Existence of Charnockites in Hellas Basin, Mars

Comment #258 Kamilla Dyreborg Hansen @ 2025-12-05 04:13

Thank you for sharing this interesting preprint. The combined use of VNIR and TIR remote sensing is exciting, and I appreciate the clear presentation of your laboratory spectra — that section was especially well executed and helpful for interpreting the orbital data. I also want to note positively that your CRISM preprocessing appears to follow established procedures, and the rationale for using MTRDR products is clearly justified.

I had a few questions which, if clarified, might further strengthen the manuscript and help readers better assess reproducibility and modelling robustness:

1) THEMIS metadata
For the THEMIS TIR analysis, would it be possible to provide more detail about the specific observations used (e.g., acquisition year, season, observation timing, and calibration/reprocessing status)? Since atmospheric conditions and calibration versions can influence emissivity, such information would strongly support reproducibility.

2) Dataset selection rationale
Was there a specific rationale behind choosing these particular THEMIS scenes rather than alternative observations in the same region? It would be interesting to know whether multiple candidates were screened before final selection.

3) Spectral residuals
For the LMM and PPNM modelling, you present RMSE values numerically, but residual spectra are not shown. Including residual plots would help readers understand which spectral regions dominate the misfit.

4) Alternative interpretations
Given that quartz–feldspar–pyroxene assemblages can occur in more than one felsic lithology, a brief discussion of alternative interpretations (and why charnockite is preferred) would help clarify the robustness of the conclusion.

Again, thank you for sharing this work — I found the laboratory characterisation and the overall approach intriguing, and I look forward to hearing more about the dataset choices and modelling reasoning.