Contourite and Turbidite Features in the Middle Caspian Sea and Their Connection to Geohazards Derived from High-Resolution Seismic Data
Round 1
Reviewer 1 Report
This is a well-written paper on the marine geology of the Caspian Sea. I didn't expect the occurrence of bottom currents in the sea, which are strong enough to produce contourites. I think this paper is a significant contribution to understanding the marine geology of enclosed seas. The paper is overall well organized and well-written with the interpretations fully supported by the data. I think the paper can be published without further revision or with minor corrections of a few typos.
Author Response
Dear reviewer, thank you very much for your high appreciation of our work. Indeed, in closed reservoirs, to which the Caspian Sea belongs, the phenomenon of near-bottom currents and their importance in the process in the process of contourites formation has not been studied very fully so far. We have carefully reviewed the text of the article and corrected some typos.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Please kindly see attach.
Comments for author File: Comments.pdf
Author Response
Dear reviewer, thank you very much for your positive evaluation of our manuscript. We agree that some aspects of our article could be improved. We will use your recommendation in our work. Below we will try to respond to your comments indicated in the attached file
Point 1. Lines 14-16. Comment: The phrase is crossed out.
Response: We agree, Correction done
Point 2. Line 24. Comment: Grammatical error
Response: Correction done. Grammatical error corrected
Point 3. Line 81. Comment: The worlds are crossed out.
Response: We agree, Correction done
Point 4. Lines 94-95. In text: “These landslide deformations and gravitational features have previously been considered [9-10]; therefore, in this paper we focused on the description of mostly turbidite contourite features”. Comment: Contradiction? Turbidites flow across the contours while contourite currents run parallel
Response: You are quite right. The phrase seems contradictory. We corrected it. New variant:
“…in this paper we focused on the description of turbidite features and, mostly, contourite ones”.
Point 5. Line 113. Comment: The worlds are crossed out.
Response: We agree, Correction done
Point 6. Lines 130-131. In text: “…the epi-Paleozoic period…” Comment: this is highly anachronous
Response: The term has been replaced. New version: “…and their formation was accompanied by a reworking of the Earth’s crust in the post-Paleozoic era”
Point 7. Line 549. Comment: Words “(produced in Excel)” crossed out.
Response: We agree, Correction done
General observation: Moderate English changes required
Response: We carefully checked the text of the article with the help of an English-speaking colleague.
Author Response File: Author Response.pdf
Reviewer 3 Report
This manuscript presented the contourites in the Caspian Sea. It has a broad interest to the scientific researchers and readers. The methods are adequatedly described. The results are clearly presented. Conclusions are made logically based on the results. However, narration needs to be updated, especially for the introduction and conclusions. The lacustrine contourite studies cited in the conclusions should be moved to the introduction section. About the bottom current, authors should add or refer to more details. How did the bottom current form in such a confined lake basin? Is the driving mechanism same as or different from the open ocean? Add more discussion to talk about the current mechanism in other lakes, such as, Lake Superior, etc?
Author Response
Dear reviewer, thank you very much for your positive evaluation of our manuscript. Below we will try to respond to your comments. We are confident that once your comments are corrected, our work will be greatly improved
Point 1. Comment: The lacustrine contourite studies cited in the conclusions should be moved to the introduction section.
Response: We agree, Correction done. The corresponding paragraph has been moved from the conclusion to the introduction
Point 2. Comment: About the bottom current, authors should add or refer to more details.
Response: Thank you for this observation. Really, the question of bottom currents is a very important special theme. In our references one can find all the necessary information on the hydrological regime of the Caspian Sea existing today, including the results of few direct measurements of bottom currents. We have limited ourselves to such a description, since our article deals with indirect indications of the impact of bottom currents on the seabed, which led to the formation of characteristic contourite structures.
Point 3. Comment: How did the bottom current form in such a confined lake basin?
Response: Interesting question. We have added relevant information to the text of the article: «The formation of the bottom current in the Caspian Sea is associated with the Volga River's giant outflow of water into the shallow northern part of the Caspian Sea, and its paths are determined by the relief of the Middle Caspian Sea bottom. Moving southward, this water rolls into the deep water Derbent Basin, forming a flow along its western slope. This is confirmed by the observed channels in the lower part of the slope and adjacent basin. Furthermore, when reaching the Apsheron Sill, the bottom water flow turns eastward along the southern slope of the Derbent Basin, then turns northward along the eastern slope of the Derbent Basin»
Point 4. Comment: Is the driving mechanism same as or different from the open ocean?
Response: Thanks for the valuable observation. The relevant information has been added to the text of the article: “In the open ocean, bottom contour currents are associated with thermohaline circulation created by the difference in water density resulting from the inhomogeneous distribution of temperature and salinity in the ocean. This circulation creates a global ocean conveyor belt in the world's oceans. In the closed Caspian Sea, the formation of the bottom current is associated with the giant Volga River outflow, and the geometry of this bottom current distribution is determined by the topography of the Middle Caspian Seabed.”
Point 5. Comment: Add more discussion to talk about the current mechanism in other lakes, such as, Lake Superior, etc?
Response: We have added information about some lakes characterized by the presence of sedimentary structures similar to the contourites or turbidites of the Caspian Sea. In particular, about Lake Superior, Lake Saint-Jean (Québec, Canada), Lake Ossa in West Africa, and others. In addition, the following information has been added to the text of the article: «The Caspian Sea is filled with salty sea water. This is due to the connection in the recent geological past (Pleistocene) of the Caspian Sea with the Black Sea and the Mediterranean Sea through the Manich and Bosporus Straits respectively. Whereas other large, enclosed lakes such as the Great Lakes and Baikal are freshwater. And it is the thermohaline structure of the waters that determines their density with which the formation of bottom currents is connected. »
General observation: English language and style are fine/minor spell check required
Response: We carefully checked the text of the article with the help of an English-speaking colleague.
Author Response File: Author Response.pdf
