<p>Table S1: Climate indicators from element and isotope geochemistry, and clay and carbonate minerals from boreholes FY-2, FY-1, and DY-1 in the Fuxin Basin. Table S2: Palynomorph assemblage from borehole FY-2 in the Fuxin Basin. Figure S1: Correlated sequence stratigraphy and sedimentary facies with positions of measured samples in the Fuxin Basin from borehole FY-2 in the west (A), FY-1 in the center (B), and DY-1 in the east (C) (modified after Jia et al., 2021). Figure S2: Diagrams of Al2O3 and TiO2 and δ13C and δ18O values for organic-rich mudrocks from boreholes FY-2 (A, D), FY-1 (B, E), and DY-1 (C, F). Figure S3. Microscopic characteristics of carbonate minerals observed in SEM (A) and thin section images (B) of organic-rich mudrocks from borehole FY-2. </p>
Organic matter (OM) and minerals are major particle components in lacustrine organic-rich shales. Their association and distribution control the development of the primary pore space. The response of OM-driven conduction by modifying the pore-space volume and structure in organic-rich shales of the virgin zone is still unclear. Based on a detailed study of geochemical, mineralogical, and geophysical properties from immature lacustrine oil-prone shales of the Songliao Basin (Northeast China), we have observed a novel continuous variation of electrical resistivity driven by large ranges of total-organic-carbon (TOC) content (0.64–24.51 wt%). The reduced resistivity at low TOC content ([Formula: see text]) and then enhanced resistivity at high TOC content ([Formula: see text]) are present in our immature shales. These variations in electrical resistivity are confirmed by fluid (S1) and solid organic compounds (S2). Furthermore, clay and detrital minerals in shales contribute to the variation of electrical resistivity as well as OMs at low and high TOC content. The electrical resistivity of shales is closely related to the pore-space volume and structure for the electrical flow pathway. Two resistivity trends are highlighted by pore parameters such as the pore volume, throat/pore ratio, pore diameter, and bulk density. Although reduced amounts and the arrangement of large pores for low TOC content cannot decrease the conduction, the enhanced additional clay conduction and low OM concentration reduce the resistivity of shales. Moreover, increased amounts of nonconductive fluid and solid organic compounds and the effect of OM filling on pore space during high TOC content enhance the resistivity of shales. Thus, modified minerals and pore space driven by various OMs affect the electrical resistivity of immature shales. These results improve the understanding of OM-driven conduction in shales and contribute to the evaluation of source rocks using a well-log method.
The quantitative evaluation of the Upper Cretaceous oil shale has been conducted by abundant testing, log and seismic data from the Songliao Basin in Northeast China.Based on the log-seismic characteristics of oil shale, the technique of log-seismic multi-attributes reconstruction to evaluate single-well oil shale has been adopted.By using the method of log-constrained seismic inversion, the inversion volume of wave impedance, total organic carbon (TOC), and oil yield have been obtained to carry out evaluation of oil shale.According to the evaluation results, the inversion of wave impedance can only be used for qualitative evaluation of the spatial distribution of oil shale.Meanwhile, the inversion of TOC and oil yield can be used not only to evaluate the spatial distribution of oil shale, but also for quantitative evaluation of the quality of oil shale.Hence, the evaluation technique of oil shale was developed combining single-well log evaluation and spatial seismic evaluation, which integrates the quantitative evaluation of oil shale with geophysical technique.
This EXCEL and word dataset provides the raw data on vitrinite reflectance and Rock pyrolysis parameters of organic-rich mudrocks in the Fuxin Basin. All data support the study of the tectonic controls on thermal and basin fill history evolution of supra-detachment basins in the Fuxin area (NE China).
Inertinite in coals is an important source of information regarding the palaeo-wildfire history of study area and can provide insights into the relationship between ecosystems, wildfire and its triggers. However, such information in the late Middle Jurassic coal is often overlooked, and the impacts of incidental mercury emission from wildfires on the mercury enrichment in coal are also much less known. In this study, we investigated the organic petrology, geochemistry and palynology of coal seams from Shimengou Formation in northern Qaidam Basin (NQB). Results show that these coal seams generally contain abundant records of palaeo-wildfire: inertinite and combustion-derived polycyclic aromatic hydrocarbons (PAHs). The high consistency of these two evidences confirms the existence of widespread wildfires during the late Middle Jurassic in NQB. These widespread wildfires also indicate a high level of atmospheric oxygen concentration during this period. The low reflectance of inertinite and low content of coronene in coal seams indicate that these wildfires were dominated by ground and surface fire with some small-scale crown fires. These frequent wildfires under the overall humid climate are attribute to the sufficient oxygen, fuel and intermittent dry season. The co-occurrence of wildfires records and mercury anomaly in coal seams suggests that incidental mercury emissions from wildfires enhanced mercury input in the peatlands, which is the direct trigger for mercury anomaly in coal. This study not only revealed the characteristics and causes of the widespread wildfires during the late Middle Jurassic in NQB, but also provides a new insight into abnormal enrichment of mercury in coal.
<p>Table S1: Climate indicators from element and isotope geochemistry, and clay and carbonate minerals from boreholes FY-2, FY-1, and DY-1 in the Fuxin Basin. Table S2: Palynomorph assemblage from borehole FY-2 in the Fuxin Basin. Figure S1: Correlated sequence stratigraphy and sedimentary facies with positions of measured samples in the Fuxin Basin from borehole FY-2 in the west (A), FY-1 in the center (B), and DY-1 in the east (C) (modified after Jia et al., 2021). Figure S2: Diagrams of Al2O3 and TiO2 and δ13C and δ18O values for organic-rich mudrocks from boreholes FY-2 (A, D), FY-1 (B, E), and DY-1 (C, F). Figure S3. Microscopic characteristics of carbonate minerals observed in SEM (A) and thin section images (B) of organic-rich mudrocks from borehole FY-2. </p>
Abstract Reconstruction of Aptian–Albian paleoclimate obtained from marine records remains a challenging topic, but studies on coeval terrestrial paleoclimate and trigger mechanisms have lagged substantially. In this study, new multiproxy data from mudrocks in the Fuxin Basin of NE China provide a high-resolution terrestrial climate record from East Asia. Here, we demonstrate the occurrence of terrestrial climate cooling during the late Aptian (118–113 Ma), which interrupted the mid-Cretaceous warming shown in global records. Nearly uniform long-term global climate trends attributable to tectonism, volcanism, and weathering occur in Early Cretaceous terrestrial and marine records. In the Fuxin Basin, the long-term terrestrial climate was characterized by increasing temperatures during the late early Aptian, gradual cooling during the late Aptian, and subsequent enhanced warming during the early Albian. Moreover, chemical weathering and humidity during these intervals were low, moderate to high, and then moderate, respectively. A markedly reduced high-elevation paleogeomorphology under strong continental weathering during the late Aptian increased the variability in chemical weathering fluxes as the Eurasian plate in NE China drifted SE during the Early Cretaceous and then NE during the Late Cretaceous. We suggest that a combination of enhanced continental weathering and weakened plate drift induced changes in atmospheric CO2, while the geographic setting ultimately led to cooling in the Fuxin Basin during the late Aptian. Our results illustrate the importance of exploring long-term tectonic-climatic-biotic feedbacks to improve our understanding of tectonic processes and ecological transitions across various spatiotemporal scales.
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