Geology and Petrography of Uraniferous Bitumens in Permo-Carboniferous Sediments (Vrchlabí, Czech Republic)
, Jiří Mizera 1,2,*, Miroslav Coubal 1, Vladimír Machovič 1,3, Vladimír Strunga 2,4 and Viktor Goliáš 4Round 1
Reviewer 1 Report
Intriguing study of radioactive condensed organic matter form Permian Black Shales. Methodology and descriptions of the organic matter is state of the art but I miss a bit the scientific significance of this study. The authors should make a clear definition what that organic matter is - bitumen or kerogen - and the probable origin of it. Generally a biogeochemical characterisation would also improve the qualitiy of this study. I´ll recommend also to add some bulk Corg d13C analyses of the different organic facies. The scientific merit of the paper would increase if the authors could compare the found facies and structures with possible other known occurrences of this rock and facies type.
Author Response
We thank the reviewer for valuable comments.
The paper is a part of a project aimed “Radiolytic alteration of organic matter in uraniferous environment”, and the reviewed manuscript is the 1st paper in a series of papers studying the uraniferous bitumens in Permocarboniferous sediments at Vrchlabí. This 1st paper has been aimed at geology and petrography. The ongoing study involved organic geochemistry by spectrometric methods and also C-13 isotopic analyses. Their evaluation and interpretation of results are underway and will be presented in upcoming papers. Within the project, output in the form of several papers in international journals with impact factor is required by the grant agency, thus publication of results if several stages is inevitable. We hope that the reviewer understands the situation.
As for the comment on the definition of the studied organic matter at Vrchlabí. Its bituminous character and possible is well known and has been documented by citing several previous studies from the locality, as well as supported by presented data. As for kerogen vs. bitumen, the difference is obvious and known (kerogen - insoluble in organic solvents, bitumen - soluble in organic solvents), and thus not necessary to specify. Also comparisons of results, from the petrological point of view, with other known occurrences of this rock and facies type is included and referenced in the manuscript.
Reviewer 2 Report
The research article, entitled "Geology and petrography of uraniferous bitumens in Permo-Carboniferous sediments (Vrchlabi, Chech Republic)", authored by M. Havelcova et al., reports results from petrographic and geochemical study of seventeen bitumen-rich samples from Krkonose Peidmont Basin in Chech Republic. The authors indicate that bitumen in rocks originate from deep burial of in-situ organic matter and from primary/secondary migration of hydrocarbons along cracks and faults. The latter form small bitumen-rich veinlets with pronounced alteration of petrographic properties around mineral grains. The presence of brighter halos and changes of bitumen reflectance are attributed to radiolytic influence of U-bearing minerals. The latter are characterized using back-scattered electron microscopy coupled with wavelength dispersive detector, as being dominated by uraninite grains. Results are interpreted in terms of origin of the uraniferous bitumen and indicate mixture of hydrocarbon migration products with U-bearing hydrothermal fluids.
The paper is well written and concise. The used methodology is adequate and the data are of good quality. I think the manuscript can be published as is, but minor grammatical/stylistic changes can further improve it. However, since I'm not native English speaker, I will leave this decision to the other reviewers and the Editor, which are hopefully fluent in English.
Author Response
We thank the reviewer for valuable comments. The language has been edited and corrected mainly based on comments and suggestions of R3 (changes in the revised MS highlighted in yellow).
Reviewer 3 Report
The manuscript deals with the very interesting and up-to-date subject of Uranium. The data is swell presented yet there are many issues that the authors need to address in order for the manuscript to be solid enough for publication.
Some of the issues that need to be addressed are:
- Significant corrections in the English language employed. In many occasions, the authors' arguments are not comprehensible
- The structure of the manuscript needs to be changed too, as there are significant results, especially for the organic matter/bitumens, that need to be presented in a clear manner (Discussion) in order for the unfamiliar reader to understand what the authors are supporting.
For more information please see the attached file
Comments for author File: 
Comments.pdf
Author Response
We thank the reviewer for valuable comments which have certainly improved the overall quality of the paper. Changes made in the revised MS have been highlighted in yellow.
The language has been edited and corrected based on comments and suggestions of R3. All suggested changes have been accepted. Where R3 commented on poor language but made no suggestion, we attempted to reword the parts highlighted by R3.
As for requirement to change the MS structure, we are not sure what should be changed and how any reorganization should help an “unfamiliar reader” to understand better the research presented in the paper. We hope that already the fact that the paper is a part of the Minerals Special Issue “Organic Matter in Sedimentary Systems: Insights from Organic Petrology and Organic Geochemistry” ensures that most readers will understand the results presented in the paper and can possibly made their own interpretations. The paper is a part of a project aimed “Radiolytic alteration of organic matter in uraniferous environment”, and the reviewed manuscript is the 1st paper in a series of papers studying the uraniferous bitumens in Permocarboniferous sediments at Vrchlabí. This 1st paper has been aimed at geology and petrography. The ongoing study involved organic geochemistry by spectrometric methods, U-Pb dating, and also C-13 isotopic analyses. Their evaluation and interpretation of results are underway and will be presented in upcoming papers. Within the project, output in the form of several papers in international journals with impact factor is required by the grant agency, thus publication of results if several stages is inevitable. We hope that the reviewer understands the situation. This response applies also to R3’s comments requiring reduction of the Geological Setting section and revision of the Discussion section (R3-commented MS, lines 78 and 344, respectively).
All other minor suggestions, e.g., corrections of improper terminology, improvements of figures or their captions, have been accepted, also using other means for clarification such as rewording or adding references. Below we try to address some more specific comments of R3.
Line 398: The issue of “reduction of soluble uranyl ions to insoluble uraninite”. Reduction of soluble U(VI) (uranyl) to insoluble U(IV) (e.g., uraninite) is a well known and generally accepted mechanism, playing a crucial part in the complex mechanism of uranium mineralization in the presence of organic matter. Of course we have not identified uranyl ions, not only due lack of tools to do that, but also because they are not present anymore. But their presence and role in the processes of genesis of the uranium mineralization at the studied sedimentary formation should be clear.
Line 404: The issue of “formation of fine-grained mineral particles in an amorphous mass”. The proposed mechanisms have been based partly on information from literature referred repeatedly in previous sections of the paper, and partly on own observations and results presented in the paper. We have not found necessary to refer here to any specific reference from literature.
Round 2
Reviewer 1 Report
The authors have carefully checked the recommendation and revised most of the questioned text parts. The manuscript has gained quality and I believe it has now a better overall merit and is an important contribution to the understanding of geology of uraniferous organic matter
Author Response
We thank again the reviewer for the valuable comments in the 1st review round and for appreciation of the revised manuscript.
The authors.
Reviewer 3 Report
The authors have addressed the majority of the previous review comments. The manuscript has been greatly improved and the scientific soundness is improved overall.
Some minor grammar and spelling corrections are required. The major improvement involves the abstract, as in its current state doesn't support the manuscript.
Please see more details in the uploaded revised version.
Congratulations on your work!
Comments for author File: Comments.pdf
Author Response
We thank again the reviewer for the valuable comments in both review rounds. All language corrections have been accepted and implemented.
The abstract has been extended (last two sentences) to complete it with a brief, generalized conclusion.
The text in lines 107-114 (new 109-115) has been reworded/reduced. We agree that the information on (horizontal) length of the outcrop (500 m) vs. thickness of the horizon (200 m) may have been confusing.
The text about U and Cu minerals in line 383-387 (new 385-388) has been reworded, and hopefully improved.
The text about "mechanical migration" in lines 412-413 (new 413-414) has been reworded, and hopefully improved.
We thank also for appreciation of our work.
Authors.
