First observations of core-transiting seismic phases on Mars.

Autor:	Irving JCE; School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, United Kingdom., Lekić V; Department of Geology, University of Maryland, College Park 20742., Durán C; Institute of Geophysics, ETH Zurich, Zurich 8092, Switzerland., Drilleau M; Institut Supérieur de l'Aéronautique et de l'Espace ISAE-SUPAERO, Toulouse 31055, France., Kim D; Institute of Geophysics, ETH Zurich, Zurich 8092, Switzerland., Rivoldini A; Royal Observatory of Belgium, Brussels 1180, Belgium., Khan A; Institute of Geophysics, ETH Zurich, Zurich 8092, Switzerland.; Institute of Geochemistry and Petrology, ETH Zurich, Zurich 8092, Switzerland., Samuel H; Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris 75005, France., Antonangeli D; Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Paris 75005, France., Banerdt WB; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109., Beghein C; Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095., Bozdağ E; Department of Applied Mathematics and Statistics & Department of Geophysics, Colorado School of Mines, Golden, CO 80401.; Department of Geophysics, Colorado School of Mines, Golden, CO 80401., Ceylan S; Institute of Geophysics, ETH Zurich, Zurich 8092, Switzerland., Charalambous C; Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2AZ, United Kingdom., Clinton J; Swiss Seismological Service, ETH Zurich, Zurich 8092, Switzerland., Davis P; Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095., Garcia R; Institut Supérieur de l'Aéronautique et de l'Espace ISAE-SUPAERO, Toulouse 31055, France., Domenico Giardini; Institute of Geophysics, ETH Zurich, Zurich 8092, Switzerland., Horleston AC; School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, United Kingdom., Huang Q; Department of Geophysics, Colorado School of Mines, Golden, CO 80401., Hurst KJ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109., Kawamura T; Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris 75005, France., King SD; Department of Geosciences, Virginia Tech, Blacksburg, VA 24061., Knapmeyer M; DLR, Institute of Planetary Research, Berlin 12489, Germany., Li J; Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095., Lognonné P; Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris 75005, France., Maguire R; Department of Geology, University of Illinois Urbana-Champaign, Urbana, IL 61801., Panning MP; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109., Plesa AC; DLR, Institute of Planetary Research, Berlin 12489, Germany., Schimmel M; Geosciences Barcelona - CSIC, Barcelona 08028, Spain., Schmerr NC; Department of Geology, University of Maryland, College Park 20742., Stähler SC; Institute of Geophysics, ETH Zurich, Zurich 8092, Switzerland.; Physik-Institut, Universität Zürich, Zurich 8057, Switzerland., Stutzmann E; Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris 75005, France., Xu Z; Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris 75005, France.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2023 May 02; Vol. 120 (18), pp. e2217090120. Date of Electronic Publication: 2023 Apr 24.
DOI:	10.1073/pnas.2217090120
Abstrakt:	We present the first observations of seismic waves propagating through the core of Mars. These observations, made using seismic data collected by the InSight geophysical mission, have allowed us to construct the first seismically constrained models for the elastic properties of Mars' core. We observe core-transiting seismic phase SKS from two farside seismic events detected on Mars and measure the travel times of SKS relative to mantle traversing body waves. SKS travels through the core as a compressional wave, providing information about bulk modulus and density. We perform probabilistic inversions using the core-sensitive relative travel times together with gross geophysical data and travel times from other, more proximal, seismic events to seek the equation of state parameters that best describe the liquid iron-alloy core. Our inversions provide constraints on the velocities in Mars' core and are used to develop the first seismically based estimates of its composition. We show that models informed by our SKS data favor a somewhat smaller (median core radius = 1,780 to 1,810 km) and denser (core density = 6.2 to 6.3 g/cm 3 ) core compared to previous estimates, with a P-wave velocity of 4.9 to 5.0 km/s at the core-mantle boundary, with the composition and structure of the mantle as a dominant source of uncertainty. We infer from our models that Mars' core contains a median of 20 to 22 wt% light alloying elements when we consider sulfur, oxygen, carbon, and hydrogen. These data can be used to inform models of planetary accretion, composition, and evolution.
Databáze:	MEDLINE
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