Geochemical Features of Lacustrine Shales in the Upper Cretaceous Qingshankou Formation of Changling Sag, Songliao Basin, Northeast China

Round 1

Reviewer 1 Report

Please see the attached file.

Comments for author File: Comments.pdf

Author Response

Thank you very much for your valuable comments, which have been revised as required. Please see the word document for details

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors present experimentally derived results of their geochemical analysis tests of the continental shale of the Qingshankou Formation in the Changling Fault Depression in the southern Songliao Basin. Total organic carbon, rock pyrolysis, and saturated hydrocarbon mass spectrography are applied as test methods.

The results are well explained and presented graphically. The manuscript should be published.

Author Response

Modified as required, refer to word document

Author Response File: Author Response.docx

Reviewer 3 Report

The MS, titled "Geochemical features of lacustrine shales in the Upper Cretaceous Qingshankou Formation of Changling sag, Songliao Ba-3 sin, Northeast China", reports source rock evaluation of shale and mudstone samples obtained from the oil-production area. The applied methodology and organisation of the MS are suitable; however, the authors should re-organize some parts of the MS and provide additional data in order to have a more robust evaluation. Firstly, the introduction part is quite confusing and some parts are hard to follow and understand. Therefore, the authors should re-organize and provide a brief literature overview of the study area and its hydrocarbon generation potential. Additionally, in the introduction sections and some parts of the maturity and redox discussions, the authors mentioned "Previous studies" or "Some researchers" but they did not provide any citation afterwards. Furthermore, the reference list is quite confusing because I could not find any journal names or the citations are from book chapters. The authors should check their reference lists. The authors should also provide citations for the used diagrams. since these diagrams are commonly used for source rock evaluation. Secondly, the authors reported %Ro values in Table 1; nevertheless, it is not clear whether this data is based on measured %Ro from vitrinite grains or dispersed organic matter or from calculated %Ro values using Tmax values according to Dr. Jarvie’s formula. If the latter case is valid, please mention it in section 3 and report %Ro values as "calculated %Ro". If the former case is valid, please provide selected microphotographs of identified macerals. Since the HI values of some samples are higher than 500 mg HC/TOC, the samples should contain alginite, which also supports the discussion about the source of organic matter. If the authors did not perform organic petrography observation, I highly recommend this analysis of at least shale samples. Providing such data will increase the scientific soundness of the study. Some recent studies also reported that mineralogical as well maceral compositions of the shale and coal samples could have some impacts on S2 and S3 measurements, which could elevate or reduce these values. In order to have a more robust discussion, the authors should also provide XRD data. Hence, they could eliminate any further discussion about their data. Finally, the authors should provide the lithological data in Table 1. Because the authors mentioned shale samples several times, I could not understand which samples were shale and which were mudstone. The latter one could also sometimes have hydrocarbon generation potential. I added several notes and suggestions in the revised MS. Overall, I could advise a major revision and re-consider the MS after suggested corrections are made.

Comments for author File: Comments.pdf

Author Response

Thank you very much for your valuable comments, which have been revised as required. Please see the word document for details

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

A revision version should include clean version and changes-marked manuscripts. And also a letter to reviewers addressing comments and replies should be provided, instead of comments and replies in the manuscript. I suggest the authors are lack of experiences about how to submit and revise the manuscript. Also there are some small mistakes:

References. 9 Journal is missing. 24. No page numbers. 31, complete? what does that mean? Please check all your references.

Fig. 8. what is the magnification of the objective?

English is not readable, and has to be polished by native speakers before the manuscript is considered for publication.

Author Response

Paragraphs marked with blue shading have been modified as required

Author Response File: Author Response.docx

Reviewer 3 Report

The authors did almost all suggested corrections. I added some corrections in the revised MS. The authors should provide an explain what they meant with sapropellitic in the petrographical analyses and snap of these macerals. After the suggested corrections done, the MS could send to production service. Nevertheless, I would like to check the final version of the MS

Comments for author File: Comments.pdf

Author Response

Paragraphs marked with yellow shading have been modified as required

Author Response File: Author Response.docx

Round 3

Reviewer 1 Report

accept