Geochemical Analysis of Two Samples of Bitumen from Jars Discovered on Muhut and Masirah Islands (Oman)
, Michael H. Engel 2, Robert B. Jackson 3, Seth Priestman 4, Tom Vosmer 5 and Alex Zumberge 6Round 1
Reviewer 1 Report
As the title of the paper shows, the authors achieved their aim: to determine the geographical origin of the bitumen from two different ancestral jars using stable isotopes of hydrogen and carbon measured from hydrocarbons fractions extracted from bitumen lining, in addition to the classic approaches used in archeological science.
The methods are standard; the interpretation of data is supported by the results.
Page 9 Line 240 - write the uncertainty for hydrogen isotope analysis; explanations about what the isotopic ratio means must be made starting with line 225 (useful also to understand the carbon 13 values, not only for deuterium, as it appears in the paper at line 243).
Page 10 Table 1 - I recommend writing the symbol for stable isotope values for hydrogen and carbon in accordance with the specialized literature for all measured compounds: e.g. δ13CVPDB (‰) and δ2HVSMOW (‰), then followed by the acronyms for compounds; the same recommendation for all article content, where the authors used these symbols.
Author Response
uncertainty was added
your symbol for isotope was used
Reviewer 2 Report
Dear Authors,
I’ve carefully read your manuscript and I recommend its publication in this journal. The context of the investigation is properly explained in the introduction, with a very detailed and informative description of the topic, as well as its purpose. The scientific strategy applied by the authors allowed obtaining useful information for the provenance identification of the jars and results support the conclusions reported by the authors. For future studies, I think it might be interesting to add other types of chemical analysis (e.g. comparison between multi-element analysis of original samples of different origin and unknown samples) and PC data analysis for a more powerful provenance recognition.
I would like to highlight some minor changes:
- line 152: I assume that TORP-S refers to sandy torpedo jars described in the previous sentence. For clarity, I would add the “TORP-S” acronym closer to the jar description. “..containing profuse well-sorted mixed sandy inclusions (TORP-S). The earliest examples of TORP-S can..”
- figures 9, 10, 11, 12: the position of the axis-label is confusing. I would move them parallel to their corresponding axis. Moreover, a legend could help in the symbol interpretation (or symbols added to the figure caption).
Comments for author File: 
Comments.pdf
Author Response
We have not changed the text for torpdo jar for it was quite clear
position of legends were put along axis
Reviewer 3 Report
The article is fine, clearly presented and scientifically correct. I suggest shortening the discussion on Muhut Island (P.3) as it is not relevant to the topic.
Author Response
We found that the discussion is bringing useful information
Reviewer 4 Report
Dear authors, This is a well written manuscript. I have no comments concerning the Scientific soundness and presentation.My only concern is on the significance of content since that the samples are very few and thus your conclusions concerning possible trade roots cannot be established.
Author Response
The results on the two samples are included in a larger ongoing study with samples from Thailand, Indonesia, Sri Lanka, India , Abu Dhabi, Saudi Arabia, Iran, Oman. They fit with the trade routes deduced from this larger amount of data.
