Search

To investigate the molecular structure and micropore structure of organic matters in coal-measure shale, the black shale samples of the Shanxi formation were collected from Xishan Coalfield, Taiyuan, and a hybrid experimental–simulation method was used for realistic macromolecular models of organic matter (OM). Four experimental techniques were used to determine the structural information of OM, including elemental analysis, state 13C nuclear magnetic resonance (13CNMR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). With structural parameters, two-dimensional (2D) average molecular models of OM were established as C177H160O8N2S with a molar weight of 2474, which agreed well with the experimental 13C-NMR spectra. A realistic three-dimensional (3D) OM macromolecular model was also reconstructed, containing 20 2D molecules with a density of 1.41 g/cm3. To determine the connectivity and spatial disposition of the OM pores, focused ion beam microscope (FIB-SEM) and transmission electron micrographs (TEM) were utilized. The 3D OM pores models were developed. The results show that whether the OM pores varied from 20 to 350 nm as obtained from FIB-SEM images or less than 10 nm as observed in the TEM images, both were of poor connectivity. However, the ultra-micro pores from the 3D OM macromolecular model varied from 3Å to 10 Å and showed certain connectivity, which may be the main channel of diffusion. Furthermore, with the pressure increased, the methane adsorption capacity of the 3D OM model increased with a maximum value of 103 cm3/g at 7 MPa, indicating that OM pores less than 1 nm have a huge methane adsorption capacity. Therefore, our work provides an analysis method that is a powerful and superior tool in further research on gas migration. [ABSTRACT FROM AUTHOR]

Lower Middle Devonian strata (Eifelian to lower Givetian stages) of New York are identified under the names Onondaga and Marcellus. As has been New York practice for over 80 years, they represent time-significant allostratigraphic units, which to some degree cut across lithologic boundaries. The Onondaga Formation is a relatively tabular, limestone-dominated unit throughout New York. Strata thin from both east and west into more basinward facies in the central part of the state. In contrast, the (revised) "Marcellus subgroup" forms an eastward-thickening and coarsening wedge of siliciclastic-dominated facies. Marcellus-equivalent strata range in thickness from less than seven meters in the western New York subsurface to an estimated maximum thickness of 580 meters in the Hudson Valley, eastern New York. Few stratigraphic revisions have been proposed for the Onondaga Formation since 1975, beyond minor revisions to two members associated with the abandonment of the informal, former Clarence member, chert-rich facies in western New York. In contrast, the term "Marcellus" has been raised in New York State from formation to subgroup status, with three formation-level units: a lower Union Springs and coeval upper Marcellus Oatka Creek and Mount Marion formations. The latter two represent correlative basinal dark shales and proximal dark shales to shoreface sandstones, respectively. Overall, following Cooper's classic 1930s stratigraphy of one formation with 11 members, 13 members are now recognized in the Marcellus subgroup; two in the Union Springs Formation and 11 in the upper Marcellus Oatka Creek and Mount Marion succession. Onondaga and Marcellus strata form three third-order depositional sequences, which feature three very distinct faunas. The sequences, termed Devonian Sequences Ic, Id, and Ie (alternatively Eif-1, Eif-2, and Eif-Giv) consist, respectively of 1) lower to middle Onondaga; 2) upper Onondaga and Union Springs; and 3) coeval Oatka Creek and Mount Marion formations, except where upper Mount Marion strata are not yet clearly distinguished form lower Skaneateles equivalents in eastern New York. The fossil assemblages of the Eifelian to lower Givetian have been subdivided into three "faunas" or ecological-evolutionary subunits. The oldest of the three faunas, the Onondaga Fauna, is succeeded by the Stony Hollow Fauna in shallow facies of the upper Union Springs and lowermost Mount Marion-Oatka Creek formations. The Stony Hollow Fauna is, in turn, succeeded by the classic Middle Devonian Hamilton Fauna throughout the remainder of upper Marcellus strata and Hamilton strata above. Numerous post-1970 studies have examined the stratigraphy, petrology, sedimentology, basin analyses, paleobiology, and geochemical characters of the Onondaga Formation and Marcellus subgroup. Overviews of these studies are presented herein. In the Appalachian Basin, the correlatives of these units across have been assigned the same names, Onondaga and Marcellus, in eastern Pennsylvania. More argillaceous Onondaga-correlative strata form the upper part of the Needmore Formation from central Pennsylvania to the vicinity of Highland and Pocahontas counties, in Virginia and West Virginia, respectively (Selinsgrove to the informal "calcareous shale and limestone" members). Continuing southwest along the Virginia-West Virginia border, Onondagacorrelative strata are replaced by chert and shale-dominated strata in the upper part of the Huntersville Formation. South of New York in the Appalachian Basin, the term "Marcellus" is applied lithostratigraphically, not allostratigraphically, so that lowest strata assigned the term Marcellus may variously range from lower Eifelian (middle Onondaga-equivalent, e.g., Frankstown, Pennsylvania) to correlative with the base of the Marcellus in New York. Similarly, youngest strata assigned to the Marcellus in Pennsylvania and southward may range from upper Eifelian Union Springs-equivalent (below proximal sandstones of the Turkey Ridge Member, central Pennsylvania) to lower Givetian, post-Marcellus black shales correlative with at least the Skaneateles Formation of New York in distal, basinward areas. From Highland County, Virginia, and adjacent West Virginia to the southwest, Marcellus strata are assigned to the lower part of the Millboro Shale, Finally, in southwestern Virginia and adjacent West Virginia, strata termed Marcellus in New York occur in lower parts of an interval sometimes termed "New Albany Shale" but shown by their correlation to be equivalent to upper Onondaga or lower Marcellus strata, based upon airfall volcanic tephras. [ABSTRACT FROM AUTHOR]

Porphyry Mo deposits are important suppliers of molybdenum for industrial applications, but the origin and source of metals in these deposits remain debated. Here, we present Mo isotope data for Miocene mineralized porphyritic monzogranites (MPMs) and Paleocene barren biotite monzogranites and tuffs (BMTs) from the Bangpu porphyry Mo (Cu) deposit in the Gangdese metallogenic belt. The results show that the MPMs display radiogenic Sr and Pb isotopes and elevated δ98/95Mo (relative to NIST SRM 3134; +0.07%c-1.2%c) and Mo contents, which exceed the range of the depleted mantle. These characteristics cannot be attributed to surface weathering, hydrothermal alteration, magmatic differentiation, or partial melting but rather reflect the incorporation of Mo from black shales into their magma sources, as evidenced by the significant correlations between δ98/95Mo and εNd(i) and aluminum saturation index (ASI) values. In contrast, the BMTs display lower Mo and δ98/95Mo values than the mineralized samples, and their δ98/95Mo values display no correlations with radiogenic isotopes or ASI values. The contrasting characteristics of mineralized and barren samples provide strong evidence that the addition of black shales played an important role in the formation of the Bangpu porphyry Mo deposit. Our study thus establishes a possible link between porphyry Mo deposits and organic-rich sediments and highlights the great potential of Mo isotopes in studying porphyry Mo deposits. [ABSTRACT FROM AUTHOR]

The end-Devonian Hangenberg Crisis was one of the biggest Phanerozoic mass extinctions. However, the mechanism(s) that triggered this event is still debated. In this study, multiple geochemical paleoredox proxies (redox-sensitive trace metals [e.g., Mo, U, Re, V] and isotope systems [Mo, U, S, C]) were applied to the Exshaw Formation black shales to infer ocean redox conditions during the Hangenberg Crisis. The measured δ13C org values generally decrease upsection in the Exshaw Formation. The Exshaw black shales have increasing maturity levels from east to west in the Western Canada Sedimentary Basin. Large sulfur isotope fractionations (–15‰ to 65‰) between original seawater sulfate and pyrite is best explained by microbial sulfate reduction during deposition and early diagenesis rather than thermochemical sulfate reduction. Precise Re-Os ages previously reported for the Exshaw Formation suggest that metal geochemical signatures in these shales, including overmature shales, were minimally affected by hydrocarbon maturation and reflected depositional conditions. Both Sr/Ba and TS/TOC ratios (the latter only from immature shales affected minimally by hydrocarbon generation) suggest predominantly brackish and marine settings with significant water exchange between the basin and open ocean. The TOC contents, redox-sensitive trace metal concentrations (Mo, U, Re), and Fe speciation indicate local bottom waters ranged from suboxic (with sulfidic pore waters) to euxinic. The authigenic δ98Mo and δ238U values for the Exshaw shales range from 0.3‰ to 1.1‰, and from –0.23‰ to 0.39‰, respectively. The δ98Mo of the Exshaw Formation may have been offset to lower values than coeval seawater because of a local particulate Fe-Mn shuttle and/or local weakly euxinic bottom waters. Two different correlation patterns (positive correlation and no correlation) of δ238U and U enrichment factors (EF) were observed for Exshaw black shales deposited from locally euxinic bottom waters. The positive correlation group samples (−0.13‰ to 0.23‰) suggest U isotope fractionations (0.4‰ to 0.8‰) between sediments and seawater like those observed in modern euxinic basins. Higher δ238U values (>0.2‰) in the no correlation group suggest even larger U isotope offsets (0.8–1.2‰) from seawater, possibly associated with removal of U into organic floccule layers during deposition. Applying the above Mo and U isotope fractionations to the Exshaw shales, global seawater δ98Mo and δ238U at the Devonian-Carboniferous boundary (DCB) may have been in the range of 1.4‰ to 1.9‰ and −0.9‰ to −0.5‰, respectively. A Mo and U isotope mass balance model suggests a large areal extent of euxinic seafloor (6–10%) at the DCB, which could be pervasive along continental margins and in epicontinental seas during transgression. Therefore, our data support expanded ocean euxinia at the DCB as an important contributor to the Hangenberg Crisis. [ABSTRACT FROM AUTHOR]

BACKGROUND: High geochemical background has a greater impact on soil Cd pollution than human activities and is more detrimental to the environment and human health on a regional level. Research shows that the bioavailability of Cd in soil is the key factor to determine its bioavailability and biotoxicity, so it is of great theoretical and practical significance to find an effective method to evaluate the bioavailability of Cd in soil for the safe use and risk control of contaminated agricultural land. Single extraction methods with relatively simple operation and relatively low cost and sequential extraction methods providing morphological distribution feature information, are the most common methods for evaluation of heavy metals bioavailability in soil. In general, the available amount of soil heavy metals obtained by chemical extraction methods can better reflect the level of plant absorption than the total amount. However, chemical extraction methods have some drawbacks, including differences between the extraction principle and crop absorption process, a lack of universality in the extracts, redistribution and re-adsorption during the extraction process, and most notably, the failure to take into account dynamic changes in heavy metal concentrations in the root environment. Diffusive gradients in thin-films (DGT) technique is a new biomimetic in-situ sampling technique, which has been widely used to assess the bioavailability of various elements in soil, water, sediment and other environmental media in recent years. The process of DGT absorbing target elements is similar to plants absorption, which can better reflect bioavailability. However, existing research results using DGT to evaluate soil Cd pollution is mainly based on indoor pot experiments. Exogenous addition of heavy metals to contaminated soil not only has high bioavailability, but also reduces the sensitivity of soil pH and other factors to the bioavailability of heavy metals in soil, which does not accurately represent the complex situation in naturally contaminated soil. It is not clear whether the results of DGT can accurately reflect the bioavailability of soil Cd in high geological background areas. In order to confirm whether DGT technology can effectively evaluate the bioavailability of soil Cd in high geochemical background areas when compared to existing chemical extraction methods, 80 sets of paddy soil-rice and 20 sets of dry soil-bok choy samples were collected in the black shale area of Northwest Zhejiang Province. The DGT technology, 0.01mol/L CaCl2 extraction method, seven-step extraction method and soil solution method were used to evaluate the bioavailability of Cd in soil. Inductively coupled plasma- mass spectrometry (ICP-MS) was used to determine Cd content and available Cd in soil and crop. Soil pH was determined by potentiometry (POT), and soil organic matter (OM) was determined by oxidation combustion potentiometry (POT). The migration and accumulation characteristics of Cd in a soil-crop system were analyzed. The evaluation effects of different bioavailability evaluation methods were compared by the correlation between available Cd and crop Cd content. RESULTS: (1) The total content and fraction distribution characteristics of Cd in soil. The results show that the Cd average contents in paddy soil and dry soil in the study area are 1.07mg/kg and 0.73mg/kg, respectively, remarkably higher than the background values of soil in Zhejiang Province and China. The abnormal enrichment of Cd is mainly related to the widespread black shale in Northwest Zhejiang. For the sequential extraction procedures, the average content in paddy soil of water-soluble and exchangeable Cd, carbonate-bound Cd, humic acid-bound Cd, Fe-Mn oxide-bound Cd, strong organic-bound Cd and residual Cd are 54%, 5.9%, 9.3%, 13.5%, 4.2% and 13.2%, respectively. The average content in dry soil of water-soluble and exchangeable Cd, carbonate-bound Cd, humic acid-bound Cd, Fe-Mn oxide-bound Cd, strong organic-bound Cd and residual Cd are 47.2%, 4.6%, 11.5%, 14.3%, 5.5% and 16.9%, respectively. On the whole, the bioavailable component of Cd in the study area accounts for a relatively high proportion. (2) Characteristics of Cd content in crop. The content of Cd in rice seed in the study area ranges from 0.01mg/kg to 3.29mg/kg, with an average of 0.26mg/kg. The Cd content in bok choy ranges from 0.01mg/kg to 0.31mg/kg, with an average of 0.08mg/kg. In comparison to China's contaminant limit of national food safety standards (GB2762-2017), the over-standard rates of Cd in rice and bok choy are 34% and 10%, respectively. The soil samples are further assessed according to Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land (GB15618—2018), the Cd over-standard rates of paddy soil and dry soil are 70% and 75%, respectively. The Cd over-standard rate of soil samples is significantly higher than crop samples. Therefore, the bioavailability of Cd in soil should be considered to scientifically evaluate the pollution level of Cd in soil. (3) Assessment of Cd bioavailability in soil by four extraction methods. The DGT technology, 0.01mol/L CaCl2 extraction method, seven-step extraction method and soil solution method are used to evaluate the bioavailability of Cd in soil. The results are as follows: CDGT, CCaCl2, CF₁+F₂+F, and Csoln(Fig.3). There is a significant positive correlation between Cd-P and available Cd determined by different methods, but the correlation between CDGT and crop Cd content is better than 0.01mol/L CaCl2 extraction method, seven-step extraction method and soil solution method. The correlation between available Cd in paddy soil and rice are Csoln>CDGT CCaCl2 CF₁+F₂+F₁. The correlation between available Cd in dry soil and bok choy are CDGT >CCaCl2 CF, +F₂+F3 Csoln(Table 3). DISSCUSION: (1) Results of DGT technique. The available Cd (CDGT) content measured by DGT for paddy and dry soil in the study area ranges from 0.02µg/L to 1.69µg/L and from 0.14µg/L to 1.88µg/L, with average values of 0.78µg/L and 0.62µg/L, respectively (Fig.3). The correlation coefficients between CDGT and Cd-P in paddy soil and dry soil are 0.622 and 0.887, respectively (Table 3), which are larger than Ccach, CF,+F₂+F, and Csoln. The DGT technique is superior to the 0.01mol/L CaCl2 extraction method, seven-step sequential extraction method and soil solution method in reflecting soil Cd bioavailability, and the evaluation effect is not affected by land use types. The DGT technique can be used to simulate Cd release process from soil to solution cased by plant root absorption, and reflects the Cd content in crops more accurately than chemical extraction methods. (2) Results of 0.01mol/L CaCl2 extraction method. The available Cd (Ccach) content measured by 0.01mol/L CaCl2 extraction method for paddy and dry soil in the study area ranges from 0.07mg/kg to 0.95mg/kg and from 0.08mg/kg to 0.55mg/kg, with average values of 0.58mg/kg and 0.31mg/kg, respectively (Fig.3). The correlation coefficients between Ccaci, and Cd-P in paddy soil and dry soil are 0.583 and 0.795 respectively (Table 3), which shows a good level of correlation. On the whole, its evaluation effect is second only to DGT technology. Studies have shown that Ccach, solution can effectively replace metal ions adsorbed by soil particles, and the change of soil pH and soil structure has little effect on the replacement rate, giving it a wide range of applications. Ccaci, solution mainly displaces the adsorbed Cd from soil through static ion exchange, and the extracted available Cd is mainly water-soluble and exchangeable Cd, but some bioavailable metals in soil (such as soil particles or unstable organic/inorganic complexes in soil solution) may not be extracted, so the bioavailability of Cd in soil may be underestimated. (3) Results of seven-step extraction method. Compared with the single extraction method, the sequential extraction method provides the speciation characteristics of heavy metals, and can be used to more comprehensively evaluate the mobility, availability and potential toxicity of heavy metals in soil. Water-soluble Cd, exchangeable Cd and carbonate-bound Cd are generally classified as bioavailable components (CF,+F₂+F). The available Cd (CF₁+F₂+F3) content measured by the seven-step extraction method for paddy and dry soil in the study area ranges from 0.08mg/kg to 3.95mg/kg and from 0.13mg/kg to 1.61mg/kg, with average values of 0.64mg/kg and 0.40mg/kg, respectively (Fig.3). The correlation coefficients between CF,+F₂+F, and Cd-P in paddy soil and dry soil are 0.577 and 0.717 respectively (Table 3), which are lower than 0.01mol/L CaCl2 extraction method and DGT technique. The migration factor (MF) is the relative proportion of the bioavailable components CF,+F₂+F1 of Cd in the soil. The MF of Cd in paddy soil and dry soil are as high as 59.9% and 51.8%, respectively, which indicate that Cd is easy to migrate and enrich in the soil-crop system. (4) Results of soil solution method. Soil solution (Csoln) is the main place of substance exchange between plants and soil, so it can indicate the bioavailability of heavy metals in soil. The available Cd (Csoln) content measured by soil solution method for paddy and dry soil in the study area ranges from 0.03µg/L to 2.18µg/L and from 0.15µg/L to 2.9µg/L, with average values of 1.22µg/L and 1.99µg/L, respectively (Fig.3). The correlation coefficient between Csoln and Cd-P in paddy soil is larger than CDGT, CCach, and CF1+F2+F3. However, the correlation coefficient in dry soil is the smallest, so the effect of bioavailability evaluation is unstable (Table 3). This is mainly due to the fact that some inert Cd in soil solution cannot be absorbed and utilized by plants, and it is difficult to extract potential available Cd, which has great limitations. (5) A comprehensive evaluation of four extraction methods. Comparing the characteristic and applicability of different methods, DGT technology, single extraction method, sequential extraction method and soil solution method have different application scope and significance, and they all play an irreplaceable role in bioavailability evaluation of soil Cd. There is a significant positive correlation between soil available Cd determined by the four methods and crop Cd, the extraction techniques of soil available Cd can effectively reflect the content level of available Cd in soil. DGT technology can simulate the dynamic absorption process of Cd by plants which can more accurately reflect the bioavailability of Cd in soil. The single extraction method is relatively simple in operation and relatively low in cost, which is mainly used for quickly judging the bioavailability level of Cd in soil. 0.01mol/L CaCl2 is recommended as an extractant for available Cd in soil. The sequential extraction can be used to obtain the speciation characteristics of soil Cd, which focuses on the analysis of available Cd and potentially available Cd in soil. Soil solution can not only reflect the bioavailability of heavy metals, but is also a key parameter for environmental models to predict and quantitatively assess the surface runoff and infiltration of heavy metals in soil. [ABSTRACT FROM AUTHOR]

BACKGROUND: Shale, as an important component of sedimentary rocks, is also a valuable source rock and “reservoir” of shale gas. The study of nitrogen isotope distribution characteristics can provide geochemical indexes for judging the sedimentary environment and oil-source correlation of crude oil. It is helpful to understand the organic matter enrichment mechanism of black shale, shale oil, and gas exploration[14-17] . Nitrogen isotope ratio analysis in sedimentary rocks is faced with problems such as low content, and the influence of pretreatment on analysis and the reference materials, which affect the accurate analysis of nitrogen isotope ratio in shale and restrict the development of this technology in related studies. First, the low content in rocks will affect the analysis results by elemental analyzer-isotope ratio mass spectrometry (EA-IRMS)[16,18,20] . Second, the method of direct sample analysis is often used to analyze nitrogen isotope ratio of whole rock, to improve the relative content of nitrogen and remove carbonate to meet the requirement of organic carbon isotope analysis; samples treated with acid can also be used for analysis. There are differences in treatment methods in different laboratories, which can also increase the variation in content and isotope ratios, as well as the difficulty of data comparison[9-13,21,25] . Finally, there are relatively few international standard materials based on rocks and minerals for nitrogen isotope and there are still some problems and limitations in these standards[7,21,24,30] . Therefore, the accurate analysis of nitrogen isotope ratio in shale is affected, thus restricting the development of this technology in related studies. OBJECTIVES: To improve the precision and accuracy of nitrogen isotope analysis in shales. METHODS: (1) The analysis was carried out by EA-IRMS, with the use of MAT253 Plus gas stable isotope mass spectrometer, Flash 2000 HT element analyzer and ConFlo Ⅳ interface. The furnace tube was filled with the recommended scheme of the instrument, and the water removal trap was adjusted according to the measured object, that is, only magnesium perchlorate was used or carbon adsorbent was added on this basis (the main component was sodium hydroxide), which accounted for 50% each. Carbon and nitrogen isotope ratios were measured separately. (2) Carbon and nitrogen isotope standard materials included: USGS40, USGS41a, IAEA-600, Urea, GBW04701, GBW04702, GBW04703, GBW07424 and GBW07107 as calibration, monitoring and experimental study (Table 1). Typical shale samples of the upper Yangtze Longmaxi Formation were selected as the research object. Both samples are rich in organic carbon. Combined with hand samples and XRD analysis, their mineral composition is mainly as follows: Quartz, potassium feldspar, illite and pyrite in SAMPLE-1, SAMPLE-2 are similar in mineral composition in general, but there is obvious dolomite in SAMPLE-2. (3) The experiment consisted of three parts. First, the impact of increasing oxygen injection time and using double tin cup encapsulation on nitrogen isotope ratio analysis was studied. Urea was applied to determine δ15N under the same conditions but with different oxygen injection time (3s or 5s) and the differences were compared. Urea and GBW07424 were used to encapsulate the sample with double tin cup (two layers of tin cup for the same sample) and conventional single tin cup for comparison under the same conditions. The composition of total nitrogen and total carbon isotope ratios in GBW04701, GBW04702 and GBW04703 was determined by single-tin cup encapsulation. Second, the influence of acid rinse method on the analysis was conducted. Standards were weighed and gradually added with an excess of 6mol/L HCl to remove carbonate minerals. During the reaction, the centrifuge tube was placed in an ultrasonic cleaner for ultrasonic treatment for 3 to 5 times, 10min each time. Centrifuge was used, acid was discarded and deionized water was added. After ultrasonic treatment in ultrasonic cleaner, centrifuge treatment was continued. This process was repeated until it reached neutral. The samples were then compared and analyzed with unprocessed samples and recommended values. Finally, the shale samples SAMPLE-1 and SAMPLE-2 from Longmaxi Formation were analyzed. The isotopic ratios of total nitrogen and DISCUSSION: (1) The optimized measurement conditions of EA-IRMS. Attempts were made to improve combustion efficiency by using double tin cup wrapping and increasing oxygen injection time. The relative deviation of double tin cup method was greater than 0.2‰ and obviously higher than that of single tin cup method, indicating that this method is not suitable. The reason may be related to the difference in combustion efficiency caused by the gap between double tin cups and the introduction of air when the sample is wrapped[19] . Appropriate increase of oxygen injection time in the analysis of GBW04701, GBW04702 and GBW04703 obtained satisfactory results, indicating that this method can effectively improve the accuracy of the technique, while this method did not significantly improve the standard deviation of δ15N value of Urea, which may be related to the matrix of the sample[20] . It may be the abundant carbon in shale. Therefore, it is necessary for nitrogen isotope ratio analysis in shale to be determined by carbon and nitrogen separately and adding carbon adsorbent. (2) The acid rinse method. The acid rinse method adopted has no significant effect on GBW04701 and GBW04702 on δ15N analysis and can effectively remove carbonate components. Ultrasonic was used to promote the reaction between acid/water and sample in the process of acid reaction and acid washing in the experiment, and the centrifugation time was appropriately increased in the centrifugation stage, which was conducive to the preservation of fine particle components. Compared with static reaction, the addition of ultrasonic reaction could improve the washing effect. The less washing times were thus contributing to the accuracy of δ15N analysis[47] . (3) The shale sample analysis. Although the acid treatment method adopted in the experiment has no obvious effect on the δ15N analysis of standards, significant composition loss and δ15N change were still observed in the analysis of shale samples. Moreover, the nitrogen content of shale samples of Longmaxi Formation was relatively high. Therefore, in order to accurately analyze the nitrogen content and δ15N analysis, direct analysis of samples is recommended for the whole-rock nitrogen isotope analysis of such samples. (4) The standard and reference materials. Carbon and nitrogen isotope reference materials with different characters and compositions were selected as calibration, monitoring and experimental study. USGS40, USGS41a and IAEA-600 standard samples were used for calibration and quality monitoring, and no obvious influence of matrix difference was found. Although they are Marine sediments, GBW04701, GBW04702, GBW04703 provide isotopic compositions of total carbon, organic carbon, total nitrogen and organic nitrogen. They are suitable for the analysis of carbon and nitrogen isotope ratios and the monitoring of acid treatment processes, especially the analysis of EA-IRMS technology[50] . In shale analysis, GBW04701, GBW04702 and GBW04703 were selected as monitoring to meet the requirements of nitrogen and total carbon and organic carbon isotope ratio analysis. [ABSTRACT FROM AUTHOR]

Acid sulfate soils (ASS) cause big problems worldwide due to their potential to form sulfuric acid during oxidation of sulfidic materials, resulting in very acid soil (pH <4.0). Impacts include acidification of soil and water, leaching of metals, decreased nutrient supply, deterioration of water fauna and flora, and corrosion of infrastructure. These soils also exhibit poor geotechnical properties. Finland has the largest occurrences of ASS in Europe, mainly along the coast of the Baltic Sea. The EU Water Framework Directive brought about wide co-operation to reduce the harmful impacts of ASS in Finland. One urgent step was to localize and characterize the occurrences of ASS The more than 10 year-long programme, led by the Geological Survey of Finland (GTK), started in 2009 and field work was completed in 2021. During the programme observations, measurements, sampling and analyses were made at 23 000 sites in an area of 5 010 000 ha. Traditionally ASS in Finland have been considered to comprise fine-grained sulfidic sediments and/or their oxidized layers, occurring on agricultural land along the coast below the highest shoreline of the Littorina Sea transgression. This study recognized and classified significant occurrences of other types of potentially harmful ASS materials: (1) coarse-grained ASS (sand), (2) organic ASS (peat) and (3) unsorted ASS (till material). The methods, definition and classification of Finnish ASS have been revised. We calculated the extent of ASS along the coast to be about 1000 000 ha corresponding to 21% of the area covered in the past by the Littorina Sea. and three to six times more than earlier estimates. In addition, some occurrences of ASS were recognized inland, mainly related to black shales and sulfidic ores. The mapping data can be accessed via the GTK map service (www.gtk.fi) providing information about the distribution and properties of ASS. [ABSTRACT FROM AUTHOR]

The Mousty Formation has unique and particularly interesting lithological, mineralogical, sedimentological, metamorphic and tectonic characteristics which have been the subject of much research in connection with the new geological map of Wallonia, but also within the framework of a large amount of academic research, sometimes unpublished. An effort to synthesise and upgrade it in an updated framework seemed necessary. After a history of its definition, mapping and outcrop areas, the following topics are successively addressed in detail and illustrated with diagrams and photos: its lithostratigraphy with the probable discovery of its base near the Court-St-Etienne anticline, its well-constrained biostratigraphy and chronostratigraphy, a new estimate of its minimum thickness, its sedimentology--a subject little addressed until now--, and the resulting depositional sedimentary environment. Its geochemistry, never addressed, is comparable to black shale international standards, except for abnormally high manganese and very low calcium contents; high radon levels in buildings are related to the black slate presence in outcrops. Its mineralogy is rich in manganese-bearing metamorphic minerals, its metamorphism in which we go beyond the strict framework of the formation to deal with the entire southern outcropping rim of the Brabant Massif. Finally, the relationship between the Mousty Formation and the tectonic is discussed, with additional field data, in the context of the innovative and unifying concept of a low-angle extensional detachment called the Asquempont Detachment System. All these observations, some old and some very recent, discussed in the updated framework of the geology of the Caledonian basement of Brabant and in the global stratigraphy and palaeogeography of the lower Palaeozoic, allow us to renew in depth the vision we had of the Mousty Formation and of its place in the Brabant Massif. [ABSTRACT FROM AUTHOR]

The Carboniferous Ha'erjiawu Formation in the Santanghu Basin represents a significant potential target for shale oil exploration, yet its characteristics remain largely unknown. This study utilizes a combination of elemental and organic geochemical analyses to investigate the paleoenvironmental conditions and shale oil potential of the Carboniferous Ha'erjiawu Formation black shales within the Santanghu Basin. The results suggest that the Ha'erjiawu Formation black shales were deposited in water columns with low salinity and dysoxic conditions, as indicated by paleosalinity and redox proxies such as Rb/K, B/Ga, B content, V/Cr, V/(V + Ni), V/Al, and Mo/Al. Furthermore, the climatic proxies (Ga/Rb, Sr/Cu and K2O/Al2O3) indicate that the Santanghu Basin underwent a warm-humid/cold-dry oscillating climate during the deposition of the Ha'erjiawu Formation black shales, potentially influenced by synsedimentary volcanic activity or the Late Paleozoic glaciation. The organic geochemical analyses have revealed that the Ha'erjiawu Formation black shales are rich in type II kerogen, which is in the early mature to mature stage, indicating a significant potential for oil generation. However, there is considerable variation in the oil content of the analyzed samples, with only a few containing movable oil. Given the high abundance of brittle minerals within the Ha'erjiawu Formation black shales, it will be indispensable to meticulously evaluate and identify intervals exhibiting abundant movable oil for successful shale oil exploration and development within this geological unit. [ABSTRACT FROM AUTHOR]

The recycling of lithium-ion batteries presents challenges due to the complex composition of waste streams generated by current processes. Achieving higher purity levels, particularly in the reclamation of aluminium metal and transition metal black mass, is essential for improved valorisation. In this study, we propose a high-efficiency, low-energy, and environmentally friendly method using organic acids to separate cathodic black mass from the aluminium current collector. The acids selected in this study all show >86% peeling efficiency with acetic acid showing 100% peeling efficiency of black mass from the current collector. The recovered materials were subjected to X-ray diffraction, electron microscopy, and elemental analysis techniques. We show that oxalic-acid-treated material exhibited two distinct active material components with a minimal change in mass ratio compared to the untreated material. We show by elemental analysis of the leachates that the majority of critical materials were retained in the black mass and limited aluminium was leached during the process, with almost 100% of Al recovery achieved. This methodology enables the production of high-purity concentrated aluminium and critical metal feedstocks (Mn, Co, Ni, and Li) for further hydro-metallurgical processes, upcycling of the cathode material, and direct recycling. The proposed approach offers significant potential for enhancing valorization in lithium-ion battery recycling, facilitating efficient separation and optimal recovery of valuable metals. [ABSTRACT FROM AUTHOR]

Copyright of Geology & Exploration is the property of Geology & Exploration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Late Ordovician–Early Silurian period was a significant transitional phase in geological history and has garnered global interest. This study focuses on the black shale series of the Wufeng Formation–Longmaxi Formation of the Upper Ordovician–Lower Silurian period in the Sichuan Basin. Based on the logging curves and lithological characteristics of the Yucan-1 Well, 46 black shale samples were collected from the target layer section for clay mineral XRD (46 samples) analysis and whole-rock XRF (14 samples) analysis. The results indicate that three third-order sequences (SQ1, SQ2, and SQ3) are present in the Wufeng Formation–Longmaxi Formation of the Yucan-1 Well, and two subfacies and three microfacies were identified. In conjunction with the characteristics as well as the characteristic parameters of whole-rock oxide and clay mineral content ((I/C), (S + I/S)/(I + C), CIA, CIA-error, CIW, PIA, MAP, and LST), the Wufeng Formation–Longmaxi Formation of the Yucan-1 Well is divided into three intervals. Interval I is the Wufeng Formation. During this interval, weathering intensity, surface temperature, and precipitation gradually decreased, while the climate shifted from warm and humid to cold and dry. This corresponds to two pulse-type biological extinction events and represents an interval of increasing organic carbon burial. Interval II encompasses the bottom-middle part of the Longmaxi Formation. Weathering intensity, surface temperature, and precipitation were characterized by smooth, low values. Subsequently, the climate was predominantly cold and dry. This was the primary interval of organic carbon enrichment. Interval III extends from the upper part to the top of the Longmaxi Formation. Weathering intensity, surface temperature, and precipitation gradually increased. The climate transitioned from cold and dry to warm and humid. Organic carbon burial gradually decreased, while sea levels dropped. This indicates that climate cooling was the primary controlling factor for this biological extinction event. In combination with previous divisions of graptolite zones in the Yucan-1 Well, it is postulated that this biological extinction event may primarily have been pulse extinction. The continuous cooling of the climate in the later period led to the continuous extinction of organisms that survived the disaster. Until approximately 438.76 Ma at the top of the Longmaxi Formation, the climate environment recovered to pre-extinction conditions, with a transition to a warm and humid climate again. [ABSTRACT FROM AUTHOR]

In this study, recycled high-density polyethylene (REHDPE)/black shale (B-shale) composites were prepared by a melt-blending method using a B-shale nucleating agent and polyolefin elastomer (POE) and acrylic impact modifier (ACR) as plasticizers. The melt index, microstructure, mechanical properties, and non-isothermal crystallization behavior of REHDPE were analyzed to determine the effects of the nucleating agent and plasticizer. Scanning electron microscopy and the melt index indicated that POE and ACR increased the melt flow rate of the composites and improved the interfacial properties of B-shale and REHDPE. The non-isothermal crystallization processes of the REHDPE and REHDPE composites were successfully described by Hoffmann–Lauritzen theory, demonstrating that B-shale, POE, and ACR can synergistically accelerate the crystallization process of REHDPE. The Friedman method revealed that B-shale, POE and ACR reduced the crystallization activation energy by heterogeneous nucleation and increasing the melt flow, respectively. The POE and ACR further enhanced the nucleation activity of B-shale and the nucleation activity is negatively correlated with the B-shale content according to the Dobreva and Gutzow's methods. The synergistic effect of nucleating agent and plasticizer improved the mechanical properties of REHDPE and solved the problem in relatively low mechanical properties of recycled plastics. And it will provide a new strategy for the practical production of REHDPE. [ABSTRACT FROM AUTHOR]

Petrogenesis of lacustrine dolostone is closely related with paleo-lake water conditions. Here we report the high spatial-resolution petrographic and geochemical results of a lacustrine dolomite nodule from the Qingshankou Formation, the Songliao Basin. Sedimentary and elemental signatures confirm the protogenetic origin of this nodule and its effectiveness in recording geochemical characteristics of paleolake water during dolomitization. The low Y/Ho ratios, middle rare earth element (MREE) enrichment and subtle positive Eu anomalies within the nodule indicate a fresh water source. However, the Sr isotope values in the core of the nodule (0.7076-0.7080) are close to contemporaneous seawater (0.7074), yet different from the modern river (0.7120) and the host black shale (0.7100). On the premise of excluding the influence of hydrothermal fluids, the significantly low strontium isotope values of the lacustrine dolomite might be caused by seawater interference during dolomitization. Our findings demonstrate that lacustrine dolomite within black shales is not only a faithful tracer of diagenetic water environment, but also a novel and easily identified mineralogical evidence for episodic seawater intrusion event (91 Ma) in the Songliao Basin, which supplements other paleontological and geochemical evidence. [ABSTRACT FROM AUTHOR]

By virtue of remarkable tolerance on hypoxia and adaptive specialization in morphology, diverse hexactinellid sponges prospered in an early Cambrian environment characterized by dysoxic bottom waters documented by black shales. New fossils from the black shale of the Niutitang Formation (basal Stage 3 of Cambrian) in Hunan Province of China, reveal for the first time an articulated body of the sponge Hyalosinica archaica Mehl & Reitner in Steiner et al., 1993, which possesses an ovoid main body and an impressive long stalk. The spicular skeleton includes large diactines that are generally organized as fan-shaped clusters, a few small stauractines and hexactines, and twisted bundles of long monaxons that form the stalk/root tuft. This hexactinellid sponge represents the oldest extinct taxon that took advantage of a long stalk to elevate the main body above the sediment surface and thus to adapt to the oxygen-deficient sea-bottom environment. The long root tuft links Hyalosinica to a series of fossil and recent sponge taxa and proves a deep origin of the stalk-bearing morphology, indicating a likely parallel evolution within the Hexactinellida in response to special environmental pressures. Furthermore, the overall skeletal organization indicates that Hyalosinica, as well as related early ‘rossellimorphs’, are basal stem group representatives of Hexactinellida and probably branched before the extinct Reticulosa and before the two extant hexactinellid subclasses. [ABSTRACT FROM AUTHOR]

Sedimentary and hydrothermal pyrites contained in selected Malaysian black shale and cherts have been analysed using laser ablation inductively coupled plasma (LA ICP-MS) and electron probe microanalysis (EPMA) at the University of Tasmania, Australia. This study shows that gold is concentrated in sedimentary and hydrothermal pyrite in the Middle Permian to Late Triassic black shales and Devonian cherts. According to LA ICP-MS analysis, gold contents in pyrite varied from 0.5 to 0.8 ppm Au in the Permo-Triassic black shale and between 0.2 and 0.8 ppm Au in the Devonian cherts. The lowest level of gold (0.3 ppm Au) was observed in the Permo-Triassic black shale that crops out at the Selinsing gold mine. In the Permo-Triassic period, the selenium contents display one peak (average range: 63.4–103.4 ppm Se) that is far from any gold deposit and one lowest point (average: 5.3 ppm Se) at the Selinsing gold deposit. In the Devonian period, the selenium content in sedimentary pyrite shows a peak (72.6–243.8 ppm Se) in the cherts. EPMA and LA ICP-MS data show consistent Se content variation in the Devonian and Permo-Triassic periods. Using selenium as a proxy for atmospheric oxygenation, the lowest level of Se content in the Permo-Triassic period is believed to decrease atmospheric oxygenation, as recorded in sedimentary pyrite found in black shale from the Selinsing gold deposit. The two peaks of selenium contents are interpreted as periods of increased atmospheric oxygenation. From an exploration perspective, the concentration of gold in sedimentary pyrites makes them sources for gold in the central sedimentary basin of Peninsular Malaysia. Therefore, the two maximum levels of Se and gold content during Permo-Triassic and Devonian times correspond to two stratigraphic levels of potential for orogenic gold mineralisation in the district. The EPMA data show significant values of Co over Ni in pyrite from the Gua Musang, Semantan, and Karak formation black shales, indicating a volcanic contribution of Co during the formation of sedimentary pyrite. Based on the current study's findings, gold exploration should not be restricted to areas in and around the Selinsing gold mine, Buffalo Reef, Penjom mine, Tersang mine, and Bukit Koman mine but can be extended to BRSZ Units 1 and 2, Gua Musang, and Karak formations in the central belt of Peninsular Malaysia. [ABSTRACT FROM AUTHOR]

The Aptian–Albian (A–A) transition encompassed a critical timing in the evolution of Fars Platform (Zagros Basin, SW Iran), such that a number of previous studies on its proximal part (called "Coastal Fars") illustrated platform recovery after sustained demise due to latest Aptian maximum sea-level lowstand. So far, much less attention has been given to the distal part of the platform – "Interior Fars" – where the lack of proper geological age interpretations, in particular, has been limiting a full paleoenvironmental reconstruction of the southern shallower Neo-Tethys. In order to establish the chronostratigraphic framework of Interior Fars, this study presents a novel set of planktonic foraminiferal record for the A–A Kazhdumi Formation at the Saroie section. The identified fauna comprises nine species from four genera, all of which are reported for the first time from Fars Platform. The observed new bioevents are generally consistent with those of the proposed reference section at a deeper intrashelf setting (Tang-e-Maghar, Dezful Embayment), allowing for the establishment of a local upper Aptian–Lower Albian zonation and leading to adequate constraints on the local Aptian/Albian boundary and the timing of prominent black shale deposition (possible "Jacob" equivalent). Based on this new Saroie chronostratigraphic scheme, it is evident that sedimentation across the A–A transition was maintained fully marine at the Saroie section, Interior Fars. This finding does not support the previous inference of extensive subaerial exposure of the entire Fars Platform at that time, thereby calling for a major revision of the published prevailing model for latest Aptian paleogeography of this region. These new insights will facilitate better understanding of the Fars Platform evolution in the Zagros Basin as well as paleoenvironmental reconstructions along the southern Neo-Tethys. [ABSTRACT FROM AUTHOR]

Despite intensive study of the early Cambrian Nanhua Basin (ECNB) in South China, its degree of connectedness to the open ocean remains uncertain, impeding analysis of contemporaneous oceanic redox evolution and its role in the Cambrian Explosion. We analyzed bulk-shale B/Ga, a newly proposed proxy for watermass salinity in ancient depositional systems, for three sections (Daotuo, Yuanjia, and Zhalagou) representing a range of water depths in the ECNB and spanning early Cambrian Stages 2 and 3. The B/Ga proxy records a salinity gradient in the basin, with increasing salinity from shallow- to deep-water areas, particularly during the deposition of black shales of the lower Jiumenchong/Niutitang/Zhalagou Formation. The gradient was probably due to the mixing of freshwater from adjacent landmasses with marine waters within a moderately restricted basin. All three study sections exhibit a monotonic rise in salinity over the ~9-Myr study interval, reflecting increased watermass exchange with the open ocean due to regional tectonic and/or global sea-level changes. The improved watermass exchange may have weakened water-column stratification and reduced deep-water anoxia in the ECNB, contributing the enhanced oceanic oxygenation along with global environmental controls and further modulating the expression of the Cambrian Explosion recorded in Lower Cambrian sections of South China. Our study thus highlights the need for comprehensive analyses of hydrographic dynamics in marginal-marine settings that are used to explore co-evolutionary relationships between early animals and environmental oxygen levels. [ABSTRACT FROM AUTHOR]

In the present paper, we describe several coleoid jaws discovered in the lower Toarcian black shales, cropping out along the Vilyui River (Yakutia, Russia). This is the first record of a Lower Jurassic coleoid jaw outside Europe and the first report of such a finding from the Mesozoic of Siberia. The described coleoid jaws demonstrate the same mode of preservation and morphology as the coeval jaws previously reported from Europe. Their preservation in Siberia became possible due to the widespread occurrence of black shale facies associated with the early Toarcian oceanic anoxic event (TOAE). [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The global carbon cycle model is presented as a natural self-regulating machine that provides renewable biomass synthesis during evolution. The machine consists of two parts, geological and biosphere. Between the parts, there is an interaction. The geological part is controlled by the movement of lithosphere plates, which is under the guidance of gravitational forces from celestial bodies acting on the Earth. The movement of the lithosphere plates is divided into a phase of a relatively quick movement, occurring in the tectonically active state of the Earth's crust, named the orogenic period, and a phase of a relatively slow movement, occurring in the phase of the tectonically quiet state of the crust, named geosynclinal period. In the orogenic period, the energy of moving plates' collisions is sufficient to initiate sulfate reduction, proceeding in the subduction zone. This is the reaction where sedimentary organic matter is oxidized. Resultant CO2 is injected into "atmosphere—hydrosphere" system of the Earth. Its concentration achieves maximal values, whereas oxygen concentration drops to a minimum since it reacts with the reduced sulfur forms that evolve in the thermochemical sulfate reduction and due to binding with reduced forms of metals, coming to the Earth's surface with volcanic exhalations. Carbon dioxide initiates photosynthesis and the associated biosphere events. In the geosynclinal period, the sulfate reduction ceases, and CO2 does not enter the system anymore, though photosynthesis in the biosphere proceeds in the regime of CO2 pool depletion. Under such conditions, the surface temperature on the Earth decreases, ending with glaciations. The successive depletion of the CO2 pool results in a regular sequence of climatic changes on the Earth. The ratio of CO2/O2 is the key environmental parameter in the orogenic cycle providing climatic changes. They consistently vary from hot and anaerobic in the orogenic period to glacial and aerobic by the end of the geosynclinal period. The climatic changes provide biotic turnover. Especially abrupt changes accompany the transition to a new orogenic cycle, resulting in mass extinction of organisms and the entry of huge masses of biogenic material into the sediment. This provided the conditions for the formation of rocks rich in organic matter ("black shales"). It is shown that the suggested model is supported by numerous geological and paleontological data evidencing the orogenic cycles' existence and their relationship with the evolution of photosynthesis. [ABSTRACT FROM AUTHOR]

This study focuses on understanding the association of rare earth elements (REE; lanthanides + yttrium + scandium) with organic matter from the Middle Devonian black shales of the Appalachian Basin. Developing a better understanding of the role of organic matter (OM) and thermal maturity in REE partitioning may help improve current geochemical models of REE enrichment in a wide range of black shales. We studied relationships between whole rock REE content and total organic carbon (TOC) and compared the correlations with a suite of global oil shales that contain TOC as high as 60 wt.%. The sequential leaching of the Appalachian shale samples was conducted to evaluate the REE content associated with carbonates, Fe–Mn oxyhydroxides, sulfides, and organics. Finally, the residue from the leaching experiment was analyzed to assess the mineralogical changes and REE extraction efficiency. Our results show that heavier REE (HREE) have a positive correlation with TOC in our Appalachian core samples. However, data from the global oil shales display an opposite trend. We propose that although TOC controls REE enrichment, thermal maturation likely plays a critical role in HREE partitioning into refractory organic phases, such as pyrobitumen. The REE inventory from a core in the Appalachian Basin shows that (1) the total REE ranges between 180 and 270 ppm and the OM-rich samples tend to contain more REE than the calcareous shales; (2) there is a relatively higher abundance of middle REE (MREE) to HREE than lighter REE (LREE); (3) there is a disproportionate increase in Y and Tb with TOC likely due to the rocks being over-mature; and (4) the REE extraction demonstrates that although the OM has higher HREE concentration, the organic leachates contain more LREE, suggesting it is more challenging to extract HREE from OM than using traditional leaching techniques.

The commercial exploitation of unconventional petroleum resources (e.g., shale oil/gas and tight oil/gas) has drastically changed the global energy structure within the past two decades. Sweet-spot intervals (areas), the most prolific unconventional hydrocarbon resources, generally consist of extraordinarily high organic matter (EHOM) deposits or closely associated sandstones/carbonate rocks. The formation of sweet-spot intervals (areas) is fundamentally controlled by their depositional and subsequent diagenetic settings, which result from the coupled sedimentation of global or regional geological events, such as tectonic activity, sea level (lake level) fluctuations, climate change, bottom water anoxia, volcanic activity, biotic mass extinction or radiation, and gravity flows during a certain geological period. Black shales with EHOM content and their associated high-quality reservoir rocks deposited by the coupling of major geological events provide not only a prerequisite for massive hydrocarbon generation but also abundant hydrocarbon storage space. The Ordovician–Silurian Wufeng–Longmaxi shale of the Sichuan Basin, Devonian Marcellus shale of the Appalachian Basin, Devonian–Carboniferous Bakken Formation of the Williston Basin, and Triassic Yanchang Formation of the Ordos Basin are four typical unconventional hydrocarbon systems selected as case studies herein. In each case, the formation of sweet-spot intervals for unconventional hydrocarbon resources was controlled by the coupled sedimentation of different global or regional geological events, collectively resulting in a favorable environment for the production, preservation, and accumulation of organic matter, as well as for the generation, migration, accumulation, and exploitation of hydrocarbons. Unconventional petroleum sedimentology, which focuses on coupled sedimentation during dramatic environmental changes driven by major geological events, is key to improve the understanding of the formation and distribution of sweet-spot intervals (areas) in unconventional petroleum systems.

Black shales are highly enriched in essential elements containing critical information on metallic richness and paleoclimatic imprints during deposition. The Cretaceous period marks the age of Basin formation from which the Mamfe Basin was formed from the Albian to Cenomanian. The purpose of this study is to investigate the geochemical behaviour of the shales in the Mamfe Basin and their paleoclimatic and metallogenic significance. Twenty-five representative shale samples were collected from seven sites outcrops in the Mamfe Basin. The major and trace elements composition in the shale samples were analysed using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In comparison with standard values for metalliferous shales, the shales from the Mamfe Basin are enriched in Boron (B), with only few samples enriched in Li, Rb, Cu, Pb and Zn. The Aluminium module (Alm) and ternary diagram plotted from Al–Fe–Mn shows that all the shales are considered as terrigenous sediments with only 02 samples (08%) falling within the zone of metalliferous sediments. The paleoclimatic characteristics that were inferred from the C-values (0.3–3.1), Sr/Cu (0.6–8.9), Sr/Ba (0.1–2.8), Rb/Sr (0.3–0.9), Fe/Mn (1.8–180), Al/Mg (0.31–31) and Mg/Ca (0.05–16.4) data of the shales in the Mamfe Basin indicate a that the climate that existed during source area weathering ranged from a sub humid to a more humid climate with few samples ≤5% displaying arid climate.

The Spiti region, renowned as the Museum of Indian Geology, is a world-famous sedimentary succession containing well-exposed sequences from Neoproterozoic to Cretaceous age. In this study, Triassic siliciclastic sedimentary rocks of the Lilang Supergroup were chosen to understand weathering history, provenance, paleoclimate, and depositional conditions using a geochemical and isotopic approach. Triassic shales show more or less similar compositions with substantial enrichment in CaO compared to PAAS (Post Archean shales from Australia), which may be attributed to the association with limestones in the region. However, the sandstones display significant depletion in the trace element concentrations signifying the effect of quartz dilution. The relative depletion of mobile elements (Rb, Ba) as against immobile elements (Zr, Nb, Hf) can be noticed in the trace element spider diagram of the shales. The Triassic sedimentary rocks are characterized by enriched LREE and depleted HREE patterns with pronounced negative Eu anomalies. The Chemical Index of Alteration (CIA; 56–86) indicates low to intense chemical weathering in the source area. The unusual decrease in CIA and other weathering indices in the stratigraphically up section is attributed to changes in climate and environmental conditions during the deposition of sediments in the Triassic period. Detangling the signatures is crucial to understanding the mass extinction crisis, particularly the role of anoxia in these events. Triassic black shales represent suboxic to anoxic depositional conditions in the redox-sensitive elemental binary diagrams. The carbon isotope data of the present study is very well supported by the Total Organic Carbon (TOC), which infers that the oceanic biological system tried to recover from the depletion of biological life. The εNd and 87Sr/86Sr systematics record a shift in source terrains from the Early to Late Triassic period. The Early Triassic samples show much older depleted mantle model ages (TDM = 1.94–1.98 Ga) compared to Late Triassic sediments (TDM = 1.76–1.91 Ga). Similar interpretations can be drawn from Th/Sc ratios (from ∼ 6 to ∼ 0.05) and (La/Yb) N ratios (from ∼ 32 to ∼ 5), which record an increase in these ratios from Early Triassic to Late Triassic formations of the Spiti sedimentary rocks. Overall, trace elemental ratios and radiogenic isotopic signatures of the Triassic rocks of the Spiti region point towards Pan African granitic origin with minor impressions from the juvenile mafic-rich sources, such as Panjal Traps, the African craton, and Arabian-Nubian shield.

The black shales of the Middle Triassic Botneheia Formation in Svalbard are known for their fossil richness with abundant ichthyosaur remains and beds of the bivalve Daonella. Vertebrate remains from the Muen Mountain on Edgeøya are shown to have exceptional X-ray contrast due to a combination of sulphide and sulphate permineralisation and pseudomorphing. Radiography imaging of a previously described specimen, PMO 219.250, revealed new and spectacular details such as more carpals, teeth, and skull sutures. Teeth and skull characters are taxonomically significant. supporting the referral of PMO 219.250 to Phalarodon and further suggesting an affinity to P. atavus. Three sulphur phases were identified, with the sulphide sphalerite (ZnS) being the highest temperature phase, followed by the sulphate baryte (BaSO4), and the sulphide pyrite (FeS2). Sulphate permineralisation is also seen in specimens from the Upper Jurassic on Svalbard. We suggest that sulphur-rich fluids have flowed and dissolved barium from the shales and deposited the sphalerite and baryte, and that this could be linked to the Cretaceous HALIP. The Jurassic specimens are only permineralised by baryte, while the Triassic specimens have also been permineralised, but mainly pseudomorphed by baryte with crystals of sphalerite. Lithology differences appear to have controlled the compaction of the Triassic specimens, while the Jurassic specimens have retained their three-dimensional shape due to the baryte emplacement relatively earlier in their depositional history. Although soft tissues are not preserved, the excellent X-ray contrast in the Middle Triassic specimens is reminiscent of pyritised fossil sites such as the Hunsrück Slate (Devonian), Beecher's Trilobite Bed (Ordovician), and the La Voulte-sur-Rhône marls (Jurassic). [ABSTRACT FROM AUTHOR]

The availability of oxygen and nutrients during the Mesoproterozoic (1.6–1.0 Ga) is thought to influence the rate of eukaryote evolution. The cause of the transition from low productivity in the upper Wumishan Formation to organic‐rich sediments in the Hongshuizhuang Formation remains unknown. We report FeHR/FeT, Fepy/FeHR, MoEF, UEF, VEF, and [Ce/Ce*]SN in one core of the Yanliao Basin to study the redox evolution and compare it with other sections in different depths of the Yanliao Basin to get clues of the spatial and temporal redox heterogeneity. Mo‐U covariation, low Co × Mn and CoEF × MnEF, and distribution patterns of trace metals indicate the upwelling events. An upwelling system could fuel nutrients to promote productivity levels in surface water and contribute to anoxic deep waters. The uniformly positive δ15N values are interpreted as sufficient NO3− reduction via denitrification and dissimilatory nitrate reduction to ammonium in a ferruginous upwelling condition. Plain Language Summary: During the Mesoproterozoic Era (1.6–1.0 Ga), ocean anoxia and nutrient limitation have been suggested to explain why complex multicellular eukaryotes did not expand until later in the Neoproterozoic Era. Among several kilometers thick marine carbonates that dominated the Early Mesoproterozoic Era (∼1.6–1.4 Ga) in North China, a suite of black shales discovered in the Hongshuizhuang Formation (∼1.46–1.45 Ga) exhibits high nutrient contents. The origin of nutrient availability needs to be correctly understood. To reveal the potential cause behind these highly productive sediments, we use multiple proxies to study the changes in nutrient and oxygen levels during the Hongshuizhuang Formation deposition. Our results demonstrate that upwelling events provide nutrient availability, which further constrains inconsistent redox evolution in different areas. The loss of sufficient nutrient nitrogen to N2 in the oxic surface water could be largely traced from persistent deep‐ocean Fe(II) consumption brought by upwelling. Key Points: The Yanliao Basin has good connectivity with the Proto‐Asian Ocean, with upwelling events at ∼1.46–1.45 GaSpatial and temporal redox heterogeneity is observed in the Hongshuizhuang Formation, North China, at ∼1.46–1.45 GaIncreasing surface productivity in the Hongshuizhuang Formation was fueled mainly by open‐marine upwelling [ABSTRACT FROM AUTHOR]

A biotic origin of isotopically light graphite in Hadean zircon remains contested, in part because it is unclear how biogenic carbon in sediments behaves during diagenesis, metamorphism and anatexis, and how it can be preserved as inclusions in zircon. Here, we report the discovery of graphitic inclusions in zircon from Rumburk granite in the Lusatian Block of eastern central Europe as the first example of such inclusion-bearing zircon in a well-constrained geological and petrological context. Most graphite inclusions are trapped at the interface between inherited zircon interiors of early Cambrian–Proterozoic age and late Cambrian (496.2 ± 2.3 Ma; 95% confidence) zircon overgrowths that crystallized at ∼700 °C under highly reducing conditions (typically −4.6 log units relative to the fayalite-magnetite-quartz buffer). Zircon overgrowths are also enriched in xenotime component (up to 93 µmol/g P) and δ18O (average δ18O = 7.7‰), both typical for S-type granitic melts. Raman microspectroscopy reveals crystalline and disordered graphitic carbon, but because overgrowth temperatures reached >700 °C, sufficient for complete graphitization, disordering is presumably secondary and caused by in-situ irradiation from the zircon host. Because organic materials were avoided during sample preparation, and inclusions were excavated by ion beam sputtering, exposure to potential C-bearing contaminants can be dismissed. Inclusions range in δ13C from −44.6 to −7.5‰ with a dominant mode at δ13C = −34‰ that is positively skewed. Rayleigh-type graphite precipitation from a CO 2 -CH 4 fluid with a starting composition equivalent to regional black shale (δ13C = −32‰) explains inclusion carbon isotopic range and distribution. Collectively, these observations suggest that graphite was initially trapped in voids formed via dissolution-reprecipitation of trace element enriched, and possibly metamict, detrital zircon in metasedimentary protoliths when exposed to C-O-H fluids during prograde metamorphism. Subsequently, graphite-filled voids in inherited zircon became enclosed when zircon rims crystallized from highly reduced S-type granitic melts. Besides partial disordering of graphitic carbon due to irradiation, there is no indication for post-entrapment alteration, demonstrating that graphitic inclusions in zircon can preserve isotopic biosignatures over hundreds of millions of years. [ABSTRACT FROM AUTHOR]

Vase‐shaped microfossils (VSMs) are found globally in middle Neoproterozoic (800–730 Ma) marine strata and represent the earliest evidence for testate (shell‐forming) amoebozoans. VSM tests are hypothesized to have been originally organic in life but are most commonly preserved as secondary mineralized casts and molds. A few reports, however, suggest possible organic preservation. Here, we test the hypothesis that VSMs from shales of the lower Walcott Member of the Chuar Group, Grand Canyon, Arizona, contain original organic material, as reported by B. Bloeser in her pioneering studies of Chuar VSMs. We identified VSMs from two thin section samples of Walcott Member black shales in transmitted light microscopy and used scanning electron microscopy to image VSMs. Carbonaceous material is found within the internal cavity of all VSM tests from both samples and is interpreted as bitumen mobilized from Walcott shales likely during the Cretaceous. Energy dispersive X‐ray spectroscopy (EDS) and wavelength dispersive X‐ray spectroscopy (WDS) reveal that VSM test walls contain mostly carbon, iron, and sulfur, while silica is present only in the surrounding matrix. Raman spectroscopy was used to compare the thermal maturity of carbonaceous material within the samples and indicated the presence of pyrite and jarosite within fossil material. X‐ray absorption spectroscopy revealed the presence of reduced organic sulfur species within the carbonaceous test walls, the carbonaceous material found within test cavities, and in the sedimentary matrix, suggesting that organic matter sulfurization occurred within the Walcott shales. Our suite of spectroscopic analyses reveals that Walcott VSM test walls are organic and sometimes secondarily pyritized (with the pyrite variably oxidized to jarosite). Both preservation modes can occur at a millimeter spatial scale within sample material, and at times even within a single specimen. We propose that sulfurization within the Walcott Shales promoted organic preservation, and furthermore, the ratio of iron to labile VSM organic material controlled the extent of pyrite replacement. Based on our evidence, we conclude that the VSMs are preserved with original organic test material, and speculate that organic VSMs may often go unrecognized, given their light‐colored, translucent appearance in transmitted light. [ABSTRACT FROM AUTHOR]

The discovery of Santonggou manganese deposit is an important breakthrough in manganese prospecting in East Kunlun. The detrital zircon from two siltstone samples of Santonggou manganese deposit were used for LA-ICP-MS U-Pb dating. The detrital zircon U-Pb ages are ranging from(1 497±17)Ma to(427±4)Ma, with two peaks of 441 and 473 Ma, respectively. The youngest detrital zircon age is(427±4)Ma, indicating the age of Santonggou manganese deposit is later than 427 Ma. The age peaks of detrital zircon are consisting with Early Paleozoic Naji Tal Group, and indicate that the detritals provenance are the middle strata of Naji Tal Group. The Re-Os isochron age of black shale from Santonggou manganese deposits are(387.4±6.2)Ma, indicating that the age of burial diagenesis is Middle Devonian, and the initial precipitation of manganese is earlier. Based on isotopic dating results, the sedimentary age of Santonggou manganese deposit is limited in Late Silurian-Middle Devonian. The relationship between the mineralization of Santonggou manganese deposit and the subduction of Proto-Tethys ocean is discussed based on the main view about genesis of Early Paleozoic marine sedimentary manganese deposit. It is considered that the subduction and closure of Proto-Tethys ocean in Early Paleozoic is the main reason for the mineralization of Santonggou manganese deposit, and the metallogenic age of Santonggou manganese deposit is basically consistent with the closure time of Proto-Tethys ocean. [ABSTRACT FROM AUTHOR]

The Lower Cretaceous syn‐rift deposits of the Douala Basin (Mundeck Formation), located in the equatorial West African margin were investigated in order to determine the palaeoenvironment and organic matter source, redox conditions, palaeoclimate, and tectonic settings, based on facies, organic and inorganic geochemical analyses. The sediments consist of pebble, coarse, medium‐ to fine‐grained sandstone, siltstone, and grey to black fossiliferous shales. The shales are characterized by an average total organic carbon (TOC) of 1.02%, fair to poor source generative potential with present‐day hydrogen index values, which range from 31 to 350 mg HC/g TOC suggesting that the shale contains Type III kerogens with mainly gas generative potential. The organic particles are dominated by phytoclasts (40% on average) and non‐fluorescent amorphous organic matter (34% on average). The palynomorphs represent about 26% on average with a large amount of pollen grain and a minor amount of dinoflagellate cysts and microforaminifera test linings. The inferred depositional environment of the studied sediments is an alluvial fan to fluvio‐lacustrine with shallow marine incursion. This depositional environment received the contribution of aquatic algae and microorganisms with a large amount of terrestrial organic matter, evidenced by the presence of some dinoflagellate cysts and microforaminifera test linings, and relatively higher amounts of SiO2, Al2O3, and phytoclasts. The presence of trace elements such as Ba, Sr, V, Ni, Co and Cr in the analysed samples and their ratio, suggest suboxic to anoxic conditions of deposition with low salinity. The warm to cold and dry climatic conditions prevailed during the deposition of the Mundeck deposits and sediments from active continental margin setting during the lower Cretaceous periods in the Douala Basin as confirmed by inorganic geochemical data. This study sheds light on the early stage of the evolution of the Douala Basin which could be integrated into the context of a mid‐Jurassic to lower Cretaceous regional evolution of the opening of a passive margin. This evolution is characterized by an alluvial fan, fluviatile, lacustrine, lagoon and marine depositional system. This depositional system is recognized as part of the petroleum system recognized within the syn‐rift deposits in the others basins along the West African margin, where giant hydrocarbons have been discovered. [ABSTRACT FROM AUTHOR]

The organic‐rich shale in the upper Permian Dalong Formation in Southern Anhui Province is not only regarded as a high‐quality hydrocarbon source rock, but one of the potential targets for shale oil and gas exploration in Southern China. Organic matter types in such a setting remain a subject of debate. The major point of controversy is whether they are dominated by oil‐prone types or gas‐prone types. A total of 20 rock samples collected from Gangdi‐1 well were conducted for analysis of organic geochemistry. Results show that Dalong Formation shale extracts exhibit a wide range of C12‐C35n‐alkanes and acyclic isoprenoids. The chromatograms display an unimodal distribution with carbon peak in the range of nC18‐nC22 and low quantities of long‐chain (nC25+) n‐alkanes. Relatively high ratios of nC21‐/nC22+ and C27/C29 regular steranes demonstrate that organic matter is mainly originated from lower aquatic organisms and followed by higher plants in a local area. This is also supported by the variations of the δ13C values of C13‐C26n‐alkanes for the target samples being in the range of 3.0‰–5.6‰ offset, which is slightly higher than the corresponding value (1.6‰) of n‐alkanes from a single source. All these pieces of information decipher that the organic matter in Dalong Formation shale may be dominated by type I and followed by type II1. Moreover, the maturity proxies according to both organic petrography (Ro and Tmax) and biomarkers such as ratios of C29 20 S/(20 S + 20R) and C29 ββ/(αα + ββ) together indicate that organic matter in Dalong Formation shale is in a mature stage of hydrocarbon generation. Furthermore, a cross‐plot of total organic carbon versus total sulphur as well as Pr/Ph ratio and Pr/nC17‐Ph/nC18 diagram elucidates that Dalong Formation shales were mainly formed in a marine reducing environment. Finally, two depositional models of organic matter enrichment are proposed. The abundant lower aquatic organisms with few terrestrial detrital inputs and the reducing water environment together promote organic matter accumulation. [ABSTRACT FROM AUTHOR]

A siliciclastic succession is exposed at the Faraghan mountain, northern Persian Gulf, southeastern Iran. A detailed, high-resolution palynological analysis was performed on the Zardkuh, Seyahou, Dargaz, and Sarchahan formations to verify the exact age and palaeogeographic position of the High Zagros Mountains. Two hundred surface samples from this succession were collected and analysed. Most samples yielded abundant and well-preserved chitinozoans, acritarchs, scolecodonts, and cryptospores. Fifty-three chitinozoan species (21 genera) were identified that permitted to establish the Eremochitina brevis, Desmochitina ornensis, Belonechitina henryi, Siphonochitina formosa, Belonechitina robusta, Tanuchitina fistulosa, Acanthochitina barbata, Armoricochitina nigerica, Ancyrochitina merga, Tanuchitina elongata, Spinachitina oulebsiri, and Spinachitina fragilis biozones in ascending stratigraphic order as was previously established for the North Gondwana Domain. These results indicate that the Zagros Mountain Belt of Iran was part of the North Gondwana palaeo-province during the Ordovician-Silurian. On the other hand, these chitinozoan biozones and other associated fauna (e.g. graptolites, trilobites, brachiopods, and conodonts) suggest a late Early Ordovician (Floian) to Early Silurian (Rhuddanian) age range, with unconformities, for this succession. Based on chitinozoan biozones, a distinctive hiatus is present between the Zardkuh and Seyahou formations at Faraghan mountain, which corresponds to the absence of jenkinsi-tanvillensis chitinozoan biozones, encompassing the latest Middle Ordovician (latest Darriwilian: stage slice Dw3) and the early Late Ordovician (Sandbian: the stage slices Sa1 to Sa2 and time slices 5a to 5b). Two chitinozoan species were erected: Belonechitina bifurcaspina sp. nov., Angochitina persianense sp. nov., and Eremochitina cf. brevis was left in open nomenclature. Siliciclastic deposits of the Faraghan mountain yielded rich chitinozoan assemblages. Fifty-three identified chitinozoan species resulted in 12 chitinozoan biozones. Kerogenous black shales contain both the S. oulebsiri and N. persculptus biozones. A hiatus was identified, corresponding to the Dw3 and Sa1–Sa2 stage slices. Two new taxa: B. bifurcaspina and A. persianense, are proposed. [ABSTRACT FROM AUTHOR]

Recently, 2D semiconductor-based heterojunctions emerge as a focal point of intensive research owing to their unique properties, including efficient charge separation and large interface areas. Herein, Ni or Co-doped black phosphorus/molybdenum disulfide (BP/MoS 2 –Y (Y: Ni, Co)) heterojunctions fabricate for photocatalytic H 2 evolution and electrochemical nitrite sensor. Compared to the BP/MoS 2 , the BP/MoS 2 –Ni and BP/MoS 2 –Co exhibit enhanced H 2 performance, as 6.4139 mmol h−1 g−1 and 7.4282 mmol h−1 g−1, respectively, in the presence of Eosin-Y (λ ≥ 420 nm). Furthermore, BP/MoS 2 –Co applies as an electrocatalyst on a GCE for the electrochemical detection of nitrite. To optimize the nitrite sensing performance of BP/MoS 2 –Co, the effect of the pH, amount of material, scan rates, and other conditions study in detail. The BP/MoS 2 –Co displays a linear response within the range of 100–2000 μM with a detection limit of 4.1 μM for DPV. This work can offer an opportunity for hydrogen systems as well as electrochemical sensor applications. • A general method is settled for fabrication of BP/MoS 2 –Y (Y: Ni, Co) heterojunctions. • BP-MoS 2 -Y heterojunctions were tested as catalysts in the photocatalytic HER. • BP-MoS 2 -Y heterojunctions were used as sensor for electrochemical nitride sensing. • A plausible mechanism was proposed for the BP-MoS 2 -Y catalyzed photocatalytic HER. [ABSTRACT FROM AUTHOR]

The characteristics of high concentrations or high activity levels of heavy metals, especially Cd, in soils caused by the pedogenesis of rocks are attracting increased attention. Carbonate rocks and black shales often coexist during geological deposition, but the risk characteristics of heavy metals are different after their weathering into the soil. The purpose of this study was to investigate the element concentrations of a naturally high background value area, to identify patterns of different risk areas, and to make recommendations for the safe usage of farmland. The results showed that, compared with the soil in the carbonate rock area, the soil in the black shale area was more acidified and most of the heavy metal elements were leached. Based on the soil pH value and the heavy metal concentrations, an identification method for land risk areas within naturally high background values was established, and land planning was carried out using this method. The exceeding rates of Cd in rice for the preferential protection area and strict control area were 0.0 and 50.0%, respectively. Therefore, in naturally high background area, the identified lithology can apply to maximize the use of farmland resources. This method provides a basis for preliminary ecological risk screening in naturally high background value areas using the results of the soil survey. A suggestion for the prevention and control of soil pollution in areas with naturally high background values was put forward. In carbonate rock areas, the soil should be closely monitored to prevent soil acidification. [ABSTRACT FROM AUTHOR]

To study the microscopic pore characteristics of marine–continental transitional shale, we studied the Daning–Jixian block of the Shanxi Formation using low-pressure CO2 adsorption (LP-CO2A) and low-temperature N2 adsorption (LT-N2A) methods in conjunction with field emission scanning electron microscopy (FE-SEM), geochemistry, and mineral composition analysis in order to obtain pore structure characteristic parameters. The fractal dimension of the pores was calculated using the Frankel–Halsey–Hill (FHH) model, and the study also discusses the factors that influence the pore structure. The study found that the marine–continental transitional phase shale of the Shanxi Formation has clay mineral contents ranging from 36.24% to 65.21%. The total organic carbon (TOC) contents range from 0.64% to 9.70%. Additionally, the organic matter maturity is high. The FE-SEM and gas adsorption experiments revealed that the transitional shale of the Shanxi Formation possesses a diverse range of pore types with relatively large pore sizes. The dominant pore types are organic and intragranular pores, with pore morphologies predominantly appearing as slit and parallel plate structures. According to the experimental data on gas adsorption, the total SSA values range from 11.126 to 47.220 m2/g. The total PV values range from 0.014 to 0.056 cm3/g. Micropores make up a greater proportion of the total SSA, whereas mesoporous pores make up a greater proportion of the total PV. The distribution of shale pore fractal dimensions D1 and D2 (D1 is 2.470 to 2.557; D2 is 2.531 to 2.755), obtained through LT-N2A data, is relatively concentrated. D1 and D2 have a positive correlation with the TOC content, clay mineral content, and BET-SSA, and D1 and D2 have a negative correlation with the quartz content. D2 is positively correlated with the Langmuir volume, showing that D2 can be used to evaluate the methane adsorption capacity. [ABSTRACT FROM AUTHOR]

The Lower Paleozoic reservoir in the Micangshan tectonic belt is a new shale gas exploration area with excellent potential. However, the black shale's sedimentary environment and tectonic setting and their effects on pore-scale fluid flow have not been thoroughly elucidated and urgently require further research. A large amount of trace and rare earth element data of black shale in this area was tested to analyze the sediment's provenance, tectonic setting, and coupling process, and nuclear magnetic resonance was applied for fluid flow ability determination. The characteristics of trace elements and rare earth elements in shale samples were drilled from the Upper Sinian Doushantuo Formation, the Lower Cambrian Niutitang Formation, and the Lower Silurian Longmaxi Formation in the Micangshan tectonic belt. The results reveal that the provenance of the shales was dominated by island arc volcanic rocks and some ancient fine-grained sediments. The provenances of shale in the Micangshan, Huijunba, and Zhenba areas may have a strong genetic relationship with the igneous rocks from the nearest Hannan massif. The provenance of the Niutitang shale in the Ningqiang area may comprise sediments derived from the Longmenshan continental rift system. The provenance of the shale tends to transition from the island arc to the continental margin from the depositional stage of the Doushantuo Formation to the Longmaxi Formation. The Micangshan tectonic belt inherited the tectonic evolution of the South China block, North China block, and Qinling, and those blocks provided the igneous provenance of the shale by island arcs, which were formed due to weathering caused by the process of subduction and collision orogeny. The movable fluid distribution of the Longmaxi Formation and Niutitang Formation is relatively uniform, and excessive pursuit of large amount of movable fluid will be counterproductive to the shale reservoir. The proportion of the cracks was generally less than 3% except for one sample from the Doushantuo Formation with 12.06%. Based on the centrifugation force in this research, the low fluid flow limits were less than 1.47, and there are strong positive relationships between movable fluid saturation and saturated porosity. In this study, the coupling relationship between the material source and pore scale flow is discussed for the first time, and the results can provide theoretical references for local provenance analysis and tectonic movement. [ABSTRACT FROM AUTHOR]

During the Marinoan Ice Age (ca. 654–635 Ma), one of the 'Snowball Earth' events in the Cryogenian Period, continental icesheets reached the tropical oceans. Oceanic refugia must have existed for aerobic marine eukaryotes to survive this event, as evidenced by benthic phototrophic macroalgae of the Songluo Biota preserved in black shales interbedded with glacial diamictites of the late Cryogenian Nantuo Formation in South China. However, the environmental conditions that allowed these organisms to thrive are poorly known. Here, we report carbon-nitrogen-iron geochemical data from the fossiliferous black shales and adjacent diamictites of the Nantuo Formation. Iron-speciation data document dysoxic-anoxic conditions in bottom waters, whereas nitrogen isotopes record aerobic nitrogen cycling perhaps in surface waters. These findings indicate that habitable open-ocean conditions were more extensive than previously thought, extending into mid-latitude coastal oceans and providing refugia for eukaryotic organisms during the waning stage of the Marinoan Ice Age. Based on geochemical and paleontological data, this study shows that habitable open-oceans extended to mid-latitude coastal oceans during the waning stage of the Marinoan snowball Earth, offering refugia for benthic photosynthetic eukaryotes [ABSTRACT FROM AUTHOR]

The Longmaxi-1 black shales in the Upper Yangtze region are a vital source rocks in southern China. This study investigates the palaeoweathering conditions, provenance, and tectonic setting of the Longmaxi-1 black shale from an elemental geochemical perspective, ultimately revealing its tectonic setting. The results showed that the Longmaxi-1 black shales in the sedimentary period have the characteristics of primary deposition. The Longmaxi-1 black shales were deposited as a primary deposition under a mainly humid climate. However, fluctuations in climatic conditions were recorded from the bottom to the upper part of the formation. The parent rock of the Longmaxi-1 black shales in the Upper Yangtze region is a mixture provenance, mainly composed of intermediate-acid volcanic lithologies (granite and granodiorite), followed by mature quartzite and basalt. Black shale deposition is related to the tectonic setting of active continental margin and island arc-continent collision. The Cathayian orogenic belts and the North Qiangling orogenic belt may have played a role in the genesis of the Longmaxi-1 black shales within the Upper Yangtze region. This study provides significant clues regarding the reconstruction of the palaeoclimatic and palaeogeographical conditions of the Upper Yangtze region during the Early Silurian period. [ABSTRACT FROM AUTHOR]

The Mjølnir impact crater in the Norwegian Barents Sea features among the 20 largest impact craters listed in the Earth Impact Database. The impact is dated to 142 ± 2.6 Ma, corresponding closely to the Jurassic/Cretaceous boundary in the Boreal stratigraphy. Multidisciplinary studies carried out over the last three decades have suggested that the up to 40 km wide crater was created by a 1–3 km diameter impactor colliding with a shallow epicontinental sea, causing regional havoc and a regional ecological crisis that followed in its wake. Only minor evidence for the consequences of the impact for the surrounding depositional basins has been documented so far. This study describes a large submarine slump penetrated by hydrocarbon exploration well 7121/9‐1, located in the southern Hammerfest Basin and approximately 350 km away from the impact site. The slump is dated by a black shale drape, which contains characteristic impact‐related biotic assemblages and potential ejecta material. This precise dating enables us to associate the slump with large‐scale fault movements and footwall collapse along the basin‐bounding Troms‐Finnmark Fault Complex, which we conclude were caused by shock waves from the Mjølnir impact and the passage of associated tsunami trains. The draping black shale is interpreted to represent significant reworking of material from the contemporary seabed by tsunamis and currents set up by the impact. [ABSTRACT FROM AUTHOR]

Samples spanning the Cenomanian–Turonian transition at Guern Halfaya Section of North-Central Tunisia were analysed for elemental and isotopic chemostratigraphic characterization of the OAE-2 global anoxic event. Comparison with other published sections of the same age was achieved. These geochemical analyses, which cover the local Bahloul Formation, add new insights into the palaeoceanographic evolution of the southern Tethyan margin during the Cenomanian–Turonian transition. The use of discrete redox-sensitive and primary productivity-sensitive trace element data coupled to isotopic and biostratigraphic events is shown as leading proxies for the determination of prevailing warming palaeoceanographic conditions, in terms of productivity and climate, during the OAE-2 in the northern margin of Africa. Such event is believed to have generated one among the most significant source rocks of the region. [ABSTRACT FROM AUTHOR]

The shale gas exploration in Changning, Weiyuan, Fuling Jiaoshiba, and other areas has achieved great success in the Sichuan Basin, and the basin margin of the Sichuan Basin will be an important target in the future. In view of the lack of understanding of shale gas reservoir characteristics of the basin margin area of the Sichuan Basin, this paper conducts a study on reservoir characteristics and gas-bearing properties of this area using qualitative and quantitative techniques. The results show that the thickness of the black shale reservoir in the Qianjiang area is up to 33 m, the kerogen sapropelic type (I) is dominant, and Ro ranges from 2.2 wt% to 3.39 wt%. The mineral composition is relatively complex, mainly composed of quartz and clay minerals. Quartz content is in the range between 9.4 wt% and 79 wt% (average = 47.48 wt %), while clay content is in the range between 10.02 wt% and 43.6 wt% (average = 29.41 wt %). There are various types of reservoir spaces, mainly including organic pores dominated by matrix pores, intergranular and intragranular pores, intergranular and intragranular dissolution pores, secondary dissolution pores, and microfractures, among which organic pores are the main pore types. The pore volume of nanopores is 0.009897-0.017177 cm3/g (average = 0.01304 c m 3 / g), and the specific surface area ranges from 12.1 m2/g to 35.1 m2/g (average = 20.47 m 2 / g). Micropores and mesopores are the main pore sizes for the development of organic pores. Quartz particles promote the development of reservoir space, while clay minerals are not conducive to the development of pores. The total gas content ranges from 0.5 m3/t to 4.43 m3/t (average = 1.69 m 3 / t). Its enrichment is controlled by many factors. The increase of organic matter abundance is the material basis for shale gas enrichment. The development of organic pores provides high-quality storage space for shale gas preservation. The development of different mineral components restricts the enrichment of shale gas. [ABSTRACT FROM AUTHOR]