
- CNRS, École Normale Supérieure de LyonLaboratoire de Géologie de Lyon, CNRS UMR 5276LyonFrance
| |
Collapse
|
17
|
Pressure-induced structural change in MgSiO 3 glass at pressures near the Earth's core-mantle boundary. Proc Natl Acad Sci U S A 2018; 115:1742-1747. [PMID: 29432162 DOI: 10.1073/pnas.1716748115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Knowledge of the structure and properties of silicate magma under extreme pressure plays an important role in understanding the nature and evolution of Earth's deep interior. Here we report the structure of MgSiO3 glass, considered an analog of silicate melts, up to 111 GPa. The first (r1) and second (r2) neighbor distances in the pair distribution function change rapidly, with r1 increasing and r2 decreasing with pressure. At 53-62 GPa, the observed r1 and r2 distances are similar to the Si-O and Si-Si distances, respectively, of crystalline MgSiO3 akimotoite with edge-sharing SiO6 structural motifs. Above 62 GPa, r1 decreases, and r2 remains constant, with increasing pressure until 88 GPa. Above this pressure, r1 remains more or less constant, and r2 begins decreasing again. These observations suggest an ultrahigh-pressure structural change around 88 GPa. The structure above 88 GPa is interpreted as having the closest edge-shared SiO6 structural motifs similar to those of the crystalline postperovskite, with densely packed oxygen atoms. The pressure of the structural change is broadly consistent with or slightly lower than that of the bridgmanite-to-postperovskite transition in crystalline MgSiO3 These results suggest that a structural change may occur in MgSiO3 melt under pressure conditions corresponding to the deep lower mantle.
Collapse
|
18
|
Xie L, Yoneda A, Yoshino T, Yamazaki D, Tsujino N, Higo Y, Tange Y, Irifune T, Shimei T, Ito E. Synthesis of boron-doped diamond and its application as a heating material in a multi-anvil high-pressure apparatus. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:093904. [PMID: 28964227 DOI: 10.1063/1.4993959] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 09/04/2017] [Indexed: 06/07/2023]
Abstract
We developed methods to use synthesized boron-doped diamond (BDD) as a heater in a multi-anvil high-pressure apparatus. The synthesized BDD heater could stably generate an ultra-high temperature without the issues (anomalous melt, pressure drop, and instability of heating) arising from oxidation of boron into boron oxide and graphite-diamond conversion. We synthesized BDD blocks and tubes with boron contents of 0.5-3.0 wt. % from a mixture of graphite and amorphous boron at 15 GPa and 2000 °C. The electrical conductivity of BDD increased with increasing boron content. The stability of the heater and heating reproducibility were confirmed through repeated cycles of heating and cooling. Temperatures as high as ∼3700 °C were successfully generated at higher than 10 GPa using the BDD heater. The effect of the BDD heater on the pressure-generation efficiency was evaluated using MgO pressure scale by in situ X-ray diffraction study at the SPring-8 synchrotron. The pressure-generation efficiency was lower than that using a graphite-boron composite heater up to 1500 tons. The achievement of stable temperature generation above 3000 °C enables melting experiments of silicates and determination of some physical properties (such as viscosity) of silicate melts under the Earth's lower mantle conditions.
Collapse
Affiliation(s)
- Longjian Xie
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
| | - Akira Yoneda
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
| | - Takashi Yoshino
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
| | - Daisuke Yamazaki
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
| | - Noriyoshi Tsujino
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
| | - Yuji Higo
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 689-5198, Japan
| | - Yoshinori Tange
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 689-5198, Japan
| | - Tetsuo Irifune
- Geodynamics Research Center, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Toru Shimei
- Geodynamics Research Center, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Eiji Ito
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
| |
Collapse
|
19
|
Li M, McNamara AK, Garnero EJ, Yu S. Compositionally-distinct ultra-low velocity zones on Earth's core-mantle boundary. Nat Commun 2017; 8:177. [PMID: 28769033 PMCID: PMC5540928 DOI: 10.1038/s41467-017-00219-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 06/09/2017] [Indexed: 11/09/2022] Open
Abstract
The Earth’s lowermost mantle large low velocity provinces are accompanied by small-scale ultralow velocity zones in localized regions on the core-mantle boundary. Large low velocity provinces are hypothesized to be caused by large-scale compositional heterogeneity (i.e., thermochemical piles). The origin of ultralow velocity zones, however, remains elusive. Here we perform three-dimensional geodynamical calculations to show that the current locations and shapes of ultralow velocity zones are related to their cause. We find that the hottest lowermost mantle regions are commonly located well within the interiors of thermochemical piles. In contrast, accumulations of ultradense compositionally distinct material occur as discontinuous patches along the margins of thermochemical piles and have asymmetrical cross-sectional shape. Furthermore, the lateral morphology of these patches provides insight into mantle flow directions and long-term stability. The global distribution and large variations of morphology of ultralow velocity zones validate a compositionally distinct origin for most ultralow velocity zones. Ultralow velocity zones are detected on the core-mantle boundary, but their origin is enigmatic. Here, the authors find that the global distribution and large variations of morphology of ultralow velocity zones are consistent with most having a compositionally-distinct origin.
Collapse
Affiliation(s)
- Mingming Li
- Arizona State University, School of Earth and Space Exploration, PO Box 871404, Tempe, AZ, 85287-1404, USA.
| | - Allen K McNamara
- Michigan State University, Department of Earth and Environmental Sciences, Natural Science Building, East Lansing, MI, 48824, USA
| | - Edward J Garnero
- Arizona State University, School of Earth and Space Exploration, PO Box 871404, Tempe, AZ, 85287-1404, USA
| | - Shule Yu
- Arizona State University, School of Earth and Space Exploration, PO Box 871404, Tempe, AZ, 85287-1404, USA
| |
Collapse
|
20
|
Nishi M, Kuwayama Y, Tsuchiya J, Tsuchiya T. The pyrite-type high-pressure form of FeOOH. Nature 2017; 547:205-208. [DOI: 10.1038/nature22823] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 05/08/2017] [Indexed: 11/09/2022]
|
21
|
Melting temperatures of MgO under high pressure by micro-texture analysis. Nat Commun 2017; 8:15735. [PMID: 28580945 PMCID: PMC5465366 DOI: 10.1038/ncomms15735] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 04/25/2017] [Indexed: 01/27/2023] Open
Abstract
Periclase (MgO) is the second most abundant mineral after bridgmanite in the Earth's lower mantle, and its melting behaviour under pressure is important to constrain rheological properties and melting behaviours of the lower mantle materials. Significant discrepancies exist between the melting temperatures of MgO determined by laser-heated diamond anvil cell (LHDAC) and those based on dynamic compressions and theoretical predictions. Here we show the melting temperatures in earlier LHDAC experiments are underestimated due to misjudgment of melting, based on micro-texture observations of the quenched samples. The high melting temperatures of MgO suggest that the subducted cold slabs should have higher viscosities than previously thought, suggesting that the inter-connecting textural feature of MgO would not play important roles for the slab stagnation in the lower mantle. The present results also predict that the ultra-deep magmas produced in the lower mantle are peridotitic, which are stabilized near the core–mantle boundary. Melting behaviour of MgO under pressure remains unclear despite the importance of constraining the rheology and composition of the Earth's mantle. Here, the authors show that melting temperatures in earlier static experiments were underestimated based on micro-texture analysis of the quenched samples.
Collapse
|
22
|
Iizuka-Oku R, Yagi T, Gotou H, Okuchi T, Hattori T, Sano-Furukawa A. Hydrogenation of iron in the early stage of Earth's evolution. Nat Commun 2017; 8:14096. [PMID: 28082735 PMCID: PMC5241797 DOI: 10.1038/ncomms14096] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 11/29/2016] [Indexed: 11/09/2022] Open
Abstract
Density of the Earth's core is lower than that of pure iron and the light element(s) in the core is a long-standing problem. Hydrogen is the most abundant element in the solar system and thus one of the important candidates. However, the dissolution process of hydrogen into iron remained unclear. Here we carry out high-pressure and high-temperature in situ neutron diffraction experiments and clarify that when the mixture of iron and hydrous minerals are heated, iron is hydrogenized soon after the hydrous mineral is dehydrated. This implies that early in the Earth's evolution, as the accumulated primordial material became hotter, the dissolution of hydrogen into iron occurred before any other materials melted. This suggests that hydrogen is likely the first light element dissolved into iron during the Earth's evolution and it may affect the behaviour of the other light elements in the later processes. The Earth's core has lower density than pure iron and many studies have looked into which light elements may be present. The authors here carry out in situ high pressure and temperature neutron experiments indicating that hydrogen may have been the first light element to dissolve into the iron core.
Collapse
Affiliation(s)
- Riko Iizuka-Oku
- Geodynamics Research Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.,Geochemical Research Center, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takehiko Yagi
- Geochemical Research Center, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hirotada Gotou
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Takuo Okuchi
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
| | - Takanori Hattori
- Japan Proton Accelerator Research Complex (J-PARC) Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195, Japan
| | - Asami Sano-Furukawa
- Japan Proton Accelerator Research Complex (J-PARC) Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195, Japan
| |
Collapse
|
23
|
Fukuhara M. Possible generation of heat from nuclear fusion in Earth's inner core. Sci Rep 2016; 6:37740. [PMID: 27876860 PMCID: PMC5120317 DOI: 10.1038/srep37740] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 11/01/2016] [Indexed: 12/02/2022] Open
Abstract
The cause and source of the heat released from Earth's interior have not yet been determined. Some research groups have proposed that the heat is supplied by radioactive decay or by a nuclear georeactor. Here we postulate that the generation of heat is the result of three-body nuclear fusion of deuterons confined in hexagonal FeDx core-centre crystals; the reaction rate is enhanced by the combined attraction effects of high-pressure (~364 GPa) and high-temperature (~5700 K) and by the physical catalysis of neutral pions: 2D + 2D + 2D → 21H + 4He + 2 + 20.85 MeV. The possible heat generation rate can be calculated as 8.12 × 1012 J/m3, based on the assumption that Earth's primitive heat supply has already been exhausted. The H and He atoms produced and the anti-neutrino are incorporated as Fe-H based alloys in the H-rich portion of inner core, are released from Earth's interior to the universe, and pass through Earth, respectively.
Collapse
Affiliation(s)
- Mikio Fukuhara
- New Industry Creation Hatchery Centre, Tohoku University, Sendai, 980-8579, Japan
- Waseda University Research Organization for Nano & Life Innovation, Green Device Laboratory, Tokyo, Japan
| |
Collapse
|
24
|
Ghosh DB, Karki BB. Solid-liquid density and spin crossovers in (Mg, Fe)O system at deep mantle conditions. Sci Rep 2016; 6:37269. [PMID: 27872491 PMCID: PMC5118715 DOI: 10.1038/srep37269] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 10/27/2016] [Indexed: 11/08/2022] Open
Abstract
The low/ultralow-velocity zones in the Earth's mantle can be explained by the presence of partial melting, critically depending on density contrast between the melt and surrounding solid mantle. Here, first-principles molecular dynamics simulations of (Mg, Fe) O ferropericlase in the solid and liquid states show that their densities increasingly approach each other as pressure increases. The isochemical density difference between them diminishes from 0.78 (±0.7) g/cm3 at zero pressure (3000 K) to 0.16 (±0.04) g/cm3 at 135 GPa (4000 K) for pure and alloyed compositions containing up to 25% iron. The simulations also predict a high-spin to low-spin transition of iron in the liquid ferropericlase gradually occurring over a pressure interval centered at 55 GPa (4000 K) accompanied by a density increase of 0.14 (±0.02) g/cm3. Temperature tends to widen the transition to higher pressure. The estimated iron partition coefficient between the solid and liquid ferropericlase varies from 0.3 to 0.6 over the pressure range of 23 to 135 GPa. Based on these results, an excess of as low as 5% iron dissolved in the liquid could cause the solid-liquid density crossover at conditions of the lowermost mantle.
Collapse
Affiliation(s)
- Dipta B. Ghosh
- School of Electrical Engineering and Computer Science, Louisiana State University, Baton Rouge, LA 70803
| | - Bijaya B. Karki
- School of Electrical Engineering and Computer Science, Louisiana State University, Baton Rouge, LA 70803
- Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803
- Center for Computation and Technology, Louisiana State University, Baton Rouge, LA 70803
| |
Collapse
|
25
|
Abstract
Understanding the ultralow velocity zones (ULVZs) places constraints on the chemical composition and thermal structure of deep Earth and provides critical information on the dynamics of large-scale mantle convection, but their origin has remained enigmatic for decades. Recent studies suggest that metallic iron and carbon are produced in subducted slabs when they sink beyond a depth of 250 km. Here we show that the eutectic melting curve of the iron-carbon system crosses the current geotherm near Earth's core-mantle boundary, suggesting that dense metallic melt may form in the lowermost mantle. If concentrated into isolated patches, such melt could produce the seismically observed density and velocity features of ULVZs. Depending on the wetting behavior of the metallic melt, the resultant ULVZs may be short-lived domains that are replenished or regenerated through subduction, or long-lasting regions containing both metallic and silicate melts. Slab-derived metallic melt may produce another type of ULVZ that escapes core sequestration by reacting with the mantle to form iron-rich postbridgmanite or ferropericlase. The hypotheses connect peculiar features near Earth's core-mantle boundary to subduction of the oceanic lithosphere through the deep carbon cycle.
Collapse
|
26
|
Nomura R, Uesugi K. Note: High-pressure in situ x-ray laminography using diamond anvil cell. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:046105. [PMID: 27131721 DOI: 10.1063/1.4948315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A high-pressure in situ X-ray laminography technique was developed using a newly designed, laterally open diamond anvil cell. A low X-ray beam of 8 keV energy was used, aiming at future application to dual energy X-ray chemical imaging techniques. The effects of the inclination angle and the imaging angle range were evaluated at ambient pressure using the apparatus. Sectional images of ruby ball samples were successfully reconstructed at high pressures, up to approximately 50 GPa. The high-pressure in situ X-ray laminography technique is expected to provide new insights into the deep Earth sciences.
Collapse
Affiliation(s)
- Ryuichi Nomura
- Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8550, Japan
| | - Kentaro Uesugi
- Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| |
Collapse
|
27
|
Zhang Y, Sekine T, He H, Yu Y, Liu F, Zhang M. Experimental constraints on light elements in the Earth's outer core. Sci Rep 2016; 6:22473. [PMID: 26932596 PMCID: PMC4773879 DOI: 10.1038/srep22473] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 02/16/2016] [Indexed: 11/09/2022] Open
Abstract
Earth's outer core is liquid and dominantly composed of iron and nickel (~5-10 wt%). Its density, however, is ~8% lower than that of liquid iron, and requires the presence of a significant amount of light element(s). A good way to specify the light element(s) is a direct comparison of density and sound velocity measurements between seismological data and those of possible candidate compositions at the core conditions. We report the sound velocity measurements of a model core composition in the Fe-Ni-Si system at the outer core conditions by shock-wave experiments. Combining with the previous studies, we found that the best estimate for the outer core's light elements is ~6 wt% Si, ~2 wt% S, and possible ~1-2.5 wt% O. This composition satisfies the requirements imposed by seismology, geochemistry, and some models of the early core formation. This finding may help us to further constrain the thermal structure of the Earth and the models of Earth's core formation.
Collapse
Affiliation(s)
- Youjun Zhang
- Department of Earth and Planetary Systems Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan
| | - Toshimori Sekine
- Department of Earth and Planetary Systems Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan
| | - Hongliang He
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, PO Box 919-111, Mianyang 621900, China
| | - Yin Yu
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, PO Box 919-111, Mianyang 621900, China
| | - Fusheng Liu
- College of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, China
| | - Mingjian Zhang
- College of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, China
| |
Collapse
|
28
|
Sakamaki T, Ohtani E, Fukui H, Kamada S, Takahashi S, Sakairi T, Takahata A, Sakai T, Tsutsui S, Ishikawa D, Shiraishi R, Seto Y, Tsuchiya T, Baron AQR. Constraints on Earth's inner core composition inferred from measurements of the sound velocity of hcp-iron in extreme conditions. SCIENCE ADVANCES 2016; 2:e1500802. [PMID: 26933678 PMCID: PMC4771440 DOI: 10.1126/sciadv.1500802] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 12/18/2015] [Indexed: 05/19/2023]
Abstract
Hexagonal close-packed iron (hcp-Fe) is a main component of Earth's inner core. The difference in density between hcp-Fe and the inner core in the Preliminary Reference Earth Model (PREM) shows a density deficit, which implies an existence of light elements in the core. Sound velocities then provide an important constraint on the amount and kind of light elements in the core. Although seismological observations provide density-sound velocity data of Earth's core, there are few measurements in controlled laboratory conditions for comparison. We report the compressional sound velocity (V P) of hcp-Fe up to 163 GPa and 3000 K using inelastic x-ray scattering from a laser-heated sample in a diamond anvil cell. We propose a new high-temperature Birch's law for hcp-Fe, which gives us the V P of pure hcp-Fe up to core conditions. We find that Earth's inner core has a 4 to 5% smaller density and a 4 to 10% smaller V P than hcp-Fe. Our results demonstrate that components other than Fe in Earth's core are required to explain Earth's core density and velocity deficits compared to hcp-Fe. Assuming that the temperature effects on iron alloys are the same as those on hcp-Fe, we narrow down light elements in the inner core in terms of the velocity deficit. Hydrogen is a good candidate; thus, Earth's core may be a hidden hydrogen reservoir. Silicon and sulfur are also possible candidates and could show good agreement with PREM if we consider the presence of some melt in the inner core, anelasticity, and/or a premelting effect.
Collapse
Affiliation(s)
- Tatsuya Sakamaki
- Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
- Corresponding author. E-mail:
| | - Eiji Ohtani
- Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
| | - Hiroshi Fukui
- Center for Novel Material Science under Multi-Extreme Conditions, Graduate School of Material Science, University of Hyogo, Kamigori, Hyogo 678-1297, Japan
- Materials Dynamics Laboratory, RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - Seiji Kamada
- Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai Miyagi 980-8578, Japan
| | - Suguru Takahashi
- Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Takanori Sakairi
- Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Akihiro Takahata
- Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Takeshi Sakai
- Geodynamics Research Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Satoshi Tsutsui
- Research and Utilization Division, Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Daisuke Ishikawa
- Research and Utilization Division, Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Rei Shiraishi
- Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Yusuke Seto
- Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501, Japan
| | - Taku Tsuchiya
- Geodynamics Research Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Alfred Q. R. Baron
- Materials Dynamics Laboratory, RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Research and Utilization Division, Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| |
Collapse
|
29
|
Carbon-depleted outer core revealed by sound velocity measurements of liquid iron-carbon alloy. Nat Commun 2015; 6:8942. [PMID: 26596912 PMCID: PMC4673837 DOI: 10.1038/ncomms9942] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 10/19/2015] [Indexed: 12/03/2022] Open
Abstract
The relative abundance of light elements in the Earth's core has long been controversial. Recently, the presence of carbon in the core has been emphasized, because the density and sound velocities of the inner core may be consistent with solid Fe7C3. Here we report the longitudinal wave velocity of liquid Fe84C16 up to 70 GPa based on inelastic X-ray scattering measurements. We find the velocity to be substantially slower than that of solid iron and Fe3C and to be faster than that of liquid iron. The thermodynamic equation of state for liquid Fe84C16 is also obtained from the velocity data combined with previous density measurements at 1 bar. The longitudinal velocity of the outer core, about 4% faster than that of liquid iron, is consistent with the presence of 4–5 at.% carbon. However, that amount of carbon is too small to account for the outer core density deficit, suggesting that carbon cannot be a predominant light element in the core. The composition of the Earth's core, particularly the light elements present, is not well constrained. Here, the authors report sound velocities of liquid iron-carbon alloy as measured at very high pressures using inelastic X-ray scattering and suggest that carbon cannot be predominant in the outer core.
Collapse
|
30
|
Righter K. Magma Ocean Depth and Oxygen Fugacity in the Early Earth--Implications for Biochemistry. ORIGINS LIFE EVOL B 2015; 45:361-6. [PMID: 26037825 DOI: 10.1007/s11084-015-9445-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 06/30/2014] [Indexed: 11/28/2022]
Abstract
A large class of elements, referred to as the siderophile (iron-loving) elements, in the Earth's mantle can be explained by an early deep magma ocean on the early Earth in which the mantle equilibrated with metallic liquid (core liquid). This stage would have affected the distribution of some of the classic volatile elements that are also essential ingredients for life and biochemistry - H, C, S, and N. Estimates are made of the H, C, S, and N contents of Earth's early mantle after core formation, considering the effects of variable temperature, pressure, oxygen fugacity, and composition on their partitioning. Assessment is made of whether additional, exogenous, sources are required to explain the observed mantle concentrations, and areas are identified where additional data and experimentation would lead to an improved understanding of this phase of Earth's history.
Collapse
Affiliation(s)
- Kevin Righter
- Mailcode XI2, NASA-Johnson Space Center, 2101 NASA Parkway, Houston, TX, 77058, USA,
| |
Collapse
|
31
|
Andrault D, Pesce G, Bouhifd MA, Bolfan-Casanova N, Hénot JM, Mezouar M. Melting of subducted basalt at the core-mantle boundary. Science 2014; 344:892-5. [PMID: 24855266 DOI: 10.1126/science.1250466] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The geological materials in Earth's lowermost mantle control the characteristics and interpretation of seismic ultra-low velocity zones at the base of the core-mantle boundary. Partial melting of the bulk lower mantle is often advocated as the cause, but this does not explain the nonubiquitous character of these regional seismic features. We explored the melting properties of mid-oceanic ridge basalt (MORB), which can reach the lowermost mantle after subduction of oceanic crust. At a pressure representative of the core-mantle boundary (135 gigapascals), the onset of melting occurs at ~3800 kelvin, which is ~350 kelvin below the mantle solidus. The SiO2-rich liquid generated either remains trapped in the MORB material or solidifies after reacting with the surrounding MgO-rich mantle, remixing subducted MORB with the lowermost mantle.
Collapse
Affiliation(s)
- Denis Andrault
- Laboratoire Magmas et Volcans, Université Blaise Pascal, CNRS, IRD, Clermont-Ferrand, France.
| | - Giacomo Pesce
- Laboratoire Magmas et Volcans, Université Blaise Pascal, CNRS, IRD, Clermont-Ferrand, France
| | - Mohamed Ali Bouhifd
- Laboratoire Magmas et Volcans, Université Blaise Pascal, CNRS, IRD, Clermont-Ferrand, France
| | | | - Jean-Marc Hénot
- Laboratoire Magmas et Volcans, Université Blaise Pascal, CNRS, IRD, Clermont-Ferrand, France
| | | |
Collapse
|