Variations in chemistry of macerals as refl ected by micro-scale analysis of a Spanish coal

An Oligocene lignite (Ebro Basin, Spain) and its density fractions were analyzed petrographically and with microscale techniques (electron microprobe and micro-FTIR) to gain insight into differences between individual macerals of low rank high-sulfur coal. The density of the alginite-dominated fraction is below 1.26g/cm3, and that of the huminite-dominated fraction is above 1.38g/cm3. Densities within 1.26-1.38g/cm3 represent mixtures of liptinite and huminite macerals. With regard to elemental composition, alginite has the highest carbon content (75.6% on average) and the lowest oxygen content (6.1% on average). Corpohuminite is characterized by the lowest carbon content (62.3% on average) and the highest oxygen content (21.5% on average). Nitrogen contents for corpohuminite and ulminite (~1%) are similar, but are signifi cantly lower in alginite (0.2% on average). Sulfur content is highest in alginite (13.4% on average), followed by corpohuminite (9.8%) and ulminite (7.7%). Functional group analysis documents large differences between macerals of the huminite and liptinite group, but also indicates differences between individual macerals within both the huminite and liptinite group. These differences are most notable in aromaticity, degree of aromatic ring condensations, and hydrocarbon potential

Constraints on the Emplacement and Uplift History of the Pine Mountain Thrust Sheet, Eastern Kentucky: Evidence from Coal Rank Trends

In this paper coal rank trends on both sides of the Pine Mountain thrust in eastern Kentucky are used to place constraints on thrust evolution. Vitrinite reflectance () measurements on a single Pennsylvanian coal horizon (Fire Clay coal) in eastern Kentucky increase from 0.5% in the north to about 1.0% toward the SE in front of the Pine Mountain thrust. The same horizon in the hangingwall of the thrust displays lower Rmax values (0.8-0.85%). The reflectance isograds are subparallel to the thrust within approximately 10 km of the trace of the fault. We attribute thermal maturation to (1) pre-orogenic maturation by burial to a depth of about 2 km followed by (2) maturation due to conductive relaxation in the footwall after thrusting. Isotherms would not have been offset unless the thrust velocity was \u3e\u3e 10km / Mα. Assuming no erosion, the emergent thrust would have been approximately 3 km thick. In order to explain the relatively low reflectance values observed in the footwall, rapid uplift (\u3e3 km/Ma) after thrust emplacement is required. Alternatively, if erosion kept pace with thrusting, the thrust sheet would have been substantially thinner (\u3c1 \u3ekm), and thermal equilibrium would be rapidly attained in the footwall. Localized frictional heating may have caused elevated reflectance values observed in sheared coals from outcrop scale faults

Geochemistry, Petrology, and Palynology of the Princess No. 3 Coal, Greenup County, Kentucky

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

Migmatite-Like Textures in Anthracite: Further Evidence for Low-Grade Metamorphic Melting and Resolidification in High-Rank Coals

Previous studies demonstrated that melting, initiated by supercritical fluids in the 375–400 °C range, occurred as part of anthracite metamorphism in the Appalachian Basin. Based on the known behavior of vitrinite at high temperatures and, to a lesser extent, at high pressures, it was determined that the duration of the heating, melting, and resolidification event was about 1 h. In the current study, featureless vitrinite within banded maceral assemblages demonstrates the intimate association of melted and resolidified vitrinite with anthracite-rank macerals. By analogy with metamorphosed inorganic rocks, such associations represent diadysites and embrechites, i.e., cross-cutting and layered migmatites, respectively. Even though the temperature of formation of the anthracite structures is several hundred °C lower than that seen in metamorphosed inorganic rocks, anthracites are metamorphic rocks and the nomenclature for metamorphic rocks may be appropriate for coal

Gas emissions, minerals, and tars associated with three coal fires, Powder River Basin, USA.

Ground-based surveys of three coal fires and airborne surveys of two of the fires were conducted near Sheridan, Wyoming. The fires occur in natural outcrops and in abandoned mines, all containing Paleocene-age subbituminous coals. Diffuse (carbon dioxide (CO(2)) only) and vent (CO(2), carbon monoxide (CO), methane, hydrogen sulfide (H(2)S), and elemental mercury) emission estimates were made for each of the fires. Additionally, gas samples were collected for volatile organic compound (VOC) analysis and showed a large range in variation between vents. The fires produce locally dangerous levels of CO, CO(2), H(2)S, and benzene, among other gases. At one fire in an abandoned coal mine, trends in gas and tar composition followed a change in topography. Total CO(2) fluxes for the fires from airborne, ground-based, and rate of fire advancement estimates ranged from 0.9 to 780mg/s/m(2) and are comparable to other coal fires worldwide. Samples of tar and coal-fire minerals collected from the mouth of vents provided insight into the behavior and formation of the coal fires

Variations in chemistry of macerals as refl ected by micro-scale analysis of a Spanish coal

An Oligocene lignite (Ebro Basin, Spain) and its density fractions were analyzed petrographically and with microscale techniques (electron microprobe and micro-FTIR) to gain insight into differences between individual macerals of low rank high-sulfur coal. The density of the alginite-dominated fraction is below 1.26g/cm3, and that of the huminite-dominated fraction is above 1.38g/cm3. Densities within 1.26-1.38g/cm3 represent mixtures of liptinite and huminite macerals. With regard to elemental composition, alginite has the highest carbon content (75.6% on average) and the lowest oxygen content (6.1% on average). Corpohuminite is characterized by the lowest carbon content (62.3% on average) and the highest oxygen content (21.5% on average). Nitrogen contents for corpohuminite and ulminite (~1%) are similar, but are significantly lower in alginite (0.2% on average). Sulfur content is highest in alginite (13.4% on average), followed by corpohuminite (9.8%) and ulminite (7.7%). Functional group analysis documents large differences between macerals of the huminite and liptinite group, but also indicates differences between individual macerals within both the huminite and liptinite group. These ifferences are most notable in aromaticity, degree of aromatic ring condensations, and hydrocarbon potential

Interlaboratory comparisons of petrography of liquefaction residues from three Argonne Premium coals

Three Argonne Premium coal samples, the Beulah-Zap lignite (North Dakota), the high volatile A bituminous Stockton (West Virginia), and the low volatile Pocahontas No. 3 (Virginia), were ground to three initial sizes: -20 mesh, -100 mesh, and "micronized". The samples were each subjected to liquefaction at 673 K for 30 min at a 2:1 tetralin :coal ratio and in an H 2 atmosphere at 13.79 MPa (~ 2000 psi). Polished pellets of the unconverted residues were circulated to three laboratories for a study designed to determine, albeit on a limited scale, the interlaboratory consistency in constituent identification and the problem areas in maceral/neo-maceral/mineral recognition. Within broad categories, the agreement for the Beulah-Zap and Pocahontas No. 3 residues is good. The high volatile A bituminous Stockton coal was the most plastic and most altered, resulting in a residue lending itself to more subjective interpretations. The biggest discrepancy between the laboratories is in the distinction of granular residue and mineral matter and in the transitions between "partially reacted macerals" and "vitroplast" and between "vitroplast" and "granular residue". The initial size of the feed coal appears to influence the recognition of material in the residue

GPU Concurrency: Weak Behaviours and Programming Assumptions

Concurrency is pervasive and perplexing, particularly on graphics processing units (GPUs). Current specifications of languages and hardware are inconclusive; thus programmers often rely on folklore assumptions when writing software. To remedy this state of affairs, we conducted a large empirical study of the concurrent behaviour of deployed GPUs. Armed with litmus tests (i.e. short concurrent programs), we questioned the assumptions in programming guides and vendor documentation about the guarantees provided by hardware. We developed a tool to generate thousands of litmus tests and run them under stressful workloads. We observed a litany of previously elusive weak behaviours, and exposed folklore beliefs about GPU programming---often supported by official tutorials---as false. As a way forward, we propose a model of Nvidia GPU hardware, which correctly models every behaviour witnessed in our experiments. The model is a variant of SPARC Relaxed Memory Order (RMO), structured following the GPU concurrency hierarchy

Volcanic Emissions and Atmospheric Pollution: A Study of Nanoparticles

The influence of emissions of an active volcano on the composition of nanoparticles and ultrafine road dust was identified in an urban area of the Andes. Although many cities are close to active volcanoes, few studies have evaluated their influence in road dust composition. Air quality in urban areas is significantly affected by non-exhaust emissions (e.g. road dust, brake wear, tire wear), however, natural sources such as volcanoes also impact the chemical composition of the particles. In this study, elements from volcanic emissions such as Si \u3e Al \u3e Fe \u3e Ca \u3e K \u3e Mg, and Si—Al with K were identified as complex hydrates. Similarly, As, Hg, Cd, Pb, As, H, Cd, Pb, V, and salammoniac were observed in nanoparticles and ultrafine material. Mineral composition was detected in the order of quartz\u3e mullite\u3e calcite\u3e kaolinite\u3e illite\u3e goethite\u3e magnetite\u3e zircon\u3e monazite, in addition to salammoniac, a tracer of volcanic sources. The foregoing analysis reflects the importance of carrying out more studies relating the influence of volcanic emissions in road dust in order to protect human health. The road dust load (RD10) ranged between 0.8 and 26.8 mg m−2 in the city

Volcanic emissions and atmospheric pollution: a study of nanoparticles

The influence of emissions of an active volcano on the composition of nanoparticles and ultrafine road dust was identified in an urban area of the Andes. Although many cities are close to active volcanoes, few studies have evaluated their influence in road dust composition. Air quality in urban areas is significantly affected by non-exhaust emissions (e.g. road dust, brake wear, tire wear), however, natural sources such as volcanoes also impact the chemical composition of the particles. In this study, elements from volcanic emissions such as Si > Al > Fe > Ca > K > Mg, and Si Al with K were identified as complex hydrates. Similarly, As, Hg, Cd, Pb, As, H, Cd, Pb, V, and salammoniac were observed in nanoparticles and ultrafine material. Mineral composition was detected in the order of quartz> mullite> calcite> kaolinite> illite> goethite> magnetite> zircon> monazite, in addition to salammoniac, a tracer of volcanic sources. The foregoing analysis reflects the importance of carrying out more studies relating the influence of volcanic emissions in road dust in order to protect human health. The road dust load (RD10) ranged between 0.8 and 26.8 mg m−2 in the city