Multi-scale analysis and modelling of aeromagnetic data over the Bétaré-Oya area in eastern Cameroon, for structural evidence investigations

Nyaban, Christian Emile; Ndougsa-Mbarga, Théophile; Bikoro-Bi-Alou, Marcelin; Manekeng Tadjouteu, Stella Amina; Assembe, Stephane Patrick

doi:https://doi.org/10.5194/se-12-785-2021

Articles | Volume 12, issue 4

https://doi.org/10.5194/se-12-785-2021

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

https://doi.org/10.5194/se-12-785-2021

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

Articles | Volume 12, issue 4

Research article

|

06 Apr 2021

Research article |

| 06 Apr 2021

Multi-scale analysis and modelling of aeromagnetic data over the Bétaré-Oya area in eastern Cameroon, for structural evidence investigations

Christian Emile Nyaban, Théophile Ndougsa-Mbarga, Marcelin Bikoro-Bi-Alou, Stella Amina Manekeng Tadjouteu, and Stephane Patrick Assembe

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Final revised paper (published on 06 Apr 2021)
Preprint (discussion started on 23 Jul 2020)

Interactive discussion

Status: closed

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

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RC1: 'Reviewer comments', Bruno Gavazzi, 24 Sep 2020
- AC1: 'response to reviewer 1 remarks', Théophile Ndougsa-Mbarga, 01 Dec 2020
RC2: 'Review', Anonymous Referee #2, 02 Nov 2020
- AC2: 'response to reviewer 2 remarks', Théophile Ndougsa-Mbarga, 01 Dec 2020

Peer-review completion

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

AR by Théophile Ndougsa-Mbarga on behalf of the Authors (28 Dec 2020) Author's response Manuscript

ED: Publish as is (04 Jan 2021) by Nicolas Gillet

ED: Referee Nomination & Report Request started (05 Jan 2021) by Nicolas Gillet

RR by Bruno Gavazzi (31 Jan 2021)

Suggestions for revision or reasons for rejection

The revised manuscript that was strongly improved from the first version. Corrections suggested by the reviewers have been nicely implemented and the methodology part is now more detailed. Nonetheless, I think the paper needs some precisions on the tilt method before publication: I understand you use the tilt depth method on data reduced to the equator (RTE), but Salem et al 2007 described the tilt derivative on data reduced to the pole (RTP) and stated that this necessity is one of the limits of their method. You should explain how it works with your RTE data and what the limits of such an approach are compared to tilt on RTP data (and why you can use it I your case).
I deduced that you can consider that the shallow contacts are vertical and that therefore you can use tilt to map them. But I think it is not stated clearly enough : please make it clear that you have proofs or strong hypothesis that the contacts are vertical before mapping them.

I also provide hereafter some technical corrections and suggestions:

L 39: These

L 118: “were” instead of “are”?

L134 to 136: is is plural (and should be “...maps have been…”) or a singular map ( and it should be “The aeromagnetic...”

L142: I think you should replace “fields” (general case) with “magnetic field”) your case

L145: “their effect” instead of “regional effect”? The regional effect might be defined as something different, using their (the deep sources) avoids the confusion

L155: I would add “vertical” before “contacts” (because for non vertical contact h=+/-90)

L168: it could be understood that the operator highlight only the vertical contacts (it is not true, but for the other the position depends on the slope angle), I could propose : “Computed the position of the contacts considered as vertical...”

L 197: it reads as if the operator have been done in 1970, could you rephrase that it is clear that it was performed with the inclination and declination of 1970, the ref to the latest IGRF would be appropriate here (IGRF-12, Thébault et al 2015)

L216: “magnetization” (remanent+induced) instead of “susceptibilities” (only induced) (strictly speaking it is even contrast of magnetization of the causative bodies with the neighboring/surrounding materials)

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ED: Publish subject to minor revisions (review by editor) (01 Feb 2021) by Nicolas Gillet

AR by Théophile Ndougsa-Mbarga on behalf of the Authors (06 Feb 2021) Author's response Manuscript

ED: Publish as is (08 Feb 2021) by Nicolas Gillet

ED: Publish as is (09 Feb 2021) by Susanne Buiter (Executive editor)

AR by Théophile Ndougsa-Mbarga on behalf of the Authors (15 Feb 2021) Manuscript

Short summary

A multi-scale analysis of aeromagnetic data combining tilt derivative, Euler deconvolution, upward continuation, and 2.75D modelling was applied over Cameroon between the latitudes 5°30'–6° N and the longitudes 13°30'–14°45' E. Major families of faults oriented ENE–WSW, E–W, NW–SE, and N–S with a NE–SW prevalence were mapped. Depths of interpreted faults range from 1000 to 3400 m, mylonitic veins were identified, and 2.75D modelling revealed fault depths greater than 1200 m.