Hi Dennis,

Thank you for your detailed response letter and your revisions. I have a few comments and questions on your revised ms and would appreciate if you could clarify, where appropriate, in the ms:

I am confused about the paragraph starting on line 585 of your tracked ms. “’ the computed trends cannot explain the observed data”--you mean any single fractionation process in isolation, but to some extent the three types of fractionation processes would potentially occur together, wouldn’t they? Are they mutually exclusive? I don’t think they are. If that is correct, couldn’t they account for the spread of data in Fig 4b without invoking non-equilibrium effects?

You seem to dismiss open-system conditions, but mass-balance considerations would make a closed system conditions difficult to justify. That would be a strong claim. For isolated veins in a tight rock sure, but where you have a distinct meteoric signal I would consider this as evidence for open conditions.

Ln 599: phenomenon is singular, either phenomena or a major phenomenon. Why not processes?

Ln 602: Two-phase trapping would be indicative of a rapid CO2 degassing (i.e. CO2 bubbles in the water) but this does not rule out slow CO2 degassing at the water table. I think that would be expected in most moving meteoric systems (i.e. formation of speleothems in caves).

Lastly, because you use SMOW for calcite d18O I get confused in some places in the manuscript if you are referring to calcite d180 or water d18O (first paragraph of section 5.2). My preference is to use PDB for calcite and SMOW for water, but if you use SMOW for calcite please make sure it is clear if you talk about calcite or (calculated) water values.

Thanks,

Peter