To investigate the paleoenvironmental controls on organic matter accumulation of Upper Paleozoic shales in the eastern Ordos Basin, China, 26 shale samples were collected from two wells drilled into the Shanxi and Taiyuan Formations. The total organic carbon (TOC) content, mineral compositions and elemental geochemistry of the samples were analyzed. Quartz (35.42%) and clay minerals (48.34%) are the dominant minerals and trace elements (Li, Cs, Cu, V, Co, and Cr) are commonly enriched in the shale samples compared to the Upper Continental Crust. C-values (ranging from 0.2 to 4.5), chemical indices of weathering (CIW) values (48.82 to 99.11), and Sr/Cu ratios (1.00 to 11.05) suggest that the paleoclimate was humid in the study area during the Late Paleozoic. Elemental redox indices (e.g., Al₂O₃/(Al₂O₃+Fe₂O₃), V/Cr, Ni/Co, V/(V + Ni) and U/Th) indicate a dysoxic to oxic paleoenvironment characterized by transitional sedimentary deposits in a continental margin setting. In addition, chemical index of alteration (CIA, ranging from 77.92% to 98.36%) and CIW (89.19% to 99.11%) values suggest that there was intense chemical weathering in the study area, while the Al₂O₃-CaO^*+ Na₂O-K₂O (A-CN-K) ternary diagram demonstrates that the shales were not subjected to potassium metasomatism during diagenesis. Al₂O₃/TiO₂ and TiO₂/Zr ratios, as well as REE characteristics suggest a felsic source rocks and discount seawater as an REE source. Ce anomalies indicate an oxic environment with terrigenous input during black shale deposition, and LREE enrichment with negative Eu anomalies suggests that both shale formations were affected by detrital input rather than hydrothermal fluids. The correlation of TOC (ranging from 1.10% to 6.39%, with an average of 2.77%) with trace elemental redox indices (Sr/Cu, Sr/Ba, V/Cr, and U/Th) indicates that a warm-humid, dysoxic to oxic environment preserved much of the organic matter.

为研究鄂尔多斯盆地东部上古生界页岩有机质积累的古环境控制作用，从山西组和太原组两口井采集了26个页岩样品。分析了样品的总有机碳 (TOC) 含量、矿物组成和元素地球化学。与上大陆地壳相比，石英 (35.42%) 和粘土矿物 (48.34%) 是主要矿物，微量元素 (Li、Cs、Cu、V、Co 和 Cr) 通常在页岩样品中富集。C值（范围从0.2到4.5）、化学风化指数（CIW）值（48.82到99.11）和Sr/Cu比（1.00到11.05）表明研究区晚古生代古气候潮湿。元素氧化还原指数（例如，Al ₂ O ₃/(Al ₂ O ₃ +Fe ₂ O ₃ )、V/Cr、Ni/Co、V/(V + Ni) 和 U/Th) 表明以大陆边缘过渡沉积沉积物为特征的缺氧到含氧古环境。此外，化学蚀变指数（CIA，77.92%~98.36%）和CIW（89.19%~99.11%）值表明研究区存在强烈的化学风化，而Al ₂ O ₃ -CaO ^* + Na ₂ O-K ₂ O (A-CN-K) 三元图表明页岩在成岩作用过程中没有经历钾交代作用。Al ₂ O ₃ /TiO ₂和TiO₂ /Zr 比值以及 REE 特征表明长英质烃源岩和折扣海水作为 REE 来源。Ce 异常表明黑色页岩沉积过程中存在陆源输入的含氧环境，具有负 Eu 异常的轻稀土富集表明两种页岩地层都受到碎屑输入而不是热液流体的影响。TOC（范围从 1.10% 到 6.39%，平均为 2.77%）与微量元素氧化还原指数（Sr/Cu、Sr/Ba、V/Cr 和 U/Th）的相关性表明，暖湿、缺氧到有氧环境保留了大部分有机物。