the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
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
Jianying Guo
Yanbin Wang
Zhenxue Jiang
Chengju Zhang
Chuanming Li
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.
Huan Miao et al.
Status: open (until 21 Apr 2023)
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RC1: 'Comment on egusphere-2022-1433', Anonymous Referee #1, 04 Mar 2023
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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
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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
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AC1: 'Reply on RC1', Huan Miao, 19 Mar 2023
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Huan Miao et al.
Huan Miao et al.
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