Abstract —The composition of compounds employed as markers for anoxia in the photic layer of the sedimentation basin is studied in samples from Upper Devonian domanik-type sediments (Sargaevian, Semilukian, and Mendymian horizons, Famennian stage), which are widespread over the Volga–Urals basin. The studies were carried out along the north-south section spanning the northern and central parts of the Volga–Urals areas. The H 2 S contamination of photic layer was determined over the most part of the studied territory. During the Semilukian time, the boundary of H 2 S contamination passed through the middle part of the near-slope zone of the Mukhanovo–Erokhov Trough; the contamination reached the highest thickness in the northern part of the region. The intense H 2 S contamination also occurred in this part in the Pashiiskian and Sargaevian time. The Mukhanovo–Erokhov Trough during Mendymian and Famennian was characterized by a strong change of setting: from a steady strong contamination to its complete absence. It is shown that changes in the content of anoxia markers in samples from the the Kama–Belsk Basin and South Tatar Arch were caused by variations of thickness of the contaminated layer. It is revealed that the processes of complete hydrogenation of initial polyenes prevail over cyclization for the domanik-type sediments over the entire region. It was found that the ratio of the total content of alkyl benzenes in the fraction of aromatic compounds to the total content of products of complete hydrogenation of initial polyenes in OM from the domanik-type sediments of the studied areas does not depend on the OM maturity. Explanation of this fact is proposed.

中文翻译：

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伏尔加-乌拉尔盆地北部和中部地区多马尼克沉积物中有机质形成过程中沉积盆地光层缺氧条件的分布

摘要 —从上泥盆统多马尼克型沉积物（Sargaevian、Semlukian 和 Mendymian 层位，法门阶）的样品中研究了用作沉积盆地光层中缺氧标志物的化合物的组成，这些沉积物广泛分布于伏尔加河 -乌拉尔盆地。这些研究是沿着横跨伏尔加-乌拉尔地区北部和中部的南北部分进行的。光层的 H 2 S 污染是在大部分研究区域内确定的。塞米鲁克纪，H 2 S 污染边界穿过穆哈诺沃-叶罗霍夫海槽近坡带中部；污染达到该地区北部最严重的程度。在Pashiiskian 和Sargaevian 时期，该部分也发生了强烈的H 2 S 污染。Mendymian 和 Famennian 期间的 Mukhanovo-Erokhov 海槽的特点是环境发生了强烈变化：从稳定的强污染到完全消失。结果表明，Kama-Belsk 盆地和南鞑靼拱门样品中缺氧标志物含量的变化是由污染层厚度变化引起的。结果表明，在整个地区，多马尼克型沉积物的初始多烯完全加氢过程优于环化过程。从研究区的domanik型沉积物中发现，芳香族化合物馏分中烷基苯的总含量与OM中初始多烯完全加氢产物的总含量的比值与OM成熟度无关。 . 建议解释这一事实。