Brenda S. Pierce

Facies development in the Lower Freeport coal bed, west-central Pennsylvania, U.S.A.

Abstract The Lower Freeport coal bed in west-central Pennsylvania is interpreted to have formed within a lacustrine-mire environment. Conditions of peat formation, caused by the changing chemical and physical environments, produced five coal facies and two mineral-rich parting facies within the coal bed. The coal bed facies are compositionally unique, having developed under varying conditions, and are manifested by megascopic, petrographic, palynologic and quality characteristics. The initial environment of the Lower Freeport peat resulted in a coal facies that is relatively high in ash yield and contains large amounts of lycopod miospores and moderate abundances of cryptotelinite, crypto-gelocollinite, inertinite and tree fern miospores. This initial Lower Freeport peat is interpreted to have been a topogenous body that was low lying, relatively nutrient rich (mesotrophic to eutrophic), and susceptible to ground water and to sediment influx from surface water. The next facies to form was a ubiquitous, clay-rich durain parting which is attributed to a general rise in the water table accompanied by widespread flooding. Following formation of the parting, peat accumulation resumed within an environment that inhibited clastic input. Development of doming in this facies restricted deposition of the upper shale parting to the margins of the mire and allowed low-ash peat to form in the interior of the mire. Because this environment was conducive to preservation of cellular tissue, this coal facies also contains large amounts of crypto-telinite. This facies development is interpreted to have been a transitional phase from topogenous, planar peat formation to slightly domed, oligotrophic (nutrient-poor) peat formation. As domed peat formation continued, fluctuations in the water table enabled oxidation of the peat surface and produced high inertinite concentrations toward the top of the coal bed. Tree ferns became an increasingly important peat contributor in the e upper facies, based on the palynoflora. This floral change is interpreted to have resulted from the peat surface becoming less wet or better drained, a condition that inhibited proliferation of lycopod trees. Accumulation of the peat continued until rising water levels formed a freshwater lake within which clays and silts were deposited. The development of the Lower Freeport peat from a planar mire through transitional phases toward domed peat formation may be an example of the type of peat formation of other upper Middle and Upper Pennsylvanian coal beds.

Isotopic evidence for the source of sulfur in the Upper Freeport coal bed (west-central Pennsylvania, U.S.A.)

Abstract Sulfur isotopic variations were used to determine the sources of sulfur in a medium-sulfur coal (∼2 wt%S) that lacked marine influence, which is often cited as a major source of sulfur in coal. Variations in the amount and isotopic composition of the organic and pyritic sulfur among the coal-bed facies of the Upper Freeport coal bed (Middle Pennsylvanian) are attributed to differential incorporation of syngenetic and epigenetic sulfur. These variations reflect varying environmental conditions during paleopeat formation, porosity and permeability, and the availability of sulfate and iron. A large increase in the abundance and sulfur isotopic value of pyritic sulfur in the upper facies of the coal bed, in proximity to the overlying lacustrine shale, corresponds to an increase in massive and irregular forms of pyrite. This relationship is attributed to at least two stages of epigenetic pyrite incorporation. An early stage of epigenetic pyrite, moderately enriched in 34S, apparently formed during the fluvial-lacustrine period immediately following peat accumulation. A late stage of epigenetic pyrite, highly enriched in 34S, formed after compaction of the original peat as cleat- and fracture-filling pyrite; this sulfur was probably derived from bacterial reduction of dissolved sulfate in groundwater. Isotopic mass-balance calculations indicate that this late-stage epigenetic pyrite may account for up to ∼50% of the pyritic sulfur in some upper facies of the coal bed. These results suggest that most of the pyritic sulfur in the Upper Freeport coal bed may be epigenetic, incorporated either soon after peat accumulation or later during coalification.

Palynology, petrography and geochemistry of the Sewickley coal bed (Monongahela Group, Late Pennsylvanian), Northern Appalachian Basin, USA

Abstract 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 ( 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.

Petrography, geochemistry and palynology of the Stockton coal bed (Middle Pennsylvanian), Martin County, Kentucky

Abstract The Middle Pennsylvanian (Westphalian D) Stockton (also known as the Broas) coal bed of the Breathitt Formation is an important energy resource in Kentucky. Petrographic, geochemical and palynologic studies were undertaken from mine, core and highway exposures in Martin and northern Pike counies, Kentucky, in order to determine the influence of the Stockton depositional ecosystem on those parameters. Vitrinite-rich Stockton lithotypes are dominated by Lycospora . Dull lithotypes, including both high- and low-ash yield durains, generally have abundant Densosporites , suggesting that the parent plant inhabited a fairly wide range of environments. Lithologies having tree ferns as an important component also have high fusinite + semifusinite and a low telinite/gelocollinite ratio. The aerial root bundles of the tree ferns were susceptible to oxidation and, for tissue not oxidized to inertinite, to preservation as gelocollinite. In the initial stages of formation, the Stockton mire was discontinuous and had a rather restricted floral assemblage. The presence of durains higher in the Stockton section, particularly the low-ash yield durains having petrographic indicators of degradation, suggests that portions of the mire developed as a domed peat. The termination of the mire as a high-sulfur, arboreous lycopod-domimated mire is consistent with the return to more planar mire development.

Comparison of the petrography, palynology and paleobotany of the Stockton coal bed, West Virginia and implications for paleoenvironmental interpretations

Abstract The Stockton coal bed (Middle Pennsylvanian) is a relatively high ash coal composed primarily of moderately thin banded, sparsely thin banded, and nonbanded coal (splint and cannel coal). Comparisons of petrographic, palynologic, and paleobotanic data gathered from the same sample sets from a single column of the Stockton coal bed indicate that compositional correspondences among the sets exist regardless of coal type. Some correspondences are believed to exist because of original plant constituents and others because of the paleoenvironment of peat formation. Using some combination of these data is critical when interpreting paleoenvironmental conditions because (1) a direct correspondence is lacking between many of the data and (2) each of the three data sets provides a unique and important perspective on the paleomire. The Stockton paleomire in the area of this study supported a diverse flora that consisted of both small and arboreous lycopsids, small ferns and tree ferns, calamites, cordaites, and pteridosperms. There appear to have been two successions of Lycospora spore-dominated, vitrinite-rich, liptinite-poor peat formation, which were followed by inertinite-rich peat formation marked by a tree fern-dominant spore assemblage and abundant unidentifiable plant tissues. These are interpreted to be two water-laden or topogenous peat formational stages followed by slightly domed, better drained peat formation.

Comparison of the petrography, palynology, and paleobotany of the Little Fire Creek coal bed, southwestern Virginia, U.S.A.

Abstract Two continuous cores that penetrated the Lower Pennsylvanian Little Fire Creek coal bed in the Southwestern coal field in southwestern Virginia were sampled and X-ray radiographed to determine subunit distinctions. Comparison of petrographic, palynologic, and paleobotanic data from the same sample sets from the two cores allowed for comparison of compositional data within the Little Fire Creek coal bed. The proximate, petrographic, palynologic, and plant tissue data from two sets of samples indicate a high ash, gelocollinite- and liptinite-rich coal consisting of a relatively diverse paleoflora, including lycopsid trees, small lycopsids, tree ferns, small ferns, pteridosperms (seed ferns), and rare calamites and cordaites. The relatively very high ash yields (3–80 wt%), the relatively thin subunits (1–28 cm), and the large scale vertical variations in palynomorph floras suggest that the study area was at the edge of the paleopea-forming environment. As a result, most of the compositional correspondences are among those components indicative of degradation or decomposition.

A Framework for Quantitative Assessment of Impacts Related to Energy and Mineral Resource Development

Natural resource planning at all scales demands methods for assessing the impacts of resource development and use, and in particular it requires standardized methods that yield robust and unbiased results. Building from existing probabilistic methods for assessing the volumes of energy and mineral resources, we provide an algorithm for consistent, reproducible, quantitative assessment of resource development impacts. The approach combines probabilistic input data with Monte Carlo statistical methods to determine probabilistic outputs that convey the uncertainties inherent in the data. For example, one can utilize our algorithm to combine data from a natural gas resource assessment with maps of sage grouse leks and piñon-juniper woodlands in the same area to estimate possible future habitat impacts due to possible future gas development. As another example: one could combine geochemical data and maps of lynx habitat with data from a mineral deposit assessment in the same area to determine possible future mining impacts on water resources and lynx habitat. The approach can be applied to a broad range of positive and negative resource development impacts, such as water quantity or quality, economic benefits, or air quality, limited only by the availability of necessary input data and quantified relationships among geologic resources, development alternatives, and impacts. The framework enables quantitative evaluation of the trade-offs inherent in resource management decision-making, including cumulative impacts, to address societal concerns and policy aspects of resource development.

Quality and petrographic characteristics of Paleocene coals from the Hanna basin, Wyoming

Coal beds from the Ferris and Hanna Formations, in the Hanna basin, south-central Wyoming, exhibit distinct differences in ash yield, sulfur content, and petrographic and palynologic constituents. These differences are interpreted to be controlled by tectonic changes of the Hanna basin and adjoining uplifts during evolutionary development, which, in turn, controlled mire chemistry and sedimentation. These conditions created two very different settings under which the peats developed during deposition of the Ferris and the Hanna Formations. In addition, there appears to be a geographic (latitudinal) and/or climatic control on the coal characteristics manifested by major differences of Paleocene coals in the Hanna basin compared to those in the Raton basin in Colorado and New Mexico and the Powder River basin in Wyoming.

Geology, coal quality, and resources of the Antaramut-Kurtan-Dzoragukh coal field, north-central Armenia

Abstract The Antaramut–Kurtan–Dzoragukh (AKD) coal deposit is a previously unrecognized coal field in north-central Armenia. Coal has been known to exist in the general vicinity since the turn of the century, but coal was thought to be restricted to a small (1 km2) area only near the village of Antaramut. However, through detailed field work and exploratory drilling, this coal deposit has been expanded to at least 20 km2, and thus renamed the Antaramut–Kurtan–Dzoragukh coal field, for the three villages that the coal field encompasses. The entire coal-bearing horizon, a series of tuffaceous sandstones, siltstones, and claystones, is approximately 50 m thick. The AKD coal field contains two coal beds, each greater than 1 m thick, and numerous small rider beds, with a total resource of approximately 31,000,000 metric tonnes. The coals are late Eocene in age, high volatile bituminous in rank, relatively high in ash yield (approximately 40%, as-determined basis) and moderate in sulfur content (approximately 3%, as-determined basis). The two coal beds (No. 1 and No. 2), on a moist, mineral-matter-free basis, have high calorific values of 32.6 MJ/kg (7796 cal/g) and 36.0 MJ/kg (8599 cal/g), respectively. Coal is one of the few indigenous fossil fuel resources occurring in Armenia and thus, the AKD coal field could potentially provide fuel for heating and possibly energy generation in the Armenian energy budget.

Washability Characteristics of Facies of Upper Freeport Coal Bed: Homer City, Pennsylvania Area: ABSTRACT

Washability testing data were obtained for samples of Upper Freeport coal-bed facies (mappable subunits). The facies, which were identified and correlated using core and mine-face descriptions, are relatively uniform in thickness as units and vary less in quality than the entire bed because the number of facies are not the same throughout the deposit. Washability characteristics of a coal bed were inferred from collective megascopic descriptions, x-ray radiographic analyses, and coal-quality characteristics of the facies. In addition, certain petrographic, physical, and chemical data such as inertodetrinite content, pyrite forms, density, and contents of Zr and La of coal-bed facies samples were related to washability characteristics such as weight percent of recovery and pounds of sulfur/million Btu of recovery for a particular specific gravity of separation. Petrographic characterization of pyrite forms and associations, weight percent of pyritic sulfur, and density were used to estimate sulfur cleanability in the samples. Good estimates of product recoverability at specific gravity float levels were made from the density of the unprocessed samples. Sulfur variability (1) is commonly greatest in the uppermost facies of the Upper Freeport coal bed, (2) results from variability in the amount of different pyrite forms (irregular pyrite that replaced organic matter), and (3) has a positive correlation with the lithology of the overlying rock. Specifically, sulfur is commonly highest in those facies overlain by sandstone. Facies analysis of a coal bed provides data that are more reliable for the assessment of coal-bed quality than are data from whole-bed analyses. In addition, stratigraphic data, such as the quality and extent of coal-bed facies, can aid in evaluating coal beds for mining and preparation as well as in interpreting the conditions of paleopeat formation. End_of_Article - Last_Page 1448------------