Coupled dynamics and evolution of primordial and recycled heterogeneity in Earth's lower mantle

Gülcher, Anna Johanna Pia; Ballmer, Maxim Dionys; Tackley, Paul James

doi:https://doi.org/10.5194/se-12-2087-2021

Articles | Volume 12, issue 9

https://doi.org/10.5194/se-12-2087-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/se-12-2087-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 12, issue 9

Research article

|

14 Sep 2021

Research article |

| 14 Sep 2021

Coupled dynamics and evolution of primordial and recycled heterogeneity in Earth's lower mantle

Anna Johanna Pia Gülcher, Maxim Dionys Ballmer, and Paul James Tackley

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Final revised paper (published on 14 Sep 2021)
Supplement to the final revised paper
Preprint (discussion started on 16 Dec 2020)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review of Gülcher et al.', Craig ONeill, 11 Mar 2021
- AC1: 'Reply on RC1', Anna Gülcher, 07 Apr 2021
RC2: 'review of SE-2020-205', Shijie Zhong, 18 Mar 2021
- AC2: 'Reply on RC2', Anna Gülcher, 07 Apr 2021

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Anna Gülcher on behalf of the Authors (17 May 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (22 May 2021) by Juliane Dannberg

RR by Shijie Zhong (24 May 2021)

Suggestions for revision or reasons for rejection

The authors made significant effort in revising the manuscript and I am satisfied with all the responses except that I think that the response to resolution issue needs some more clarification. The newly added appendix B on resolution tests is helpful. The authors used 3 diagnoses for resolution tests: relative volumes of primitive material and ROC in the lower mantle and RMS velocity, v_RMS (Fig. B1). The authors concluded that their results are qualitatively unchanged for different resolutions, which I agree and was what I suspected in my original review. However, two issues need to be clarified and acknowledged. 1) v_RMS (Fig. B1c) shows some modest resolution dependence even at the highest resolution (~15% change when the resolution is doubled, which is not insignificant, in my view). 2) The relative volumes in the lower mantle are different from entrainment which often measures the change of mass or volume for a chemical reservoir or domain with time in previous studies (e.g., Zhong and Hager, 2003) and is probably more sensitive to resolution. Perhaps, in using the relative volumes in the lower mantle, the small drips of entrained materials are also included, thus making relative volumes in the lower mantle less sensitive to resolution. An extreme case is to compute the relative volume for the whole mantle, in which case the relative volume is a measure of the total conservation of composition. I am sorry if I sound somewhat insistent on this issue, as I have seen over the years that the calculations of entrainment or preservation of chemical reservoirs (e.g., LLSVP) in numerical models are over-simplified. I think that it would be helpful for the authors to acknowledge these two points in the paper to avoid misunderstanding.

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ED: Publish subject to minor revisions (review by editor) (28 Jun 2021) by Juliane Dannberg

AR by Anna Gülcher on behalf of the Authors (11 Jul 2021) Author's response

ED: Publish as is (20 Jul 2021) by Juliane Dannberg

ED: Publish subject to minor revisions (review by editor) (21 Jul 2021) by Susanne Buiter (Executive editor)

AR by Anna Gülcher on behalf of the Authors (26 Jul 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (02 Aug 2021) by Susanne Buiter

ED: Publish as is (02 Aug 2021) by Susanne Buiter (Executive editor)

AR by Anna Gülcher on behalf of the Authors (16 Aug 2021) Manuscript

Short summary

The lower mantle extends from 660–2890 km depth, making up > 50 % of the Earth’s volume. Its composition and structure, however, remain poorly understood. In this study, we investigate several hypotheses with computer simulations of mantle convection that include different materials: recycled, dense rocks and ancient, strong rocks. We propose a new integrated style of mantle convection including piles, blobs, and streaks that agrees with various observations of the deep Earth.