International Journal of Coal Geology最新文献

{"title":"Evaluation of coal mine drainage and associated precipitates for radium and rare earth element concentrations","authors":"Bonnie McDevitt ,&nbsp;Charles A. Cravotta III ,&nbsp;Ryan J. McAleer ,&nbsp;John C. Jackson ,&nbsp;Aaron M. Jubb ,&nbsp;Glenn D. Jolly ,&nbsp;Benjamin C. Hedin ,&nbsp;Nathaniel R. Warner","doi":"10.1016/j.coal.2024.104547","DOIUrl":"https://doi.org/10.1016/j.coal.2024.104547","url":null,"abstract":"<div><p>Coal mine drainage (CMD) and associated metal-rich precipitates have recently been proposed as unconventional sources of rare earth elements (REEs). However, the potential occurrence of radium (Ra), a known carcinogen, with the REE-bearing phases has not been investigated. We hypothesized that Ra may occur in solids that are precipitated from CMD as a “radiobarite” solid solution ((Ba,Sr,Ra)SO₄) and/or adsorbed with hydrous metal oxides. REEs have been documented to sorb or co-precipitate with iron (Fe), manganese (Mn), and aluminum (Al) oxyhydroxide in CMD solids. Likewise, Ra has been documented to sorb to hydrous Fe and Mn oxides especially where sulfate (SO₄) and/or barium (Ba) concentrations are insufficient to precipitate radiobarite. Thus, we conducted the first-ever survey of Ra concentrations in corresponding CMD water and solid samples in the United States. Samples were analyzed from 4 untreated and 9 treated CMD sites in both the bituminous and anthracite coal regions of Pennsylvania across a range of pH and SO₄ concentrations. The dissolved Ra in CMD was relatively low (&lt;0.5 Bq/L), consistent with radiobarite solubility; however, CMD solids were largely composed of amorphous Fe, Al, and Mn oxyhydroxide and silicate minerals. Ra was associated with Mn-enriched CMD solids, upwards of 875 Bq/kg. Total REE + yttrium (Y) content in the CMD solids was enriched upwards of 3600 mg/kg and was significantly correlated with Al content. These preliminary results suggest that REE extraction may target Al-rich solids to avoid Ra in Mn-rich solids.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0166516224001046/pdfft?md5=67423a80d2c08b9416a3db6ead8d212b&pid=1-s2.0-S0166516224001046-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141324630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diagenesis and mineralization in the Central African Copperbelt, implications from the reflectance of pyrobitumen and Kübler (illite crystallinity) index","authors":"Qiuping Liu ,&nbsp;Pascal Mambwe ,&nbsp;Ralf Littke ,&nbsp;Philippe Muchez","doi":"10.1016/j.coal.2024.104534","DOIUrl":"https://doi.org/10.1016/j.coal.2024.104534","url":null,"abstract":"<div><p>The Central African Copperbelt stands out as one of the world's largest sediment-hosted Cu-Co provinces, contributing to over 60% of global Co production. A comprehensive basin analysis approach is imperative for unraveling the ore-forming processes, encompassing an understanding of the diagenesis or metamorphism that the mineralized rocks underwent. In this study, two types of pyrobitumen (burial related and burial plus hydrothermal related) reflectance values have been measured, which record maximum temperatures during deep burial and hydrothermal imprint. The calculated temperatures provide important information about the maximum burial and hydrothermal fluid temperatures in distinct regions of the Copperbelt. The average burial related pyrobitumen reflectance for Nkana, the southeastern part of the Copperbelt, ranges between 3.43 and 3.75% BR_r, indicating a maximum burial temperature of about 240 °C. Moving towards the central part of the Copperbelt at Luiswishi, the average pyrobitumen reflectance varies between 2.65 and 2.87% BR_r, with calculated maximum burial temperatures reaching about 220 °C. In the northwestern part (Tenke Fungurume mining district, TFMD), the maximum burial temperatures decrease to approximately 200 °C, based on the calculation of pyrobitumen reflectance at 2.10% BR_r. This decreasing temperature trend from southeast to northwest corresponds to the observed decrease in metamorphic grade across the Copperbelt, ranging from amphibolite and upper greenschist facies in the Zambian part to prehnite-pumpellyite facies in the Congolese Copperbelt. The temperatures calculated during maximum burial, especially at the Nkana ore deposit, are lower than those previously proposed based on the mineralogy of the rocks, i.e. upper greenschist facies. However, the latter does correspond to the temperatures reached by the mineralizing fluids in this area and thus rather reflects the alteration assemblage and temperature. The average burial plus hydrothermal related pyrobitumen reflectance measured at TFMD ranges between 3.06 and 5.36% BR_r, indicating calculated average temperatures of 300–350 °C. These temperatures align with those recorded for the late diagenetic to syn-orogenic mineralization by fluid inclusion microthermometry (180–340 °C) at TFMD. The data suggests a pervasive migration of hydrothermal fluid through the rocks, contributing to the observed pyrobitumen reflectance. The illite crystallinity of the examined samples is notably high. At Nkana, the KI values range between 0.10 Δ°2θ and 0.22 Δ°2θ, for Luiswishi between 0.12 Δ°2θ and 0.24 Δ°2θ, for Kamoto between 0.17 Δ°2θ and 0.23 Δ°2θ, for TFMD between 0.17 Δ°2θ and 0.25 Δ°2θ, which indicates all these samples were placed in epizone, with only a few in anchizone. This high value could be attributed to two potential factors: the admixing of detrital muscovite to the sediments or the influx of potassium due to the pervasive","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141303307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding the burial history and the hydrocarbon potential of the late Paleozoic Claromecó foreland Basin (Southwestern Gondwana, Argentina) by combining organic geochemistry, organic petrology, and thermal modeling","authors":"María Belén Febbo ,&nbsp;Silvia Omodeo-Salé ,&nbsp;Andrea Moscariello","doi":"10.1016/j.coal.2024.104546","DOIUrl":"https://doi.org/10.1016/j.coal.2024.104546","url":null,"abstract":"<div><p>The Claromecó foreland Basin (Carboniferous–Permian; southern Buenos Aires province, Argentina) is key to understanding the paleotectonic evolution of the southwestern Gondwana margin and is relevant to energy resource exploration. This study reconstructs the thermal and burial history of the Claromecó Basin by integrating geochemical data, organic petrology, and thermal modeling techniques. Cores samples of the Tunas Formation (Pillahuincó Group, Early Permian) were studied. A 1D thermal model was constructed, calibrated with vitrinite reflectance measurements (VRo %), and corroborated with fluid inclusion and apatite fission track data from previous studies. Rock-Eval pyrolysis results show TOC% values ranging from 0.13 to 60.35 wt%. The Hydrogen index (HI &lt; 50 mg HC/g TOC) and Oxygen index (OI &lt; 50 mg CO₂/g TOC) indicate the dominance of Type III and Type IV kerogens, most likely resulting from the thermal maturation of an original Type III kerogen. Petrologic observations confirm the presence of macerals from the inertinite group, as well as minor amounts of vitrinite and liptinite. The Tmax displays a temperature range mostly from 460 to 610 °C. The VRo % values range from 1.5 to 2.0%. Geochemical data combined with VRo % measurements confirm a late catagenesis to metagenesis stage within the wet to dry gas window for coals and organic-rich strata.</p><p>In order to constrain the thermal evolution of the basin infill, different scenarios were tested by varying the heat flow and the missing section thickness associated with the uplift and erosion of the basin (Permian–Cenozoic unconformity). The best calibration results were obtained with an erosion thickness of 3000 up to 4200 m and paleo heat flow peaks of either 60 or 80 mW/m² during the Lower Permian–Lower Cretaceous. The Tunas Formation was deposited and buried during the Permian–Triassic (Gondwanides Orogeny phase), reaching a maximum temperature of 180 °C. The results obtained by combining geochemical analysis, organic petrology, and thermal modeling techniques indicate that the coal beds of the Tunas Formation could have a current potential as gas-prone source rocks. Despite that, the hydrocarbon generation capacity of coal levels is currently low due to the high percentage of residual (Type IV) kerogen. Further research could help clarify if the hydrocarbons potentially expelled by these source rocks have been lost due to migration or could be trapped somewhere in the basin.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141302474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineralogy and geochemistry of rare metal (Zr-Nb-Hf-Ta-REE-Ga) coals of the seam XXX of the Izykh Coalfield, Minusinsk Basin, Russia: Implications for more widespread rare metal mineralization in North Asia","authors":"A.V. Vergunov ,&nbsp;S.I. Arbuzov ,&nbsp;D.A. Spears ,&nbsp;A.S. Kholodov ,&nbsp;S.S. Ilenok","doi":"10.1016/j.coal.2024.104542","DOIUrl":"10.1016/j.coal.2024.104542","url":null,"abstract":"<div><p>This study focuses a comprehensive mineralogical and geochemical study of rare-metal (Zr-Nb-Hf-Ta-REE-Ga) mineralization in the Permian coal seam XXX-XXXa of the Izykh Coalfield, Minusinsk Basin, southern Siberia. A link is demonstrated between the accumulation of rare metals in the coal with a volcanogenic rock parting up to 45 cm thick separating the coal seams. The floor of seam XXX is also characterized by the presence of pyroclastic material, which affects the level of accumulation of rare elements in the coal of the seam. Coals and intra-seam rock partings in seam XXX-XXXa have abnormally high concentrations of Zr, Nb, Hf, Ta, REE and Ga. In coal ash samples, the contents of some elements are highly evaluated, e.g., 1.4% Zr, 0.26% Nb, 164 ppm Hf, 17.9 ppm Ta, 0.8% REE, 0.13% Y, and 226 ppm Ga. The concentration of rare elements is higher in the coal and coal ash of the XXX coal seam than in the XXXa coal seam. The accumulation of anomalous concentrations of Zr-Nb-Hf-Ta-REE and Ga is mostly specific for the rock parting between the XXX and XXXa seams, as well as for the coals in contact with this parting. Zirconium, Nb, Y, and REE form more contrasting halos near the parting compared to Ta, Hf, and Ga. This is explained by the different mobility of the elements under weathering and diagenetic conditions. Other ore elements are concentrated to a greater extent in the coal in the near-contact zone, as well as at a distance from the partings. Ore material is concentrated primarily in the fine-dispersed mineral phase represented mainly by Zr-Nb-Ti-Fe oxides, complex Nb-Zr-P silicates, and REY-bearing phosphates (monazite, xenotime). Volcanogenic pyroclastics of acidic and alkaline composition (rhyolite-pantellerite) influenced the accumulation of rare metals in coal. Volcanic ash, transported from a distant source, served as the raw material for the formation of the rock interlayer in coal. The composition of this volcanic ash is believed to correspond to a pantelleritic tuff. These findings are comparable to those reached in earlier work on the altered ash in the coal seam XI of the Kuznetsk Coal Basin, which has similar geochemical features and is also of Permian age. Complex Zr-Nb-Hf-Ta-REE-Ga mineralization in the coals of the Kuznetsk and Minusinsk basins, associated with volcanogenic pyroclastics, indicates a wide manifestation of active acid and alkaline volcanism during the formation of coal deposits and the possibility of identifying similar mineralization in Permian coals of East and North Asia.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141281203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geomechanical characterization and mineralogical correlation of compositionally diverse world-class Kazakhstani source rocks: Insights from nanoindentation testing","authors":"Riza Nurbekova ,&nbsp;Xiangyun Shi ,&nbsp;Randy Hazlett ,&nbsp;David Misch ,&nbsp;Milovan Fustic ,&nbsp;Reinhard F. Sachsenhofer","doi":"10.1016/j.coal.2024.104545","DOIUrl":"10.1016/j.coal.2024.104545","url":null,"abstract":"<div><p>Extensive nanoindentation testing over a range of deflection depths of up to 4 μm yielded a large dataset, providing a viable framework for the statistical assessment of the mechanical properties, specifically elastic modulus (<em>E</em>) and hardness (<em>H</em>), of compositionally diverse organic-rich mudstone samples. The data from indentations as shallow as 300–400 nm were clustered using the <em>k</em>-means algorithm to identify three mechanical categories in the samples: a soft pseudophase (e.g., organic matter, gypsum, and clay minerals), a stiff pseudophase (e.g., quartz and feldspar), and a transitional composite-like pseudophase bridging the soft and hard minerals. The initially diverse values of <em>E</em> and <em>H</em> for the mechanical pseudophases were observed to converge to a constant value at indentations beyond 2–2.5 μm (varying between different samples), implying the existence of a minimal probing depth for assessing the bulk <em>E</em> and <em>H</em> of heterogeneous mudstone samples. The obtained bulk <em>E</em> and <em>H</em> values (8–21 GPa and 0.3–0.9 GPa, respectively) demonstrated a strong correlation with the mineralogical composition of the indented samples. Despite containing a notable proportion of mechanically stiff components (&gt;45 vol%), the bulk mechanical parameters determined in this study were significantly lower than those reported for major shale formations such as the Barnett and Longmaxi Shale. This discrepancy is primarily due to the presence of organic matter with low thermal maturity (R_o &lt; 0.6%), which constitutes &lt;36 vol% of the samples, and a significant gypsum content, accounting for &lt;15 vol%.</p><p>The employed approach not only demonstrated the importance of choosing the proper indentation depths for investigating the mechanical properties of highly heterogeneous mudstone rocks and their constituent minerals, but it also illustrated the capability of examining various volumes of investigation using nanoindentation, approaching macroscopic values, and identifying a representative element volume (REV). The findings also provided crucial insights into the fracability and overall producibility of the investigated formations, thereby enhancing our understanding of their extraction potential.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141277094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical tracers associated with methane in aquifers overlying a coal seam gas reservoir","authors":"J.K. Pearce ,&nbsp;H. Hofmann ,&nbsp;K. Baublys ,&nbsp;D.I. Cendón ,&nbsp;S.D. Golding ,&nbsp;S.J. Herbert ,&nbsp;Z. Bhebhe ,&nbsp;A. Nguyen ,&nbsp;P. Hayes","doi":"10.1016/j.coal.2024.104535","DOIUrl":"https://doi.org/10.1016/j.coal.2024.104535","url":null,"abstract":"<div><p>Understanding inter-aquifer connectivity or leakage of greenhouse gases and groundwater to aquifers overlying gas reservoirs is important for environmental protection and social licence to operate. Australia's Great Artesian Basin (GAB) is the largest artesian groundwater system in the world with groundwater extracted for agriculture, livestock, mines, energy, private or town water supply. Microbial coal seam gas (CSG) and production water are also extracted from the GAB. Here a range of groundwater tracers is used to investigate the potential for gas and groundwater connectivity between the CSG reservoir and aquifers.</p><p>The GAB aquifer and alluvium contained a range of methane concentrations (0.001 to 2100 mg/L) that exhibit an increase with depth and δ¹³C-CH₄. Aquifer and alluvium groundwater ⁸⁷Sr/⁸⁶Sr were in the range 0.7042 to 0.7082. CSG production waters however had non-radiogenic, distinctive ⁸⁷Sr/⁸⁶Sr signatures &lt;0.7036, indicating a lack of significant groundwater leakage. One gassy aquifer bore with 160 mg/L methane conversely has ⁸⁷Sr/⁸⁶Sr, δ¹³C-CH₄, δ²H-CH₄ and δ¹³C-DIC values overlapping the CSG waters. In several aquifers δ³⁴S-SO₄ and δ¹⁸O-SO₄ are sourced from windblown surface salts of inland Australian playa lakes in recharge waters. Bacterial sulphate reduction is additionally occurring in a regional aquifer. Cosmogenic isotopes and tritium show recent recharge and mixing with older groundwaters in several shallow aquifers.</p><p>Groundwater and gas signatures indicate that leakage of groundwater and methane from the CSG reservoir was not occurring in the majority of areas investigated here. Methane was consistent with in situ generation in shallow GAB aquifers by primary microbial CO₂ reduction or acetate fermentation. Connectivity of one alluvial bore and the underlying GAB aquifer could not be completely ruled out. Separately, one gassy Springbok GAB aquifer bore is either connected to the underlying CSG gas reservoir, or has in situ secondary microbial CO₂ reduction producing methane from interbedded coal within the aquifer. This study is relevant to other basins in Australia and internationally where gas is observed in aquifers that overly conventional, unconventional or coal seam gas reservoirs.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0166516224000922/pdfft?md5=79a21be44647689570498e729acffea5&pid=1-s2.0-S0166516224000922-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141290912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Palynostratigraphy of the Mississippian-Pennsylvanian boundary in the Tyler Formation, Williston Basin, USA: Implications for organic matter-rich source rocks and paleoenvironmental reconstruction","authors":"Ahmed Mansour ,&nbsp;Thomas Gentzis ,&nbsp;Timothy O. Nesheim ,&nbsp;Jian Wang ,&nbsp;Xiugen Fu ,&nbsp;Mohamed S. Ahmed ,&nbsp;Humberto Carvajal-Ortiz","doi":"10.1016/j.coal.2024.104533","DOIUrl":"10.1016/j.coal.2024.104533","url":null,"abstract":"<div><p>The Carboniferous was a period of intense environmental perturbations, climate changes between greenhouse and icehouse, eustatic sea level change, and accumulation of organic carbon-rich sediments. At this time, the Tyler Formation was deposited in the midcontinent USA. A detailed palynological analysis of the Tyler Formation revealed a highly diverse assemblage of spores with minor pollen content, represented by 100 species belonging to 51 genera. Stratigraphically constrained spores and pollen grains were used to construct three interval zones of middle-late Chesterian (late Viséan-Serpukhovian) to early Morrowan (middle Bashkirian) ages. The stratigraphic position of the Mississippian-Pennsylvanian boundary was determined in the lower Tyler Formation based on the last appearance of typical forms of the late Chesterian, including <em>Tripartites vetustus</em>, <em>Knoxisporites triradiatus</em>, <em>Knoxisporites stephanephorus</em>, <em>Densosporites diatretus</em>, and <em>Schopfipollenites acadiensis</em>, compared to the first appearance of early Morrowan <em>Crassispora kosankei</em>, <em>Cirratriradites saturnii</em>, <em>Radiizonates aligerens</em>, and <em>Raistrickia saetosa</em>. Palynofacies analysis and statistical clustering of the Tyler Formation showed three palynofacies assemblages. PFA-1 showed moderate relative abundances of phytoclasts and AOM, suggesting deposition close to fluvio-deltaic and shallow marine environments, while PFA-2 exhibited high abundances of phytoclasts, mostly of opaque wood, reflecting deposition in active river-dominated delta plains. PFA-3 showed the highest abundances of AOM, suggesting deposition in a shallow marine environment. Organic petrography and geochemistry data indicate that the Tyler Formation is one of the best source rock intervals throughout the midcontinent USA. Based on organic matter richness, the Tyler Formation is subdivided into three groups. The first group has TOC contents higher than 10 wt% of kerogen Types III, mixed II/III, and II with excellent hydrocarbon generation potential. The second group has TOC content in the range of 2–10 wt% of kerogen Types III, mixed II/III, and II, and fair to excellent hydrocarbon generation potential. The third group shows organic matter richness with TOC content below 2 wt% with good organic matter richness and kerogen Types III to IV, and poor to fair hydrocarbon generation potential. The organic matter thermal maturity is evaluated based on T_max and VRo% values, suggesting that all samples of Tyler Formation are in the early to late stages of the oil window. However, care should be considered when assessing a mature source rock because the kerogen typing and generation is based on present-day TOC, S₂, and HI rather than their original values.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141187741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Organic petrology, palynology, and geochemistry of soils from serpentine barrens, Chester and Lancaster counties, Pennsylvania: Notes on maceral development","authors":"James C. Hower ,&nbsp;Jennifer M.K. O'Keefe ,&nbsp;Roger Earl Latham ,&nbsp;Shifeng Dai ,&nbsp;Luis F.O. Silva ,&nbsp;Kevin R. Henke ,&nbsp;Jon S. Thorson","doi":"10.1016/j.coal.2024.104532","DOIUrl":"10.1016/j.coal.2024.104532","url":null,"abstract":"<div><p>An investigation of the soils developed on ultramafic rocks in the State Line Serpentinite Belt in southeastern Pennsylvania demonstrated that the mineral assemblages are dominated by quartz, with lesser amounts of the serpentine group minerals lizardite and antigorite, and clinochlore, among other minerals. The samples have up to 39.91% MgO, 22,500 μg/g Cr, and 3300 μg/g Ni (ash basis). The light rare earth elements have a significant correlation to MgO/(MgO + SiO₂) while the distribution of Cr is random. The organic matter in the soil bears a strong similarity to lignite and subbituminous macerals. Wood-derived macerals showed variations from relatively pristine wood to degraded and attrital forms with evidence of fungal and faunal activity. Macrinite ranged from coprolitic forms to amorphous masses with little or no recognizable structure. The pollen assemblages were dominated by <em>Pinus</em> sp., <em>Quercus</em> sp., and <em>Ribes</em> sp. Analysis of the fungal assemblages and guild structures suggests that the Goat Hill Barrens assemblage differed from the New Texas Barrens and Nottingham Barrens assemblages and that the guild structures encountered are both similar to those encountered in peatlands while also very different, especially in the proportion of arbuscular mycorrhizal fungal remains.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141187738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Raman Spectroscopy for the characterization of the macromolecular structure of Highveld coals (South Africa)","authors":"Itumeleng V. Matlala ,&nbsp;Ofentse M. Moroeng ,&nbsp;Stavros Kalaitzidis ,&nbsp;Nicola J. Wagner","doi":"10.1016/j.coal.2024.104531","DOIUrl":"10.1016/j.coal.2024.104531","url":null,"abstract":"<div><p>Industrial applications of coal rely on understanding its macromolecular structure, which is primarily controlled by coal type and rank. The present study assessed five (5) samples from different collieries extracting coal from the No. 4 Seam of the Highveld Coalfield and their float products, produced at relative densities (RD) of 1.7 and 1.9 g/cm³. The aim was to assess changes in maceral composition and coal quality following the density fractionation, and to use Raman Spectroscopy to compare differences in macromolecular structures between the parent samples and the float products. Raman parameters were also determined for specific macerals, i.e., semifusinite and collotelinite. Mean random vitrinite reflectance (%RoV) values for the studied coals range between 0.57 and 0.60% (medium rank D/C bituminous) and the parent coals are inertinite-rich (70.3 to 88.7 vol% mmf), enriched in semifusinite and inertodetrinite. Following density fractionation, reactive macerals (a combination of liptinite, vitrinite, and reactive semifusinite) are enriched in the float products (designated by “F”), specifically in the products obtained at the 1.7 RD. In comparison, the proportion of inert macerals is higher in the F1.9 samples. These differences in maceral composition are reflected in the Raman spectra and parameters. Although the G and D1 bands for the parent coals and F1.9 samples are similar, these bands are narrower than for the F1.7 samples, indicative of greater aromaticity. The G FWHM values for the F1.9 samples are comparable to those for the parent coal samples, and lower than for the F1.7 samples. This reflects larger differences in maceral composition between the parent coals and the F1.7 samples. In contrast, the D1 FWHM values for the float products, particularly the F1.7 samples, are slightly higher than the parent coals, reflecting a disordered aromatic character mainly related to the presence of aliphatic chains. The Raman spectra for the F1.7 samples are more like that for collotelinite. In contrast, the Raman spectra and parameters (G and D1 FWHM) for the F1.9 samples are more comparable to semifusinite. Thus, the increased aliphaticity for the F1.7 samples is attributed to the relative enrichment of reactive macerals, whereas higher aromaticity for the F1.9 samples reflects a larger proportion of inert macerals<strong>.</strong> Raman spectroscopy expanded on the petrographic data by interrogating the macromolecular structure of the isorank Highveld coals and their float products. This may assist in predicting the behaviour of the coals during industrial applications (i.e., liquefaction, gasification, combustion, and carbon fibre production).</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0166516224000880/pdfft?md5=0f0d6ad7ecf7e2e6f30b2aeac9a5c94d&pid=1-s2.0-S0166516224000880-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141134850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ranking the oil contribution of individual layers in a lacustrine shale oil system based on non-hydrocarbon analysis by FT-ICR MS","authors":"Ming Yuan ,&nbsp;Caineng Zou ,&nbsp;Songqi Pan ,&nbsp;Guosheng Zhang ,&nbsp;Quan Shi ,&nbsp;Lingyuan Xie ,&nbsp;Zhengfu Zhao ,&nbsp;Yating Shen ,&nbsp;Zhenhua Jing","doi":"10.1016/j.coal.2024.104528","DOIUrl":"10.1016/j.coal.2024.104528","url":null,"abstract":"<div><p>Identifying the dominating oil-producing layer(s) within a shaly system, typically characterized by multiple layers with similar properties, is always a critical yet formidable task, as the oil component disparities among these closely adjacent layers are too minor to be resolved by the traditional geochemical fingerprints. This challenge is now likely addressed by high-resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS), which can resolve thousands of non-hydrocarbons that could serve as new fingerprints. Taking a typical shaly system in the Ordos Basin in China as an example, the specific proportions of non-hydrocarbon compounds from the retained petroleum of different source rock layers (rock extracts) and the produced oil at the wellhead were identified by FT-ICR MS. Their compositional similarity was calculated using a multidimensional scaling (MDS) method, and the layers hosting the retained petroleum with higher compositional similarity to the produced oils are considered to be the main contributors to oil production. The results show that the main producing layers identified by FT-ICR MS differ from those proposed based on traditional fingerprints like the Rock-Eval parameters. A typical example is that the thick low-TOC shales, conventionally proposed to be unessential to oil production, seem to have a similar contribution, if not higher, to their thick silty counterparts. This divergence may be attributed to the fact that the conventional fingerprints primarily rely on the rock extracts from a vertical well section, which may only represent a limited lateral area, while the non-hydrocarbon similarity approach involving the produced oil appears to be more realistic, as it can consider the engineering processes, like the horizontal well track and the hydraulic fracturing effects. The current approach provides a novel route for identifying the dominating producing layer(s) in a shale oil system, which may have extensive potential for optimizing the production strategy of shale oil wells.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141033487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}