The lacustrine shales in the Lodève Basin, southern France, serve as excellent archives of paleo-lake development as well as climatic evolution during the Early Permian. In this study, an extensive dataset is presented encompassing organic petrographic data, major and trace element quantification, bulk and molecular organic geochemical proxies, as well as compound-specific stable carbon isotope data derived from the analysis of 36 black shale outcrop samples originating from the Usclas-St. Privat Formation (USPF), Tuilières-Loiras Formation (TLF), and Viala Formation (VF). All sample are thermally oil-mature, as evident from a vitrinite reflectance (VR) of around 0.8%. The lower section of the USPF, characterized by notably higher total sulfur (TS) concentrations, displays total organic carbon (TOC) and TS contents spanning from 2.69 to 7.83 (avg. 4.28) wt% and 0.42–1.55 (avg. 1.09) wt%, respectively. In contrast, the upper section of the USPF (average TOC of 2.59 wt%), TLF (average TOC of 2.66 wt%), and VF (average TOC of 3.17 wt%) exhibit considerably lower TS contents of 0.26 wt%, 0.22 wt%, and 0.17 wt%, respectively. The lower section of the USPF, characterized by the lowest pristane/phytane (Pr/Ph) ratio and the highest TS/TOC ratios and chemical index of alteration (CIA) values, was deposited in oxygen-depleted and saline lacustrine environments. These conditions prevailed under more humid climatic conditions and were probably related to marine incursions. In contrast, the upper section of the USPF, the TLF, and the VF display elevated Pr/Ph ratios but reduced TS/TOC and CIA values, signifying deposition within oxic-dysoxic and freshwater-brackish bottom water conditions with a significant change towards arid conditions. All samples are characterized by low vitrinite and inertinite contents together with consistently similar average values of AlO and TiO. The biomarker analysis suggests that the organic matter (OM) in most samples mainly originates from planktonic/algal biomass with additional microbial OM. Only the lower section of the USPF displays a slightly enhanced contribution of terrestrial OM input and also more detrital elements. It is concluded that the structural evolution of the basin from narrow deep towards wider and shallower settings as well as the postulated marine transgressive events during early stages played a crucial role in shaping the deposition environments of the two distinct sets of lacustrine shales, thereby influencing the OM accumulation mechanisms. In contrast, the substantial climatic aridification seems to have a relatively minor impact on the sources of OM and the conditions prevailing within the water column.

中文翻译：

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法国南部洛代夫盆地早二叠世湖相页岩的地球化学和岩石学：沉积历史、有机质积累和热成熟度

法国南部洛代夫盆地的湖泊页岩是早二叠世古湖泊发育和气候演化的优秀档案。在这项研究中，提供了一个广泛的数据集，包括有机岩相数据、主量和微量元素定量、大量和分子有机地球化学代理，以及通过对来自 36 个黑色页岩露头样品的分析得出的特定化合物的稳定碳同位素数据。乌斯克拉斯-圣。私人地层 (USPF)、图利埃-洛伊拉斯地层 (TLF) 和维亚拉地层 (VF)。所有样品都是热油成熟的，从镜质体反射率 (VR) 约为 0.8% 即可看出。USPF 的下半部分以总硫 (TS) 浓度明显较高为特征，显示总有机碳 (TOC) 和 TS 含量范围为 2.69 至 7.83（平均 4.28）wt% 和 0.42–1.55（平均 1.09）wt% ％， 分别。相比之下，USPF 的上半部分（平均 TOC 为 2.59 wt%）、TLF（平均 TOC 为 2.66 wt%）和 VF（平均 TOC 为 3.17 wt%）表现出相当低的 TS 含量，分别为 0.26 wt%、0.22 wt%分别为 % 和 0.17 wt%。USPF 的下部沉积在缺氧和含盐湖相环境中，其特征是最低的植烷烷/植烷 (Pr/Ph) 比率和最高的 TS/TOC 比率和化学蚀变指数 (CIA) 值。这些情况在更潮湿的气候条件下普遍存在，可能与海洋入侵有关。相比之下，USPF、TLF 和 VF 的上部显示 Pr/Ph 比值升高，但 TS/TOC 和 CIA 值降低，这表明在好氧-缺氧和淡水-微咸底水条件下沉积，并显着向干旱变化。状况。所有样品的特点是镜质体和惰质体含量较低，并且 Al2O 和 TiO 的平均值始终相似。生物标志物分析表明，大多数样品中的有机物 (OM) 主要来源于浮游/藻类生物质以及额外的微生物 OM。只有 USPF 的下部显示了陆地 OM 输入和更多碎屑元素的贡献略有增强。结论是，盆地从狭窄的深部向更宽、更浅的环境的构造演化以及早期假设的海侵事件在塑造两套不同的湖相页岩的沉积环境中发挥了至关重要的作用，从而影响了OM积累机制。相比之下，严重的气候干旱化似乎对有机质的来源和水体中普遍存在的条件的影响相对较小。