Dear Manuel Reinhardt,

First of all I would like to thank Jan de Leeuw and both anonymous reviewers for their insightful reviews and you for your comments. All there reviewers are quite positive and only have minor, usually very technical comments and you have replied adequately to these comments.
I do think there is one issue you could spend a bit more time on explaining or clarifying. You use the Pleistocene settings as analogs for Archean hydrothermal cherts and I think you need to spend a little bit more time on this to make it more than a way to “sell” your Pleistocene study. The analogy is comparable deposits, hydrothermal cherts, right? I think it is entirely valid to test your approach, methods and types of analysis on a more modern setting to see what works and what doesn’t, what type of information you get etc., before actually working on these really old deposits. I am assuming you are actually going to do that? So that sense it works, in your answer to one of the reviewers you actually mention using methods for these samples you would also use for Archean samples. However, there is a few billion years of evolution between the Archean and Pleistocene, so biologically and on a larger environmental scale these settings are not analogues. Not only in the sense that a lot of organisms were not present in the Archean that were present in the Pleistocene, but even the microorganisms present in the Archean continued to evolve for that enormous amount of time. If the settings are similar, you do expect similar functions in both settings, but how that translates in lipids and isotopic compositions? This, together with all kinds of alterations that take place over time for the Archean organic matter, would make it very useful to study the organic matter from the Pleistocene as complete and detailed as possible and not only using techniques you would use for these really old samples. Things might move in and out of analytical windows with time. So I would like to ask you to put a little bit more time in explaining how you see this analogy in your rebuttal and possibly at some key points in the manuscript as well.
In one of your comments you mention CO2 limitation as a possible reason for the 13C enriched lipids in LM-1694, Looking at your table 4, not all compounds are extremely enriched in 13C relative to the other samples. The short chain alkanols and alkanoic acids are very similar to the other samples, mainly the monoethers and archaeol and to a lesser extend extended archaeol and even phytane perhaps a little are 13C enriched. The carbon isotopic composition of archaeol seems a bit variable any way. Of course something like CO2 limitation could play a role, it is a bit strange that you see this mainly in this subset of compounds. In this type of setting it would not be surprising to see other CO2 fixation pathways with different carbon isotopic fractionation, variable relative contribution from different pathways could potentially explain the observed differences. Any way something to think about.

I think if you would make the changes as you suggested and spend some time, at least in the rebuttal, on how you see this analogy I think this manuscript would be suitable for publication in Biogeosciences. I am looking forward to your rebuttal and updated manuscript.

Best regards,

Marcel

Dear Manuel Reinhardt and co-authors,

First of all I would like to thank Jan de Leeuw and two anonymous reviewers for reviewing this manuscript and you for replying to the comments and modifying your manuscript accordingly. I think it has improved significantly and should be published in Biogeosciences.

Best regards,

Marcel