1
|
Ho WGD, Zhang P, Haule K, Jackson JM, Dobrosavljević V, Dobrosavljevic VV. Quantum critical phase of FeO spans conditions of Earth's lower mantle. Nat Commun 2024; 15:3461. [PMID: 38658590 PMCID: PMC11043421 DOI: 10.1038/s41467-024-47489-w] [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: 02/08/2023] [Accepted: 03/28/2024] [Indexed: 04/26/2024] Open
Abstract
Seismic and mineralogical studies have suggested regions at Earth's core-mantle boundary may be highly enriched in FeO, reported to exhibit metallic behavior at extreme pressure-temperature (P-T) conditions. However, underlying electronic processes in FeO remain poorly understood. Here we explore the electronic structure of B1-FeO at extreme conditions with large-scale theoretical modeling using state-of-the-art embedded dynamical mean field theory (eDMFT). Fine sampling of the phase diagram reveals that, instead of sharp metallization, compression of FeO at high temperatures induces a gradual orbitally selective insulator-metal transition. Specifically, at P-T conditions of the lower mantle, FeO exists in an intermediate quantum critical state, characteristic of strongly correlated electronic matter. Transport in this regime, distinct from insulating or metallic behavior, is marked by incoherent diffusion of electrons in the conducting t2g orbital and a band gap in the eg orbital, resulting in moderate electrical conductivity (~105 S/m) with modest P-T dependence as observed in experiments. Enrichment of solid FeO can thus provide a unifying explanation for independent observations of low seismic velocities and elevated electrical conductivities in heterogeneities at Earth's mantle base.
Collapse
Affiliation(s)
- Wai-Ga D Ho
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - Peng Zhang
- MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Advanced Functional Materials and Mesoscopic Physics, School of Physics, Xi'an Jiaotong University, 710049, Xi'an, Shaanxi, PR China.
| | - Kristjan Haule
- Center for Materials Theory, Department of Physics, Rutgers University, Piscataway, NJ, USA
| | - Jennifer M Jackson
- Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Vladimir Dobrosavljević
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - Vasilije V Dobrosavljevic
- Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA.
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC, USA.
| |
Collapse
|
2
|
Quantification of Small-Scale Heterogeneity at the Core–Mantle Boundary Using Sample Entropy of SKS and SPdKS Synthetic Waveforms. MINERALS 2022. [DOI: 10.3390/min12070813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Qualitative and quantitative analysis of seismic waveforms sensitive to the core–mantle boundary (CMB) region reveal the presence of ultralow-velocity zones (ULVZs) that have a strong decrease in compressional (P) and shear (S) wave velocity, and an increase in density within thin structures. However, understanding their physical origin and relation to the other large-scale structures in the lowermost mantle are limited due to an incomplete mapping of ULVZs at the CMB. The SKS and SPdKS seismic waveforms is routinely used to infer ULVZ presence, but has thus far only been used in a limited epicentral distance range. As the SKS/SPdKS wavefield interacts with a ULVZ it generates additional seismic arrivals, thus increasing the complexity of the recorded wavefield. Here, we explore utilization of the multi-scale sample entropy method to search for ULVZ structures. We investigate the feasibility of this approach through analysis of synthetic seismograms computed for PREM, 1-, 2.5-, and 3-D ULVZs as well as heterogeneous structures with a strong increase in velocity in the lowermost mantle in 1- and 2.5-D. We find that the sample entropy technique may be useful across a wide range of epicentral distances from 100° to 130°. Such an analysis, when applied to real waveforms, could provide coverage of roughly 85% by surface area of the CMB.
Collapse
|
3
|
Kilometer-scale structure on the core-mantle boundary near Hawaii. Nat Commun 2022; 13:2787. [PMID: 35589765 PMCID: PMC9120171 DOI: 10.1038/s41467-022-30502-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 04/28/2022] [Indexed: 11/08/2022] Open
Abstract
The lowermost mantle right above the core-mantle boundary is highly heterogeneous containing multiple poorly understood seismic features. The smallest but most extreme heterogeneities yet observed are 'Ultra-Low Velocity Zones' (ULVZ). We exploit seismic shear waves that diffract along the core-mantle boundary to provide new insight into these enigmatic structures. We measure a rare core-diffracted signal refracted by a ULVZ at the base of the Hawaiian mantle plume at unprecedentedly high frequencies. This signal shows remarkably longer time delays at higher compared to lower frequencies, indicating a pronounced internal variability inside the ULVZ. Utilizing the latest computational advances in 3D waveform modeling, here we show that we are able to model this high-frequency signal and constrain high-resolution ULVZ structure on the scale of kilometers, for the first time. This new observation suggests a chemically distinct ULVZ with increasing iron content towards the core-mantle boundary, which has implications for Earth's early evolutionary history and core-mantle interaction.
Collapse
|
4
|
Li J, Sun D, Bower DJ. Slab control on the mega-sized North Pacific ultra-low velocity zone. Nat Commun 2022; 13:1042. [PMID: 35210453 PMCID: PMC8873298 DOI: 10.1038/s41467-022-28708-8] [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: 12/07/2020] [Accepted: 01/24/2022] [Indexed: 11/09/2022] Open
Abstract
Ultra-low velocity zones (ULVZs) are localized small-scale patches with extreme physical properties at the core-mantle boundary that often gather at the margins of Large Low Velocity Provinces (LLVPs). Recent studies have discovered several mega-sized ULVZs with a lateral dimension of ~900 km. However, the detailed structures and physical properties of these ULVZs and their relationship to LLVP edges are not well constrained and their formation mechanisms are poorly understood. Here, we break the degeneracy between the size and velocity perturbation of a ULVZ using two orthogonal seismic ray paths, and thereby discover a mega-sized ULVZ at the northern edge of the Pacific LLVP. The ULVZ is almost double the size of a previously imaged ULVZ in this region, but with half of the shear velocity reduction. This mega-sized ULVZ has accumulated due to stable mantle flow converging at the LLVP edge driven by slab-debris in the lower mantle. Such flow also develops the subvertical north-tilting edge of the Pacific LLVP.
Collapse
Affiliation(s)
- Jiewen Li
- Laboratory of Seismology and Physics of Earth's Interior, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, China.,CAS Center for Excellence in Comparative Planetology, China, Hefei, Anhui, 233500, China
| | - Daoyuan Sun
- Laboratory of Seismology and Physics of Earth's Interior, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, China. .,CAS Center for Excellence in Comparative Planetology, China, Hefei, Anhui, 233500, China.
| | - Dan J Bower
- Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012, Bern, Switzerland
| |
Collapse
|
5
|
Bao X, Lithgow-Bertelloni CR, Jackson MG, Romanowicz B. On the relative temperatures of Earth's volcanic hotspots and mid-ocean ridges. Science 2022; 375:57-61. [PMID: 34990241 DOI: 10.1126/science.abj8944] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Volcanic hotspots are thought to be fed by hot, active upwellings from the deep mantle, with excess temperatures (Tex) ~100° to 300°C higher than those of mid-ocean ridges. However, Tex estimates are limited in geographical coverage and often inconsistent for individual hotspots. We infer the temperature of oceanic hotspots and ridges simultaneously by converting seismic velocity to temperature. We show that while ~45% of plume-fed hotspots are hot (Tex ≥ 155°C), ~15% are cold (Tex ≤ 36°C) and ~40% are not hot enough to actively upwell (50°C ≤ Tex ≤ 136°C). Hot hotspots have an extremely high helium-3/helium-4 ratio and buoyancy flux, but cold hotspots do not. The latter may originate at upper mantle depths. Alternatively, the deep plumes that feed them may be entrained and cooled by small-scale convection.
Collapse
Affiliation(s)
- Xiyuan Bao
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095, USA
| | | | - Matthew G Jackson
- Department of Earth Science, University of California, Santa Barbara, CA 93106, USA
| | - Barbara Romanowicz
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
| |
Collapse
|
6
|
Karakostas F, Schmerr N, Maguire R, Huang Q, Kim D, Lekic V, Margerin L, Nunn C, Menina S, Kawamura T, Lognonné P, Giardini D, Banerdt B. Scattering Attenuation of the Martian Interior through Coda Wave Analysis. THE BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA : BSSA 2021; 111:3035-3054. [PMID: 35001980 PMCID: PMC8739495 DOI: 10.1785/0120210253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We investigate the scattering attenuation characteristics of the Martian crust and uppermost mantle to understand the structure of the Martian interior. We examine the energy decay of the spectral envelopes for 21 high-quality Martian seismic events from Sol 128 to Sol 500 of InSight operations. We use the model of Dainty et al. (1974b) to approximate the behavior of energy envelopes resulting from scattered wave propagation through a single diffusive layer over an elastic half-space. Using a grid search, we mapped the layer parameters that fit the observed InSight data envelopes. The single diffusive layer model provided better fits to the observed energy envelopes for High Frequency (HF) and Very High Frequency (VF) than for the Low Frequency (LF) and Broadband (BB) events. This result is consistent with the suggested source depths (Giardini et al., 2020) for these families of events and their expected interaction with a shallow scattering layer. The shapes of the observed data envelopes do not show a consistent pattern with event distance, suggesting that the diffusivity and scattering layer thickness is non-uniform in the vicinity of InSight at Mars. Given the consistency in the envelope shapes between HF and VF events across epicentral distances and the tradeoffs between the parameters that control scattering, the dimensions of the scattering layer remain unconstrained but require that scattering strength decreases with depth and that the rate of decay in scattering strength is fastest near the surface. This is generally consistent with the processes that would form scattering structures in planetary lithospheres.
Collapse
Affiliation(s)
- Foivos Karakostas
- Department of Geology, University of Maryland, College Park, MD, USA
- Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Italy
| | - Nicholas Schmerr
- Department of Geology, University of Maryland, College Park, MD, USA
| | - Ross Maguire
- Department of Geology, University of Maryland, College Park, MD, USA
- Michigan State University, Department of Computational Mathematics, Science and Engineering, East Lansing MI, USA
| | - Quancheng Huang
- Department of Geology, University of Maryland, College Park, MD, USA
- Department of Physics, New Mexico State University, Las Cruces, NM, USA
| | - Doyeon Kim
- Department of Geology, University of Maryland, College Park, MD, USA
| | - Vedran Lekic
- Department of Geology, University of Maryland, College Park, MD, USA
| | - Ludovic Margerin
- Institut de Recherche en Astrophysique et Planétologie, Université Toulouse III Paul Sabatier, CNRS, CNES, Toulouse, France
| | | | - Sabrina Menina
- Université de Paris, Institut de Physique du Globe de Paris, France
| | - Taichi Kawamura
- Université de Paris, Institut de Physique du Globe de Paris, France
| | | | | | | |
Collapse
|
7
|
Affiliation(s)
- Meghan S. Miller
- Research School of Earth Sciences, Australian National University, Canberra, Australia
| |
Collapse
|