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Khan A, Huang D, Durán C, Sossi PA, Giardini D, Murakami M. Evidence for a liquid silicate layer atop the Martian core. Nature 2023; 622:718-723. [PMID: 37880439 PMCID: PMC10600012 DOI: 10.1038/s41586-023-06586-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 08/29/2023] [Indexed: 10/27/2023]
Abstract
Seismic recordings made during the InSight mission1 suggested that Mars's liquid core would need to be approximately 27% lighter than pure liquid iron2,3, implying a considerable complement of light elements. Core compositions based on seismic and bulk geophysical constraints, however, require larger quantities of the volatile elements hydrogen, carbon and sulfur than those that were cosmochemically available in the likely building blocks of Mars4. Here we show that multiply diffracted P waves along a stratified core-mantle boundary region of Mars in combination with first-principles computations of the thermoelastic properties of liquid iron-rich alloys3 require the presence of a fully molten silicate layer overlying a smaller, denser liquid core. Inverting differential body wave travel time data with particular sensitivity to the core-mantle boundary region suggests a decreased core radius of 1,675 ± 30 km associated with an increased density of 6.65 ± 0.1 g cm-3, relative to previous models2,4-8, while the thickness and density of the molten silicate layer are 150 ± 15 km and 4.05 ± 0.05 g cm-3, respectively. The core properties inferred here reconcile bulk geophysical and cosmochemical requirements, consistent with a core containing 85-91 wt% iron-nickel and 9-15 wt% light elements, chiefly sulfur, carbon, oxygen and hydrogen. The chemical characteristics of a molten silicate layer above the core may be revealed by products of Martian magmatism.
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Affiliation(s)
- A Khan
- Institute of Geochemistry and Petrology, ETH Zürich, Zurich, Switzerland.
- Institute of Geophysics, ETH Zürich, Zurich, Switzerland.
| | - D Huang
- Institute of Geochemistry and Petrology, ETH Zürich, Zurich, Switzerland.
| | - C Durán
- Institute of Geophysics, ETH Zürich, Zurich, Switzerland
| | - P A Sossi
- Institute of Geochemistry and Petrology, ETH Zürich, Zurich, Switzerland
| | - D Giardini
- Institute of Geophysics, ETH Zürich, Zurich, Switzerland
| | - M Murakami
- Institute of Geochemistry and Petrology, ETH Zürich, Zurich, Switzerland
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2
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Samuel H, Drilleau M, Rivoldini A, Xu Z, Huang Q, Garcia RF, Lekić V, Irving JCE, Badro J, Lognonné PH, Connolly JAD, Kawamura T, Gudkova T, Banerdt WB. Geophysical evidence for an enriched molten silicate layer above Mars's core. Nature 2023; 622:712-717. [PMID: 37880437 PMCID: PMC10600000 DOI: 10.1038/s41586-023-06601-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 08/31/2023] [Indexed: 10/27/2023]
Abstract
The detection of deep reflected S waves on Mars inferred a core size of 1,830 ± 40 km (ref. 1), requiring light-element contents that are incompatible with experimental petrological constraints. This estimate assumes a compositionally homogeneous Martian mantle, at odds with recent measurements of anomalously slow propagating P waves diffracted along the core-mantle boundary2. An alternative hypothesis is that Mars's mantle is heterogeneous as a consequence of an early magma ocean that solidified to form a basal layer enriched in iron and heat-producing elements. Such enrichment results in the formation of a molten silicate layer above the core, overlain by a partially molten layer3. Here we show that this structure is compatible with all geophysical data, notably (1) deep reflected and diffracted mantle seismic phases, (2) weak shear attenuation at seismic frequency and (3) Mars's dissipative nature at Phobos tides. The core size in this scenario is 1,650 ± 20 km, implying a density of 6.5 g cm-3, 5-8% larger than previous seismic estimates, and can be explained by fewer, and less abundant, alloying light elements than previously required, in amounts compatible with experimental and cosmochemical constraints. Finally, the layered mantle structure requires external sources to generate the magnetic signatures recorded in Mars's crust.
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Affiliation(s)
- Henri Samuel
- Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris, France.
| | - Mélanie Drilleau
- Institut Supérieur de l'Aéronautique et de l'Espace ISAE-SUPAERO, Toulouse, France
| | | | - Zongbo Xu
- Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris, France
| | - Quancheng Huang
- Department of Geophysics, Colorado School of Mines, Golden, CO, USA
- University of Maryland, College Park, MD, USA
| | - Raphaël F Garcia
- Institut Supérieur de l'Aéronautique et de l'Espace ISAE-SUPAERO, Toulouse, France
| | | | | | - James Badro
- Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris, France
| | - Philippe H Lognonné
- Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris, France
| | | | - Taichi Kawamura
- Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris, France
| | - Tamara Gudkova
- Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia
| | - William B Banerdt
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
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3
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Li J, Beghein C, McLennan SM, Horleston AC, Charalambous C, Huang Q, Zenhäusern G, Bozdağ E, Pike WT, Golombek M, Lekić V, Lognonné P, Bruce Banerdt W. Constraints on the martian crust away from the InSight landing site. Nat Commun 2022; 13:7950. [PMID: 36572693 PMCID: PMC9792460 DOI: 10.1038/s41467-022-35662-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 12/15/2022] [Indexed: 12/27/2022] Open
Abstract
The most distant marsquake recorded so far by the InSight seismometer occurred at an epicentral distance of 146.3 ± 6.9o, close to the western end of Valles Marineris. On the seismogram of this event, we have identified seismic wave precursors, i.e., underside reflections off a subsurface discontinuity halfway between the marsquake and the instrument, which directly constrain the crustal structure away (about 4100-4500 km) from the InSight landing site. Here we show that the Martian crust at the bounce point between the lander and the marsquake is characterized by a discontinuity at about 20 km depth, similar to the second (deeper) intra-crustal interface seen beneath the InSight landing site. We propose that this 20-km interface, first discovered beneath the lander, is not a local geological structure but likely a regional or global feature, and is consistent with a transition from porous to non-porous Martian crustal materials.
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Affiliation(s)
- Jiaqi Li
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA, 90095, USA.
| | - Caroline Beghein
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA, 90095, USA
| | - Scott M McLennan
- Department of Geosciences, Stony Brook University, Stony Brook, NY, 11794-2100, USA
| | | | | | - Quancheng Huang
- Department of Geophysics, Colorado School of Mines, Golden, CO, USA
| | | | - Ebru Bozdağ
- Department of Geophysics, Colorado School of Mines, Golden, CO, USA
| | - W T Pike
- Department of Electrical and Electronic Engineering, Imperial College London, London, UK
| | - Matthew Golombek
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA
| | - Vedran Lekić
- Department of Geology, University of Maryland, College Park, MD, USA
| | - Philippe Lognonné
- Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris, F-75005, France
| | - W Bruce Banerdt
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA
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5
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Posiolova LV, Lognonné P, Banerdt WB, Clinton J, Collins GS, Kawamura T, Ceylan S, Daubar IJ, Fernando B, Froment M, Giardini D, Malin MC, Miljković K, Stähler SC, Xu Z, Banks ME, Beucler É, Cantor BA, Charalambous C, Dahmen N, Davis P, Drilleau M, Dundas CM, Durán C, Euchner F, Garcia RF, Golombek M, Horleston A, Keegan C, Khan A, Kim D, Larmat C, Lorenz R, Margerin L, Menina S, Panning M, Pardo C, Perrin C, Pike WT, Plasman M, Rajšić A, Rolland L, Rougier E, Speth G, Spiga A, Stott A, Susko D, Teanby NA, Valeh A, Werynski A, Wójcicka N, Zenhäusern G. Largest recent impact craters on Mars: Orbital imaging and surface seismic co-investigation. Science 2022; 378:412-417. [DOI: 10.1126/science.abq7704] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Two >130-meter-diameter impact craters formed on Mars during the later half of 2021. These are the two largest fresh impact craters discovered by the Mars Reconnaissance Orbiter since operations started 16 years ago. The impacts created two of the largest seismic events (magnitudes greater than 4) recorded by InSight during its 3-year mission. The combination of orbital imagery and seismic ground motion enables the investigation of subsurface and atmospheric energy partitioning of the impact process on a planet with a thin atmosphere and the first direct test of martian deep-interior seismic models with known event distances. The impact at 35°N excavated blocks of water ice, which is the lowest latitude at which ice has been directly observed on Mars.
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Affiliation(s)
| | - P. Lognonné
- Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France
| | - W. B. Banerdt
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - J. Clinton
- Swiss Seismological Service, ETH Zurich, Zurich, Switzerland
| | - G. S. Collins
- Department of Earth Science and Engineering, Imperial College London, London, UK
| | - T. Kawamura
- Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France
| | - S. Ceylan
- Institute of Geophysics, ETH Zurich, Zurich, Switzerland
| | - I. J. Daubar
- Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI, USA
| | - B. Fernando
- Department of Earth Sciences, University of Oxford, Oxford, UK
| | - M. Froment
- Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - D. Giardini
- Institute of Geophysics, ETH Zurich, Zurich, Switzerland
| | - M. C. Malin
- Malin Space Science Systems, San Diego, CA, USA
| | - K. Miljković
- Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, Perth, WA, Australia
| | - S. C. Stähler
- Institute of Geophysics, ETH Zurich, Zurich, Switzerland
| | - Z. Xu
- Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France
| | - M. E. Banks
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - É. Beucler
- Nantes Université, Université Angers, Le Mans Université, CNRS, UMR 6112, Laboratoire de Planétologie et Géosciences, Nantes, France
| | | | - C. Charalambous
- Department of Electrical and Electronic Engineering, Imperial College London, London, UK
| | - N. Dahmen
- Institute of Geophysics, ETH Zurich, Zurich, Switzerland
| | - P. Davis
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA, USA
| | - M. Drilleau
- Institut Supérieur de l’Aéronautique et de l’Espace ISAE-SUPAERO, Toulouse, France
| | - C. M. Dundas
- U.S. Geological Survey, Astrogeology Science Center, Flagstaff, AZ, USA
| | - C. Durán
- Institute of Geophysics, ETH Zurich, Zurich, Switzerland
| | - F. Euchner
- Institute of Geophysics, ETH Zurich, Zurich, Switzerland
| | - R. F. Garcia
- Institut Supérieur de l’Aéronautique et de l’Espace ISAE-SUPAERO, Toulouse, France
| | - M. Golombek
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - A. Horleston
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - C. Keegan
- Malin Space Science Systems, San Diego, CA, USA
| | - A. Khan
- Institute of Geophysics, ETH Zurich, Zurich, Switzerland
- Physik-Institut, University of Zurich, Zurich, Switzerland
| | - D. Kim
- Institute of Geophysics, ETH Zurich, Zurich, Switzerland
- Department of Geology, University of Maryland, College Park, MD, USA
| | - C. Larmat
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - R. Lorenz
- Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA
| | - L. Margerin
- Institut de Recherche en Astrophysique et Planétologie, Université Toulouse III Paul Sabatier, CNRS, CNES, Toulouse, France
| | - S. Menina
- Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France
| | - M. Panning
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - C. Pardo
- Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France
| | - C. Perrin
- Nantes Université, Université Angers, Le Mans Université, CNRS, UMR 6112, Laboratoire de Planétologie et Géosciences, Nantes, France
| | - W. T. Pike
- Department of Electrical and Electronic Engineering, Imperial College London, London, UK
| | - M. Plasman
- Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France
| | - A. Rajšić
- Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, Perth, WA, Australia
| | - L. Rolland
- Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, IRD, Géoazur, Valbonne, France
| | - E. Rougier
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - G. Speth
- Malin Space Science Systems, San Diego, CA, USA
| | - A. Spiga
- Laboratoire de Météorologie Dynamique/IPSL, Sorbonne Université, CNRS, Ecole Normale Supérieure, PSL Research University, Ecole Polytechnique, Paris, France
| | - A. Stott
- Institut Supérieur de l’Aéronautique et de l’Espace ISAE-SUPAERO, Toulouse, France
| | - D. Susko
- Malin Space Science Systems, San Diego, CA, USA
| | - N. A. Teanby
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - A. Valeh
- Malin Space Science Systems, San Diego, CA, USA
| | - A. Werynski
- Malin Space Science Systems, San Diego, CA, USA
| | - N. Wójcicka
- Department of Earth Science and Engineering, Imperial College London, London, UK
| | - G. Zenhäusern
- Institute of Geophysics, ETH Zurich, Zurich, Switzerland
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