bluuebunny/crossref_metadata_2025_split huggingface dataset:
Faulting and porosity modification in the Sherwood Sandstone at Alderley Edge, northeastern Cheshire: an exhumed example of fault-related diagenesis
Authors: Rowe John , Burley Stuart D. 
Published: April 2008

Abstract
The Alderley Horst is an exhumed, titled structure close to the eastern margin of the Cheshire Basin, broadly analogous to the titled fault blocks in the East Irish Sea Basin. Sediments of the Lower and Middle Triassic Sherwood Sandstone Group are exposed at the crest of the horst whilst its flanks are capped by sediments of the Mercia Mudstone Group. Extensive diagenesis and porosity modification have taken place in the Sherwood Sandstone across the Alderley Horst.
Diagenetic modification includes reduction of hematite grain coatings and quartz cementation, together with Cu-Pb-Zn-Fe sulphide and barite mineralization. The distribution of this cementation is spatially related to faults that cross the horst and its style and extent varies between individual faults and between fault sets of different orientations. Different spatial distributions are observed for quartz cements, barite, sulphides, ferroan calcite, reduction of hematite grain coatings and secondary ore concentrations. Sandstone units close to the base of the Mercia Mudstone Group are more intensely altered than lower units showing that hematite reduction and mineralization are concentrated at the crest of the horst.
Fault-related mineralization and porosity modification post-dates all of the fault movement as brecciation and deformation of barite and sulphide cements are not observed. The intensity of mineralization decreases at structurally lower levels on the WNW-ESE oriented faults, so precluding them as conduits for the vertical migration of mineralizing fluids. However, the horst-bounding Kirkleyditch Fault was probably an important migration pathway that enabled valving of fluids from dowthrown sources in the Mercia Mudstone Group, Manchester Marls and Carboniferous shales, although the possibility of fluid migration up-dip from the south cannot be completely discounted. The mineralizing fluids were ponded at the crest of the horst where they were baffled by pre-existing structural barriers.
Calder Field appraisal well 110/7a-8, East Irish Sea Basin
Authors: Blow R. A. , Hardman M. 
Published: April 2008

Abstract

The Calder Field, Block 110/7a, is located approximately 5 km southwest of the South Morecambe Field in 100 feet of water. The field was discovered by well 110/7a-3 in 1982; this was the first well in the East Irish Sea Basin (EISB) to encounter sour gas (H
2
S 4500 ppm) and live oil. Well 110/7a-4 was drilled to appraise the discovery in 1983; this well produced sour gas at a combined flow rate in excess of 25 MMSCFD from the Sherwood Sandstone Group reservoir. Whilst the two wells proved the presence of gas within the Sherwood Sandstone Group they also indicated a significant velocity variation within the Mercia Mudstone Group overburden. This resulted in uncertainty in depth conversion to top reservoir and also in reserve estimates based upon the depth maps. In an attempt to narrow the reserve uncertainty an integrated geological and geophysical re-evaluation of the field was carried out. This involved detailed subdivision of the Mercia Mudstone Group based on mudstone/halite stratigraphy together with intra-Mercia Mudstone Group seismic interpretation. This approach generated a velocity and depth model successfully tested by appraisal well 110/7a-8 which was drilled during 1994. Implicit in the field model are the occurrences on seismic section of a dipping ‘flat spot’ associated with the gas/oil contact and also pseudo-faulting at top reservoir level, both generated by lateral velocity variations in the near-surface section.
Coal production and usage in the Czech Republic
Authors: Pešek J. , Dopita M. 
Published: April 2008

Abstract
Coal mining in the industrialized countries of Europe including the Czech Republic is witnessing a prolonged recession in the production of bituminous coal and lignite in particular due to reduced demands. Recession in numerous fields of industry has resulted apparently in lower production of metallurgical coke as well as in power generation. In addition, some countries have substituted the burning of solid fossil fuels with petroleum or natural gas or with other energy sources such as nuclear power, hydroenergy or geothermal energy. The Czech Republic is facing similar problems.
The origin and properties of a coal seam associated with continental thin micritic limestones, Selimoglu-Divrigi, Turkey
Authors: Karayigit A. I. , Whateley M. K. G. 
Published: April 2008

Abstract

The Selimoglu coalfield is situated at the southeastern part of Divrigi, which is geographically distinct from the major coalfields of Turkey. A number of thin and lenticular coal seams and sedimentary rocks occur in the Selimoglu unit of the Ogulbey Formation of Upper Miocene age. Only one seam, which is produced by an underground method, is associated with continental thin micritic limestones that have a total thickness of about 150 cm. It has a macroscopically bright appearance and a working thickness of 50–90 cm (70 cm average). A total of 32 channel samples were collected from the mined seam for proximate, mineralogical and petrographic analyses. The results of proximate analyses on an air-dried basis show that the coal is characterized by low moisture content (1.68% average), high ash yield (24.04% average), high total sulphur content (up to 8.92%) and high calorific value (5606 kcal kg
−1
average). The coals average 65.5% vitrinite, 4.5% liptinite, 2.5% inertinite and 27.4% mineral matter. Desmocollinite is the dominant maceral in the vitrinite group and calcites in the whole-coal minerals. Carbonate minerals with irregular shapes are in general early-diagenetic, and occur in desmocollinites in all the samples. The micritic texture of the limestone shows both diagenetic and authigenic origin in subaquatic conditions with high pH, but organic debris is allochthonous in origin. The reflectance values of telocollinite (0.77% Rr) show a high volatile bituminous coal rank. The random reflectance of telocollinite and spectral maxima (625–661 nm) of sporinites, and proximate analyses reveal that the thermal history may have been affected by volcanic activity that occurred in the coal field.
The main coal facies and lithotypes of the Pliocene coal basin, Oltenia, Romania
Authors: Ţicleanu Nicolae , Diaconiţǎ Dorina 
Published: April 2008

Abstract
This paper presents the results of palaeobotanical studies correlated with coal petrography research carried out by the authors in the western part of the Dacic Basin (Oltenia) coal deposits. Of the seven coal facies that have been distinguished so far in the lignites of Oltenia, the present paper deals with the five main facies generated by: swamp deciduous forest, Carex ssp. grassy marsh, swamp with Glyptostrobus, reed swamp and aquatic macrophyte prairie. The palaeoecological and palaeophytocoenoical studies have led to the reconstruction of the factors that characterize the major coal facies.
Coal petrology and facies associations of the South Yakutian Coal Basin, Siberia
Authors: Stukalova I. E. 
Published: April 2008

Abstract

The South Yakutian Coal Basin consists of isolated depressions in the south of the Yakutian region of Eastern Siberia in Russia, which are filled with Jurassic and Cretaceous coal-bearing sediments. The basin contains considerable resources of high-quality bituminous coals, with a caking index (
y
) of 6–21 mm. The coal-bearing formation contains coal seams of various thickness, from 0.5–2.5 m up to 15.0 m and above. Some of them are near the surface and can be mined by opencut methods. Genetic types and facies of the Mesozoic coal-bearing strata have been recognised as proluvial, alluvial, delta, lacustrine-swamp and peat bogs sediments. The petrographic composition of the sandstones identified four terrigenous-mineral associations, which are represented by true arkoses, greywacke arkoses, feldspar-quartz and quartz-feldspar greywackes. Humic coals consists of vitrinite (70–90%), interinite (10–20%) and liptinite (0–10%) maceral groups. In the vitrinite maceral group there is a high percentage of telinite macerals, up to 60–65%. The basin is characterized by a high alteration of Mesozoic sediments and organic matter. Coals are of middle and high rank (0.65–2.15%
R
0
). There are high concentrations of bitumen in chloroform extracts of organic matter from the coals, from 0.0938% to 3.6466%. The mineral matter of terrigenous rocks is altered to the catagenetic stage and the metagenetic stage. The South Yakutian coals are of high quality because of their rank and composition.
Coal rank variations with depth related to major thrust detachments in the South Wales coalfield: implications for fluid flow and mineralization
Authors: Gayer Rod , Fowler Richard , Davies Gareth 
Published: April 2008

Abstract

Coal maturity data in the form of volatile matter (daf and dmmf) and random vitrinite reflectance have been analysed for the South Wales coalfield. They show that in general coals increase in rank with depth, obeying Hilt’s law, and increase in rank laterally from high volatile bituminous coals in the south and east of the coalfield to anthracite in the northwest of the coalfield. The lateral increase in rank does not coincide with the basin depocentre which was located to the southwest of the coal basin during Westphalian times. The rank pattern with depth in the Westphalian A-Lower Westphalian C Coal Measures of the eastern half of the coalfield suggests a palaeogeothermal gradient of approx. 310°C km
−1
, equivalent to a basal heatflow of 295 m Wm
−2
. Investigation of vitrinite reflectance in a coal sequence repeated by intense Variscan thrusting indicates that coal rank was acquired both pre- and syn-thrusting. Detailed analysis of the volatile matter data reveals the presence of excursions from Hilt’s law present in one or more coal seams close to the boundary between Westphalian A & B. Of the 154 data sets analysed from the coalfield, 94 (61%) show one or more excursion. It is shown that the excursions correlate with thrust detachments within the coal seams, and it is argued that the excursions represent an increase in maturity temperature caused by fluids carrying heat into the coal seam along the seismically active thrusts. The fluids may also have been responsible for the carbonate, oxide and sulphide mineralization of the coalfield. Preliminary comparisons with the Ruhr coal basin in Germany suggest that future studies involving computer generated thermal models are required to understand the thermal evolution of both basins.
Deep borehole evidence for a southward extension of the Early Namurian deposits near Němčičky, S. Moravia, Czech Republic: implication for rapid coalification
Authors: Dvořák J. , Honěk J. , Pešek J. , Valterová P. 
Published: April 2008

Abstract

Unexpected Early Namurian (Namurian A) sediments were identified in several boreholes in the vicinity of Němčičky (the Němčičky basin), south Moravia. Coal fragments were recovered from the boreholes Něm 1, 2, 5 and 6. These fragments come partly from
in situ
coal seams, partly from eroded coal seams and partly from coalified logs. Although these fragments were recovered from depths of 2690.9 m (Něm 5) to 4803 m (Něm 1), their mean reflectance (
R
0
) is 0.57% up to 0.9% which corresponds to subbituminous to high volatile bituminous coal. The very low rank of the coal at these depths argues for very fast coalification of the coal fragments most likely during the Carboniferous. The rank of the coal is believed not to have been affected by later burial beneath Jurassic sediments or by tectonic burial under Carpathian nappes.
Comparison of solid state
13
C NMR of algal coals/anthracite and charcoal-like fusinites: further evidence for graphitic domains
Authors: Premović P. I. , Nikolić R. S. , Premović M. P. 
Published: April 2008

Abstract

Carbon distribution in coals and coal macerals was studied by
13
C NMR cross-polarization (CP)/ magic angle spinning (MAS) spectrometry. We examined two charcoal-like fusinites from Serbia: the Jerma (Jerma mine) and Miroč (mine ‘Aliksar’) seams. This examination revealed that atomic H/C ratios calculated (on the basis of the CP/MAS parameters) for fusinites studied are higher by 68% (Jerma) and by 64% (Miroč) than the H/C values which are determined by elemental analysis. Calculated H/C values infer that either more carbon or less hydrogen is required for the fusinite structures than is contained in the samples. We conclude that the differences in the estimation of H/C for bituminous charcoal-like fusinites between solid state
13
C NMR and elemental analysis can be explained by graphitic domains within the maceral ‘invisible’ in the CP/MAS experiment.
Composition and properties of North Bohemian coals
Authors: Sýkorová Ivana , Černý Jaroslav , Pavlíková Helena , Weishauptová Zuzana 
Published: April 2008

Abstract
This work presents the mean chemical, micropetrographic, surface and other characteristics of coal seams from western, central, and eastern parts of the North Bohemian brown coal basin. Attention was especially paid to the elemental composition, ash content, content and forms of sulphur, occurrence of syngenetic and epigenetic sulphides, maceral composition, and degree of gelification and decomposition of components in the huminite maceral group. Some other coal characteristics were also assessed, such as pore texture, extractability and solvent swelling of the coals.
The coals examined were huminitic with a variable xylite and detrite content. Huminite reflectance varied between 0.33 and 0.39%. Substantial differences in pore texture of the coals were found in the range of meso- and macropores. These differences largely affected the extractability of the North Bohemian coals. The coals also exhibited extremely high swelling ratios in basic solvents, such as pyridine.
Floristic characters of the upper coal-bearing formation in the Transcarpathians
Authors: Syabryaj Svetilana 
Published: April 2008

Abstract
The results of palynological studies of samples from outcrops, boreholes and mines in the Transcarpathians are presented. Megafloral remains from the Ilnitsa suite show the age of the upper coal-bearing formation to be Romanian. The palynological analysis allows the reconstruction of changes in the plant cover during the Romanian, and the determination of the climatic and palaeogeographic conditions.
Sulphur distribution in a multi-bed seam
Authors: Cavender Paul F. , Alan Spears D. 
Published: April 2008

Abstract
The Parkgate Seam (Langsettian) is an important seam for the coal industry in the UK. It extends over a considerable part of the East Pennine Coalfield and a large database of information on the seam has been complied by (the former) British Coal for the Nottinghamshire area from many sampling locations. The seam has been subdivided into a series of mappable units termed plies. This paper demonstrates how sulphur concentrations may vary considerably on a vertical scale and that spatial distributions within individual plies may be markedly different to other plies within the seam. Often seam sulphur maps for industrial use are produced for a composite of the whole thickness of the seam, typically as the whole seam-less-dirt. The neglect of the vertical variation in seam sulphur content may lead to the production of maps which are of limited industrial use. Variations in sulphur distributions also has implications for the origin of the sulphur in the coal. Distribution maps have allowed the controls on sulphur in the Parkgate Seam to be investigated, and these are dominated by complex depositional processes.
Values of δ
34
S in iron disulphides of the North Bohemian Lignite Basin, Czech Republic
Authors: Bouška Vladimír , Pešek Jiří , Žák Karel 
Published: April 2008

Abstract
Three main, genetically different, types of iron disulphides occur in lignite of the North Bohemian Basin — synsedimentary, diagenetic and epigenetic. Among them the synsedimentary disulphide appears to be the most abundant. It forms fine dispersed microscopic framboids or veinlets mostly parallel with the coal bedding. This disulphide is mostly represented by pyrite. The other types are much less abundant. The epigenetic variety consists of large macroscopic clusters of crystals of marcasite twins or crystalline filling of fractures.

The shift in sulphur isotopic composition between the original sulphate and the derived sulphides, which originated through bacterial reduction, may vary considerably depending on conditions, particularly on the open or closed nature of the system with respect to sulphate. The largest shifts in the isotopic composition between sulphate and sulphide sulphur are typical for an open system. Dissolved sulphate which supplied the North Bohemian Basin during the Miocene is likely to have been derived from weathered sulphides of the Krušné hory crystalline complex. This unit has isotopic compositions of sulphide sulphur varying between −1 and +5‰ and assuming no significant shifts in sulphur isotope compositions, the sulphate supplying the basin should exhibit a slightly positive δ
34
S value. Organic sulphur is thought to have played a much less important role.

Synsedimentary pyrites, which form microframboids or veinlets in coal, show δ
34
S values close to 0‰. These values when compared with those of sulphur dioxide in gases exhaled by power stations burning lignite of the North Bohemian Basin indicate that they correspond to mean values for synsedimentary pyrite. This also implies that no considerable shifts in isotopic composition take place during thermal oxidation in power plants.
Origin of vanadium in coals: parts of the Western Kentucky (USA) No. 9 coal rich in vanadium
Authors: Premović P. I. , Nikolić N. D. , Pavlović M. S. , Jovanović LJ. S. , Premović M. P. 
Published: April 2008

Abstract

The existence of vanadyl (VO
2+
)-non-porphyrins (P) in a thin band (enriched with vanadium) of the Western (W.) Kentucky (KY) No. 9 coal seam was shown by electron spin resonance (ESR). The ESR analysis indicates that VO
2+
-non-P are associated with the coal organic insoluble fraction. ESR parameters show that VO
2+
ion is in an environment with approximately axial symmetry and chelated possibly by carboxylic/phenolic oxygen ligand donor atoms. These parameters are compared with those of VO
2+
-fulvic acid complexes and the model complexes with salicylic/phthalic acids reported by others. It is concluded that the vanadylation of W. KY No. 9 thin coal band occurred during its diagenetic (peat-forming) stage in the Pennsylvanian swamp. The extraordinary V enrichment of the top 15 cm, relative to the lower parts of the W. KY No. 9 coalbed is interpreted by a high V concentration of the past swamp water attained through a sudden and exceptional external supply. The predominant source of the metal was probably volcanic ash on the land that was weathered/leached of its vanadium. The association of V/Cr (together with their enrichment in the top of the seam) and Ni implies that the volcanic ash was derived from basalts. Abundant organic (humic) materials (with the high V enrichment factor) and low rate of deposition were the primary factors responsible for the high vanadium content of the coal. From the chemistry of VO
2+
, FeS
2
and CrOH
2+
it is deduced that the oxidation potential Eh and pH of the ancient peat interstitial water were approximately −0.2 to −0.3 V and 5–6, respectively.
Environmental impact of minerals in UK coals
Authors: Spears D. A. 
Published: April 2008

Abstract

Both detrital and diagenetic minerals are quantitatively important in UK coals. The detrital minerals include quartz, and the clay minerals illite, mixed-layer illite-smectite, kaolinite and chlorite. The diagenetic minerals are dominated by pyrite/marcasite, carbonates, mainly ankerite and calcite, and kaolinite. Pyrite makes an important contribution to the S contents of the coals and is largely responsible for the variation in total S. The S content of coals delivered to power stations could be reduced by selective extraction during mining and improved physical coal-cleaning. Pyrite is a major location for trace elements of environmental concern and the elimination of pyrite would reduce both SO
2
and trace element emissions. Pyrite is also important in the weathering environment due to its instability. Its breakdown in coal stocks and colliery discard heaps may lead to spontaneous combustion. In discard heaps, pyrite breakdown is also responsible for acid porewaters and toxic elements in solution which inhibit colonization by vegetation and thus hinder reclamation of derelict land. If carbonates are sufficiently abundant, acid conditions may be eliminated. Acid porewaters are one facet of the general problem of acid mine drainage, which has a major impact on water quality, particularly in streams and rivers. In the UK acid mine drainage is a problem of growing concern due to reduction of deep-mine pumping following closure of collieries. Although pyrite breakdown in colliery spoil has an important influence on porewater compositions, it does not greatly influence the engineering stability because the major component, the mudrocks, contain very little pyrite. Upon exposure, the mudrocks break down relatively rapidly due to sedimentary structures to form an aggregate. Loss of interparticle bonding is a much slower process but there are a few mudrocks associated with low rank bituminous coals with both a high mixed-layer clay content and porosity which disintegrate rapidly during cycles of wetting and drying. There are also regional variations in the relative proportions of the clay minerals which influence the engineering properties. Kaolinite is dominant in the northern coalfields. This is also detected in the composition of fly ash produced by coal-fired power stations. Fly ash is enriched in those trace elements which have an environmental impact. The volatile elements, many of which were sulphide-associated in the coal, are enriched on the surface of the ash particles where they are accessible to leaching in the weathering environment, resulting in the contamination of natural waters.