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Journal articles on the topic 'Earth lower mantle'

Author: Grafiati

Published: 14 December 2024

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1

Murakami, Motohiko, Amir Khan, Paolo A. Sossi, Maxim D. Ballmer, and Pinku Saha. "The Composition of Earth's Lower Mantle." Annual Review of Earth and Planetary Sciences 52, no. 1 (July 23, 2024): 605–38. http://dx.doi.org/10.1146/annurev-earth-031621-075657.

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Determining the composition of Earth's lower mantle, which constitutes almost half of its total volume, has been a central goal in the Earth sciences for more than a century given the constraints it places on Earth's origin and evolution. However, whether the major element chemistry of the lower mantle, in the form of, e.g., Mg/Si ratio, is similar to or different from the upper mantle remains debated. Here we use a multidisciplinary approach to address the question of the composition of Earth's lower mantle and, in turn, that of bulk silicate Earth (crust and mantle) by considering the evidence provided by geochemistry, geophysics, mineral physics, and geodynamics. Geochemical and geodynamical evidence largely agrees, indicating a lower-mantle molar Mg/Si of ≥1.12 (≥1.15 for bulk silicate Earth), consistent with the rock record and accumulating evidence for whole-mantle stirring. However, mineral physics–informed profiles of seismic properties, based on a lower mantle made of bridgmanite and ferropericlase, point to Mg/Si ∼ 0.9–1.0 when compared with radial seismic reference models. This highlights the importance of considering the presence of additional minerals (e.g., calcium-perovskite and stishovite) and possibly suggests a lower mantle varying compositionally with depth. In closing, we discuss how we can improve our understanding of lower-mantle and bulk silicate Earth composition, including its impact on the light element budget of the core. ▪The chemical composition of Earth's lower mantle is indispensable for understanding its origin and evolution.▪Earth's lower-mantle composition is reviewed from an integrated mineral physics, geophysical, geochemical, and geodynamical perspective.▪A lower-mantle molar Mg/Si of ≥1.12 is favored but not unique.▪New experiments investigating compositional effects of bridgmanite and ferropericlase elasticity are needed to further our insight.

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2

Sunil, K., and B. S. Sharma. "Thermoelastic properties of the earth lower mantle." International Journal of Modern Physics B 31, no. 14 (March 27, 2017): 1750108. http://dx.doi.org/10.1142/s0217979217501089.

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For investigating the pressure dependence of thermal expansivity of materials, we have developed a formulation using the Stacey relationship between the reciprocal of pressure derivative of bulk modulus and the ratio of pressure and bulk modulus. The formulation presented here satisfies the boundary conditions both at zero pressure and also in the limit of infinite pressure at extreme compression. A physically acceptable relationship has been obtained between the volume derivative of thermal expansivity and the pressure derivatives of bulk modulus under adiabatic condition. The seismological data for the Earth lower mantle have been used to demonstrate the validity of the relationship between thermoelastic properties derived in the present study.

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3

Tsuchiya, Taku, Jun Tsuchiya, Haruhiko Dekura, and Sebastian Ritterbex. "Ab Initio Study on the Lower Mantle Minerals." Annual Review of Earth and Planetary Sciences 48, no. 1 (May 30, 2020): 99–119. http://dx.doi.org/10.1146/annurev-earth-071719-055139.

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Recent progress in theoretical mineral physics based on the ab initio quantum mechanical computation method has been dramatic in conjunction with the rapid advancement of computer technologies. It is now possible to predict stability, elasticity, and transport properties of complex minerals quantitatively with uncertainties that are comparable to or even smaller than those attached in experimental data. These calculations under in situ high-pressure ( P) and high-temperature conditions are of particular interest because they allow us to construct a priori mineralogical models of the deep Earth. In this article, we briefly review recent progress in studying high- P phase relations, elasticity, thermal conductivity, and rheological properties of lower mantle minerals including silicates, oxides, and some hydrous phases. Our analyses indicate that the pyrolitic composition can describe Earth's properties quite well in terms of density and P- and S-wave velocity. Computations also suggest some new hydrous compounds that could persist up to the deepest mantle and that the postperovskite phase boundary is the boundary of not only the mineralogy but also the thermal conductivity. ▪ The ab initio method is a strong tool to investigate physical properties of minerals under high pressure and high temperature. ▪ Calculated thermoelasticity indicates that the pyrolytic composition is representative to the chemistry of Earth's lower mantle. ▪ Simulations predict new dense hydrous phases stable in the whole lower mantle pressure and temperature condition. ▪ Calculated lattice thermal conductivity suggests a heat flow across the core mantle boundary no greater than 10 TW.

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4

Bower, Dan J., Michael Gurnis, and Maria Seton. "Lower mantle structure from paleogeographically constrained dynamic Earth models." Geochemistry, Geophysics, Geosystems 14, no. 1 (January 2013): 44–63. http://dx.doi.org/10.1029/2012gc004267.

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5

Zhang, Li. "Bridgmanite across the lower mantle." Nature Geoscience 15, no. 12 (December 2022): 964. http://dx.doi.org/10.1038/s41561-022-01099-7.

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6

Nakagawa, Takashi, and Tomoeki Nakakuki. "Dynamics in the Uppermost Lower Mantle: Insights into the Deep Mantle Water Cycle Based on the Numerical Modeling of Subducted Slabs and Global-Scale Mantle Dynamics." Annual Review of Earth and Planetary Sciences 47, no. 1 (May 30, 2019): 41–66. http://dx.doi.org/10.1146/annurev-earth-053018-060305.

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In this review, we address the current status of numerical modeling of the mantle transition zone and uppermost lower mantle, focusing on the hydration mechanism in these areas. The main points are as follows: ( a) Slab stagnation and penetration may play significant roles in transporting the water in the whole mantle, and ( b) a huge amount of water could be absorbed into the deep mantle to preserve the surface seawater over the geologic timescale. However, for further understanding of water circulation in the deep planetary interior, more mineral physics investigations are required to reveal the mechanism of water absorption in the lower mantle and thermochemical interaction across the core–mantle boundary region, which can provide information on material properties to the geodynamics community. Moreover, future investigations should focus on determining the amount of water in the early planetary interior, as suggested by the planetary formation theory of rocky planets. Moreover, the supplying mechanism of water during planetary formation and its evolution caused by plate tectonics are still essential issues because, in geodynamics modeling, a huge amount of water seems to be required to preserve the surface seawater in the present day and to not be dependent on an initial amount of water in Earth's system. ▪ Slab stagnation and penetration of the hydrous lithosphere are essential for understanding the global-scale material circulation. ▪ Thermal feedback caused by water-dependent viscosity is a main driving mechanism of water absorption in the mantle transition zone and uppermost lower mantle. ▪ The hydrous state in the early rocky planets remains to be determined from cosmo- and geochemistry and planetary formation theory. ▪ Volatile cycles in the deep planetary interior may affect the evolution of the surface environment.

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7

Revenaugh, Justin, and Thomas H. Jordan. "Mantle layering fromScSreverberations: 4. The lower mantle and core-mantle boundary." Journal of Geophysical Research: Solid Earth 96, B12 (November 10, 1991): 19811–24. http://dx.doi.org/10.1029/91jb02163.

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8

YAMAZAKI, Daisuke. "High Pressure Earth Science. Rheological Properties of the Lower Mantle." REVIEW OF HIGH PRESSURE SCIENCE AND TECHNOLOGY 9, no. 1 (1999): 19–25. http://dx.doi.org/10.4131/jshpreview.9.19.

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9

Bovolo, C. Isabella. "The physical and chemical composition of the lower mantle." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, no. 1837 (October 31, 2005): 2811–36. http://dx.doi.org/10.1098/rsta.2005.1675.

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This article reviews some of the recent advances made within the field of mineral physics. In order to link the observed seismic and density structures of the lower mantle with a particular mineral composition, knowledge of the thermodynamic properties of the candidate materials is required. Determining which compositional model best matches the observed data is difficult because of the wide variety of possible mineral structures and compositions. State-of-the-art experimental and analytical techniques have pushed forward our knowledge of mineral physics, yet certain properties, such as the elastic properties of lower mantle minerals at high pressures and temperatures, are difficult to determine experimentally and remain elusive. Fortunately, computational techniques are now sufficiently advanced to enable the prediction of these properties in a self-consistent manner, but more results are required. A fundamental question is whether or not the upper and lower mantles are mixing. Traditional models that involve chemically separate upper and lower mantles cannot yet be ruled out despite recent conflicting seismological evidence showing that subducting slabs penetrate deep into the lower mantle and that chemically distinct layers are, therefore, unlikely. Recent seismic tomography studies giving three-dimensional models of the seismic wave velocities in the Earth also base their interpretations on the thermodynamic properties of minerals. These studies reveal heterogeneous velocity and density anomalies in the lower mantle, which are difficult to reconcile with mineral physics data.

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10

Day, James M. D., D. Graham Pearson, and Lawrence A. Taylor. "Highly Siderophile Element Constraints on Accretion and Differentiation of the Earth-Moon System." Science 315, no. 5809 (January 12, 2007): 217–19. http://dx.doi.org/10.1126/science.1133355.

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A new combined rhenium-osmium– and platinum-group element data set for basalts from the Moon establishes that the basalts have uniformly low abundances of highly siderophile elements. The data set indicates a lunar mantle with long-term, chondritic, highly siderophile element ratios, but with absolute abundances that are over 20 times lower than those in Earth's mantle. The results are consistent with silicate-metal equilibrium during a giant impact and core formation in both bodies, followed by post–core-formation late accretion that replenished their mantles with highly siderophile elements. The lunar mantle experienced late accretion that was similar in composition to that of Earth but volumetrically less than (∼0.02% lunar mass) and terminated earlier than for Earth.

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11

Gülcher, Anna Johanna Pia, Maxim Dionys Ballmer, and Paul James Tackley. "Coupled dynamics and evolution of primordial and recycled heterogeneity in Earth's lower mantle." Solid Earth 12, no. 9 (September 14, 2021): 2087–107. http://dx.doi.org/10.5194/se-12-2087-2021.

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Abstract. The nature of compositional heterogeneity in Earth's lower mantle remains a long-standing puzzle that can inform about the long-term thermochemical evolution and dynamics of our planet. Here, we use global-scale 2D models of thermochemical mantle convection to investigate the coupled evolution and mixing of (intrinsically dense) recycled and (intrinsically strong) primordial heterogeneity in the mantle. We explore the effects of ancient compositional layering of the mantle, as motivated by magma ocean solidification studies, and of the physical parameters of primordial material. Depending on these physical parameters, our models predict various regimes of mantle evolution and heterogeneity preservation over 4.5 Gyr. Over a wide parameter range, primordial and recycled heterogeneity are predicted to co-exist with each other in the lower mantle of Earth-like planets. Primordial material usually survives as medium- to large-scale blobs (or streaks) in the mid-mantle, around 1000–2000 km depth, and this preservation is largely independent of the initial primordial-material volume. In turn, recycled oceanic crust (ROC) persists as large piles at the base of the mantle and as small streaks everywhere else. In models with an additional dense FeO-rich layer initially present at the base of the mantle, the ancient dense material partially survives at the top of ROC piles, causing the piles to be compositionally stratified. Moreover, the addition of such an ancient FeO-rich basal layer significantly aids the preservation of the viscous domains in the mid-mantle. Finally, we find that primordial blobs are commonly directly underlain by thick ROC piles and aid their longevity and stability. Based on our results, we propose an integrated style of mantle heterogeneity for the Earth involving the preservation of primordial domains along with recycled piles. This style has important implications for early Earth evolution and has the potential to reconcile geophysical and geochemical discrepancies on present-day lower-mantle heterogeneity.

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12

KUSHWAH, S. S., and N. K. BHARDWAJ. "HIGHER ORDER THERMOELASTIC PROPERTIES OF THE EARTH LOWER MANTLE AND CORE." International Journal of Modern Physics B 24, no. 09 (April 10, 2010): 1187–200. http://dx.doi.org/10.1142/s0217979210055238.

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We have used some of the most reliable high pressure equations of state (EOS) to determine the thermoelastic Grüneisen parameter and its higher order volume derivatives for the lower mantle, outer core and inner core of the Earth. The cross derivatives of bulk modulus with respect to pressure and temperature have also been obtained for the deep interior of the Earth using the results based on the modified free volume theory for the Grüneisen parameter. We have used five EOS viz. (a) modified Rydberg EOS, (b) modified Poirier–Tarantola EOS, (c) Hama–Suito EOS, (d) Stacey EOS, and (e) Kushwah EOS to determine pressure derivatives of bulk modulus. The results for thermoelastic parameters obtained in the present study show systematic variations with the increase in pressure.

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13

Stewart, D. N., F. H. Busse, K. A. Whaler, and D. Gubbins. "Geomagnetism, Earth rotation and the electrical conductivity of the lower mantle." Physics of the Earth and Planetary Interiors 92, no. 3-4 (December 1995): 199–214. http://dx.doi.org/10.1016/0031-9201(95)03035-4.

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14

Fiquet, G., F. Guyot, and J. Badro. "The Earth's Lower Mantle and Core." Elements 4, no. 3 (June 1, 2008): 177–82. http://dx.doi.org/10.2113/gselements.4.3.177.

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15

Ferreira, Ana M. G., Manuele Faccenda, William Sturgeon, Sung-Joon Chang, and Lewis Schardong. "Ubiquitous lower-mantle anisotropy beneath subduction zones." Nature Geoscience 12, no. 4 (March 25, 2019): 301–6. http://dx.doi.org/10.1038/s41561-019-0325-7.

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16

Ritsema, Jeroen, and Vedran Lekić. "Heterogeneity of Seismic Wave Velocity in Earth's Mantle." Annual Review of Earth and Planetary Sciences 48, no. 1 (May 30, 2020): 377–401. http://dx.doi.org/10.1146/annurev-earth-082119-065909.

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Seismology provides important constraints on the structure and dynamics of the deep mantle. Computational and methodological advances in the past two decades improved tomographic imaging of the mantle and revealed the fine-scale structure of plumes ascending from the core-mantle boundary region and slabs of oceanic lithosphere sinking into the lower mantle. We discuss the modeling aspects of global tomography including theoretical approximations, data selection, and model fidelity and resolution. Using spectral, principal component, and cluster analyses, we highlight the robust patterns of seismic heterogeneity, which inform us of flow in the mantle, the history of plate motions, and potential compositionally distinct reservoirs. In closing, we emphasize that data mining of vast collections of seismic waveforms and new data from distributed acoustic sensing, autonomous hydrophones, ocean-bottom seismometers, and correlation-based techniques will boost the development of the next generation of global models of density, seismic velocity, and attenuation. ▪ Seismic tomography reveals the 100-km to 1,000-km scale variation of seismic velocity heterogeneity in the mantle. ▪ Tomographic images are the most important geophysical constraints on mantle circulation and evolution.

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17

DeFelice, C., S. Mallick, A. E. Saal, and S. Huang. "An isotopically depleted lower mantle component is intrinsic to the Hawaiian mantle plume." Nature Geoscience 12, no. 6 (April 22, 2019): 487–92. http://dx.doi.org/10.1038/s41561-019-0348-0.

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18

Machetel, Philippe. "Short-wavelength lower mantle seismic velocity anomalies." Geophysical Research Letters 17, no. 8 (July 1990): 1145–48. http://dx.doi.org/10.1029/gl017i008p01145.

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19

van den Berg, Arie P., and David A. Yuen. "Is the lower-mantle rheology Newtonian today?" Geophysical Research Letters 23, no. 16 (August 1, 1996): 2033–36. http://dx.doi.org/10.1029/96gl02065.

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20

Weber, M., and M. Körnig. "Lower mantle inhomogeneities inferred from PcP precursors." Geophysical Research Letters 17, no. 11 (October 1990): 1993–96. http://dx.doi.org/10.1029/gl017i011p01993.

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21

Hermann, Andreas, and Mainak Mookherjee. "High-pressure phase of brucite stable at Earth’s mantle transition zone and lower mantle conditions." Proceedings of the National Academy of Sciences 113, no. 49 (November 21, 2016): 13971–76. http://dx.doi.org/10.1073/pnas.1611571113.

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We investigate the high-pressure phase diagram of the hydrous mineral brucite, Mg(OH)2, using structure search algorithms and ab initio simulations. We predict a high-pressure phase stable at pressure and temperature conditions found in cold subducting slabs in Earth’s mantle transition zone and lower mantle. This prediction implies that brucite can play a much more important role in water transport and storage in Earth’s interior than hitherto thought. The predicted high-pressure phase, stable in calculations between 20 and 35 GPa and up to 800 K, features MgO6 octahedral units arranged in the anatase–TiO2 structure. Our findings suggest that brucite will transform from a layered to a compact 3D network structure before eventual decomposition into periclase and ice. We show that the high-pressure phase has unique spectroscopic fingerprints that should allow for straightforward detection in experiments. The phase also has distinct elastic properties that might make its direct detection in the deep Earth possible with geophysical methods.

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22

Mashino, Izumi, Motohiko Murakami, Nobuyoshi Miyajima, and Sylvain Petitgirard. "Experimental evidence for silica-enriched Earth’s lower mantle with ferrous iron dominant bridgmanite." Proceedings of the National Academy of Sciences 117, no. 45 (October 22, 2020): 27899–905. http://dx.doi.org/10.1073/pnas.1917096117.

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Determination of the chemical composition of the Earth’s mantle is of prime importance to understand the evolution, dynamics, and origin of the Earth. However, there is a lack of experimental data on sound velocity of iron-bearing Bridgmanite (Brd) under relevant high-pressure conditions of the whole mantle, which prevents constraints on the mineralogical model of the lower mantle. To uncover these issues, we have conducted sound-velocity measurement of iron-bearing Brd in a diamond-anvil cell (DAC) up to 124 GPa using Brillouin scattering spectroscopy. Here we show that the sound velocities of iron-bearing Brd throughout the whole pressure range of lower mantle exhibit an apparent linear reduction with the iron content. Our data fit remarkably with the seismic structure throughout the lower mantle with Fe2+-enriched Brd, indicating that the greater part of the lower mantle could be occupied by Fe2+-enriched Brd. Our lower-mantle model shows a distinctive Si-enriched composition with Mg/Si of 1.14 relative to the upper mantle (Mg/Si = 1.25), which implies that the mantle convection has been inefficient enough to chemically homogenize the Earth’s whole mantle.

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23

Zhang, Baolong, Xiangfang Zeng, Jun Xie, and Vernon F. Cormier. "Validity of Resolving the 785 km Discontinuity in the Lower Mantle with P′P′ Precursors?" Seismological Research Letters 91, no. 6 (August 19, 2020): 3278–85. http://dx.doi.org/10.1785/0220200210.

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Abstract P ′ P ′ precursors have been used to detect discontinuities in the lower mantle of the Earth, but some seismic phases propagating along asymmetric ray paths or scattered waves could be misinterpreted as reflections from mantle discontinuities. By forward modeling in standard 1D Earth models, we demonstrate that the frequency content, slowness, and decay with distance of precursors about 180 s before P′P′ arrival are consistent with those of the PKPPdiff phase (or PdiffPKP) at epicentral distances around 78° rather than a reflection from a lower mantle interface. Furthermore, a beamforming technique applied to waveform data recorded at the USArray demonstrates that PKPPdiff can be commonly observed from numerous earthquakes. Hence, a reference 1D Earth model without lower mantle discontinuities can explain many of the observed P′P′ precursors signals if they are interpreted as PKPPdiff, instead of P′785P′. However, this study does not exclude the possibility of 785 km interface beneath the Africa. If this interface indeed exists, P′P′ precursors at distances around 78° would better not be used for its detection to avoid interference from PKPPdiff. Indeed, it could be detected with P′P′ precursors at epicentral distances less than 76° or with other seismic phases such as backscattered PKP·PKP waves.

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24

Sharma, S. K. "Volume thermal expansivity for lower mantle region of earth under adiabatic condition." Physica B: Condensed Matter 419 (June 2013): 37–39. http://dx.doi.org/10.1016/j.physb.2013.03.007.

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25

Yuen, David A., Nicola Tosi, and Ondrej Čadek. "Influences of lower-mantle properties on the formation of asthenosphere in oceanic upper mantle." Journal of Earth Science 22, no. 2 (April 2011): 143–54. http://dx.doi.org/10.1007/s12583-011-0166-9.

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26

Romanowicz, Barbara. "3D structure of the Earth's lower mantle." Comptes Rendus Geoscience 335, no. 1 (January 2003): 23–35. http://dx.doi.org/10.1016/s1631-0713(03)00012-9.

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27

Gasperini, Paolo, David A. Yuen, and Roberto Sabadini. "Postglacial rebound with a non-Newtonian upper mantle and a Newtonian lower mantle rheology." Geophysical Research Letters 19, no. 16 (August 21, 1992): 1711–14. http://dx.doi.org/10.1029/92gl01456.

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28

Davis, J. Peter, and Michael Weber. "Lower mantle velocity inhomogeneity observed at GRF array." Geophysical Research Letters 17, no. 2 (February 1990): 187–90. http://dx.doi.org/10.1029/gl017i002p00187.

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29

Petersons, H. F., and S. Constable. "Global mapping of the electrically conductive lower mantle." Geophysical Research Letters 23, no. 12 (June 1, 1996): 1461–64. http://dx.doi.org/10.1029/96gl01412.

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30

Meade, Charles, Paul G. Silver, and Satoshi Kaneshima. "Laboratory and seismological observations of lower mantle isotropy." Geophysical Research Letters 22, no. 10 (May 15, 1995): 1293–96. http://dx.doi.org/10.1029/95gl01091.

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31

Sleep, Norman H. "Simple features of mantle-wide convection and the interpretation of lower-mantle tomograms." Comptes Rendus Geoscience 335, no. 1 (January 2003): 9–22. http://dx.doi.org/10.1016/s1631-0713(03)00008-7.

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32

Cordier, Patrick, Karine Gouriet, Timmo Weidner, James Van Orman, Olivier Castelnau, Jennifer M. Jackson, and Philippe Carrez. "Periclase deforms more slowly than bridgmanite under mantle conditions." Nature 613, no. 7943 (January 11, 2023): 303–7. http://dx.doi.org/10.1038/s41586-022-05410-9.

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AbstractTransport of heat from the interior of the Earth drives convection in the mantle, which involves the deformation of solid rocks over billions of years. The lower mantle of the Earth is mostly composed of iron-bearing bridgmanite MgSiO3 and approximately 25% volume periclase MgO (also with some iron). It is commonly accepted that ferropericlase is weaker than bridgmanite1. Considerable progress has been made in recent years to study assemblages representative of the lower mantle under the relevant pressure and temperature conditions2,3. However, the natural strain rates are 8 to 10 orders of magnitude lower than in the laboratory, and are still inaccessible to us. Once the deformation mechanisms of rocks and their constituent minerals have been identified, it is possible to overcome this limitation thanks to multiscale numerical modelling, and to determine rheological properties for inaccessible strain rates. In this work we use 2.5-dimensional dislocation dynamics to model the low-stress creep of MgO periclase at lower mantle pressures and temperatures. We show that periclase deforms very slowly under these conditions, in particular, much more slowly than bridgmanite deforming by pure climb creep. This is due to slow diffusion of oxygen in periclase under pressure. In the assemblage, this secondary phase hardly participates in the deformation, so that the rheology of the lower mantle is very well described by that of bridgmanite. Our results show that drastic changes in deformation mechanisms can occur as a function of the strain rate.

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33

Ryabchikov, I. D. "Conditions of diamond formation in the Earth’s lower mantle." Doklady Earth Sciences 438, no. 2 (June 2011): 788–91. http://dx.doi.org/10.1134/s1028334x11060110.

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34

Petersen, Robert I., Dave R. Stegman, and Paul J. Tackley. "The subduction dichotomy of strong plates and weak slabs." Solid Earth 8, no. 2 (March 24, 2017): 339–50. http://dx.doi.org/10.5194/se-8-339-2017.

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Abstract. A key element of plate tectonics on Earth is that the lithosphere is subducting into the mantle. Subduction results from forces that bend and pull the lithosphere into the interior of the Earth. Once subducted, lithospheric slabs are further modified by dynamic forces in the mantle, and their sinking is inhibited by the increase in viscosity of the lower mantle. These forces are resisted by the material strength of the lithosphere. Using geodynamic models, we investigate several subduction models, wherein we control material strength by setting a maximum viscosity for the surface plates and the subducted slabs independently. We find that models characterized by a dichotomy of lithosphere strengths produce a spectrum of results that are comparable to interpretations of observations of subduction on Earth. These models have strong lithospheric plates at the surface, which promotes Earth-like single-sided subduction. At the same time, these models have weakened lithospheric subducted slabs which can more easily bend to either lie flat or fold into a slab pile atop the lower mantle, reproducing the spectrum of slab morphologies that have been interpreted from images of seismic tomography.

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35

Fukuhara, Mikio, Alexander Yoshino, and Nobuhisa Fujima. "Earth factories: Creation of the elements from nuclear transmutation in Earth’s lower mantle." AIP Advances 11, no. 10 (October 1, 2021): 105113. http://dx.doi.org/10.1063/5.0061584.

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36

Dubrovinsky, L., C. McCammon, K. Glazyrin, O. Narygina, M. Merlini, I. Kantor, M. Hanfland, and A. Chumakov. "Interplay between structural and electronic behavior in iron-bearing earth lower mantle minerals." Acta Crystallographica Section A Foundations of Crystallography 66, a1 (August 29, 2010): s42. http://dx.doi.org/10.1107/s0108767310099058.

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37

SRIVASTAVA, S. K. "VOLUME DEPENDENCE OF GRÜNEISEN RATIO FOR LOWER MANTLE AND CORE OF THE EARTH." Modern Physics Letters B 25, no. 18 (July 20, 2011): 1549–56. http://dx.doi.org/10.1142/s0217984911026449.

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In this study, we have examined the various formulations for volume dependence of the Grüneisen ratio, γ. The thermodynamic constraints for γ∞, q∞ and λ∞ have been used to discuss the validity of various relationships. The volume dependence of γ and its derivatives, reported by Stacey and Davis [F. D. Stacey and P. M. Davis, Phys. Earth Planet. Inter.142 (2004) 137–184], are analyzed. The Al'tshuler et al.'s relationship of γ(V), widely used in recent literature, has been found to be inadequate on the variation of λ with compression. The estimates of γ, q and λ are obtained with the combination of generalized free volume theory and reciprocal K-prime equations of state for the Earth's interior.

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38

Nie, Chuanhui, Jinghua Wei, and Lifang Yu. "Anderson–Grüneisen parameter for lower mantle region of the Earth under adiabatic condition." High Pressure Research 32, no. 3 (September 2012): 425–29. http://dx.doi.org/10.1080/08957959.2012.722212.

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39

Kuskov, O. L., E. V. Kronrod, and V. A. Kronrod. "Effect of thermal state on the chemical composition of the mantle and the sizes of the moon’s core." Геохимия 64, no. 6 (June 26, 2019): 567–84. http://dx.doi.org/10.31857/s0016-7525646567-584.

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Based on the joint inversion of seismic and gravity data in combination with the Gibbs free energy minimization method for calculating phase equilibria in the framework of the Na2O-TiO2-CaO-FeO-MgO-Al2O3-SiO2 system, the influence of the thermal state on the chemical composition models of the mantle and the sizes of the Fe-S core of the Moon has been studied. The boundary conditions used are seismic models from Apollo experiments, mass and moment of inertia from the GRAIL mission. As a result of solving the inverse problem, constraints on the chemical composition (concentration of rock-forming oxides) and the mineralogy of a three-layer mantle are obtained. It is shown that regardless of the temperature distribution, the FeO content of 11–14 wt.% and magnesian number MG# 80–83 are approximately the same in the upper, middle and lower mantle of the Moon, but differ sharply from that for the bulk composition of the silicate Earth (Bulk Silicate Earth = BSE, FeO ~8 wt% and MG# 89). On the contrary, estimates of the Al2O3 content in the mantle rather noticeably depend on the temperature distribution. For the considered scenarios of the thermal state with a difference in temperature of 100–200°C at different depths, Al2O3 concentrations increase from 1–5% in the upper and middle mantles to 4–7 wt.% in the lower mantle with garnet amounts up to 20 wt.%. For the “cold” models, the bulk abundance of aluminum oxide in the Moonis Al2O3 ~1–1.2 × BSE, and for the “hot” models it can be in the range of 1.3–1.7 × BSE. Concentrations of SiO2 to a lesser extent depend on the temperature distribution and constitute 50–55% in the upper and 45–50 wt.% in the lower mantle; orthopyroxene, rather than olivine, is the dominant mineral of the upper mantle. Based on the modeling of the density of Fe-S melts at high Р-Т parameters, the sizes of the lunar core are estimated. The Fe-S core radii with an average density of 7.1 g/cm3 and a sulfur content of 3.5–6 wt.% are in the range of 50–350 km with a most likely value of about 300 km and rather weakly depend on the thermal regime of the Moon. The simulation results suggest that a lunar mantle is stratified by chemical composition and indicate significant differences in the compositions of the Earth and its satellite.

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40

Dorfman, Susannah M., Farhang Nabiei, Charles-Edouard Boukaré, Vitali B. Prakapenka, Marco Cantoni, James Badro, and Philippe Gillet. "Composition and Pressure Effects on Partitioning of Ferrous Iron in Iron-Rich Lower Mantle Heterogeneities." Minerals 11, no. 5 (May 12, 2021): 512. http://dx.doi.org/10.3390/min11050512.

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Both seismic observations of dense low shear velocity regions and models of magma ocean crystallization and mantle dynamics support enrichment of iron in Earth’s lowermost mantle. Physical properties of iron-rich lower mantle heterogeneities in the modern Earth depend on distribution of iron between coexisting lower mantle phases (Mg,Fe)O magnesiowüstite, (Mg,Fe)SiO3 bridgmanite, and (Mg,Fe)SiO3 post-perovskite. The partitioning of iron between these phases was investigated in synthetic ferrous-iron-rich olivine compositions (Mg0.55Fe0.45)2SiO4 and (Mg0.28Fe0.72)2SiO4 at lower mantle conditions ranging from 33–128 GPa and 1900–3000 K in the laser-heated diamond anvil cell. The resulting phase assemblages were characterized by a combination of in situ X-ray diffraction and ex situ transmission electron microscopy. The exchange coefficient between bridgmanite and magnesiowüstite decreases with pressure and bulk Fe# and increases with temperature. Thermodynamic modeling determines that incorporation and partitioning of iron in bridgmanite are explained well by excess volume associated with Mg-Fe exchange. Partitioning results are used to model compositions and densities of mantle phase assemblages as a function of pressure, FeO-content and SiO2-content. Unlike average mantle compositions, iron-rich compositions in the mantle exhibit negative dependence of density on SiO2-content at all mantle depths, an important finding for interpretation of deep lower mantle structures.

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Dorfman, Susannah M., James Badro, Farhang Nabiei, Vitali B. Prakapenka, Marco Cantoni, and Philippe Gillet. "Carbonate stability in the reduced lower mantle." Earth and Planetary Science Letters 489 (May 2018): 84–91. http://dx.doi.org/10.1016/j.epsl.2018.02.035.

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42

Hirose, Kei, Ryosuke Sinmyo, and John Hernlund. "Perovskite in Earth’s deep interior." Science 358, no. 6364 (November 9, 2017): 734–38. http://dx.doi.org/10.1126/science.aam8561.

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Silicate perovskite-type phases are the most abundant constituent inside our planet and are the predominant minerals in Earth’s lower mantle more than 660 kilometers below the surface. Magnesium-rich perovskite is a major lower mantle phase and undergoes a phase transition to post-perovskite near the bottom of the mantle. Calcium-rich perovskite is proportionally minor but may host numerous trace elements that record chemical differentiation events. The properties of mantle perovskites are the key to understanding the dynamic evolution of Earth, as they strongly influence the transport properties of lower mantle rocks. Perovskites are expected to be an important constituent of rocky planets larger than Mars and thus play a major role in modulating the evolution of terrestrial planets throughout the universe.

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43

Ni, Huaiwei, Yong-Fei Zheng, Zhu Mao, Qin Wang, Ren-Xu Chen, and Li Zhang. "Distribution, cycling and impact of water in the Earth's interior." National Science Review 4, no. 6 (October 27, 2017): 879–91. http://dx.doi.org/10.1093/nsr/nwx130.

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Abstract The Earth's deep interior is a hidden water reservoir on a par with the hydrosphere that is crucial for keeping the Earth as a habitable planet. In particular, nominally anhydrous minerals (NAMs) in the silicate Earth host a significant amount of water by accommodating H point defects in their crystal lattices. Water distribution in the silicate Earth is highly heterogeneous, and the mantle transition zone may contain more water than the upper and lower mantles. Plate subduction transports surface water to various depths, with a series of hydrous minerals and NAMs serving as water carriers. Dehydration of the subducting slab produces liquid phases such as aqueous solutions and hydrous melts as a metasomatic agent of the mantle. Partial melting of the metasomatic mantle domains sparks off arc volcanism, which, along with the volcanism at mid-ocean ridges and hotspots, returns water to the surface and completes the deep water cycle. There appears to have been a steady balance between hydration and dehydration of the mantle at least since the Phanerozoic. Earth's water probably originates from a primordial portion that survived the Moon-forming giant impact, with later delivery by asteroids and comets. Water could play a critical role in initiating plate tectonics. In the modern Earth, the storage and cycling of water profoundly modulates a variety of properties and processes of the Earth's interior, with impacts on surface environments. Notable examples include the hydrolytic weakening effect on mantle convection and plate motion, influences on phase transitions (on the solidus of mantle peridotite in particular) and dehydration embrittlement triggering intermediate- to deep-focus earthquakes. Water can reduce seismic velocity and enhance electrical conductivity, providing remote sensing methods for water distribution in the Earth's interior. Many unresolved issues around the deep water cycle require an integrated approach and concerted efforts from multiple disciplines.

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44

McCammon, C., I. Kantor, O. Narygina, J. Rouquette, U. Ponkratz, I. Sergueev, M. Mezouar, V. Prakapenka, and L. Dubrovinsky. "Stable intermediate-spin ferrous iron in lower-mantle perovskite." Nature Geoscience 1, no. 10 (September 14, 2008): 684–87. http://dx.doi.org/10.1038/ngeo309.

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45

Timmerman, Suzette, Anna V. Spivak, and Adrian P. Jones. "Carbonatitic Melts and Their Role in Diamond Formation in the Deep Earth." Elements 17, no. 5 (October 1, 2021): 321–26. http://dx.doi.org/10.2138/gselements.17.5.321.

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Carbonatitic high-density fluids and carbonate mineral inclusions in lithospheric and sub-lithospheric diamonds reveal comparable compositions to crustal carbonatites and, thus, support the presence of carbon-atitic melts to depths of at least the mantle transition zone (~410–660 km depth). Diamonds and high pressure–high temperature (HP–HT) experiments confirm the stability of lower mantle carbonates. Experiments also show that carbonate melts have extremely low viscosity in the upper mantle. Hence, carbonatitic melts may participate in the deep (mantle) carbon cycle and be highly effective metasomatic agents. Deep carbon in the upper mantle can be mobilized by metasomatic carbonatitic melts, which may have become increasingly volumetrically significant since the onset of carbonate subduction (~3 Ga) to the present day.

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Wang, Yanbin, and Donald J. Weidner. "Thermoelasticity of CaSiO3perovskite and implications for the lower mantle." Geophysical Research Letters 21, no. 10 (May 15, 1994): 895–98. http://dx.doi.org/10.1029/94gl00976.

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47

Weber, M. "Lamellae inD″?: An alternative model for lower mantle anomalies." Geophysical Research Letters 21, no. 23 (November 15, 1994): 2531–34. http://dx.doi.org/10.1029/94gl01859.

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48

Domeier, Mathew, Pavel V. Doubrovine, Trond H. Torsvik, Wim Spakman, and Abigail L. Bull. "Global correlation of lower mantle structure and past subduction." Geophysical Research Letters 43, no. 10 (May 23, 2016): 4945–53. http://dx.doi.org/10.1002/2016gl068827.

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49

Duffy, Thomas S. "Some recent advances in understanding the mineralogy of Earth's deep mantle." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, no. 1883 (September 30, 2008): 4273–93. http://dx.doi.org/10.1098/rsta.2008.0172.

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Understanding planetary structure and evolution requires a detailed knowledge of the properties of geological materials under the conditions of deep planetary interiors. Experiments under the extreme pressure–temperature conditions of the deep mantle are challenging, and many fundamental properties remain poorly constrained or are inferred only through uncertain extrapolations from lower pressure–temperature states. Nevertheless, the last several years have witnessed a number of new developments in this area, and a broad overview of the current understanding of the Earth's lower mantle is presented here. Some recent experimental and theoretical advances related to the lowermost mantle are highlighted. Measurements of the equation of state and deformation behaviour of (Mg,Fe)SiO 3 in the CaIrO 3 -type (post-perovskite) structure yield insights into the nature of the core–mantle boundary region. Theoretical studies of the behaviour of MgSiO 3 liquids under high pressure–temperature conditions provide constraints on melt volumes, diffusivities and viscosities that are relevant to understanding both the early Earth (e.g. deep magma oceans) and seismic structure observed in the present Earth (e.g. ultra-low-velocity zones).

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Aktas, Kadircan, and David W. Eaton. "Upper-mantle velocity structure of the lower Great Lakes region." Tectonophysics 420, no. 1-2 (June 2006): 267–81. http://dx.doi.org/10.1016/j.tecto.2006.01.020.

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