Construction Engineering College, Jilin University, ChangChun, 130000, People's Republic of China.
National-Local Joint Engineering Laboratory of In-Situ Conversion, Drilling and Exploitation Technology for Oil Shale, Changchun, 130021, Jilin, People's Republic of China.
Sci Rep. 2021 Feb 25;11(1):4561. doi: 10.1038/s41598-021-83415-6.
The genetic type of the Bayanerhet Formation oil shale in the Bayanjargalan mine area is an inland lacustrine oil shale deposit. Inorganic element analysis and organic geochemical testing of oil shale samples collected in three boreholes show that the Bayanerhet Formation oil shale has relatively high organic contents, e.g., average TOC values of 6.53, 7.32 and 8.84 (corresponding to oil contents of 5.49%, 6.07% and 7.50%) in boreholes BJ3807, BJ3405 and BJ3005, respectively. Analysis of organic matter sources with biomarkers indicates that lower aquatic organisms such as algae contribute more to the organic matter than higher plants do. According to research on the values of Fe2O3/FeO, Rb/Sr and w (La) n/w (Yb)n in cores from the three boreholes, the Bayanjargalan oil shale is inferred to have formed in a humid paleoclimate with a relatively high sedimentation rate. In research on the evolution of the paleoaquifer in which the oil shale formed, the values of Fe/Fe, V/V + Ni, Ni/V, Ceanom and δCe are applied as sensitive indicators of the redox conditions in the aqueous medium. These values indicate that the Bayanjargalan oil shale formed in a water body with a weak redox environment. Moreover, the values of Ca/(Ca + Fe) and Sr/Ba and the values of gammacerane/αβC30 hopane in biomarkers show that the oil shale was formed in a saltwater environment. Analysis of Mo and U shows high endogenous lake productivity, corresponding to high TOC, which suggests that the lacustrine productivity played an important role in organic matter enrichment. The Lower Cretaceous Bayanerhet Formation (K1bt) in the Bayanjargalan mine area encompasses a complete sequence and was formed during lowstand, transgression, highstand and regression periods. The dominant oil shale deposits were formed in the transgression system tract and high stand system tract, and these oil shales have a high oil content and stable occurrence. A large set of thick, high-TOC and high-oil-content oil shales in the second member of the Bayanerhet Formation was deposited under such conditions. The abundant terrigenous supply under warm and humid conditions significantly promoted the primitive biological productivity, and the weak redox saltwater environment had relatively high productivity. All the favorable conditions promoted the formation of high-quality oil shale.
巴彦淖尔地区巴彦尔合同 Formation 油页岩的成因类型为内陆湖泊油页岩矿床。对在三个钻孔中采集的油页岩样品进行无机元素分析和有机地球化学测试表明，巴彦尔合同 Formation 油页岩具有较高的有机含量，例如，在钻孔 BJ3807、BJ3405 和 BJ3005 中，TOC 值的平均值分别为 6.53、7.32 和 8.84（对应油含量为 5.49%、6.07%和 7.50%）。利用生物标志物对有机质来源的分析表明，较低等水生生物如藻类对有机质的贡献大于高等植物。根据三个钻孔岩芯的 Fe2O3/FeO、Rb/Sr 和 w（La）n/w（Yb）n 值研究，巴彦淖尔油页岩形成于气候湿润、沉积速率较高的古气候条件下。在研究油页岩形成的古水盆地演化过程中，Fe/Fe、V/V+Ni、Ni/V、Ceanom 和 δCe 值被用作水相介质氧化还原条件的敏感指标。这些值表明，巴彦淖尔油页岩形成于氧化还原环境较弱的水体中。此外，生物标志物中 Ca/(Ca+Fe) 和 Sr/Ba 值以及伽马蜡烷/αβC30 藿烷值表明油页岩形成于盐水环境中。Mo 和 U 的分析表明，内源湖泊生产力较高，对应 TOC 较高，表明湖泊生产力对有机质富集起到了重要作用。巴彦淖尔矿区下白垩统巴彦尔合同 Formation（K1bt）具有完整的层序，形成于低水位期、海侵期、高水位期和退水期。主要的油页岩矿床形成于海侵体系域和高水位体系域，油含量高且稳定。在温暖湿润的条件下，第二套巴彦尔合同 Formation 形成了大量厚层、高 TOC 和高油含量的油页岩。丰富的陆源供应显著促进了原始生物生产力，而弱氧化还原盐水环境具有较高的生产力。所有有利条件都促进了高质量油页岩的形成。
