Inertinite Macerals Research Articles

Organic petrology of Carbondale Formation coal beds and marine roof shales in Western Kentucky, Eastern Interior (Illinois) Basin, USA

Abstract Ten samples of Carbondale Formation (late Middle Pennsylvanian, Westphalian D) roof shale strata from the Western Kentucky Coal Field (Eastern Interior Basin, USA) were analyzed petrographically to gain a better understanding of the organic composition of the shales. The samples were collected in conjunction with a coal bed methane exploration program, so a direct comparison of the organic composition of the shales, and the coal beds that directly underlie them, could be made. Petrographically, total vitrinite contents in the shales average 20.8% (mineral matter free basis, mmf), which is significantly lower than the average vitrinite content of Carbondale Formation coal beds (avg. 81.8%, mmf; n = 32). In contrast, total liptinite contents average 49.7% (mmf) in the shales, which is significantly higher than the average liptinite content of Carbondale coals (avg. 7.0%, mmf). Amorphinite and bituminite were found to be the most abundant liptinite macerals in the shales, but were not recorded from the coal samples. Likewise, total inertinite contents were much higher in the shales (avg. 29.6%, mmf), than in the coals (avg. 11.0%, mmf). A type of macrinite identified as “granular macrinite” was the dominant inertinite maceral in the shales, but was absent in the coal samples. Although the average desorbed gas contents of Carbondale Formation coals and shales are low and currently uneconomical (avg. 0.9 ml/g [28.8 scf/ton] for the shales, 2.4 ml/g [76.9 scf/ton] for the coals, as received basis), they nonetheless represent a potential future gas resource.

Liquid hydrocarbon generation potential from Tertiary Nyalau Formation coals in the onshore Sarawak, Eastern Malaysia

Tertiary coals exposed in the north-central part of onshore Sarawak are evaluated, and their depositional environments are interpreted. Total organic carbon contents (TOC) of the coals range from 58.1 to 80.9 wt. % and yield hydrogen index values ranging from 282 to 510 mg HC/g TOC with low oxygen index values, consistent with Type II and mixed Type II–III kerogens. The coal samples have vitrinite reflectance values in the range of 0.47–0.67 Ro %, indicating immature to early mature (initial oil window). T max values range from 428 to 436 °C, which are good in agreement with vitrinite reflectance data. The Tertiary coals are humic and generally dominated by vitrinite, with significant amounts of liptinite and low amounts of inertinite macerals. Good liquid hydrocarbons generation potential can be expected from the coals with rich liptinitic content (>35 %). This is supported by their high hydrogen index of up to 300 mg HC/g TOC and Py-GC (S 2) pyrograms with n-alkane/alkene doublets extending beyond C30. The Tertiary coals are characterised by dominant odd carbon numbered n-alkanes (n-C23 to n-C33), high Pr/Ph ratio (6–8), high T m /T s ratio (8–16), and predominant regular sterane C29. All biomarkers parameters clearly indicate that the organic matter was derived from terrestrial inputs and the deposited under oxic condition.

Effect of volatile matter release on optical properties of macerals from different rank coals

Ever since the recognition that macerals behave differently during the coking process, their thermal behaviour and its relationship with coke properties have become research topics of widespread interest. The present study is focused on the characterization of six bituminous coals of different rank from Upper Silesia (Poland) and their carbonized products obtained in a relatively high-capacity thermogravimeter under inert atmosphere and well-controlled heating conditions. A combined maceral–reflectance analysis was performed on samples carbonized at temperatures of 400, 450, 550, 750 and 1000°C. Under such conditions, only coals with a reflectance of over 1.0% passed through a fluid stage as a result of which the coal particles lost their integrity. The reflectance of all the macerals was observed to increase with the pyrolysis temperature, temperature being the most relevant factor in determining the reflectance of inertinite macerals. The amount of unreactive inertinite exhibited a wide range of variation, with the lowest rank coals showing the smallest proportion of unreactive inertinite. The reflectance cut-off values separating reactive and unreactive inertinite decreased with coal rank to a stable value of ca. 1.5% for the highest rank coal. A 67–75% volatile matter release was required to cause a significant increase in the reflectance of the components.

A critical re-examination of the petrology of the No. 5 Block coal in eastern Kentucky with special attention to the origin of inertinite macerals in the splint lithotypes

Abstract The Pennsylvanian No. 5 Block coal bed in eastern Kentucky is one of several coals considered to be among the splint coals of the Central Appalachians. The coals are generally noted for their inertinite-rich dull lithotypes. Petrographic aspects of the lithologies reveal both fire-derived and degradation-derived inertinites in the assemblages. Fire is not an exclusive contributor to the origin to inertinite macerals; there are many other biological factors, such as the actions and interactions of fungi, bacteria, and insects, which must be considered in the alteration of plant materials to form inertinite macerals. Fungi physically and chemically alter plant tissues to form macerals with a distinct morphology and chemistry different than those formed from fire and other abiological processes. Insects, as secondary sources of wood degradation within a mire, are responsible for physical, such as boreholes from wood-consuming insects, and chemical alteration of plants. Degradation observed in macrinite may be boreholes from wood-consuming insects such as mites. Some inertinite macerals, in particular, macrinite, may be the result of inert fecal pellet conglomerates preserved in the mire. Overall, macerals of the same name can form from multiple and complex biological and abiological processes.

Petrological and Geochemical Investigations of Rajpardi Lignite Deposit, Gujarat, India

The present paper entails the petrographic and chemical characteristics of the lignite samples drawn from the Rajpardi lignite deposit of Bharuch district, Gujarat. This lignite contains a high concentration of huminite which is dominated by telohuminite, followed by detrohuminite. Liptinite and inertinite macerals are very low in concentration. The dominant microlithotype is humite. Its elevated volatile matter and high hydrogen content depicts its perhydrous nature. The study reveals that this lignite originated in a limno-telmatic to telmatic condition. The paleomire is further characterized as a wet moor having moderate to high flooding with good tissue preservation and increasing bacterial activity.

Petrographic characteristics and palaeoenvironmental setting of Upper Triassic Olang coal deposits in northeastern Iran

This study investigates the petrographic analysis, microlithotype, and palaeoenviroment of deposition of the upper Triassic Olang coal deposits in northeastern Iran. The average maceral composition of the studied coals consisted of 82.3, 8.9, 0.4 (vol.%), vitrinite, inertinite and liptinite groups, respectively. Vitrinite macerals include equal portions of collotelinite and; collodetrinite and a small quantity of corpogelinite also is present in all coal seams. Semifusinite and fusinite are the most abundant inertinite macerals. The Ground Water Index (GWI) suggests that these coal seams have evolved in a limnic coal facies (a bog palaeomire system) under ombrotrophic hydrological conditions, except the K 6 G coal seam, which evolved a limnic coal facies (a bog palaeomire system) under mesotrophic hydrological conditions. The Vegetation Index (VI) values are indicative of the dominance of herbaceous plants in the formation of coal seams of the Olang area.

Petrology, mineralogy, and geochemistry of the Ge-rich coal from the Wulantuga Ge ore deposit, Inner Mongolia, China: New data and genetic implications

Abstract The Early Cretaceous Wulantuga high-Ge coal deposit in Inner Mongolia is one of the major coal-hosted Ge deposits in China. This paper reports new data on the petrological, mineralogical, and geochemical compositions of 13 bench samples of the high-Ge No. 6 coal from the Wulantuga deposit, and provides new insight into the origin and modes of occurrence of the minerals and elements present. The No. 6 Coal has a low rank (Ro,max = 0.45%) and is a low-ash coal (8.77%). The total content of inertinite (52.5 vol.% on average) in most coal benches is higher than that of huminite (46.8 vol.% on average). The dominant huminite maceral is textinite (averages 43.9%), and the dominant inertinite macerals are mainly fusinite (averages 33%) and semifusinite (12.5%), along with trace portions of intertodetrinite, secretinite, funginite, and macrinite. Fungus, seen as the maceral funginite, played a role in the development of degraded maceral forms in the Wulantuga coals. Funginite is present in samples examined in this study, but is not easily extracted during palynological studies; recovered fungal taxa are saprophytes, indicating woody decomposition prior to incorporation in the mire. Palynology revealed a sparse flora that is consistent with the early Cretaceous age. Minerals in the coal include quartz, kaolinite, illite (and/or illite/smectite), gypsum, pyrite, and traces of rutile and anatase. A varying proportion of bassanite was observed in the low-temperature ashes (LTAs). Bassanite in the LTAs was derived both from the dehydration of gypsum in the raw coals and from the interaction between organically-associated Ca and S during the low-temperature ashing. In addition to a proportion of detrital quartz, fine-grained and cell-filling quartz of authigenic origin is also present. Pyrite is of syngenetic origin and derived from sulfate-rich hydrothermal fluids. Compared to common Chinese and world low-rank coals, the No. 6 Coal is enriched in Be (25.7 μg/g), F (336 μg/g), Ge (274 μg/g), As (499 μg/g), Sb (240 μg/g), Cs (5.29 μg/g), W (115 μg/g), Hg (3.165 μg/g), and Tl (3.15 μg/g). Germanium in the coal is organically associated, and its enrichment is attributed to hydrothermal fluids from the adjacent granitoids. Beryllium is probably associated with Ca- and Mn-bearing carbonate minerals and to a lesser extent with clay minerals, rather than with organic matter. Fluorine largely occurs in clay minerals (kaolinite and illite). The elevated concentrations of Tl, Hg, As, and Sb are mainly distributed in pyrite and were derived from the same hydrothermal source. The high W in the coal occurs in both the organic matter and the authigenic quartz. Illite is the major carrier of Cs in the coal. The accumulation of rare earth elements (REE) in the coals had a polygenetic and multistage nature, including two syngenetic stages (early hydrothermal and terrigenous) and one diagenetic (late hydrothermal) stage. The REE distribution patterns of the early hydrothermal and terrigenous stages were characterized by the enrichment of medium REE (M-type REE) and light REE (L-type REE), respectively. A H-type REE distribution pattern (HREE enrichment) occurred in the late diagenetic hydrothermal stage. The high-Ge Wulantuga coals are also abnormally enriched in precious metals. Gold, Pt, and Pd in the coals, calculated from their concentrations in the LTAs, are 3.5–25.8,

Mineralogy and leaching characteristics of beneficiated coal products from Santa Catarina, Brazil

Abstract Petrographic, mineralogical and geochemical studies have been carried out on beneficiated coal products from mines and preparation plants in the Santa Catarina Basin, southern Brazil, to investigate the range of characteristics exhibited by the materials and the potential impact of their stockpiling and storage on the environment. The coals contain varying proportions of vitrinite and inertinite macerals, and have vitrinite reflectance values ranging from 0.44 to 1.38%. With the exception of one material blended with peat from an external source, they have relatively high percentages of ash (30–58%) and mineral matter (36–66%). The mineral matter consists mainly of clay minerals (kaolinite, illite and illite/smectite), together with 15–25% quartz, up to 10% feldspar, up to 5% calcite and/or dolomite and up to 5% pyrite, and around 1% anatase and/or rutile. Bassanite is also present in low-temperature ash derived from the coals, mainly derived from interaction of Ca and S associated with the organic matter. Jarosite is formed by pyrite oxidation in coals that have been exposed in stockpiles for extended periods. Most of the trace elements in most of the coals have higher concentrations than average values for world coals generally, probably due to the relatively high mineral matter content. A lower-ash product representing a blend of coal and peat has similar to lower concentrations of most elements, but higher concentrations of B, Ba, Be, Cd, Ge and Mn, which may be associated with the peat component. Interaction of relatively fresh coals with water in laboratory tests produces leachates with near-neutral to mildly acid pH values, but leaching of oxidized, jarosite-bearing coal produces a strongly acid leachate, with higher concentrations of Cd, Co, Cu, Ni and Zn. Leachates derived from coals in which the pyrite has been oxidized during storage would thus be expected to have a more adverse environmental impact than leachates derived from coals in which such oxidation has not had an opportunity to develop.

839 AMBULATORY BLOOD PRESSURE MONITORING AS PREDICTOR OF SUBCLINICAL ATHEROSCLEROSIS IN ADOLESCENTS

Upper Paleocene to middle Miocene coal samples collected from active mines in the western Venezuelan States of Táchira, Mérida and Zulia have been characterized through an integrated geochemical, mineralogical and petrographic investigation. Proximate, ultimate, calorific and forms of sulfur values, major and trace element, vitrinite reflectance, maceral concentrations and mineral matter content have been determined for 16 channel samples from 14 mines. Ash yield generally is low, ranging from < 1 to 17 wt.% (mean = 5 wt.%) on a dry basis (db). Total sulfur content is low to moderate, ranging from 1 to 6 wt.%, db (average = 1.7 wt.%). Calorific value ranges from 25.21 to 37.21 MJ/kg (10,840–16,000 Btu/lb) on a moist, mineral-matter-free basis (average = 33.25 MJ/kg, 14,300 Btu/lb), placing most of the coal samples in the apparent rank classification of high-volatile bituminous. Most of the coal samples exhibit favorable characteristics on the various indices developed to predict combustion and coking behavior and concentrations of possible environmentally sensitive elements (As, Be, Cd, Cr, Co, Hg, Mn, Ni, Pb, Sb, Se, Th and U) generally are similar to the concentrations of these elements in most coals of the world, with one or two exceptions. Concentrations of the liptinite maceral group range from < 1% to 70 vol.%. Five samples contain > 20 vol.% liptinite, dominated by the macerals bituminite and sporinite. Collotelinite dominates the vitrinite group; telinite was observed in quantities of ≤ 1 vol.% despite efforts to better quantify this maceral by etching the sample pellets in potassium permanganate and also by exposure in an oxygen plasma chamber. Inertinite group macerals typically represent < 10 vol.% of the coal samples and the highest concentrations of inertinite macerals are found in distantly spaced (> 400 km) upper Paleocene coal samples from opposite sides of Lago de Maracaibo, possibly indicating tectonic controls on subsidence related to construction of the Andean orogen. Values of maximum reflectance of vitrinite in oil (Ro max) range between 0.42% and 0.85% and generally are consistent with the high-volatile bituminous rank classification obtained through ASTM methods. X-ray diffraction analyses of low-temperature ash residues indicate that kaolinite, quartz, illite and pyrite dominate the inorganic fraction of most samples; plagioclase, potassium feldspar, calcite, siderite, ankerite, marcasite, rutile, anatase and apatite are present in minor or trace concentrations. Semiquantitative values of volume percent pyrite content show a strong correlation with pyritic sulfur and some sulfide-hosted trace element concentrations (As and Hg). This work provides a modern quality dataset for the western Venezuela coal deposits currently being exploited and will serve as the foundation for an ongoing coal quality research program in Venezuela.

Notes on the origin of inertinite macerals in coal: Evidence for fungal and arthropod transformations of degraded macerals

The role of fungus in the formation of coal macerals, both as a primary contributor in the form of a fungus fossil/maceral funginite, and in their role in degrading wood, thus producing degraded maceral forms, has been established. Fungus, in the course of breaking down the lignin and cellulose in wood, make the wood more digestible for grazers, such as arthropods. In turn, the remnants of the digested wood and anything else eaten but not completely digested are excreted and can be preserved intact; eaten by other fauna with a repeat of the cycle; or colonized by bacteria and/or coprophilous fungi with or without subsequent preservation. Ultimately, the coprolites can be preserved as a form of macrinite.

Splint coals of the Central Appalachians: Petrographic and geochemical facies of the Peach Orchard No. 3 split coal bed, southern Magoffin County, Kentucky

The Bolsovian (Middle Pennsylvanian) Peach Orchard coal bed is one of the splint coals of the Central Appalachians. Splint coal is a name for the dull, inertinite-rich lithologies typical of coals of the region. The No. 3 Split was sampled at five locations in Magoffin County, Kentucky and analyzed for petrography and major and minor elements. The No. 3 Split coals contain semifusinite-rich lithologies, up to 48% (mineral-free basis) in one case. The nature of the semifusinite varies with position in the coal bed, containing more mineral matter of detrital origin in the uppermost durain. The maceral assemblage of these terminal durains is dominated by detrital fusinite and semifusinite, suggesting reworking of the maceral assemblage coincident with the deposition of the detrital minerals. However, a durain in the middle of the coal bed, while lithologically similar to the uppermost durains, has a degraded, macrinite-rich, texture. The inertinite macerals in the middle durain have less distinct edges than semifusinites in the uppermost terminal durains, suggesting degradation as a possible path to inertinite formation. The uppermost durain has higher ash and semifusinite contents at the eastern sites than at the western sites. The difference in the microscopic petrology indicates that megascopic petrology alone can be a deceptive indicator of depositional environments and that close attention must be paid to the individual macerals and their implications for the depositional setting, especially within the inertinite group.

Limitation of petrographic indices in depositional environmental interpretation of coal deposits

AbstractOrganic petrology based petrographic indices (Tissue Preservation Index and Gelification Index) is a widely utilized tool in the study of depositional palaeoenvironment of coal. Evaluation of these petrographic indices suggests that, at present, utilize only vitrinite/huminite and inertinite macerals to interpret depositional environment of coal. Liptinite group macerals have important depositional environment implications, but liptinite macerals have not been taken into account in earlier petrographic indices (TPI and GI) formulations. This article examines the limitation of TPI and GI, and proposes improved TPI and GI indices, including the liptinite and inertinite macerals having depositional environment significance.

Notes on the origin of inertinite macerals in coals: Funginite associations with cutinite and suberinite

Abstract The association of fungus with plant leaves and roots is ubiquitous. While many of these occurrences are considered to be pathogenic, mycorrhizzal fungal associations with roots are essential for plant growth. Despite the common knowledge of such relationships in plant science, with a few exceptions, the fungus/leaf/root/stem association as the macerals funginite, cutinite, and suberinite in coals has not been extensively studied. In this work, examples of funginite associations with cutinite and suberinite are discussed.

Study on the structure and gasification characteristics of selected South African bituminous coals in fluidised bed gasification

The gasification characteristics of three South African bituminous coals were investigated in a bubbling fluidised bed reactor. The three coals are similar in rank, but two are inertinite-rich coals and the third has a high vitrinite content. The microstructural characteristics of the parent coals and their resultant chars were determined using XRD, FT-IR, Raman and petrographic analysis. The microstructural changes that occurred in the organic (maceral) and the inorganic (mineral) fractions of the selected coals were evaluated. The change in the carbon structure was correlated to the proportions of inertinite and vitrinite macerals in the coals. High vitrinite content resulted in an increase in the order of the disordered carbon structure after gasification and this leads to greater graphitised ordered carbon structures. While a high inertinite content resulted in low or no structural transformation of the chemical structure. The transformation of inorganic mineral constituents of the coal was correlated to the amount of inertinite present in the selected coals. Higher proportions of inertinite macerals and inertinitic chars resulted in higher proportions of melted minerals. Char samples with low proportions of organic matter resulted in higher proportion of melted minerals covering the char surface.

Chemical functionalities of high and low sulfur Australian coals: A case study using micro attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectrometry

The macerals in bituminous coals with varying organic sulfur content from the Early Permian Greta Coal Measures at three locations (Southland Colliery, Drayton Colliery and the Cranky Corner Basin), in and around the Sydney Basin (Australia), have been studied using light-element electron microprobe (EMP) analysis and micro-ATR–FTIR. Electron microprobe analysis of individual macerals reveals that the vitrinite in both the Cranky Corner Basin and Drayton Colliery (Puxtrees seam) samples have similar carbon contents (ca. 78% C in telocollinite), suggesting that they are of equivalent rank. However, the Cranky Corner coals have anomalously low vitrinite reflectance (down to 0.45%) vs. the Drayton materials (ca. 0.7%). They also have very high organic S content (3–6.5%) and lower O content (ca. 10%) than the equivalent macerals in the Drayton sample (0.7% S and 15.6% O). A study was carried out to investigate the impacts of the high organic S on the functional groups of the macerals in these two otherwise iso-rank, stratigraphically-equivalent seams. An iso-rank low-S coal from the overlying Wittingham Coal Measures near Muswellbrook and coals of slightly higher rank from the Greta Coal Measures at Southland Colliery near Cessnock were also evaluated using the same techniques to extend the data set. Although the telocollinite in the Drayton and Cranky Corner coals have very similar carbon content (ca.78% C), the ATR–FTIR spectra of the vitrinite and inertinite macerals in these respectively low S and high S coals show some distinct differences in IR absorbance from various aliphatic and aromatic functional groups. The differences in absorbance of the aliphatic stretching bands (2800–3000 cm −1) and the aromatic carbon (C C) peak at 1606 cm −1 are very obvious. Compared to that of the Drayton sample (0.7% S and 15% O), the telocollinite of the Cranky Corner coal (6% S and 10% O) clearly shows: (i) less absorbance from OH groups, represented by a broad region around 3553 cm −1, (ii) much stronger aliphatic C–H absorbance (stretching modes around 3000–2800 cm −1 and bending modes around 1442 cm −1) and (iii) less absorbance from aromatic carbon functional groups (peaking at 1606 cm −1). Evaluation of the iso-rank Drayton and Cranky Corner coals shows that: (i) the aliphatic C–H absorbances decrease with increasing oxygen content but increase with increasing organic S content and (ii) the aromatic H to aliphatic H ratio (Har/Hali) for the telocollinite increases with (organic) O%, but decreases progressively with increasing organic S. The high organic S content in the maceral appears to be accompanied by a greater proportion of aliphatic functional groups, possibly as a result of some of the O within maceral ring structures in the high S coal samples being replaced.

Petrographic characteristics of coal from the Lati Formation, Tarakan basin, East Kalimantan, Indonesia

The present paper entails the petrographic characterization on limited coal samples drawn from the Tarakan basin, Eastern Kalimantan, Indonesia. These coals contain a high concentration of huminite which, in turn, is dominated by telohuminite. As a result of telohuminite content they have high GI and TPI values. They contain, low concentrations of liptinite and inertinite macerals. The dominant microlithotype is vitrite. Based on the macerals and microlithotypes of these coals, their paleodepositional environment has been reconstructed. Accordingly it is deciphered that these coals have originated under telmatic condition. There was predominance of wood derived tissues and increased subsidence rate prevailed in the basin. Moreover, during the time of their evolution, there were alternate phases of oxic and anoxic moor conditions with intermittent moderate to high flooding in the basin.

Notes on the origin of inertinite macerals in coals: Observations on the importance of fungi in the origin of macrinite

Macrinite is a, generally, rare inertinite maceral, often incorporating remnants and fragments of other macerals, including vitrinite, liptinite, and other inertinite. The associated inertinites include multiple forms of funginite. Funginite is also commonly found in association with vitrinite of slightly elevated reflectance and with degraded varieties of vitrinite. Together with the highly degraded macrinite, the latter two associations are here inferred to be part of a continuum of fungal and microbial degradation of peat. In any case, the origin of some macrinite is potentially distinct from that of inertinite generated by fire.

Occurrence of non-mineral inorganic elements in macerals of low-rank coals

Abstract Electron microprobe study of individual macerals in low-rank coals of Permian to Tertiary age from Australia, New Zealand, Indonesia and Thailand has shown that measurable proportions of inorganic elements are consistently found in organic components, especially the vitrinite macerals, in which no minerals or mineral inclusions are visible under the microscope. The vitrinites of such coals have been found to contain up to around 0.5% Al, 1.5% Ca, 0.1% Mg, 0.7% Fe and 0.2% Ti. The Al occurs without measurable proportions of Si, and hence does not represent sub-micron clay minerals within the maceral components. Inertinite macerals in the coals, such as fusinite, typically contain lesser proportions of these elements, and often have no more than background ( Except where soluble minerals such as carbonates are also present, the proportion of Ca, Al and Fe indicated from microprobe analysis in the macerals, especially in the vitrinites, is very close to the mobile proportion of the same elements indicated in previous studies from selective leaching techniques. This suggests that the elements occur as an inherent part of the organic structure in the macerals, possibly as a combination of exchangeable ions, carboxylates, chelates and other organometallic compounds; they may also be held by physical absorption and adsorption mechanisms, or may possibly represent inorganic nanoparticles. The proportions of Al, Ca and Fe in the vitrinites of the samples studied decrease with coal rank. Although there are exceptions, these and other non-mineral inorganic elements (Mg, Ti) are also not usually detected by the microprobe in higher rank coals (above 75% carbon in vitrinite or around 0.6% vitrinite reflectance). Their absence is probably a consequence of expulsion from the maceral structures during the progressive aromatization associated with rank advance, by processes such as dehydration, decarboxylation and dehydroxylation.

Does the Presence of Pseudovitrinite Indicate Gas-saturated Coals? Some Interesting Observations from the Gething Coals in Canada

The presence of pseudovitrinite at a depth of 1,000 m in the very gassy (up to 862 scf/ton total gas content, as-received basis) but low absolute permeability (0.5 mD), low-volatile bituminous Gething coals in the Canadian Foothills has been documented. Because oxidation is unlikely to occur at such depth, it is reasonable to expect that pseudovitrinite formed as a result of desiccation in a gas-saturated environment prior to the coals being uplifted to their present day depth. This raises the possibility that a coal that contains pseudovitrinite may have moisture content that is below its equilibrium moisture, which leads to higher methane adsorptive capacity compared with the same coal that has “normal” vitrinite (collotelinite). The presence of inertinite macerals in the coal, derived from wood fibers and charred remnants, has aided in the development and preservation of phyteral porosity and in the formation of interconnected microcavities, which should result in higher micropermeability and aid the flow of gas locally within the coal seam and surrounding strata. The Gething coals in the Highhat corehole share some of these characteristics, which may have important implications on the dynamics of coal-bed methane production. Volumetric strain (matrix shrinkage) of these gassy coals during production is conservatively estimated to be 0.5–0.75%, which may result in an absolute permeability increase of between 5 to 12 times, based on studies on coals of similar rank and gas content in United States basins. Although observations made in this preliminary study do not constitute a proof, they leave open the possibility of using pseudovitrinite, under certain circumstances, as an indicator of improved gas sorptive capacity and enhanced permeability in deep coals.

H/C versus O/C atomic ratio characterization of selected coals in Slovenia

Application of the H/C and O/C atomic ratios plotted into the van Krevelen's diagram is well known approach for chemical characterization of coals, more precisely, of their organic part. Determination of coals by the two atomic ratios closely relies to their petrographic type as well as to their coalification rank. Elemental data, together with the coal quality data of 23 coals from the territory of Slovenia are comprised in this study. Coals vary in age from the Carnian anthracite to the Pliocene ortho-lignites, and were deposited in paralic as well as in intermountain basins of different tectonic settings. The highest H/C and O/C atomic ratios are characteristic for the xylite-rich ortho-lignites from Velenje (Pliocene) and Globoko (Pontian), whereas the lowest for the Orle anthracite (Carnian). The Upper Oligocene "hard brown coals" and younger meta- and ortho-lignites treated in this study are typical humic coals. Relatively high H/C ratios are evident for two sapropelic coals, the Sečovlje para-bituminous and the Raša (Croatia) ortho-bituminous coal, both of the lower Paleogene age. No inertinitic coals are known from our country, however, inertinite macerals are recorded in almost all of them.