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Article Dans Une Revue Proceedings of the National Academy of Sciences of the United States of America Année : 2022

Seismic detection of a deep mantle discontinuity within Mars by InSight

Quancheng Huang
Nicholas Schmerr
Scott King
  • Fonction : Auteur
Doyeon Kim
  • Fonction : Auteur
Attilio Rivoldini
  • Fonction : Auteur
Ana-Catalina Plesa
  • Fonction : Auteur
Henri Samuel
Ross Maguire
  • Fonction : Auteur
Foivos Karakostas
Vedran Lekić
Constantinos Charalambous
Max Collinet
  • Fonction : Auteur
Robert Myhill
Daniele Antonangeli
Mélanie Drilleau
  • Fonction : Auteur
Misha Bystricky
Caroline Bollinger
  • Fonction : Auteur
Chloé Michaut
  • Fonction : Auteur
Tamara Gudkova
Jessica Irving
  • Fonction : Auteur
Anna Horleston
Benjamin Fernando
Kuangdai Leng
  • Fonction : Auteur
Tarje Nissen-Meyer
  • Fonction : Auteur
Ebru Bozdağ
  • Fonction : Auteur
Caroline Beghein
Lauren Waszek
  • Fonction : Auteur
Nicki Siersch
  • Fonction : Auteur
John-Robert Scholz
  • Fonction : Auteur
Paul Davis
  • Fonction : Auteur
Baptiste Pinot
Rudolf Widmer-Schnidrig
Mark Panning
  • Fonction : Auteur
Suzanne Smrekar
Tilman Spohn
William Pike
  • Fonction : Auteur
Domenico Giardini
W. Bruce Banerdt

Résumé

Constraining the thermal and compositional state of the mantle is crucial for deciphering the formation and evolution of Mars. Mineral physics predicts that Mars’ deep mantle is demarcated by a seismic discontinuity arising from the pressure-induced phase transformation of the mineral olivine to its higher-pressure polymorphs, making the depth of this boundary sensitive to both mantle temperature and composition. Here, we report on the seismic detection of a midmantle discontinuity using the data collected by NASA’s InSight Mission to Mars that matches the expected depth and sharpness of the postolivine transition. In five teleseismic events, we observed triplicated P and S waves and constrained the depth of this discontinuity to be 1,006 ± 40 km by modeling the triplicated waveforms. From this depth range, we infer a mantle potential temperature of 1,605 ± 100 K, a result consistent with a crust that is 10 to 15 times more enriched in heat-producing elements than the underlying mantle. Our waveform fits to the data indicate a broad gradient across the boundary, implying that the Martian mantle is more enriched in iron compared to Earth. Through modeling of thermochemical evolution of Mars, we observe that only two out of the five proposed composition models are compatible with the observed boundary depth. Our geodynamic simulations suggest that the Martian mantle was relatively cold 4.5 Gyr ago (1,720 to 1,860 K) and are consistent with a present-day surface heat flow of 21 to 24 mW/m 2 .

Domaines

Planétologie
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Dates et versions

insu-03810429 , version 1 (11-10-2022)

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Quancheng Huang, Nicholas Schmerr, Scott King, Doyeon Kim, Attilio Rivoldini, et al.. Seismic detection of a deep mantle discontinuity within Mars by InSight. Proceedings of the National Academy of Sciences of the United States of America, 2022, 119 (42), ⟨10.1073/pnas.2204474119⟩. ⟨insu-03810429⟩
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