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In the search for rare earth and other critical elements in coal measures, the coals are emphasized with lesser consideration for the accompanying rocks. In this investigation, the focus is on a lanthanide-rich, 315–317 Ma (after Machlus et al., Chemical Geology, 539, art. no. 119485, 2020) volcanic ash-fall trachyandesite to trachyte tonstein which occurs in association with the Middle Pennsylvanian Duckmantian-age Fire Clay coal in eastern Kentucky. The tonstein was deposited largely during peat accumulation, although it is known to occur at the base of the coal or within the underclay. The mineralogy is dominated by kaolinite with illite and quartz as minor to major minerals. A number of accessory minerals, as detected by X-ray diffraction + Siroquant XRD software and scanning and transmission electron microscopy (S/TEM), include REE-bearing phosphates (apatite, crandallite, florencite, monazite), and Y-bearing zircon. The highest rare earth element + Y concentrations occur in the weathered tonsteins, probably due to the concentration of these minerals after weathering of kaolinite from the rock. [ABSTRACT FROM AUTHOR]

The high volatile C bituminous-rank, Bolsovian-age Princess No. 3 coal, a correlative of the heavily-mined Hazard No. 7 coal and the Peach Orchard and Coalburg Lower Split coals, was investigated three sites at a mine in Greenup County, Kentucky. The coal exhibits a "dulling upwards" trend, with decreasing vitrinite and a greater tendency towards dull clarain and bone lithotypes towards the top of the coal. The relatively vitrinite-rich basal lithotype is marked by a dominance of lycopod tree spores. The palynology transitions upwards to a middle parting co-dominated by tree fern and small lycopod spores and an upper bench dominated by tree ferns with contributions from small ferns, cordaites, and calamites. The lithotypes generally have a moderate- to high-S content with a variable ash yield. Sulfur, Fe2O3, and certain siderophile elements are highest near the top of the coal. As observed in other coals, uranium and Ge are enriched at the top and bottom margins of the coal. The rare earth chemistry at the top of the coal has a significantly lighter distribution (higher LREE/HREE) than at the base of the coal. [ABSTRACT FROM AUTHOR]

The Middle Pennsylvanian (Bolsovian) Leatherwood coal in the central part of eastern Kentucky is a moderately thick, moderate-S seam that has been one of the major energy resources in the region. Much of the seam profile consists of clarain, dull clarain, and durain with some brighter lithologies at the base of the seam and in the upper portion of the coal at one site. A previous study emphasized petrographic trends. In this investigation, the geochemistry of the coal is examined. Some elements, such as Ge and Ga, are enriched at 2× and 5× the World hard coal averages in the coal lithotypes adjacent to rock (roof, floor, partings). Arsenic and other chalcophile elements (Zn, Co, Ni) tend to be concentrated at the top and bottom of the seam profiles and below partings, generally in the coals with the highest pyritic sulfur content. Manganese enrichments occur in bright clarain lithologies at one site. No coal lithology reaches a 5× the World hard coal average, but samples between the 2× and 5× World hard coal averages tend to be at the top and bottom of the coal seam. Most coal samples tend to have a light rare earth element (LREE) enrichment. The basal lithotype at all sites, though, has a heavy REE enrichment and, via inference from the Zr and TiO 2 concentrations, a smaller influx of detrital minerals than the basal lithotypes in many Appalachian coals. While the nature of REE associations is complicated by the high volatile A bituminous coal rank, the relatively high concentrations of the heavy REE suggest an original, albeit possibly not exclusive, organic association for those elements. [ABSTRACT FROM AUTHOR]

Two coal-to-shale sequences of late Middle Pennsylvanian (Asturian) age from the southern portion of the Eastern Interior (Illinois) Basin, USA were examined geochemically, petrographically and palynologically. The Springfield coal was found to be moderately low in ash yield and high in total sulfur content. Petrographically, the coal is high in vitrinite content and low in liptinite and inertinite. Palynologically, the bed is co-dominated by spores of arborescent lycopod and tree fern affinities. The examination of closely-spaced bench samples revealed vertical species variation within both of these plant groups. Lycospora micropapillata + L. orbicula , both of which were produced by Paralycopodites , are most abundant in basal coal benches, whereas Lycospora granulata , produced by Lepidophloios is the dominant arborescent lycopod spore throughout the rest of the bed. Thymospora pseudothiessenii is the dominant tree fern spore throughout most of the coal, with Laevigatosporites globosus becoming dominant in the top-most coal benches. The Herrin coal bed is also moderately low in ash yield and high in total sulfur content. Unlike the Springfield coal, it contains two distinct inorganic partings that have regional extent. The Herrin coal also has several coal benches with increased ash and sulfur that were not present in the Springfield coal bed. Petrographically, it is dominated by vitrinite, with the partings and high ash coal benches containing more inertinite, and liptinite. Palynologically, the Herrin coal is dominated by arborescent lycopod spores with subdominant tree fern spores. As with the Springfield coal, Lycospora micropapillata + L. orbicula are the dominant arborescent lycopod spores at the base of the coal, with Lycospora granulata dominating the rest of the bed. Granasporites medius , which was produced by Diaphorodendron and Synchysidendron , occurs more frequently in the Herrin coal bed, and are most abundant in, and in proximity to, the two inorganic partings. Tree fern spores are less abundant in the Herrin coal, and do not display any discernable vertical species variation. Collectively, both the Springfield and Herrin coal beds are interpreted to have formed in extensive planar, topogenous mires. Consistently saturated peat conditions throughout the development of both paleomires are indicated by the high vitrinite contents, and prevalence of arborescent lycopods. The deposition of widespread inorganic partings in the Herrin coal represents significant events in peat accumulation, with high ash coal benches representing smaller, more local events. Both of the coals are overlain by black, very organic-rich (avg. TOC ± 20%) marine shales. The Turner Mine Shale, which directly overlies the Springfield coal, has layers at the coal/shale contact with fairly abundant vitrinite, primarily in the form of vitrodetrinite, near the base of the shale, but the majority of the shale is dominated by the liptinite macerals bituminite, lamalginite and amorphinite. Micrinite is a major organic component of the shale. The Anna Shale, which directly overlies the Herrin coal, is similar in overall maceral composition, but contains less vitrinite, and more solid bitumen and micrinite. Trace element ratios (Ni/Co, V/Cr, V/V + Ni), indicative of paleoredox conditions, indicate that both shales were deposited under mainly dysoxic to suboxic/anoxic conditions. The shales are interpreted to represent a progressively rising water table, caused by an increase in eustatic sea levels. Vitrinite reflectance values in the shales are lower than corresponding values measured from the coal, indicating some degree of vitrinite suppression occurring in the Turner Mine and Anna Shales. [ABSTRACT FROM AUTHOR]

Middle Pennsylvanian age coal beds from new outcrop exposures located along the northwest margin of the Eastern Kentucky Coal Field were sampled and analysed geochemically, petrographically and palynologically. Coal beds in the study section are bounded by two major marine shale members, the Betsie Shale Member near the base of the section, and the Magoffin Shale Member at the top. Analyses indicate that geochemical, petrographic and palynologic parameters of the coal beds are highly variable, and probably of peat accumulation in mires that were planar and topogenous with high periphery to area ratios. Palynologic analysis of the coal beds indicates they are all Middle Pennsylvanian in age, and correlative with Duckmantian (Westphalian B) age strata of western Europe, and Atokan age strata of the mid-continent, USA. [ABSTRACT FROM PUBLISHER]

A newly-discovered 12 cm thick coal seam within the Late Miocene Injana Formation in the anticlinal Hemrin South Mountain of northern Iraq was studied geologically, geochemically and petrographically. This previously unnamed coal is herein designated the Hemrin Coal Seam (HCS). To date, this coal seam has been analyzed for its proximate, ultimate, petrological, geochemical, and mineralogical characteristics. The proximate analysis showed that it contains (as median values) 0.8% moisture, 61% volatile matter (daf), 38% fixed carbon (daf), 1.9% ash yield (dry), 9% total sulfur (dry), 80% total carbon (daf) and 16,000 BTU/lb (= 37 MJ/kg) (dry) calorific value. The ultimate analysis showed that it contains (as median values) < 0.01% moisture, 2.2% ash, 9% sulfur, 80% carbon (daf), 0.9% nitrogen (daf), 8.1% hydrogen (daf), and 0.7% oxygen (daf). Organic petrography studies showed that the maceral content of HCS is dominated by huminite (96.4% mmf) with minor liptinite (3.6% mmf) and negligible intertinite. The huminites are mostly ulminite B (95.2%), very little attrinite, and negligible densinite and corpohuminite. The liptinites are mostly resinite (3.6%) and minor solid bitumen. Intertinite macerals are extremely rare, with only one sample containing minor fusinite. The mean random vitrinite reflectance is 0.37% R o , which is indicative of a thermomaturation level at the lignite/subbituminous boundary. Mineralogically, the HCS consists of quartz, clay, pyrite, calcite, rozenite, anatase and gypsum which are the source of ash and most major elements. The HCS was geochemically analyzed on a whole coal and ash basis for 11 major elements and 51 trace and rare-earth elements (REE). The HCS is a high-sulfur coal and the source of sulfur is shared between organically-bound and ash. In comparison to the Clarke of the world coal, and average of USA and Chinese coals, the coal of HCS is strongly enriched by a factor of 10's in environmentally hazardous elements V, Cr, Ni, and Mo. The ash of the HCS is also significantly enriched by a factor of 10's to 100's in V, Ni, Mo, Cd, and Ta; and less significantly by a factor of 1–10 in many other trace elements, while it is depleted in all REEs and many trace elements relative to the Clarke of the world coal ashes. The mean of coal affinity index and enrichment factor shows that the HCS has comparable values for most major and REEs relative to the Clarke of upper crust and sedimentary rocks, while it has high values for most trace elements including significantly high values for Mo, V, Se, Ni, Cd, Sb, Br, Hg, Ag, As, and Ta. The REEs distribution pattern show decreasing trend from LREE towards HREE and has very low total of 2.29 ppm relative to the world coal and international reference rocks. The Ni/Co versus V / (V + Ni) diagram showed a suboxic/anoxic environment of deposition, possibly under lacustrine or flood-plain conditions. The rank of HCS is probably bituminous coal as indicated by very high calorific value and total carbon and very low ash yield. [ABSTRACT FROM AUTHOR]

The Vancleve coal bed was studied geochemically, palynologically, and petrographically near the type area of the Vancleve coal bed, where new road construction has provided fresh exposures. In the study area, the Vancleve coal is relatively thin (< 76 cm), low in ash yield (avg. 7.0%, dry basis), and high in overall total sulfur content (avg. 3.3%, dry basis). Three very thin (< 10 cm thick) leader coals are present at two of the six sample locations. The leader coals are high in ash yield (avg. 29.4%, dry basis), and high, but variable, total sulfur content (avg. 5.0%, range 1.1 to 8.8%, dry basis). Palynologically, the coal is dominated by Lycospora (avg. 80.4%), the dispersed spore genus of Lepidophloios , Lepidodendron , and Paralycopodites . Lycospora micropapillata and Lycospora orbicula , both of which were produced by Paralycopodites , an ecotonal, colonizing lycopod, are more prevalent near the base of the coal bed. Lycospora pellucida , Lycospora granulata (produced by Lepidophloios ), and Lycospora pusilla (produced by Lepidodendron ) are more abundant in the middle and upper portions of the bed. Spores and pollen from other Pennsylvanian plant groups are minor in occurrence. Biostratigraphically, the coal is transitional Westphalian A/B in age, containing both Late Langsettian, and Early Duckmantian elements. Petrographically, the coal is high in vitrinite content (avg. 80.5%, mmf), with telovitrinite occurring more commonly than detrovitrinite and gelovitrinite (avg. TV / DV + GV = 3.3). Liptinite (avg. 9.4%, mmf) and inertinite (10.2%, mmf) occur in minor amounts by comparison. The average random vitrinite reflectance of the Vancleve coal is 0.54%, and the average calculated maximum vitrinite reflectance is 0.58%, indicating the Vancleve coal to be high volatile C/B bituminous in rank, in the study area. Low ash yields are often considered indicative, at least in part, of ombrotrophic (raised) mire origins in Pennsylvanian coal beds. However, the dominance of Lycospora , vitrinite macerals, and high sulfur contents indicates that the Vancleve coal bed is most likely formed from a planar, rheothrophic mire, with a consistently high water table. Low ash yields indicate that the paleomire was not subjected to any large influxes of sediment during peat accumulation from extra-mire sources. Palynologically, the very thin (< 10 cm thick) leader coals, more diverse in composition, though remain Lycospora dominant. Petrographically, they are high in vitrinite content, but have lower TV / DV + GV ratios (avg. 2.0). Collectively, these data indicate that the leader coals also formed from planar, rheotrophic mires, though with substantially more influence from extra mire sediment sources. The coal is locally capped and cutout by paleochannels. Sediments from a heterolithic, laterally accreting channel appear to have locally loaded the peat when it was still pliable resulting in sandstone dikes and injection structures. Loading on pliable peat may also have led to slumping in the overlying channel fill. [ABSTRACT FROM AUTHOR]

The chemistry of rare earth elements (REE) and selected critical elements was examined in the high volatile A bituminous Pond Creek coal in Pike County, Kentucky. The Pond Creek coal has been one of the most important coal resources in eastern Kentucky but, up to now, no modern methods, such as Inductively coupled plasma – mass spectroscopy (ICP-MS) have been applied to the characterization of the rare earth elements within the coal. The concentration of the REE and their internal distribution (light REE/heavy REE) varies between lithotypes through the coal, ranging from <300-ppm REE at the top of the coal to >1000-ppm REE in the bright lithotype (zone 4) in the middle of the coal. The latter lithotype has the highest light REE/heavy REE, suggesting that the mire was isolated from detrital sources of REE-bearing minerals and, instead, was influenced by hydrothermal enrichment emanating from the movements along the Pine Mountain trust fault to the south of the study area. The Mn + Fe 2 O 3 + CaO and Sr + Ba chemistry of the lithotype suggests that it's precursor mire was less acidic than other bright lithotypes with the Pond Creek profile, however the upward change in the chemistry indicates a temporal acidification of the zone 4 lithotype. [ABSTRACT FROM AUTHOR]

This study presents recently collected data examining the organic petrology, palynology, mineralogy and geochemistry of the Gray Hawk coal bed. From the Early Pennsylvanian, Langsettian substage, Gray Hawk coal has been mined near the western edge of the eastern Kentucky portion of the Central Appalachian coalfield. While the coal is thin, rarely more than 0.5-m thick, it has a low-ash yield and a low-S content, making it an important local resource. The Gray Hawk coal palynology is dominated by Lycospora spp., and contains a diverse spectrum of small lycopods, tree ferns, small ferns, calamites, and gymnosperms. The maceral assemblages show an abundance of collotelinite, telinite, vitrodetrinite, fusinite, and semifusinite. Fecal pellet-derived macrinite, albeit with more compaction than is typically seen in younger coals, was observed in the Gray Hawk coal. The minerals in the coal are dominated by clay minerals (e.g., kaolinite, mixed-layer illite/smectite, illite), and to a lesser extent, pyrite, quartz, and iron III hydroxyl-sulfate, along with traces of chlorite, and in some cases, jarosite, szomolnokite, anatase, and calcite. The clay minerals are of authigenic and detrital origins. The occurrence of anatase as cell-fillings also indicates an authigenic origin. With the exception of Ge and As, which are slightly enriched in the coals, the concentrations of other trace elements are either close to or much lower than the averages for world hard coals. Arsenic and Hg are also enriched in the top bench of the coal and probably occur in pyrite. The elemental associations (e.g., Al2O3/TiO2, Cr/Th-Sc/Th) indicate a sediment-source region with intermediate and felsic compositions. Rare metals, including Ga, rare earth elements and Ge, are highly enriched in the coal ashes, and the Gray Hawk coals have a great potential for industrial use of these metals. The rare earth elements in the samples are weakly fractionated or are characterized by heavy-REE enrichment, indicating an input of natural waters or probably epithermal solutions. [ABSTRACT FROM AUTHOR]

The petrographic, palynologic, and geochemical character of the high volatile A bituminous Pennsylvanian (Bashkerian, Duckmantian) Pond Creek coal was evaluated for a series of mine samples in the Lick Creek and Jamboree 7 ½' quadrangles in Pike County, Kentucky. In its prime years of production, the Pond Creek coal was among the most important coal resources in the leading coal producing state in the U.S. The thickness and quality of the Pond Creek coal was closely related to its position relative to the northwestward-plunging, N20° E -trending Belfry anticline with the main bed of the coal thinning and the thickness of rock between the latter and the high-S Pond Creek rider bed thinning across the anticline. This suggests that the Belfry anticline and the Pond Creek mire were contemporaneous features, with the rising anticline influencing the lithology and chemistry of the peat. Within the study area, the lower three lithotypes fill the original topography and the next higher lithotype pinching out along the rise towards the anticline. The next three lithologies, a thick bright zone (zone 4 in the nomenclature of this study), a bone coal, and a thinner bright zone are continuous through the study area, although they all thin towards the anticline. The upper durain, the termination of the coal seam, also pinches out towards the anticline. Zone 4 shows a decrease in total vitrinite towards the uppermost bench of the zone, an upwards increase in ash yield, the upwards increase in the floral diversity, and a higher concentration of Mn, CaO, and Ba + Sr in the lower lithologies of the zone. Towards the anticline, there is a greater floral stability within zone 4 compared to the relatively subsiding area to the east. Within the zone 4 bright lithologies, peat growth outpaced the level of the water table, but at the cost of the turnover of the arborescent lycopod forest to a more diminutive flora, the collapse of the ombrogenous peat, and the influx of deeper water and the consequent deposition of the overlying relatively high-ash bone coal. • High volatile A bituminous Pennsylvanian Pond Creek coal was studied in Pike County, KY • The coal thins from east to west, approaching an anticline with penecontemporaneous uplift • Mid-seam bright zone has an upwards decrease in vitrinite and ash and increase in floral diversity • The zone shows greater floral stability towards the anticline • In ombrogenous zone, peat growth led to the collapse of peat and deposition of bony coal [ABSTRACT FROM AUTHOR]

Abstract: Fifty four samples of coal and organic-rich roof shale strata were collected as part of a coal bed methane exploration program. Following canister desorption to document gas contents, the samples were analyzed by geochemical and petrographic methods. Coal samples were found to have moderate ash yields (avg. 13.5%, dry basis), and high total sulfur contents (avg. 4.3%, dry basis). The average gas content was 1.91m3/ton. Petrographically, the coals were dominated by vitrinite macerals (avg. 81.6%, mmf), especially telovitrinite. By comparison, liptinite (avg. 7.1%, mmf) and inertinite macerals (avg. 11.3%, mmf), were minor in occurrence. Coal samples ranged from high volatile C to high volatile A bituminous in rank (avg. Ro maximum, 0.76%). Shale samples had higher ash yields (avg. 76.1, dry basis), though total sulfur contents were comparable to the coal samples (avg. 4.2%, dry basis). Gas contents were lower than the corresponding coal samples (avg. 0.65m3/ton). Petrographically, the shale samples contained decreased amounts of vitrinite (avg. 25.6%, mmf), and higher amounts of liptinite (avg. 45.4%, mmf) and inertinite (avg. 29.0%, mmf) macerals, relative to the coal samples. Gas obtained from coal and shale beds in the Illinois Basin was relatively pure (high CH4 content). Limited data also indicated that Illinois Basin coals have the ability to adsorb fairly significant amounts of CO2. This suggests that CO2 injection to enhance methane production (ECBM), and/or to sequester CO2 may have some potential. Mineralization in the coals could negatively impact CBM production, but it was found that the majority of the mineralization was present in the roof strata. [Copyright &y& Elsevier]

Abstract: Coal beds that occur in the Dunkard Group are typically thin (avg. 0.3m), and are high in ash yield (avg. 27.8%) and total sulfur content (avg. 5.1%). Petrographically, Dunkard coals are high in vitrinite (avg. 83.1%, mmf), with correspondingly low to moderate amounts of liptinite (avg. 2.1%, mmf) and inertinite (avg. 13.8%, mmf). Palynologically, Dunkard coal beds are all dominated by tree fern spore taxa (avg. 96.3%), especially Punctatisporites minutus (avg. 82.8%). Calamite spores are the second most abundant plant group (avg. 2.4%), with others (lycopods, small ferns, Cordaites and other gymnosperms) having very minor representation. Overall, the coal palynofloras are strongly dominated by lowland plants (ferns and Calamites), with only rare occurrences of bisaccate–striate conifer pollen. Coal beds of the underlying Monongahela Group (Pittsburgh, Redstone, Sewickley and Waynesburg) are thicker (avg. 1.6m), and are lower in ash (avg. 13.4%) and sulfur (avg. 3.3%) than their Dunkard counterparts. Petrographically, Monongahela Group coals are very similar to Dunkard Group coals, when compared on a mineral matter free basis; coal beds that occur in both groups are strongly dominated by vitrinite macerals. Monongahela Group coals are also palynologically very similar to Dunkard Group coals, with tree fern spore taxa dominating. A coal bed of early Permian age from west-central Texas is also similar, petrographically and palynologically, to Dunkard and Monongahela coals, being vitrinite and tree fern spore dominant. The almost complete lack of coniferous pollen in Dunkard coals led earlier workers to conclude that the Dunkard was entirely Late Pennsylvanian, and not Permian, in age. However, it is now known that Late Pennsylvania lowland floras persisted into the Dunkard, especially during wet intervals. As earlier interpretations were based primarily on spore and pollen floras from coal beds, the lack of conifer pollen in Dunkard coals is probably the result of a sampling bias. Because of this ecological bias, coal palynology is a poor proxy for age dating Dunkard Group coals. Collectively, Dunkard swamps were all planar and topogenous, their formation being controlled by topography and moisture availability. A progressive decrease in wet intervals, both in terms of frequency and duration, during the Dunkard was the major control on peat accumulation and preservation. Collectively, moisture limitation appears to be the principle factor that controlled the formation of Dunkard Group coals. [Copyright &y& Elsevier]

Abstract: Stratigraphy, palynology, petrography, and geochemistry of the Bon Air coal from the Armfield, Dotson, Rutledge, and Shakerag mine sites of Franklin County, Tennessee suggest that Bon Air seams at all sites were small (≤1.0 mile, 1.6 km), spatially distinct paleomires that evolved from planar to domed within the fluviodeltaic Lower Pennsylvanian Raccoon Mountain Formation. Of observed palynoflora, 88–97% are from lycopsids prevalent in the Westphalian. Densosporites palynomorphs of small lycopsids (e.g., Omphalophloios) dominate at the shale-hosted Armfield site, while Lycospora palynoflora of large arboreous lycopsids (especially Lepidodendron, with lesser Lepidophloios harcourtii and Lepidophloios hallii) dominate where intercalated siltstone/sandstone/shale hosts the coal (all other sites). Palynoflora of other lycopsids (Sigillaria and Paralycopodites), tree ferns, seed ferns, small ferns, calamites, and cordaites are generally minor. Genera of clastic-associated Paralycopodites are most common in Shakerag''s coal (≥10%), yet quite rare in Rutledge or Dotson coals. Overall, the palynomorph assemblages suggest that the Bon Air paleomires were forest swamps, and Early Pennsylvanian in age (Westphalian A, Langsettian). Dominant macerals at all sites are vitrinites, with fine collodetrinite (from strongly decomposed plant debris) more common than coarser collotelinite (from well-preserved plant fragments), and with lesser inertinites (fusinite and semifusinite) and liptinites (dominantly sporinite). Shakerag''s coal has greatest abundance (mineral-matter-free) of collotelinite (up to 47%) and total vitrinite (74–79%) of any sites, but lowest liptinite (12–14.5%) and inertinite (7–11%). The Dotson and Rutledge seams contain moderate liptinite (21–23%) and highest inertinite (36–37%), lowest vitrinite (≤41%), and lowest collotelinite (13–15%). Armfield''s seam has relatively high liptinite (26–28%) and vitrinite (56.5–62%), but rather low inertinite (12–15%). Moderately high ash (11.0–20.0%) and low to moderate sulfur (1.24% avg.) are typical, but ash may locally be up to 38% and sulfur up to 2.9%. Volatile matter (32.1–41.3%), calorific value (33.3–34.9 MJ/kg MAF), moisture (2.2–3.4%), and vitrinite reflectance (0.70–0.84% R max; 0.64–0.79% R random) place the Bon Air''s rank as high-volatile-A bituminous (hvAb). The Armfield coal was probably a channel-distal paleomire, perhaps an oxbow lake or floodplain depression, which domed and then subsided back to planarity prior to burial. Features of its basal and uppermost benches suggest low-lying, often-flooded (but periodically dry) mires marked by fluvial influxes and diverse lycopsid growth. These include variable inertinite, common palynoflora of both small lycopsids (Omphalophloios-like) and large arboreous ones (Lepidophloios and Lepidodendron), minor but significant palynoflora of subaerial levee or levee/mire transition species (especially Paralycopodites), moderate to high ash, variable sulfur, and elevated levels of commonly fluvial trace elements (e.g., Al, Cr, REEs, Rb, Sr, Th, V, Y, and Zr). These benches also contain high total vitrinite, high collotelinite/collodetrinite ratios, and clays with moderate to low kaolinite/quartz ratios, all consistent with the near-neutral pH and limited peat degradation that typify such planar mires. By contrast, middle benches at Armfield reflect mires domed above the land surface, less-often flooded, less-preservational, and of lower pH: coals have lower ash, vitrinite, and collotelinite, less palynoflora of both large arboreous lycopsids and Paralycopodites, and high proportions of kaolinite, liptinite, and Densosporites. Similar data at Shakerag suggest that its mire also grew from planar to domed. However, more abundant Paralycopodites, a kaolinite-poor but quartz-and-illite-rich underclay, benches alternately ash-rich and ash-poor, and an upper bench truncated by channel sandstone, suggest that it was channel-proximal and prone to intermittent clastics. It is unclear if it returned to planarity prior to burial. The mires at Dotson and (especially) Rutledge, with more ferns, more inertinite, less Paralycopodites and less vitrinite, were probably topographically elevated or protractedly domed mires, more vulnerable to drought or fire. [Copyright &y& Elsevier]

Abstract: Mercury emissions from US coal-fired power plants will be regulated by the US Environmental Protection Agency (USEPA) before the end of the decade. Because of this, the control of Hg in coal is important. Control is fundamentally based on the knowledge of the amounts of Hg in mined, beneficiated, and as-fired coal. Eastern Kentucky coals, on a reserve district level, have Hg contents similar to the USA average for coal at mines. Individual coals show greater variation at the bench scale, with Hg enrichment common in the top bench, often associated with enhanced levels of pyritic sulfur. Some of the variation between parts of eastern Kentucky is also based on the position relative to major faults. The Pine Mountain thrust fault appears to be responsible for elemental enrichment, including Hg, in coals on the footwall side of the thrust. Eastern Kentucky coals shipped to power plants in 1999, the year the USEPA requested coal quality information on coal deliveries, indicate that coals shipped from the region have 0.09 ppm Hg, compared to 0.10 ppm for all delivered coals in the USA. On an equal energy basis, and given equal concentrations of Hg, the high volatile bituminous coals from eastern Kentucky would emit less Hg than lower rank coals from other USA regions. [Copyright &y& Elsevier]

Forty-two bench samples of the Sewickley coal bed were collected from seven localities in the northern Appalachian Basin and analyzed palynologically, petrographically, and geochemically. The Sewickley coal bed occurs in the middle of the Pittsburgh Formation (Monongahela Group) and is of Late Pennsylvanian age. Palynologically, it is dominated by spores of tree ferns. Tree fern spore taxa in the Sewickley include Punctatisporites minutus, Punctatosporites minutus, Laevigatosporites minimus, Spinosporites exiguus, Apiculatasporites saetiger, and Thymospora spp. In fact, Punctatisporites minutus was so abundant that it had to be removed from the standard counts and recorded separately (average 73.2%). Even when Punctatisporites minutus is removed from the counts, tree fern spores still dominate a majority of the assemblages, averaging 64.4%. Among the tree fern spores identified in the Sewickley coal, Thymospora exhibits temporal and spatial abundance variation. Thymospora usually increases in abundance from the base to the top of the bed. Thymospora is also more abundant in columns that are thick (>100 cm) and low in ash yield (<12.0%, dry basis). Calamite spores (e.g. Calamospora spp., Laevigatosporites minor, and L. vulgaris) are the next most abundant plant group represented in the Sewickley coal, averaging 20%. Contributions from all other plant groups are minor in comparison.Petrographically, the Sewickley coal contains high percentages of vitrinite (average 82.3%, mineral matter-free (mmf)), with structured forms being more common than unstructured forms. In contrast, liptinite and inertinite macerals both occur in low percentages (average 7.7% and 10.0%, respectively). Geochemically, the Sewickley coal has a moderate ash yield (average 12.4%) and high total sulfur content (average 3.4%).Four localities contained a high ash or carbonaceous shale bench. These benches, which may be coeval, are strongly dominated by tree fern spores. Unlike the lower ash benches, they contain low percentages of vitrinite, which mainly occurs as unstructured vitrinite, and higher liptinite and inertinite contents.The accumulated data suggest that the Sewickley paleomire was probably a rheotrophic, planar mire that had a consistent water cover. This is supported by the high vitrinite contents, moderate ash yields, and high total sulfur contents. The high ash and carbonaceous shale benches probably represent either periods of dryness and substrate exposure, or flooding of the mire surface, the duration of which is unknown. [Copyright &y& Elsevier]

Abstract: The Middle Pennsylvanian/Langsettian (Westphalian A) Elswick coal bed, correlative to the Upper Banner of Virginia, is a rare example of a mined high-sulfur (>2%) coal in Eastern Kentucky, a region known for low-sulfur coals. To characterize lateral variation in the geochemistry, petrography, and palynology of the Elswick coal bed, three sites were sampled along a southeast–northwest transect within a single mine. At the southeastern site, the lower 101 cm of the 116-cm thick coal is dull, generally dominated by durain and dull clarain. While all benches at this site fit within the previously-defined “mixed palynoflora — moderate/low vitrinite group,” suggesting a stressed environment of deposition, the palynology of the benches of the dull interval show greater diversity than might be expected just from the petrology. Lithology is generally similar between the sites, but each site has some differences in the petrology. Overall, the coal bed shows significant lateral variation in properties at the mine scale, some of which can be attributed to the gain or loss of upper and lower lithologies, either through an actual physical merging or through the change in character of lithotypes. Sulfur content varies between the three sites examined for this study. Site 3, located in the northwestern portion of the study area is characterized by a strikingly high sulfur zone (7.45%) in the middle of the coal bed, a feature missing at the other sites. Pyrite and marcasite, in a mid-seam lithotype at the northwestern site (site 3), show signs of overgrowths, indicating multiple generations of sulfide emplacement. The high-sulfur site 3 lithologies all have massive overgrowths of euhedral and framboidal pyrite, fracture- and cleat-fill pyrite, and sulfide emplacement in fusinite lumens. Sulfur is high throughout the mine area, but variations are evident in the extent of secondary growth of sulfides. [Copyright &y& Elsevier]

Abstract: The geochemistry, petrology, and palynology of the Duckmantian-age Pond Creek coal bed were investigated in northern Pike and southern Martin counties, eastern Kentucky. The coal bed exhibits significant vertical variation in the investigated geochemical parameters, with many diagenetic overprints of the original geochemistry. Included in the range of geochemical signatures are the presence of elements, particularly TiO2 and Zr, suggesting the detrital influences at the time of deposition of a low-vitrinite durain; a high CaO zone with elevated B/Be, both suggesting marine influence, in a lithotype in the middle of the coal bed; and the postdepositional emplacement of pyrite in the uppermost lithotype. Individual lithotypes, each representing distinct depositional environments, all complicated to some degree by diagentic overprints, comprise the complex history of the coal bed. [Copyright &y& Elsevier]

Peat depositional environments, the sites where and conditions under which peat accumulates, significantly influence a resultant coal's physical properties, chemical composition, and coal utilization behavior. Recognition of peat depositional environments for coal is a challenging endeavor because coal's observed compositional properties not only result from a variety of geological processes operating during peat accumulation, but also reflect the influence of adjoining or external depositional sedimentary environments and alteration during later diagenesis and/or epigenesis. The maceral or microlithotype composition of any one layer of peat can be the product of years or decades of plant growth, death, decay, and post-burial infiltration by roots in addition to the symbiotic, mutualistic, parasitic, and saprophytic relationships with non-plant biota, such as arthropods, fungi, and bacteria. The overprint of increasing thermal maturation and fluid migration through time on the resulting coal can make these relationships difficult to recognize. Therefore, published models based on maceral composition alone must be used with great caution. Lipid compositions, even from lipid-poor low-rank coals, can provide important information about depositional environments and paleoclimate, especially if combined with the results of organic petrography and paleontological studies. Just as sulfur derived from seawater provides environmental clues, the ratios of two particularly relevant trace elements rather than a single trace element can be used to interpret peat depositional environments. Epigenetic minerals, as well as their corresponding chemical compositions should not be used for such a purpose; similarly, resistant terrigenous minerals deposited during peat accumulation in many cases should be used with considerable caution. The interactions of the biota present in the peat-forming ecosystem, often determined using palynological and geochemical proxies, and their interpretation in the context of geography and paleoclimate are important means for deciphering peat depositional environments. Overall, a combination of evidence from geochemistry, mineralogy, palynology, and petrology of coal and from stratigraphy, sedimentology, and sedimentary facies of related rocks is necessary for accurate and comprehensive determination of depositional environments. The need for interdisciplinary studies is underscored by peat compositional properties, which have been greatly affected by various processes during the syngenetic, diagenetic or epigenetic stages of coal formation. [ABSTRACT FROM AUTHOR]

Abstract: This article addresses the fundamental difference between coal rank and coal type. While theoretically settled long ago as being different aspects of coal systems science, the two concepts are still often confounded. In recent years, this has resulted in the publication of several works stating that coal type changes with coal rank. Coal type refers solely to coals' depositional origin and the maceral–mineral admixture resulting from that origin. Coal types typically fall in to two categories: humic coals, developed from peat, and sapropelic coals, developed from organic mud. Either type may be allocthonous or autochthonous, and within types, further refinement of depositional environment can be made. Coal rank refers to the changes in geochemistry and resultant changes in reflectance caused by increasing thermal maturity of the coal. Thus, it provides an overprint of maturity on existing coal types. With proper techniques, such as use of crossed polars and etching, maceral forms can be differentiated even at high ranks, and the original coal type determined. [Copyright &y& Elsevier]