Preprints
https://doi.org/10.5194/egusphere-2022-418
https://doi.org/10.5194/egusphere-2022-418
08 Jun 2022
 | 08 Jun 2022

Influence of heterogeneous thermal conductivity on the long-term evolution of the lower mantle thermochemical structure: implications for primordial reservoirs

Joshua Martin Guerrero, Frédéric Deschamps, Yang Li, Wen-Pin Hsieh, and Paul James Tackley

Abstract. The long-term evolution of the mantle is simulated using 2D spherical annulus geometry to examine the effect of heterogeneous thermal conductivity on the stability of reservoirs of primordial material. In numerical models, mantle conductivity is often emulated using purely depth-dependent profiles (taking on values between 3 and 9 Wm-1 K-1). This approach is meant to synthesize the mean conductivities of mantle materials at their respective conditions in-situ. However, because conductivity depends also on temperature and composition, the effects of these dependencies in mantle conductivity is masked. This issue is significant because dynamically evolving temperature and composition introduce lateral variations in conductivity, especially in the deep-mantle. Minimum and maximum variations in conductivity are due to the temperatures of plumes and slabs, respectively, and depth-dependence directly controls the amplitude of the conductivity (and its variations) across the mantle depth. Our simulations allow assessing the consequences of these variations on mantle dynamics, in combination with the reduction of thermochemical pile conductivity with iron composition, which has so far not been well examined. We find that the temperature- and depth- variations combined characterize the mean conductivity ratio from top-to-bottom. For the mean conductivity profile to be comparable to the conductivity often assumed in numerical models, the depth- dependent ratio must be at least 9 times the surface conductivity. When the conductivity profile is underestimated, the imparted thermal buoyancy (from heat-producing element (HPE) enrichment) destabilizes the reservoirs and influences core-mantle boundary (CMB) coverage configuration and the onset of entrainment. The compositional correction for conductivity only plays a minor role that behaves similarly to conductivity reduction due to temperature. Nevertheless, this effect may be amplified when depth- dependence is increased. For the cases we examine, when the lowermost mantle's mean conductivity is greater than the surface conductivity, reservoirs can remain stable for periods exceeding the age of the solar system.

Journal article(s) based on this preprint

07 Feb 2023
Influence of heterogeneous thermal conductivity on the long-term evolution of the lower-mantle thermochemical structure: implications for primordial reservoirs
Joshua Martin Guerrero, Frédéric Deschamps, Yang Li, Wen-Pin Hsieh, and Paul James Tackley
Solid Earth, 14, 119–135, https://doi.org/10.5194/se-14-119-2023,https://doi.org/10.5194/se-14-119-2023, 2023
Short summary

Joshua Martin Guerrero et al.

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-418', Anonymous Referee #1, 30 Jul 2022
    • AC1: 'Reply on RC1', Joshua Guerrero, 22 Aug 2022
  • RC2: 'Comment on egusphere-2022-418', Anonymous Referee #2, 02 Aug 2022
    • CEC1: 'Reply on RC2', Susanne Buiter, 12 Aug 2022
    • AC2: 'Reply on RC2', Joshua Guerrero, 22 Aug 2022

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-418', Anonymous Referee #1, 30 Jul 2022
    • AC1: 'Reply on RC1', Joshua Guerrero, 22 Aug 2022
  • RC2: 'Comment on egusphere-2022-418', Anonymous Referee #2, 02 Aug 2022
    • CEC1: 'Reply on RC2', Susanne Buiter, 12 Aug 2022
    • AC2: 'Reply on RC2', Joshua Guerrero, 22 Aug 2022

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Joshua Guerrero on behalf of the Authors (19 Sep 2022)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (03 Oct 2022) by Juliane Dannberg
RR by Anonymous Referee #1 (31 Oct 2022)
RR by Anonymous Referee #3 (11 Nov 2022)
ED: Publish subject to minor revisions (review by editor) (20 Nov 2022) by Juliane Dannberg
AR by Joshua Guerrero on behalf of the Authors (02 Dec 2022)  Author's response   Author's tracked changes   Manuscript 
ED: Publish subject to technical corrections (09 Jan 2023) by Juliane Dannberg
ED: Publish subject to technical corrections (10 Jan 2023) by Susanne Buiter (Executive editor)
AR by Joshua Guerrero on behalf of the Authors (12 Jan 2023)  Manuscript 

Journal article(s) based on this preprint

07 Feb 2023
Influence of heterogeneous thermal conductivity on the long-term evolution of the lower-mantle thermochemical structure: implications for primordial reservoirs
Joshua Martin Guerrero, Frédéric Deschamps, Yang Li, Wen-Pin Hsieh, and Paul James Tackley
Solid Earth, 14, 119–135, https://doi.org/10.5194/se-14-119-2023,https://doi.org/10.5194/se-14-119-2023, 2023
Short summary

Joshua Martin Guerrero et al.

Joshua Martin Guerrero et al.

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Short summary
Mantle thermal conductivity's dependencies on temperature, pressure, and composition are often suppressed in numerical models. In this study, we examine the effect of these dependencies on the long-term evolution of lower mantle thermochemical structure. We propose that depth-dependent conductivities derived from mantle minerals, along with moderate temperature and compositional correction, emulate the Earth's mean lowermost mantle conductivity values and produce a stable 2-pile configuration.