Central Carpathian Paleogene Basin (CCPB, Central Western Carpathians) comprises mainly Oligocene clastic autochthonous age-equivalents of the widely known Menilite shale formation from the Outer Carpathians. However, little is known about the paleoenvironment and its subsequent changes during the basin's evolution. Furthermore, the available hydrocarbon potential data are based on anachronous methods and are not investigated on the sub-basin level. Gas chromatography-mass spectrometry (GC–MS) analyses supported by Rock-Eval data along with petrographic measurements enabled us to identify and document the paleoenvironmental evolution of the Orava sub-basin (NW remnant of CCPB). Thermal maturity based on vitrinite reflectance, 22S/(22S + 22R) homohopane ratio and 20S/(20S + 20R) sterane ratio increases from N to S and from Upper to Lower Oligocene. In the least mature samples ββ-hopanes, hopenes, and oleanenes are present, whereas in the most mature deposits less thermally stable compounds dissapeared. This maturation trend is shown also by the Rock-Eval data. Terrestrial organic matter input is documented by the predominance of III- and II/III-type of kerogen and the occurrence of several biomarkers, such as 3,3,7-trimethyl-1,2,3,4-tetrahydrochrysene, cadalene, retene, and perylene. The significant contribution of polycyclic aromatic hydrocarbons (PAHs) may be linked with wildfire-related land degradation and following runoff to the basin. Based on the measured fusinite reflectance values the wildfire types could range from hotter crown fires to colder surface fires. Depositional conditions in Lower Oligocene units are characterized by intermittent euxinia, as derived from small (<5 μm) pyrite framboid diameters and the presence of isorenieratane. Subsequently, a change of conditions to oxic/dysoxic in younger units is observed, and the input of terrestrial organic matter increased.

中文翻译：

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基于奥拉瓦盆地综合方法的中喀尔巴阡古近系盆地沉积条件、野火、成熟度和油气潜力评价

中喀尔巴阡古近纪盆地（CCPB，中西喀尔巴阡）主要由渐新世碎屑本土碎屑组成，其年龄相当于广为人知的外喀尔巴阡门尼岩页岩地层。然而，人们对盆地演化过程中的古环境及其随后的变化知之甚少。此外，现有的碳氢化合物潜力数据基于不合时宜的方法，并且没有在子盆地层面进行研究。由 Rock-Eval 数据和岩石学测量支持的气相色谱-质谱 (GC-MS) 分析使我们能够识别和记录奥拉瓦次盆地（CCPB 西北遗迹）的古环境演化。基于镜质体反射率、22S/(22S + 22R) 高藿烷比率和 20S/(20S + 20R) 甾烷比率的热成熟度从 N 到 S、从上渐新统到下渐新统增加。在最不成熟的样品中，存在ββ-藿烷、藿烯和齐墩果烯，而在最成熟的沉积物中，较少的热稳定性化合物消失。 Rock-Eval 数据也显示了这种成熟趋势。陆地有机质输入主要由 III 型和 II/III 型干酪根以及多种生物标志物的出现来记录，例如 3,3,7-三甲基-1,2,3,4-四氢、卡达烯、雷烯和苝。多环芳烃（PAH）的显着贡献可能与野火相关的土地退化和随后流入盆地的径流有关。根据测量的熔熔岩反射率值，野火类型的范围可以从较热的冠火到较冷的地表火。下渐新世单元的沉积条件以间歇性的euxinia为特征，源自小的（<5μm）黄铁矿草莓直径和异雷尼尔烷的存在。随后，观察到较年轻的单位的条件发生了有氧/缺氧的变化，并且陆地有机质的输入增加。