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Extreme redox variations in a superdeep diamond from a subducted slab. Nature 2023; 613:85-89. [PMID: 36600063 DOI: 10.1038/s41586-022-05392-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 09/28/2022] [Indexed: 01/05/2023]
Abstract
The introduction of volatile-rich subducting slabs to the mantle may locally generate large redox gradients, affecting phase stability, element partitioning and volatile speciation1. Here we investigate the redox conditions of the deep mantle recorded in inclusions in a diamond from Kankan, Guinea. Enstatite (former bridgmanite), ferropericlase and a uniquely Mg-rich olivine (Mg# 99.9) inclusion indicate formation in highly variable redox conditions near the 660 km seismic discontinuity. We propose a model involving dehydration, rehydration and dehydration in the underside of a warming slab at the transition zone-lower mantle boundary. Fluid liberated by dehydration in a crumpled slab, driven by heating from the lower mantle, ascends into the cooler interior of the slab, where the H2O is sequestered in new hydrous minerals. Consequent fractionation of the remaining fluid produces extremely reducing conditions, forming Mg-end-member ringwoodite. This fractionating fluid also precipitates the host diamond. With continued heating, ringwoodite in the slab surrounding the diamond forms bridgmanite and ferropericlase, which is trapped as the diamond grows in hydrous fluids produced by dehydration of the warming slab.
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Abstract
Seismic tomography provides unique constraints on the morphology, the deformation, and (indirectly) the rheology of subducting slabs. We use teleseismic double-difference P-wave tomography to image with unprecedented clarity the structural complexity of the Izu-Bonin slab. We resolve a tear in the slab in the mantle transition zone (MTZ) between 26.5° N and 28° N. North of the tear, the slab is folded in the MTZ. Immediately above the fold hinge, a zone of reduced P-wavespeed may result from viscous dissipation within an incipient shear zone. To the south of the tear, the slab overturns and lies flat at the base of the MTZ. The ~680 km deep 2015 Bonin earthquake (Mw~7.9) is located at the northernmost edge of the overturning part of the slab. The localised tearing, shearing and buckling of the Izu-Bonin slab indicates that it remains highly viscous throughout the upper mantle and transition zone. In the 1000 km long Izu-Bonin subduction zone to the south of Tokyo, the Pacific Plate descends beneath the Philippine Sea Plate. Here the authors use teleseismic double-difference tomography to image the complex morphology of the Izu-Bonin slab, especially in the mantle transition zone.
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A Metastable Fo-III Wedge in Cold Slabs Subducted to the Lower Part of the Mantle Transition Zone: A Hypothesis Based on First-Principles Simulations. MINERALS 2019. [DOI: 10.3390/min9030186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The metastable olivine (Ol) wedge hypothesis assumes that Ol may exist as a metastable phase at the P conditions of the mantle transition zone (MTZ) and even deeper regions due to inhibition of the phase transitions from Ol to wadsleyite and ringwoodite caused by low T in the cold subducting slabs. It is commonly invoked to account for the stagnation of the descending slabs, deep focus earthquakes and other geophysical observations. In the last few years, several new structures with the forsterite (Fo) composition, namely Fo-II, Fo-III and Fo-IV, were either experimentally observed or theoretically predicted at very low T conditions. They may have important impacts on the metastable Ol wedge hypothesis. By performing first-principles calculations, we have systematically examined their crystallographic characteristics, elastic properties and dynamic stabilities from 0 to 100 GPa, and identified the Fo-III phase as the most likely metastable phase to occur in the cold slabs subducted to the depths equivalent to the lower part of the MTZ (below the ~600 km depth) and even the lower mantle. As disclosed by our theoretical simulations, the Fo-III phase is a post-spinel phase (space group Cmc21), has all cations in sixfold coordination at P < ~60 GPa, and shows dynamic stability for the entire P range from 0 to 100 GPa. Further, our static enthalpy calculations have suggested that the Fo-III phase may directly form from the Fo material at ~22 GPa (0 K), and our high-T phase relation calculations have located the Fo/Fo-III phase boundary at ~23.75 GPa (room T) with an averaged Clapeyron slope of ~−1.1 MPa/K for the T interval from 300 to 1800 K. All these calculated phase transition pressures are likely overestimated by ~3 GPa because of the GGA method used in this study. The discrepancy between our predicted phase transition P and the experimental observation (~58 GPa at 300 K) can be explained by slow reaction rate and short experimental durations. Taking into account the P-T conditions in the cold downgoing slabs, we therefore propose that the Fo-III phase, rather than the Ol, highly possibly occurs as the metastable phase in the cold slabs subducted to the P conditions of the lower part of the MTZ (below the ~600 km depth) and even the lower mantle. In addition, our calculation has showed that the Fo-III phase has higher bulk seismic velocity, and thus may make important contributions to the high seismic speeds observed in the cold slabs stagnated near the upper mantle-lower mantle boundary. Future seismic studies may discriminate the effects of the Fo-III phase and the low T. Surprisingly, the Fo-III phase will speed up, rather than slow down, the subducting process of the cold slabs, if it metastably forms from the Ol. In general, the Fo-III phase has a higher density than the warm MTZ, but has a lower density than the lower mantle, as suggested by our calculations.
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Tidal tomography constrains Earth's deep-mantle buoyancy. Nature 2018; 551:321-326. [PMID: 29144451 DOI: 10.1038/nature24452] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 09/22/2017] [Indexed: 11/09/2022]
Abstract
Earth's body tide-also known as the solid Earth tide, the displacement of the solid Earth's surface caused by gravitational forces from the Moon and the Sun-is sensitive to the density of the two Large Low Shear Velocity Provinces (LLSVPs) beneath Africa and the Pacific. These massive regions extend approximately 1,000 kilometres upward from the base of the mantle and their buoyancy remains actively debated within the geophysical community. Here we use tidal tomography to constrain Earth's deep-mantle buoyancy derived from Global Positioning System (GPS)-based measurements of semi-diurnal body tide deformation. Using a probabilistic approach, we show that across the bottom two-thirds of the two LLSVPs the mean density is about 0.5 per cent higher than the average mantle density across this depth range (that is, its mean buoyancy is minus 0.5 per cent), although this anomaly may be concentrated towards the very base of the mantle. We conclude that the buoyancy of these structures is dominated by the enrichment of high-density chemical components, probably related to subducted oceanic plates or primordial material associated with Earth's formation. Because the dynamics of the mantle is driven by density variations, our result has important dynamical implications for the stability of the LLSVPs and the long-term evolution of the Earth system.
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Hesari Z, Hadavand BS, Hashemi MM. Synthesis and Characterization of (2E,2 E)-3,3-((9,9-diocyl-9H-flourene-2,7-diyl)bis(4,1-phenylene))bis(2-cyanoacylic acid) as a Symmetrical Metal-free Organic Dye. J CHIN CHEM SOC-TAIP 2015. [DOI: 10.1002/jccs.201400519] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Kirby S, Engdahl RE, Denlinger R. Intermediate-Depth Intraslab Earthquakes and Arc Volcanism as Physical Expressions of Crustal and Uppermost Mantle Metamorphism in Subducting Slabs. SUBDUCTION TOP TO BOTTOM 2013. [DOI: 10.1029/gm096p0195] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Dziewonski AM, Forte AM, Su W, Woodward RL. Seismic Tomography and Geodynamics. RELATING GEOPHYSICAL STRUCTURES AND PROCESSES: THE JEFFREYS VOLUME 2013. [DOI: 10.1029/gm076p0067] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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8
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Woodward RL, Forte AM, Su WJ, Dziewonski AM. Constraints on the Large-Scale Structure of the Earth's Mantle. EVOLUTION OF THE EARTH AND PLANETS 2013. [DOI: 10.1029/gm074p0089] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Park J, Levin V, Brandon M, Lees J, Peyton V, Gordeev E, Ozerov A. A Dangling Slab, Amplified Arc Volcanism, Mantle Flow and Seismic Anisotropy in the Kamchatka Plate Corner. PLATE BOUNDARY ZONES 2013. [DOI: 10.1029/gd030p0295] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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10
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Glennon MA, Chen WP. Systematics of deep-focus earthquakes along the Kuril-Kamchatka Arc and their implications on mantle dynamics. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/92jb01742] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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11
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Vasco DW, Johnson LR, Pulliam RJ, Earle PS. Robust inversion of IASP91 travel time residuals for mantle P and S velocity structure, earthquake mislocations, and station corrections. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb02023] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Kissling E, Ellsworth WL, Eberhart-Phillips D, Kradolfer U. Initial reference models in local earthquake tomography. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb03138] [Citation(s) in RCA: 630] [Impact Index Per Article: 52.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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King SD, Ita J. Effect of slab rheology on mass transport across a phase transition boundary. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb01964] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Christensen UR, Hofmann AW. Segregation of subducted oceanic crust in the convecting mantle. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb03403] [Citation(s) in RCA: 428] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Glatzmaier GA, Schubert G. Three-dimensional spherical models of layered and whole mantle convection. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb02111] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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A perovskitic lower mantle inferred from high-pressure, high-temperature sound velocity data. Nature 2012; 485:90-4. [PMID: 22552097 DOI: 10.1038/nature11004] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 02/28/2012] [Indexed: 11/08/2022]
Abstract
The determination of the chemical composition of Earth's lower mantle is a long-standing challenge in earth science. Accurate knowledge of sound velocities in the lower-mantle minerals under relevant high-pressure, high-temperature conditions is essential in constraining the mineralogy and chemical composition using seismological observations, but previous acoustic measurements were limited to a range of low pressures and temperatures. Here we determine the shear-wave velocities for silicate perovskite and ferropericlase under the pressure and temperature conditions of the deep lower mantle using Brillouin scattering spectroscopy. The mineralogical model that provides the best fit to a global seismic velocity profile indicates that perovskite constitutes more than 93 per cent by volume of the lower mantle, which is a much higher proportion than that predicted by the conventional peridotitic mantle model. It suggests that the lower mantle is enriched in silicon relative to the upper mantle, which is consistent with the chondritic Earth model. Such chemical stratification implies layered-mantle convection with limited mass transport between the upper and the lower mantle.
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Li C, van der Hilst RD. Structure of the upper mantle and transition zone beneath Southeast Asia from traveltime tomography. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jb006882] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Abstract
Abstract
Our knowledge of the structure of the Earth´s interior has been obtained by analysing seismic waves that travel in the Earth, and the reference Earth global models used by geophysicists are essentially seismological. Depth profiles of the seismic waves velocities reveal that the deep Earth is divided in several shells, separated by velocity and density discontinuities. The main discontinuity located at a depth of 2900 km corresponds to the transition between the mantle and the core. The Earth´s mantle can be further divided into the upper mantle and the lower mantle, with a transition zone characterised by two prominent increases in velocities observed at 410- and 660-km depths. This article will be focused on the mineral phases of the Earth´s mantle. The interpretation of seismological models in terms of chemical composition and temperature relies on the knowledge of the nature, structure and elastic properties of the candidate materials. We will describe to what extent recent advances in experimental mineral physics and X-ray diffraction have yielded essential knowledge on the structure and high-pressure high-temperature behaviour of pertinent materials, and major improvements in our understanding of the chemical and mineralogical composition of the Earth´s mantle.
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Asha Jhonsi M, Kathiravan A, Renganathan R. Photoinduced interaction between xanthene dyes and colloidal CdS nanoparticles. J Mol Struct 2009. [DOI: 10.1016/j.molstruc.2009.01.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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King S. Slab sliding away. Nature 2008; 451:899-900. [DOI: 10.1038/451899a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Zhao D, Hasegawa A, Kanamori H. Deep structure of Japan subduction zone as derived from local, regional, and teleseismic events. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/94jb01149] [Citation(s) in RCA: 416] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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24
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Hasegawa A, Horiuchi S, Umino N. Seismic structure of the northeastern Japan convergent margin: A synthesis. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/93jb02797] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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25
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Stern RJ. When and how did plate tectonics begin? Theoretical and empirical considerations. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/s11434-007-0073-8] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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26
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Miller MS, Kennett BLN, Toy VG. Spatial and temporal evolution of the subducting Pacific plate structure along the western Pacific margin. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jb003705] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- M. S. Miller
- Research School of Earth Sciences; Australian National University; Canberra, ACT Australia
| | - B. L. N. Kennett
- Research School of Earth Sciences; Australian National University; Canberra, ACT Australia
| | - V. G. Toy
- Research School of Earth Sciences; Australian National University; Canberra, ACT Australia
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Affiliation(s)
- Francis Albarède
- Laboratoire des Sciences de la Terre, Ecole Normale Supérieure de Lyon, 46 Allee d'Italie, 69364 Lyon Cedex 7, France.
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Abstract
The domain graph of domains and domain combinations of Arabidopsis thaliana is established based on pfam 14.0 database and analyzed via comparison with 10 eukaryotic, 30 bacterial, and 16 archaeal proteomes. The comparative analysis of the domain graphs provides a useful platform for revealing global insights on the evolution of plant kingdom. More importantly, it is a powerful tool for searching not only the possible new function of both plant-specific and nonspecific domains via specific domain combinations in Arabidopsis thaliana but also the functional role of unknown domains. As an example, we present the functional link between ubiquitin and Myb_DNA-binding domains via Bromodomain as the plant specific evidence for the association between transcription and ubiquitin. We further show that PentatricoPeptide Repeats (PPR) proteins have plant-specific links with a wide variety of domains responsible for RNA binding/metabolism, modulation of protein-protein interactions, ubiquitin-conjugation, cell growth/maintenance, catalysis, and others. This further supports the recently proposed association of PPR proteins with specific RNA transcripts and defined effector proteins. Moreover, the domain graph built from tissue-specific genes is frequently associated with DNA binding domains, suggesting that the differentiation of tissue cell types is contributed mostly by tissue-specific transcriptional process. DOGMA (DOmain Graph via coMparitive analysis for Arabidopsis thaliana) is available on-line with a variety of search tools at http://theory.med.buffalo.edu/DOGMA. The database, which allows user-specified search for plant specific domains and their combinations, will be useful as an additional tool for annotation of the proteins that play specific roles in plants and other organisms.
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Affiliation(s)
- Song Liu
- Howard Hughes Medical Institute Center for Single Molecule Biophysics, Department of Physiology & Biophysics, State University of New York at Buffalo, 124 Sherman Hall, Buffalo, New York 14214, USA
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Bellahsen N. Dynamics of subduction and plate motion in laboratory experiments: Insights into the “plate tectonics” behavior of the Earth. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004jb002999] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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30
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Affiliation(s)
- Robert D van der Hilst
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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31
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Schellart WP. Kinematics of subduction and subduction-induced flow in the upper mantle. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2004jb002970] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- W. P. Schellart
- Australian Crustal Research Centre, School of Geosciences; Monash University; Melbourne Australia
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32
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Isshiki M, Irifune T, Hirose K, Ono S, Ohishi Y, Watanuki T, Nishibori E, Takata M, Sakata M. Stability of magnesite and its high-pressure form in the lowermost mantle. Nature 2004; 427:60-3. [PMID: 14702083 DOI: 10.1038/nature02181] [Citation(s) in RCA: 190] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2003] [Accepted: 11/04/2003] [Indexed: 11/08/2022]
Abstract
Carbonates are important constituents of marine sediments and play a fundamental role in the recycling of carbon into the Earth's deep interior via subduction of oceanic crust and sediments. Study of the stability of carbonates under high pressure and temperature is thus important for modelling the carbon budget in the entire Earth system. Such studies, however, have rarely been performed under appropriate lower-mantle conditions and no experimental data exist at pressures greater than 80 GPa (refs 3-6). Here we report an in situ X-ray diffraction study of the stability of magnesite (MgCO(3)), which is the major component of subducted carbonates, at pressure and temperature conditions approaching those of the core-mantle boundary. We found that magnesite transforms to an unknown form at pressures above approximately 115 GPa and temperatures of 2,100-2,200 K (depths of approximately 2,600 km) without any dissociation, suggesting that magnesite and its high-pressure form may be the major hosts for carbon throughout most parts of the Earth's lower mantle.
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Affiliation(s)
- Maiko Isshiki
- Geodynamics Research Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
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33
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Tommasi A. Strain-induced seismic anisotropy of wadsleyite polycrystals and flow patterns in the mantle transition zone. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2004jb003158] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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34
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Nishiyama N, Yagi T. Phase relation and mineral chemistry in pyrolite to 2200°C under the lower mantle pressures and implications for dynamics of mantle plumes. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jb002216] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Takehiko Yagi
- Institute for Solid State Physics; University of Tokyo; Kashiwa Japan
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35
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Funiciello F, Faccenna C, Giardini D, Regenauer-Lieb K. Dynamics of retreating slabs: 2. Insights from three-dimensional laboratory experiments. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2001jb000896] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Claudio Faccenna
- Dipartimento di Scienze Geologiche; Universita' degli Studi “Roma Tre,”; Rome Italy
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36
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Lebedev S, Nolet G. Upper mantle beneath Southeast Asia fromSvelocity tomography. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2000jb000073] [Citation(s) in RCA: 217] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Sergei Lebedev
- Department of Geosciences; Princeton University; Princeton New Jersey USA
| | - Guust Nolet
- Department of Geosciences; Princeton University; Princeton New Jersey USA
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37
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Stern RJ, Fouch MJ, Klemperer SL. An overview of the Izu-Bonin-Mariana subduction factory. INSIDE THE SUBDUCTION FACTORY 2003. [DOI: 10.1029/138gm10] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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38
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Seismological constraints on structure and flow patterns within the mantle wedge. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/138gm05] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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39
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Allègre CJ. The evolution of mantle mixing. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2002; 360:2411-2431. [PMID: 12460474 DOI: 10.1098/rsta.2002.1075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We present a geochemical overview of the canonic model that suggests a two-layer mantle for most of the Earth's history. A change in the Rayleigh number may have modified the convection and now allows the subduction of oceanic plates into the lower mantle, which was not the case in the past. The measurement of stirring time in the source of mid-ocean-ridge basalt, together with Xe- and Pb-isotopic ratios in the mid-ocean-ridge-basalt source, suggests that the upper mantle is separated into two domains, one above the 400 km discontinuity (asthenosphere) with rapid mixing and short residence time, and another between the 400 and 670 km discontinuities with sluggish mixing and a residence time of ca. 1.5 x 10(9) yr.
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Affiliation(s)
- Claude J Allègre
- Laboratoire de Géochimie and Cosmochimie, Institut de Physique du Globe de Paris, Boite 89, 4 place Jussieu, 75252 Paris cedex 05, France.
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Levin V, Shapiro N, Park J, Ritzwoller M. Seismic evidence for catastrophic slab loss beneath Kamchatka. Nature 2002; 418:763-7. [PMID: 12181563 DOI: 10.1038/nature00973] [Citation(s) in RCA: 166] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In the northwest Pacific Ocean, a sharp corner in the boundary between the Pacific plate and the North American plate joins a subduction zone running along the southern half of the Kamchatka peninsula with a region of transcurrent motion along the western Aleutian arc. Here we present images of the seismic structure beneath the Aleutian-Kamchatka junction and the surrounding region, indicating that: the subducting Pacific lithosphere terminates at the Aleutian-Kamchatka junction; no relict slab underlies the extinct northern Kamchatka volcanic arc; and the upper mantle beneath northern Kamchatka has unusually slow shear wavespeeds. From the tectonic and volcanic evolution of Kamchatka over the past 10 Myr (refs 3-5) we infer that at least two episodes of catastrophic slab loss have occurred. About 5 to 10 Myr ago, catastrophic slab loss shut down island-arc volcanic activity north of the Aleutian-Kamchatka junction. A later episode of slab loss, since about 2 Myr ago, seems to be related to the activity of the world's most productive island-arc volcano, Klyuchevskoy. Removal of lithospheric mantle is commonly discussed in the context of a continental collision, but our findings imply that episodes of slab detachment and loss are also important agents in the evolution of oceanic convergent margins.
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Affiliation(s)
- Vadim Levin
- Department of Geology and Geophysics, Box 208109, Yale University, New Haven, Connecticut 06520, USA.
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Hirose K. Phase transitions in pyrolitic mantle around 670-km depth: Implications for upwelling of plumes from the lower mantle. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001jb000597] [Citation(s) in RCA: 234] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Kei Hirose
- Department of Earth and Planetary Sciences; Tokyo Institute of Technology; Tokyo Japan
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Abstract
Seismological images of the Earth's mantle reveal three distinct changes in velocity structure, at depths of 410, 660 and 2,700 km. The first two are best explained by mineral phase transformations, whereas the third-the D" layer-probably reflects a change in chemical composition and thermal structure. Tomographic images of cold slabs in the lower mantle, the displacements of the 410-km and 660-km discontinuities around subduction zones, and the occurrence of small-scale heterogeneities in the lower mantle all indicate that subducted material penetrates the deep mantle, implying whole-mantle convection. In contrast, geochemical analyses of the basaltic products of mantle melting are frequently used to infer that mantle convection is layered, with the deeper mantle largely isolated from the upper mantle. We show that geochemical, seismological and heat-flow data are all consistent with whole-mantle convection provided that the observed heterogeneities are remnants of recycled oceanic and continental crust that make up about 16 and 0.3 per cent, respectively, of mantle volume.
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Affiliation(s)
- G R Helffrich
- Earth and Planetary Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-Ku, Tokyo 152-8551, Japan.
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Gu YJ, Dziewonski AM, Su W, Ekström G. Models of the mantle shear velocity and discontinuities in the pattern of lateral heterogeneities. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jb000340] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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44
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Abstract
Seismic tomography models of the three-dimensional upper mantle velocity structure of the Mediterranean-Carpathian region provide a better understanding of the lithospheric processes governing its geodynamical evolution. Slab detachment, in particular lateral migration of this process along the plate boundary, is a key element in the lithospheric dynamics of the region during the last 20 to 30 million years. It strongly affects arc and trench migration, and causes along-strike variations in vertical motions, stress fields, and magmatism. In a terminal-stage subduction zone, involving collision and suturing, slab detachment is the natural last stage in the gravitational settling of subducted lithosphere.
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Affiliation(s)
- M J Wortel
- Vening Meinesz Research School of Geodynamics, Faculty of Earth Sciences, Utrecht University, Budapestlaan 4, 3584CD, Utrecht, Netherlands
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Sarda P, Moreira M, Staudacher T, Schilling JG, Allègre CJ. Rare gas systematics on the southernmost Mid-Atlantic Ridge: Constraints on the lower mantle and the Dupal source. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999jb900282] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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46
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Weidner DJ, Wang Y. Phase transformations: Implications for mantle structure. EARTH'S DEEP INTERIOR: MINERAL PHYSICS AND TOMOGRAPHY FROM THE ATOMIC TO THE GLOBAL SCALE 2000. [DOI: 10.1029/gm117p0215] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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47
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Kárason H, van der Hilst RD. Constraints on Mantle Convection From Seismic Tomography. GEOPHYSICAL MONOGRAPH SERIES 2000. [DOI: 10.1029/gm121p0277] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Bercovici D, Ricard Y, Richards MA. The Relation between mantle dynamics and plate tectonics: A Primer. GEOPHYSICAL MONOGRAPH SERIES 2000. [DOI: 10.1029/gm121p0005] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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49
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A Comparison between tomographic and geodynamic models of the Earth's mantle. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/gm121p0257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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50
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Shearer PM. Upper mantle seismic discontinuities. EARTH'S DEEP INTERIOR: MINERAL PHYSICS AND TOMOGRAPHY FROM THE ATOMIC TO THE GLOBAL SCALE 2000. [DOI: 10.1029/gm117p0115] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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