the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 07 Feb 2023
Mineralogical and elemental geochemical characteristics of Taodonggou Group in Taibei Sag , Turpan-Hami Basin: Implication for Source sink system and evolution history of lake basin
Abstract. The Middle Permian is an important basin-forming period in the Turpan-Hami Basin. Based on mineral characteristics and elemental geochemistry of the Taodonggou Group mudstone we analyze the parent rock type, source area location, sedimentary environment and source area tectonic background for this mudstone. On this basis we are able to reconstruct the source-sink system and lake basin evolution of the Taodonggou Group. We find the following: (1) Taodonggou Group mudstone minerals are mainly clay and quartz, and can be classified into four petrographic types according to mineral fraction. (2) The Taodonggou Group mudstone was deposited in a warm, humid and hot paleoclimate, with strong weathering. The parent rocks of the Taodonggou Group mudstone are two types of felsic volcanic rocks and andesites, with weak sedimentary sorting and recycling and with well-preserved source information. (3) The Taodonggou Group mudstone were deposited in dyoxic freshwater-brackish water in intermediate-depth or deep lakes with stable inputs of terrigenous debris but at slower deposition rates. Deposition of the middle of Taodonggou Group was influenced by hydrothermal activity; the tectonic setting of the Taodonggou Group source area was a continental island arc and an oceanic island arc. (4) The evolution of the Middle Permian Lake basin in the Turpan-Hami Basin can be divided into three stages: In the early part of the deposition of Taodonggou Group the depocenter was in the Bogda area. At this time the area that became Mt Bogda was not exposed and a succession of high-quality type-III source rocks was widely deposited in the basin. In the middle of the deposition of the Taodonggou Group the depocenter gradually migrated to the Taibei Sag. At this time the Mt Bogda area underwent uplift, and, together with hydrothermal activity, a succession of type-II source rocks was widely deposited in the basin. In the late part of the Taodonggou Group, uplift of the Mt Bogda area ceased and the depocenter transferred entirely to the Taibei Sag.
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RC1: 'Comment on egusphere-2022-1433', Anonymous Referee #1, 04 Mar 2023
After going through the introduction of the article, I have a very hard time understand the purpose of this contribution and the authors ignore several decades of research done in the area related to provenance and paleoclimatic reconstructions. I dont see how utilizing 16 samples from a well can therefore help unravel complex tectonic and paleoclimatic processes that are characteristic of the area during the middle Permian.
Very little is mentioned about the stratigraphy of the area, despite the fact of refined stratigraphy for the Taodongou group by Wan Yang and his colleagues. Authors disregard some of the work that Yang and others have done in the area with regards to paleoclimate, provenance, and environmental conditions in the Turpan-Hami Basin.
In the discussion, the authors start discussing paleoclimate in the region. They go on about their results (which should be included in the results section and not in the discussion) and they have one paragraph that says that they speculate the mudstone was deposited in a warm, humid and hot climate and that these results are similar to those by the same author using biomarkers. This completely disregard previous work in the region and has very minimal discussion on paleoclimate in general for the entire region. What is the novelty and how do these results compare to what has been speculated for the area before? Yang et al. (2010) found a significant amount and well developed calcisols in alluvial fans of the Taodongou group, which would suggest a different paleoclimatic setting than the one discussed here. There are others that have also looked at paleosols (Tabor and his students) which is also disregarded here.
The second part of the discussion is the parent rock. The authors also discuss their results and how their results suggest that the parent rocks are andesitic and felsic. But what about the 40 years of work done on the Carboniferous of the study area? The geological complexity is not discussed and they don’t compare the results to those published in the past about provenance. There are very complicated lithologies exposed in both the Tian Shan and Bogda Shan that are Carboniferous in age and I don’t think I have seen significant felsitic rocks in the area. Also, these rocks have been buried and dramatically changed tectonically. Can these ratios be influenced by burial processes and postdepositional modification?
The third part of the discussion is related to the uplift of the Bogda Shan. This is still debated and finding that the provenance is different between the Taodongou and Lucaogou Groups/Formations is not sufficient to make the argument about Bogda uplift. Others have argued that these basins were part of a rift system during that time.
Similarly, there is no discussion on the paleosedimentary environment nor the following sections, mainly just description of the results. Dyoxic (should be dysoxic) is also misspelled in the discussion and in the figures. How does this compare to what has already been published in the area? How does it compare to similar sedimentary basins elsewhere?
Citation: https://doi.org/10.5194/egusphere-2022-1433-RC1 -
AC1: 'Reply on RC1', Huan Miao, 19 Mar 2023
Thank you for your comment. By reading your profound and constructive comments, I believe that I must make significant revisions to the manuscript under the guidance of your comments. To facilitate your reading, I have responded to your comments as follows, each response being numbered in the order of your comment paragraphs.
- （1）正如你所说，这16个泥岩样本并不能真正代表中二叠纪的沉积演化。你的观点非常深刻，指出了问题所在。它只能代表泥岩沉积过程中泥岩、沉积环境、湖泊演化等的普罗旺斯，而不能达到源汇系统的水平。因此，我认为论文的标题和引言必须重写。（2）我们确实忽略了您之前推荐的一些研究工作，例如万阳等人的贡献。这可能与我偏爱阅读中文论文有关。目前，关于吐鲁番-哈密盆地陶东沟组沉积期的古气候，除王洋等人外，最早的还有邵磊（1999、2002）和苗建宇（2004）。他们认为陶东沟组沉积在炎热潮湿的气候中，但他们的样本相对较小。魏新乡（2016）利用树木年轮还原了陶东沟组泥岩沉积期的古气候。同样的结论也是炎热潮湿的。宋等人（2018）的研究成果也是炎热潮湿的。然而，上述学者尚未发现泥岩沉积期古气候的周期性变化，这可能是由于它们从露头取样所致。目前，台北凹陷仅钻透了YT1井。笔者根据YT1井生物标志物的CPI对泥岩沉积期的古气候进行了表征，认为可分为<>个阶段。然而，CPI是一个有争议的参数，很容易受到成熟度的影响。因此，本研究使用敏感元素进行验证。
- 感谢您的评论。地层学确实是一项重要的工作。汪洋等人在2010年和2017年进行的研究非常详细，值得借鉴。如果期刊给我修改的机会，我一定会添加这部分。但是，在仔细研究了万洋等人的研究工作后，发现万洋等人的研究与现在吐哈油田的地层划分是不一样的。我在此征求您的意见！吐哈油田认为，二叠系地层为上二叠统下仓坊组（250-255 Ma，包括国底坑组、梧桐组和泉子街组）、中二叠统陶东沟组（255-260 Ma，包括太尔朗组和大河岩组）、下二叠统易尔西图组（260-290 Ma，又称艾丁湖组）
- 感谢您对稿件结构的评论。对于我糟糕的写作技巧和忽略以前的贡献，我深表歉意。在今后的工作中，我将进一步修改和合并《结果》和《讨论》。您推荐的Yang等人（2010）的研究结果与生物标志物和元素的反应一致。陶东沟组地层沉积于不断变化的沉积环境中（图14），早、后期为暖湿，中期为热湿润。这是我在淘东沟组沉积过程中还原古气候的一个创新点，但由于文字功底差，这一特点没有突出。
- 感谢您的评论。对吐哈盆地的起源进行了大量研究。目前认为吐哈盆地的起源主要来自北部的博格达山脉和南部的Jurotage山脉，但主要区别在于博格达山脉的隆起时间。Lei Shao等（1999）认为吐鲁番-哈密盆地的起源主要由长英质火山岩和安山岩组成。他认为二叠纪博格达山部分隆起，巨罗塔奇山的中酸性火成岩是主要起源，而隆起的博格达山是次生源，而哈密洼地的主要起源区是哈里克山剥蚀区。此外，二叠系含矿砂体碎屑锆石U-Pb同位素组成测量结果表明，所得等时相关性良好（R=0.98），等时年龄为（283 ± 67）Ma，与源区斑岩花岗岩形成年龄（268 ± 13 Ma）相比，在误差范围内一致，表明吐哈盆地含矿砂源主要来自海西晚期花岗岩体。巨洛塔山脉的南部源区，因此，他认为砂岩继承了石炭系下二叠纪的起源。Zhao等人（2020）基于大量U-Pb测年数据分析了天山地区的起源。根据这一结果，吐哈盆地的早期起源应与博格达裂谷地区一致。但Song等（2018）通过元素分析认为，母岩类型也是安山岩和长英质火山岩，出处主要是博格达山。在Jonathan Obrist-Farner和Wan Yang（2017）的论文中，二叠纪Quanzijie组有中性岩石，但Jonathan Obrist-Farner和Wan Yang认为上泉子街组（260.4-265.8 Ma）接近手稿中的陶东沟组（255-260 Ma）。利用Th/Sc和Zr的交集图（图7a）分析了陶东沟组泥岩源的保存程度，结果表明，陶东沟组的源保存较好。
- 谢谢你的意见，但我有不同的看法。以往很多研究认为，在博格达裂谷时期，准噶尔盆地、吐哈盆地、尹噶盆地和吉木萨尔盆地是一个整体，产地和有机质类型一致，这导致了早期的Gang Gao等（2006）、Shiju Liu等（2020）都利用准噶尔盆地的页岩或吉木萨尔盆地的卢草沟组来解释碳氢化合物的产生潜力和沉积以淘东沟组泥岩环境为例。但是，它们的出处今天并不相同，这应该能够推断出博格达山已经隆起或部分隆起。这一结果也与最新的研究结果一致（Li et al. （2022） 和 Wang et al. （2018））
- 感谢您的仔细阅读和宝贵意见。关于稿件中的拼写错误、缺少插图等问题，我将进一步修改。我将重新组织和重写手稿的写作技巧和其他部分。再次感谢您的仔细阅读和非常有建设性的意见。相信在各位宝贵意见的指导下，我的稿件会得到很大的改进。
Citation: https://doi.org/10.5194/egusphere-2022-1433-AC1 -
AC2: 'Reply on RC1', Huan Miao, 03 Jun 2023
I am deeply sorry for my foolishness and carelessness once again. Due to my browser's automatic translation function, the English text I uploaded was translated into Chinese. If it weren't for the reminder from Reviewer 3, I might have ignored this fact. My stupidity and carelessness must have caused you great inconvenience! I am truly sorry. To make up for my foolish mistake, I will re-upload my response to you and sincerely hope that you can forgive my error.
My previous response to your feedback is as follows:
As you have pointed out, these 16 mudstone samples cannot truly represent the sedimentary evolution of the Middle Permian. Your insight is very profound and identifies where the problem lies. Your insight is very profound and identifies where the problem lies. They can only represent the mudstone sedimentation process, sedimentary environment, lake evolution, etc., and cannot reach the level of the source-sink system. Therefore, I believe that the title and introduction of the paper must be rewritten. Secondly, we did overlook some of the research work you previously recommended, such as the contributions of Yang Wan et al. This may be related to my preference for reading Chinese papers. Currently, regarding the paleoclimate of the Taodonggou Group sedimentary period in the Turpan-Hami Basin, besides Yang Wan et al., the earliest studies were by Shao Lei (1999, 2002) and Miao Jianyu (2004). They believed that the Taodonggou Group sedimented in a hot and humid climate, but their sample size was relatively small. Wei Xinxiang (2016) used tree-ring analysis to reconstruct the paleoclimate of Taodonggou Group mudstone sedimentation, and the same conclusion was reached. Song et al. (2018) also found a hot and humid climate. However, these scholars have not yet discovered the periodic changes in the paleoclimate of the Taodonggou Group mudstone sedimentation, which may be due to sampling from outcrops. Currently, only the YT1 well has been drilled in the Taibei Sag. Based on the CPI of the bio-markers in the YT1 well, the author characterized the paleoclimate of the mudstone sedimentation period into three stages. However, the CPI is a controversial parameter and is easily influenced by maturity. Therefore, this study has used sensitive elements to verify the results again.
Thank you for your comments. Stratigraphy is indeed an important work. The research conducted by Yang Wan et al. in 2010 and 2017 is very detailed and worth referencing. If the journal gives me the opportunity to revise, I will definitely add this part. However, after carefully studying the research work of Yang Wan et al., I found that their research is different from the current stratigraphic division of the Tuha Oilfield. I would like to ask for your opinion on this matter! The Tuha Oilfield believes that the Permian strata are the Lower Cangfang Group of the Upper Permian (250-255 Ma, including the Guodikeng Formation, Wutonggou Formation, and Quanzijie Formation), the Taodonggou Group of the Middle Permian (255-260 Ma, including the Taerlang Formation and Daheyan Formation), and the Yierxitu Formation of the Lower Permian (260-290 Ma, also known as the Aidinghu Formation).
Thank you for your comments on the manuscript structure. I apologize for my poor writing skills and for neglecting previous contributions. In my future work, I will make further revisions and merge the results and discussion sections. The research results of Yang et al. (2010), which you recommended, are consistent with the response of biomarkers and elements. The Taodonggou Group sedimented in a continuously changing sedimentary environment (Figure 14), with the early and late stages being warm and humid, and the middle stage being hot and humid. This is an innovative point in my reconstruction of paleoclimate during the sedimentation process of the Taodonggou Group, but I failed to highlight this feature due to my poor writing skills. The age of the Taodonggou Formation used in my study is 255-260 Ma.
Thank you for your comments. There has been a lot of research on the origin of the Turpan-Hami Basin. Currently, it is believed that the Permian origin of the Turpan-Hami Basin mainly comes from the Bogda Mountains in the north and the Jueluotage Mountains in the south, but the main difference lies in the uplift time of the Bogda Mountains. Lei Shao et al. (1999) believed that the origin of the Turpan-Hami Basin is mainly composed of felsic volcanic rocks and andesites. He believed that during the Permian period, the main origin of the Jueluotage Mountains' intermediate acidic igneous rocks was from the uplifted part of the Bogda Mountains, while the uplifted Bogda Mountains were a secondary source, and the main source of the Hami Basin was the Halike Mountains erosion area. In addition, the U-Pb isotope composition measurement results of detrital zircons in the Permian sandstone show good isochron correlation (R2=0.98), and the isochron age is (283 ± 67) Ma, which is consistent with the formation age (268 ± 13) Ma of the source area's granitic rocks within the error range, indicating that the main source of the mineral sand in the Turpan-Hami Basin is from the granitic body in the late stage of the Late Hercynian period, which is the southern source area of the Jueluotage Mountains, thus he believed that the sandstone inherited the origin of the Lower Permian in the Carboniferous. Zhao et al. (2020) analyzed the origin of the Tian Shan region based on a large amount of U-Pb dating data. According to this result, the early origin of the Turpan-hami Basin should be consistent with the Bogda Rift area. However, Song et al. (2018) believed through element analysis that the parent rock types are also andesites and felsic volcanic rocks, mainly from the Bogda Mountains. In the paper by Jonathan Obrist-Farner and Wan Yang (2017), the Permian Quanzijie Formation has neutral rocks, but Jonathan Obrist-Farner and Wan Yang believed that the Upper Quanzijie Formation (260.4-265.8 Ma) is close to the Taodonggou Formation (255-260 Ma) in the manuscript. The preservation degree of the mudstone source of the Taodonggou Group was analyzed using the intersection diagram of Th/Sc and Zr (Figure 7a), and the results showed that the source of the Taodonggou Group mudstone was well preserved and could be used to analyze the provenance information.
Thank you for your comments, However, I hold a different view. Many previous studies have suggested that during the Bogda Rift period, the Junggar Basin, Turpan-hami Basin, Yaggar Basin, and Jimusaer Basin were a single entity with consistent source and organic matter types. This led to early interpretations of the hydrocarbon generation potential and sedimentary environment of the Taodonggou Group using Lucaogou Formation shale from the Junggar Basin or the Jimusaer Basin as examples, as done by Gang Gao et al. (2006) and Shiju Liu et al. (2020). However, their sources are no longer the same today, which should be able to infer that the Bogda Mountains have already uplifted or partially uplifted. This result is also consistent with the latest research findings (Li et al. (2022) and Wang et al. (2018)).
Thank you for your careful reading and valuable feedback, and I sincerely apologize for any errors caused by my carelessness. I will make further revisions to address issues such as spelling errors and missing illustrations in the manuscript. Once again, I appreciate your careful reading and highly constructive feedback. I believe that with your guidance and feedback, my manuscript will be greatly improved.
Citation: https://doi.org/10.5194/egusphere-2022-1433-AC2 -
AC4: 'Reply on RC1', Huan Miao, 15 Jul 2023
Dear Reviewer
I apologize once again for my previous rude behavior and I would like to thank you for reviewing my manuscript. I have made adjustments based on your feedback, and the revised version is attached. To facilitate your review, I have highlighted the modified sections in yellow text.
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AC1: 'Reply on RC1', Huan Miao, 19 Mar 2023
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RC2: 'Comment on egusphere-2022-1433', Anonymous Referee #2, 13 May 2023
The authors applied elemental geochemistry and other methods to analyze the provenance, depositional environment, and tectonic background of the Middle Permian Taodonggou Group mudstone in the Turpan-hami Basin and compared the provenance of the Taodonggou Group mudstone with that of the Luchaogou Group mudstone in the Junggar Basin, providing evidence for the timing of the Bogda Mountain uplift. At the same time, the evolutionary process and model of the Middle Permian in the Turpan-hami Basin are proposed. The manuscript has a reasonable content setting and credible results, and the results enrich the geological understanding of the North Tianshan area. However, the paper has certain shortcomings, which are detailed as follows:
(1) The authors' samples are mudstones, and the results of sandstone research such as shao (1990; 2001) are cited in the discussion section, while the distribution of mudstones in relation to sandstones needs to be added by the authors;
(2) In the results section, the authors use "~" extensively, and the use of "~" and "-" is different and needs to be adjusted by the authors;
(3) The word is misspelled, "dysoxic" should be rewritten as "dyoxic";
(4) In provenance, the authors analyzed the provenance of the Turpan-hami Basin Taodonggou Group mudstone and the Junggar Basin Luchaogou Formation mudstone, but they abbreviated the Taodonggou Group mudstone as "P2td" and the Luchaogou Group mudstone as "P2l". This is not recommended, and we suggest the authors change it for international readers.
(5) Fig. 8 needs to add a legend, Fig. 11 needs to be adjusted, there are too many blank spaces, and Fig. 14 needs to add organic matter composition and type.
Citation: https://doi.org/10.5194/egusphere-2022-1433-RC2 -
AC5: 'Reply on RC2', Huan Miao, 15 Jul 2023
Dear reviewer
Thank you for reviewing my manuscript and for your valuable feedback. I have now made the necessary revisions based on your comments. The latest modifications are shown in the attached document. To facilitate your review, I have highlighted the modified portions in blue text.
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AC5: 'Reply on RC2', Huan Miao, 15 Jul 2023
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RC3: 'Comment on egusphere-2022-1433', Anonymous Referee #3, 02 Jun 2023
After reading this manuscript, two things shocked me. One thing is that, I am not sure whether it is a system problem of web page, I find the author replied the reviewer's comments in Chinese not in English. If it is true, I do not think it is polite. After all, the manuscript was written in English and submitted to an English Journal. The other one is that it is my first time to see a paper that proposed source rocks (mudstones) with kerogen type III can be deposited in deep lake facies. Is it really deep lake facies or kerogen type III? I doubt that. I think it is necessary to add evidences from Rock-Eval pyrolysis (vertical variations in HI) and sedimentary analysis (from core observation or references) to support this viewpoint as well as the lake basin evolution mode in the section 5.5. Because I remain suspicious of this mode. For example, although the authors used a plenty of ratios of elements to support their opinions on paleo-bathymetric variation, it seems that the lithology column of well YT1 shows an opposite variation. Why the dark black mudstones can be deposited in shallower water environment (middle stage), whereas the grey mudstones were deposited in deeper water environment. Is there gravity flows influencing lithology change and source rock quality in the studied area？ Again, sedimentary analysis and Rock-Eval pyrolysis are vital and indispensable for basin evolution reconstruction and source rock formation, but they are absent.
Citation: https://doi.org/10.5194/egusphere-2022-1433-RC3 -
AC3: 'Reply on RC3', Huan Miao, 03 Jun 2023
Thank you for your thoughtful and hypothetical feedback and reminders. Without your guidance, I may have continued to overlook the serious error of submitting my work to Reviewer 1 in Chinese instead of English. I offer you my sincere apologies and heartfelt appreciation for bringing this to my attention!
The second issue you raised concerns a major drawback in the manuscript, as suggested by Reviewer 2, that I should add evidence of organic geochemistry. At the time, I did not include this section in the paper because the results had already been published in another journal in 2021 and the author's thesis. Therefore, I only included citations in the main text. However, in order to support the existence of Type III kerogen in the deepwater area, I have followed your advice and added HI, as well as the ratio of ∑C21-/∑C22+ and C27-C28-C29. These all serve as evidence that Type III kerogen shale was deposited in a deepwater environment (Fig.1).
Currently, there is almost no dispute that the Taodonggou Group mudstones in the Turpan-Hami Basin were deposited in a deep or semi-deep lake environment, as evidenced by their good response to elemental ratios (Li, 2016; Li, 2019; Song et al., 2018; Xu, 2022). However, your suggestion on the relationship between water depth and organic matter type has greatly enlightened me and broadened my perspective. After conducting a literature review on the existing research in the study area, I did not find any studies on gravity flow. However, by reading studies on gravity flow sedimentation in the Fengcheng Formation shale in the Junggar Basin, there is a possibility of gravity flow sedimentation in the Taibei Sag of the Turpan-Hami Basin. Based on studies by Chen et al. (2003), Xu Haoyu (2022), and Yang Wan et al. (2010; 2017) recommended by Reviewer 1, it is believed that there is sedimentation of coarse clastic rocks at the bottom of the Daheyan Formation (the bottom of the Taodonggou Group), and different sedimentary facies can be identified in different areas of the study area. In addition, during the sedimentation of the Taerlang Formation, three sedimentary facies can be identified around the Bogeda Mountains, including the front edge of the fan delta, turbidite fan, and semi-deep lake-deep lake facies (Wang, 2017), indicating the possibility of gravity flow sedimentation in the study area. The YT1 well is located in the southern part of the Taibei Sag, which has always been the sedimentary center of the Turpan-Hami Basin (Jiang et al., 2015; Li et al., 2021). The mudstones in the study area were deposited in a deep-semi-deep lake environment, with the deeper water depth depositing III-type kerogen mudstones and some layers of relatively thin clastic rocks, suggesting that they were influenced by gravity flows during the early and late stages. However, I cannot provide actual core evidence for this conclusion because the YT1 well in the study area was drilled deep, and cores were only taken in some depth intervals (6110-6116 and 6140-6154), while other depth intervals were recorded by cuttings. The lithology of the cored intervals is basically consistent. Nevertheless, according to Wang Yue's (2017) study, there is evidence of mixing in the study area, which may prove this point.
Furthermore, I will carefully complete the revisions to the manuscript by systematically incorporating your comments and those of the other two reviewers. Finally, I would like to express my gratitude for your valuable insights. Your comments not only broadened my perspective but also provided important inspiration for my future work. I am truly grateful and have no words to express my appreciation.
Thank you for your thoughtful and hypothetical feedback and reminders. Without your guidance, I may have continued to overlook the serious error of submitting my work to Reviewer 1 in Chinese instead of English. I offer you my sincere apologies and heartfelt appreciation for bringing this to my attention!
The second issue you raised concerns a major drawback in the manuscript, as suggested by Reviewer 2, that I should add evidence of organic geochemistry. At the time, I did not include this section in the paper because the results had already been published in another journal in 2021 and the author's thesis. Therefore, I only included citations in the main text. However, in order to support the existence of Type III kerogen in the deepwater area, I have followed your advice and added HI, as well as the ratio of ∑C21-/∑C22+ and C27-C28-C29. These all serve as evidence that Type III kerogen shale was deposited in a deepwater environment (Fig.1).
Currently, there is almost no dispute that the Taodonggou Group mudstones in the Turpan-Hami Basin were deposited in a deep or semi-deep lake environment, as evidenced by their good response to elemental ratios (Li, 2016; Li, 2019; Song et al., 2018; Xu, 2022). However, your suggestion on the relationship between water depth and organic matter type has greatly enlightened me and broadened my perspective. After conducting a literature review on the existing research in the study area, I did not find any studies on gravity flow. However, by reading studies on gravity flow sedimentation in the Fengcheng Formation shale in the Junggar Basin, there is a possibility of gravity flow sedimentation in the Taibei Sag of the Turpan-Hami Basin. Based on studies by Chen et al. (2003), Xu Haoyu (2022), and Yang Wan et al. (2010; 2017) recommended by Reviewer 1, it is believed that there is sedimentation of coarse clastic rocks at the bottom of the Daheyan Formation (the bottom of the Taodonggou Group), and different sedimentary facies can be identified in different areas of the study area. In addition, during the sedimentation of the Taerlang Formation, three sedimentary facies can be identified around the Bogeda Mountains, including the front edge of the fan delta, turbidite fan, and semi-deep lake-deep lake facies (Wang, 2017), indicating the possibility of gravity flow sedimentation in the study area. The YT1 well is located in the southern part of the Taibei Sag, which has always been the sedimentary center of the Turpan-Hami Basin (Jiang et al., 2015; Li et al., 2021). The mudstones in the study area were deposited in a deep-semi-deep lake environment, with the deeper water depth depositing III-type kerogen mudstones and some layers of relatively thin clastic rocks, suggesting that they were influenced by gravity flows during the early and late stages. However, I cannot provide actual core evidence for this conclusion because the YT1 well in the study area was drilled deep, and cores were only taken in some depth intervals (6110-6116 and 6140-6154), while other depth intervals were recorded by cuttings. The lithology of the cored intervals is basically consistent. Nevertheless, according to Wang Yue's (2017) study, there is evidence of mixing in the study area, which may prove this point.
Furthermore, I will carefully complete the revisions to the manuscript by systematically incorporating your comments and those of the other two reviewers. Finally, I would like to express my gratitude for your valuable insights. Your comments not only broadened my perspective but also provided important inspiration for my future work. I am truly grateful and have no words to express my appreciation.
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AC6: 'Reply on RC3', Huan Miao, 15 Jul 2023
Dear reviewer
Thank you for reviewing my manuscript and providing valuable feedback, especially regarding the understanding of gravity flow sedimentation. I have now identified evidence of gravity flow deposition and made the necessary revisions based on your suggestions. The latest modifications can be found in the attached document. To facilitate your review, I have highlighted the modified portions in green text.
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AC3: 'Reply on RC3', Huan Miao, 03 Jun 2023
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2022-1433', Anonymous Referee #1, 04 Mar 2023
After going through the introduction of the article, I have a very hard time understand the purpose of this contribution and the authors ignore several decades of research done in the area related to provenance and paleoclimatic reconstructions. I dont see how utilizing 16 samples from a well can therefore help unravel complex tectonic and paleoclimatic processes that are characteristic of the area during the middle Permian.
Very little is mentioned about the stratigraphy of the area, despite the fact of refined stratigraphy for the Taodongou group by Wan Yang and his colleagues. Authors disregard some of the work that Yang and others have done in the area with regards to paleoclimate, provenance, and environmental conditions in the Turpan-Hami Basin.
In the discussion, the authors start discussing paleoclimate in the region. They go on about their results (which should be included in the results section and not in the discussion) and they have one paragraph that says that they speculate the mudstone was deposited in a warm, humid and hot climate and that these results are similar to those by the same author using biomarkers. This completely disregard previous work in the region and has very minimal discussion on paleoclimate in general for the entire region. What is the novelty and how do these results compare to what has been speculated for the area before? Yang et al. (2010) found a significant amount and well developed calcisols in alluvial fans of the Taodongou group, which would suggest a different paleoclimatic setting than the one discussed here. There are others that have also looked at paleosols (Tabor and his students) which is also disregarded here.
The second part of the discussion is the parent rock. The authors also discuss their results and how their results suggest that the parent rocks are andesitic and felsic. But what about the 40 years of work done on the Carboniferous of the study area? The geological complexity is not discussed and they don’t compare the results to those published in the past about provenance. There are very complicated lithologies exposed in both the Tian Shan and Bogda Shan that are Carboniferous in age and I don’t think I have seen significant felsitic rocks in the area. Also, these rocks have been buried and dramatically changed tectonically. Can these ratios be influenced by burial processes and postdepositional modification?
The third part of the discussion is related to the uplift of the Bogda Shan. This is still debated and finding that the provenance is different between the Taodongou and Lucaogou Groups/Formations is not sufficient to make the argument about Bogda uplift. Others have argued that these basins were part of a rift system during that time.
Similarly, there is no discussion on the paleosedimentary environment nor the following sections, mainly just description of the results. Dyoxic (should be dysoxic) is also misspelled in the discussion and in the figures. How does this compare to what has already been published in the area? How does it compare to similar sedimentary basins elsewhere?
Citation: https://doi.org/10.5194/egusphere-2022-1433-RC1 -
AC1: 'Reply on RC1', Huan Miao, 19 Mar 2023
Thank you for your comment. By reading your profound and constructive comments, I believe that I must make significant revisions to the manuscript under the guidance of your comments. To facilitate your reading, I have responded to your comments as follows, each response being numbered in the order of your comment paragraphs.
- （1）正如你所说，这16个泥岩样本并不能真正代表中二叠纪的沉积演化。你的观点非常深刻，指出了问题所在。它只能代表泥岩沉积过程中泥岩、沉积环境、湖泊演化等的普罗旺斯，而不能达到源汇系统的水平。因此，我认为论文的标题和引言必须重写。（2）我们确实忽略了您之前推荐的一些研究工作，例如万阳等人的贡献。这可能与我偏爱阅读中文论文有关。目前，关于吐鲁番-哈密盆地陶东沟组沉积期的古气候，除王洋等人外，最早的还有邵磊（1999、2002）和苗建宇（2004）。他们认为陶东沟组沉积在炎热潮湿的气候中，但他们的样本相对较小。魏新乡（2016）利用树木年轮还原了陶东沟组泥岩沉积期的古气候。同样的结论也是炎热潮湿的。宋等人（2018）的研究成果也是炎热潮湿的。然而，上述学者尚未发现泥岩沉积期古气候的周期性变化，这可能是由于它们从露头取样所致。目前，台北凹陷仅钻透了YT1井。笔者根据YT1井生物标志物的CPI对泥岩沉积期的古气候进行了表征，认为可分为<>个阶段。然而，CPI是一个有争议的参数，很容易受到成熟度的影响。因此，本研究使用敏感元素进行验证。
- 感谢您的评论。地层学确实是一项重要的工作。汪洋等人在2010年和2017年进行的研究非常详细，值得借鉴。如果期刊给我修改的机会，我一定会添加这部分。但是，在仔细研究了万洋等人的研究工作后，发现万洋等人的研究与现在吐哈油田的地层划分是不一样的。我在此征求您的意见！吐哈油田认为，二叠系地层为上二叠统下仓坊组（250-255 Ma，包括国底坑组、梧桐组和泉子街组）、中二叠统陶东沟组（255-260 Ma，包括太尔朗组和大河岩组）、下二叠统易尔西图组（260-290 Ma，又称艾丁湖组）
- 感谢您对稿件结构的评论。对于我糟糕的写作技巧和忽略以前的贡献，我深表歉意。在今后的工作中，我将进一步修改和合并《结果》和《讨论》。您推荐的Yang等人（2010）的研究结果与生物标志物和元素的反应一致。陶东沟组地层沉积于不断变化的沉积环境中（图14），早、后期为暖湿，中期为热湿润。这是我在淘东沟组沉积过程中还原古气候的一个创新点，但由于文字功底差，这一特点没有突出。
- 感谢您的评论。对吐哈盆地的起源进行了大量研究。目前认为吐哈盆地的起源主要来自北部的博格达山脉和南部的Jurotage山脉，但主要区别在于博格达山脉的隆起时间。Lei Shao等（1999）认为吐鲁番-哈密盆地的起源主要由长英质火山岩和安山岩组成。他认为二叠纪博格达山部分隆起，巨罗塔奇山的中酸性火成岩是主要起源，而隆起的博格达山是次生源，而哈密洼地的主要起源区是哈里克山剥蚀区。此外，二叠系含矿砂体碎屑锆石U-Pb同位素组成测量结果表明，所得等时相关性良好（R=0.98），等时年龄为（283 ± 67）Ma，与源区斑岩花岗岩形成年龄（268 ± 13 Ma）相比，在误差范围内一致，表明吐哈盆地含矿砂源主要来自海西晚期花岗岩体。巨洛塔山脉的南部源区，因此，他认为砂岩继承了石炭系下二叠纪的起源。Zhao等人（2020）基于大量U-Pb测年数据分析了天山地区的起源。根据这一结果，吐哈盆地的早期起源应与博格达裂谷地区一致。但Song等（2018）通过元素分析认为，母岩类型也是安山岩和长英质火山岩，出处主要是博格达山。在Jonathan Obrist-Farner和Wan Yang（2017）的论文中，二叠纪Quanzijie组有中性岩石，但Jonathan Obrist-Farner和Wan Yang认为上泉子街组（260.4-265.8 Ma）接近手稿中的陶东沟组（255-260 Ma）。利用Th/Sc和Zr的交集图（图7a）分析了陶东沟组泥岩源的保存程度，结果表明，陶东沟组的源保存较好。
- 谢谢你的意见，但我有不同的看法。以往很多研究认为，在博格达裂谷时期，准噶尔盆地、吐哈盆地、尹噶盆地和吉木萨尔盆地是一个整体，产地和有机质类型一致，这导致了早期的Gang Gao等（2006）、Shiju Liu等（2020）都利用准噶尔盆地的页岩或吉木萨尔盆地的卢草沟组来解释碳氢化合物的产生潜力和沉积以淘东沟组泥岩环境为例。但是，它们的出处今天并不相同，这应该能够推断出博格达山已经隆起或部分隆起。这一结果也与最新的研究结果一致（Li et al. （2022） 和 Wang et al. （2018））
- 感谢您的仔细阅读和宝贵意见。关于稿件中的拼写错误、缺少插图等问题，我将进一步修改。我将重新组织和重写手稿的写作技巧和其他部分。再次感谢您的仔细阅读和非常有建设性的意见。相信在各位宝贵意见的指导下，我的稿件会得到很大的改进。
Citation: https://doi.org/10.5194/egusphere-2022-1433-AC1 -
AC2: 'Reply on RC1', Huan Miao, 03 Jun 2023
I am deeply sorry for my foolishness and carelessness once again. Due to my browser's automatic translation function, the English text I uploaded was translated into Chinese. If it weren't for the reminder from Reviewer 3, I might have ignored this fact. My stupidity and carelessness must have caused you great inconvenience! I am truly sorry. To make up for my foolish mistake, I will re-upload my response to you and sincerely hope that you can forgive my error.
My previous response to your feedback is as follows:
As you have pointed out, these 16 mudstone samples cannot truly represent the sedimentary evolution of the Middle Permian. Your insight is very profound and identifies where the problem lies. Your insight is very profound and identifies where the problem lies. They can only represent the mudstone sedimentation process, sedimentary environment, lake evolution, etc., and cannot reach the level of the source-sink system. Therefore, I believe that the title and introduction of the paper must be rewritten. Secondly, we did overlook some of the research work you previously recommended, such as the contributions of Yang Wan et al. This may be related to my preference for reading Chinese papers. Currently, regarding the paleoclimate of the Taodonggou Group sedimentary period in the Turpan-Hami Basin, besides Yang Wan et al., the earliest studies were by Shao Lei (1999, 2002) and Miao Jianyu (2004). They believed that the Taodonggou Group sedimented in a hot and humid climate, but their sample size was relatively small. Wei Xinxiang (2016) used tree-ring analysis to reconstruct the paleoclimate of Taodonggou Group mudstone sedimentation, and the same conclusion was reached. Song et al. (2018) also found a hot and humid climate. However, these scholars have not yet discovered the periodic changes in the paleoclimate of the Taodonggou Group mudstone sedimentation, which may be due to sampling from outcrops. Currently, only the YT1 well has been drilled in the Taibei Sag. Based on the CPI of the bio-markers in the YT1 well, the author characterized the paleoclimate of the mudstone sedimentation period into three stages. However, the CPI is a controversial parameter and is easily influenced by maturity. Therefore, this study has used sensitive elements to verify the results again.
Thank you for your comments. Stratigraphy is indeed an important work. The research conducted by Yang Wan et al. in 2010 and 2017 is very detailed and worth referencing. If the journal gives me the opportunity to revise, I will definitely add this part. However, after carefully studying the research work of Yang Wan et al., I found that their research is different from the current stratigraphic division of the Tuha Oilfield. I would like to ask for your opinion on this matter! The Tuha Oilfield believes that the Permian strata are the Lower Cangfang Group of the Upper Permian (250-255 Ma, including the Guodikeng Formation, Wutonggou Formation, and Quanzijie Formation), the Taodonggou Group of the Middle Permian (255-260 Ma, including the Taerlang Formation and Daheyan Formation), and the Yierxitu Formation of the Lower Permian (260-290 Ma, also known as the Aidinghu Formation).
Thank you for your comments on the manuscript structure. I apologize for my poor writing skills and for neglecting previous contributions. In my future work, I will make further revisions and merge the results and discussion sections. The research results of Yang et al. (2010), which you recommended, are consistent with the response of biomarkers and elements. The Taodonggou Group sedimented in a continuously changing sedimentary environment (Figure 14), with the early and late stages being warm and humid, and the middle stage being hot and humid. This is an innovative point in my reconstruction of paleoclimate during the sedimentation process of the Taodonggou Group, but I failed to highlight this feature due to my poor writing skills. The age of the Taodonggou Formation used in my study is 255-260 Ma.
Thank you for your comments. There has been a lot of research on the origin of the Turpan-Hami Basin. Currently, it is believed that the Permian origin of the Turpan-Hami Basin mainly comes from the Bogda Mountains in the north and the Jueluotage Mountains in the south, but the main difference lies in the uplift time of the Bogda Mountains. Lei Shao et al. (1999) believed that the origin of the Turpan-Hami Basin is mainly composed of felsic volcanic rocks and andesites. He believed that during the Permian period, the main origin of the Jueluotage Mountains' intermediate acidic igneous rocks was from the uplifted part of the Bogda Mountains, while the uplifted Bogda Mountains were a secondary source, and the main source of the Hami Basin was the Halike Mountains erosion area. In addition, the U-Pb isotope composition measurement results of detrital zircons in the Permian sandstone show good isochron correlation (R2=0.98), and the isochron age is (283 ± 67) Ma, which is consistent with the formation age (268 ± 13) Ma of the source area's granitic rocks within the error range, indicating that the main source of the mineral sand in the Turpan-Hami Basin is from the granitic body in the late stage of the Late Hercynian period, which is the southern source area of the Jueluotage Mountains, thus he believed that the sandstone inherited the origin of the Lower Permian in the Carboniferous. Zhao et al. (2020) analyzed the origin of the Tian Shan region based on a large amount of U-Pb dating data. According to this result, the early origin of the Turpan-hami Basin should be consistent with the Bogda Rift area. However, Song et al. (2018) believed through element analysis that the parent rock types are also andesites and felsic volcanic rocks, mainly from the Bogda Mountains. In the paper by Jonathan Obrist-Farner and Wan Yang (2017), the Permian Quanzijie Formation has neutral rocks, but Jonathan Obrist-Farner and Wan Yang believed that the Upper Quanzijie Formation (260.4-265.8 Ma) is close to the Taodonggou Formation (255-260 Ma) in the manuscript. The preservation degree of the mudstone source of the Taodonggou Group was analyzed using the intersection diagram of Th/Sc and Zr (Figure 7a), and the results showed that the source of the Taodonggou Group mudstone was well preserved and could be used to analyze the provenance information.
Thank you for your comments, However, I hold a different view. Many previous studies have suggested that during the Bogda Rift period, the Junggar Basin, Turpan-hami Basin, Yaggar Basin, and Jimusaer Basin were a single entity with consistent source and organic matter types. This led to early interpretations of the hydrocarbon generation potential and sedimentary environment of the Taodonggou Group using Lucaogou Formation shale from the Junggar Basin or the Jimusaer Basin as examples, as done by Gang Gao et al. (2006) and Shiju Liu et al. (2020). However, their sources are no longer the same today, which should be able to infer that the Bogda Mountains have already uplifted or partially uplifted. This result is also consistent with the latest research findings (Li et al. (2022) and Wang et al. (2018)).
Thank you for your careful reading and valuable feedback, and I sincerely apologize for any errors caused by my carelessness. I will make further revisions to address issues such as spelling errors and missing illustrations in the manuscript. Once again, I appreciate your careful reading and highly constructive feedback. I believe that with your guidance and feedback, my manuscript will be greatly improved.
Citation: https://doi.org/10.5194/egusphere-2022-1433-AC2 -
AC4: 'Reply on RC1', Huan Miao, 15 Jul 2023
Dear Reviewer
I apologize once again for my previous rude behavior and I would like to thank you for reviewing my manuscript. I have made adjustments based on your feedback, and the revised version is attached. To facilitate your review, I have highlighted the modified sections in yellow text.
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AC1: 'Reply on RC1', Huan Miao, 19 Mar 2023
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RC2: 'Comment on egusphere-2022-1433', Anonymous Referee #2, 13 May 2023
The authors applied elemental geochemistry and other methods to analyze the provenance, depositional environment, and tectonic background of the Middle Permian Taodonggou Group mudstone in the Turpan-hami Basin and compared the provenance of the Taodonggou Group mudstone with that of the Luchaogou Group mudstone in the Junggar Basin, providing evidence for the timing of the Bogda Mountain uplift. At the same time, the evolutionary process and model of the Middle Permian in the Turpan-hami Basin are proposed. The manuscript has a reasonable content setting and credible results, and the results enrich the geological understanding of the North Tianshan area. However, the paper has certain shortcomings, which are detailed as follows:
(1) The authors' samples are mudstones, and the results of sandstone research such as shao (1990; 2001) are cited in the discussion section, while the distribution of mudstones in relation to sandstones needs to be added by the authors;
(2) In the results section, the authors use "~" extensively, and the use of "~" and "-" is different and needs to be adjusted by the authors;
(3) The word is misspelled, "dysoxic" should be rewritten as "dyoxic";
(4) In provenance, the authors analyzed the provenance of the Turpan-hami Basin Taodonggou Group mudstone and the Junggar Basin Luchaogou Formation mudstone, but they abbreviated the Taodonggou Group mudstone as "P2td" and the Luchaogou Group mudstone as "P2l". This is not recommended, and we suggest the authors change it for international readers.
(5) Fig. 8 needs to add a legend, Fig. 11 needs to be adjusted, there are too many blank spaces, and Fig. 14 needs to add organic matter composition and type.
Citation: https://doi.org/10.5194/egusphere-2022-1433-RC2 -
AC5: 'Reply on RC2', Huan Miao, 15 Jul 2023
Dear reviewer
Thank you for reviewing my manuscript and for your valuable feedback. I have now made the necessary revisions based on your comments. The latest modifications are shown in the attached document. To facilitate your review, I have highlighted the modified portions in blue text.
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AC5: 'Reply on RC2', Huan Miao, 15 Jul 2023
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RC3: 'Comment on egusphere-2022-1433', Anonymous Referee #3, 02 Jun 2023
After reading this manuscript, two things shocked me. One thing is that, I am not sure whether it is a system problem of web page, I find the author replied the reviewer's comments in Chinese not in English. If it is true, I do not think it is polite. After all, the manuscript was written in English and submitted to an English Journal. The other one is that it is my first time to see a paper that proposed source rocks (mudstones) with kerogen type III can be deposited in deep lake facies. Is it really deep lake facies or kerogen type III? I doubt that. I think it is necessary to add evidences from Rock-Eval pyrolysis (vertical variations in HI) and sedimentary analysis (from core observation or references) to support this viewpoint as well as the lake basin evolution mode in the section 5.5. Because I remain suspicious of this mode. For example, although the authors used a plenty of ratios of elements to support their opinions on paleo-bathymetric variation, it seems that the lithology column of well YT1 shows an opposite variation. Why the dark black mudstones can be deposited in shallower water environment (middle stage), whereas the grey mudstones were deposited in deeper water environment. Is there gravity flows influencing lithology change and source rock quality in the studied area？ Again, sedimentary analysis and Rock-Eval pyrolysis are vital and indispensable for basin evolution reconstruction and source rock formation, but they are absent.
Citation: https://doi.org/10.5194/egusphere-2022-1433-RC3 -
AC3: 'Reply on RC3', Huan Miao, 03 Jun 2023
Thank you for your thoughtful and hypothetical feedback and reminders. Without your guidance, I may have continued to overlook the serious error of submitting my work to Reviewer 1 in Chinese instead of English. I offer you my sincere apologies and heartfelt appreciation for bringing this to my attention!
The second issue you raised concerns a major drawback in the manuscript, as suggested by Reviewer 2, that I should add evidence of organic geochemistry. At the time, I did not include this section in the paper because the results had already been published in another journal in 2021 and the author's thesis. Therefore, I only included citations in the main text. However, in order to support the existence of Type III kerogen in the deepwater area, I have followed your advice and added HI, as well as the ratio of ∑C21-/∑C22+ and C27-C28-C29. These all serve as evidence that Type III kerogen shale was deposited in a deepwater environment (Fig.1).
Currently, there is almost no dispute that the Taodonggou Group mudstones in the Turpan-Hami Basin were deposited in a deep or semi-deep lake environment, as evidenced by their good response to elemental ratios (Li, 2016; Li, 2019; Song et al., 2018; Xu, 2022). However, your suggestion on the relationship between water depth and organic matter type has greatly enlightened me and broadened my perspective. After conducting a literature review on the existing research in the study area, I did not find any studies on gravity flow. However, by reading studies on gravity flow sedimentation in the Fengcheng Formation shale in the Junggar Basin, there is a possibility of gravity flow sedimentation in the Taibei Sag of the Turpan-Hami Basin. Based on studies by Chen et al. (2003), Xu Haoyu (2022), and Yang Wan et al. (2010; 2017) recommended by Reviewer 1, it is believed that there is sedimentation of coarse clastic rocks at the bottom of the Daheyan Formation (the bottom of the Taodonggou Group), and different sedimentary facies can be identified in different areas of the study area. In addition, during the sedimentation of the Taerlang Formation, three sedimentary facies can be identified around the Bogeda Mountains, including the front edge of the fan delta, turbidite fan, and semi-deep lake-deep lake facies (Wang, 2017), indicating the possibility of gravity flow sedimentation in the study area. The YT1 well is located in the southern part of the Taibei Sag, which has always been the sedimentary center of the Turpan-Hami Basin (Jiang et al., 2015; Li et al., 2021). The mudstones in the study area were deposited in a deep-semi-deep lake environment, with the deeper water depth depositing III-type kerogen mudstones and some layers of relatively thin clastic rocks, suggesting that they were influenced by gravity flows during the early and late stages. However, I cannot provide actual core evidence for this conclusion because the YT1 well in the study area was drilled deep, and cores were only taken in some depth intervals (6110-6116 and 6140-6154), while other depth intervals were recorded by cuttings. The lithology of the cored intervals is basically consistent. Nevertheless, according to Wang Yue's (2017) study, there is evidence of mixing in the study area, which may prove this point.
Furthermore, I will carefully complete the revisions to the manuscript by systematically incorporating your comments and those of the other two reviewers. Finally, I would like to express my gratitude for your valuable insights. Your comments not only broadened my perspective but also provided important inspiration for my future work. I am truly grateful and have no words to express my appreciation.
Thank you for your thoughtful and hypothetical feedback and reminders. Without your guidance, I may have continued to overlook the serious error of submitting my work to Reviewer 1 in Chinese instead of English. I offer you my sincere apologies and heartfelt appreciation for bringing this to my attention!
The second issue you raised concerns a major drawback in the manuscript, as suggested by Reviewer 2, that I should add evidence of organic geochemistry. At the time, I did not include this section in the paper because the results had already been published in another journal in 2021 and the author's thesis. Therefore, I only included citations in the main text. However, in order to support the existence of Type III kerogen in the deepwater area, I have followed your advice and added HI, as well as the ratio of ∑C21-/∑C22+ and C27-C28-C29. These all serve as evidence that Type III kerogen shale was deposited in a deepwater environment (Fig.1).
Currently, there is almost no dispute that the Taodonggou Group mudstones in the Turpan-Hami Basin were deposited in a deep or semi-deep lake environment, as evidenced by their good response to elemental ratios (Li, 2016; Li, 2019; Song et al., 2018; Xu, 2022). However, your suggestion on the relationship between water depth and organic matter type has greatly enlightened me and broadened my perspective. After conducting a literature review on the existing research in the study area, I did not find any studies on gravity flow. However, by reading studies on gravity flow sedimentation in the Fengcheng Formation shale in the Junggar Basin, there is a possibility of gravity flow sedimentation in the Taibei Sag of the Turpan-Hami Basin. Based on studies by Chen et al. (2003), Xu Haoyu (2022), and Yang Wan et al. (2010; 2017) recommended by Reviewer 1, it is believed that there is sedimentation of coarse clastic rocks at the bottom of the Daheyan Formation (the bottom of the Taodonggou Group), and different sedimentary facies can be identified in different areas of the study area. In addition, during the sedimentation of the Taerlang Formation, three sedimentary facies can be identified around the Bogeda Mountains, including the front edge of the fan delta, turbidite fan, and semi-deep lake-deep lake facies (Wang, 2017), indicating the possibility of gravity flow sedimentation in the study area. The YT1 well is located in the southern part of the Taibei Sag, which has always been the sedimentary center of the Turpan-Hami Basin (Jiang et al., 2015; Li et al., 2021). The mudstones in the study area were deposited in a deep-semi-deep lake environment, with the deeper water depth depositing III-type kerogen mudstones and some layers of relatively thin clastic rocks, suggesting that they were influenced by gravity flows during the early and late stages. However, I cannot provide actual core evidence for this conclusion because the YT1 well in the study area was drilled deep, and cores were only taken in some depth intervals (6110-6116 and 6140-6154), while other depth intervals were recorded by cuttings. The lithology of the cored intervals is basically consistent. Nevertheless, according to Wang Yue's (2017) study, there is evidence of mixing in the study area, which may prove this point.
Furthermore, I will carefully complete the revisions to the manuscript by systematically incorporating your comments and those of the other two reviewers. Finally, I would like to express my gratitude for your valuable insights. Your comments not only broadened my perspective but also provided important inspiration for my future work. I am truly grateful and have no words to express my appreciation.
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AC6: 'Reply on RC3', Huan Miao, 15 Jul 2023
Dear reviewer
Thank you for reviewing my manuscript and providing valuable feedback, especially regarding the understanding of gravity flow sedimentation. I have now identified evidence of gravity flow deposition and made the necessary revisions based on your suggestions. The latest modifications can be found in the attached document. To facilitate your review, I have highlighted the modified portions in green text.
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AC3: 'Reply on RC3', Huan Miao, 03 Jun 2023
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Jianying Guo
Yanbin Wang
Zhenxue Jiang
Chengju Zhang
Chuanming Li
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