Editorial comments on reviews, and response to reviews.

The three reviewers provide thorough and constructive comments on the manuscript. You have dealt carefully with all the specific points raised in the reviews, and the revised manuscript seems likely to address many of their concerns.

You have not provided a response to the opening comments of the three referees, however. In places this makes it difficult to know how you plan to address some of the most substantial points. I will try to draw these points out in comments below. These are issues that I will be keen to see addressed in the revised manuscript.

Referee 1: A key point made by this referee is that your arguments about relationships between Al and Si are weakened by lack of sufficient discussion and, particularly, of relevant figures. You partially address this concern at the start of your response to Referee 1, but without providing any details. I will be keen to see that this issue is fully dealt with in revision.

Referee 2: Makes the point that the structure of the paper sometimes weakens links between various aspects of the discussion. In general, I find the structure logical and clear. I do, though, agree with the referee that it would be appropriate to give more recognition to the fact that several processes might be important (or compete with each other). The Referee’s comment about Section 3.3.1 is a good example. Again, I will be keen to see that this issue is dealt with in the revised manuscript.

Referee 3: This referee makes a constructive point in their opening comments; that your analysis can benefit significantly from the presence of BSi and PAl data, which has not often measured before with DAl. They go on to suggest that it is important this BSi and PAl data is therefore available to the reader. I agree with this point – it is impossible for the reader to really assess your work without sight of that data. You address this issue in specific comments, and I think your answer is reasonable. If the BSi and PAl data are published in exactly the same issue of BG, then the reader can readily find them and therefore assess your conclusions. As yet, however, no papers by Gourain et al., or by Sarthou et al. 
have been submitted to the special volume, nor any others that provide BSi or PAl data. Are you confident that these will be submitted by the 31st May deadline? If they are not, they will not be available to the reader, so you ought to include the sections, as you do in your response, in the main paper.

Based on your response to issues raised here, and on the basis of the thorough response you make to the reviewers’ specific comments, I hope to be able to recommend the manuscript for acceptance without another round of review.

Gideon Henderson
3rd May 2018

I have carefully read your Response to Referees document and the revised manuscript. Thank you for dealing thoroughly with all the points raised in review. I consider these responses appropriate, and that the paper is now ready for publication in the GEOVIDE Special Volume.

There are, however, three small changes that I ask you to make before publication, and which lead me to mark this as “Publish subject to technical corrections”.

i. Please cite the intro paper to the volume when you discuss BSi distributions. This will be Sarthou et al and, since Geraldine is one of your co-authors, I hope you can get full title/author details from her. I have confirmed with Geraldine that the BSi data will be shown in a Figure in that paper.
That paper may also contain a figure that compares the dAl and pAl sections, in which case it would be good to cite that paper in addition to Gourain et al at an appropriate place in your paper.

ii. Please correct spelling of “artic” in caption to Fig 1

iii. Please make the minor correction that you emailed me about outside the BG system – on p7, line 27 of the original m/s.

Thanks for contributing your paper to this Special Volume – it will be great to see it published.

I hope that your Ph.D. defence went well recently.

Gideon.