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Journal Articles Proceedings of the National Academy of Sciences of the United States of America Year : 2022

Seismic detection of a deep mantle discontinuity within Mars by InSight

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

Abstract

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 .
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Dates and 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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