USGS Science⌕ Search

Geology topics

C.F. Eble

Publications and source records attributed to C.F. Eble.

At least 37 records · Page 2Linked to original sources
USGS2004

Coal facies studies in the eastern United States

Coals in the eastern United States (east of the Mississippi River) have been the subject of a number of coal facies studies, going back to the 19th century. Such studies would not necessarily fall within a strict modern classification of coal facies studies, but if a study encompassed some aspects of paleobotany, palynology, petrology, geochemistry, or sedimentology, we assumed that some data and interpretations may be of use in evaluations of the facies. References are presented, as a guide for further research, with annotation in the tables. ?? 2004 Elsevier B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2003

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

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. ?? 2003 Elsevier B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2002

Multiple-bench architecture and interpretations of original mire phases - Examples from the Middle Pennyslvanian of the Central Appalachian Basin, USA

Coal seams often exhibit lateral and vertical variability in composition. When sampled as a whole seam this variability is masked. But if a seam is subdivided into correlateable components, this variability can be tested and better understood. Herein, an architectural approach is used to divide seams into intra-seam components. Clastic splits and mineral partings, as well as persistent fusain and durain layers, can be used as intra-seam bounding units to subdivide a seam into subdivisions called benches. Regional examination of Lower and Middle Pennsylvanian-age coal seams shows that many contain laterally persistent bounding surfaces that can be used to define multiple benches of coal within each seam. Inter-bench analyses from some of the most extensively mined seams in the central Appalachian Basin show that individual benches often have different spatial and quality trends. Hence, some component of whole-seam variability is a function of changes in the relative contribution of these different benches to the seam as a whole. Many coal benches also exhibit intra-bench variation in coal parameters. Intra-bench variation can be analyzed in terms of parameters such as sulfur content and ash yield in order to address changes in coal quality for regional resource evaluation. Intra-bench variation can also be analyzed in terms of a combination of palynologic, petrographic, and geochemical parameters, termed compositional groups, in order to better understand the development of the original mire systems. Compositional groups are defined by ranges of multiple criteria, which are inferred to owe their origin to the mire type in which they formed. Vertical changes in compositional groups within coal benches can be used to infer paleo-edaphic conditions during peat accumulation. If seam thickness is a product of bench configuration, and trends in compositional groups occur in benches, then trends in quality can be marginally predicted based upon seam thickness and inferred bench architecture. Additionally, changes in inter-bench and intra-bench thickness and compositional profiles can be used to infer original depositional controls, such as paleotopography, syndepositional structural movement, and syndepositional clastic influx for more accurate reserve estimates. ?? 2002 Elsevier Science B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2002

Palynology of late Middle Pennsylvanian coal beds in the Appalachian Basin

Fossil spores and pollen have long been recognized as valuable tools for identifying and correlating coal beds. This paper describes the palynology of late Middle Pennsylvanian coal beds in the Appalachian Basin with emphasis on forms that assist both intra- and interbasinal coal bed correlation. Stratigraphically important palynomorphs that originate in late Middle Pennsylvanian strata include Torispora securis, Murospora kosankei, Triquitrites minutus, Cadiospora magna, Mooreisporites inusitatus, and Schopfites dimorphus. Taxa that terminate in the late Middle Pennsylvanian include Radiizonates difformis, Densosporites annulatus, Dictyotriletes bireticulatus, Vestispora magna, and Savitrisporites nux. Species of Lycospora, Cirratriradites, Vestispora, and Thymospora, as well as Granasporites medius, Triquitrites sculptilis, and T. securis and their respective ranges slightly higher, in earliest Late Pennsylvanian age strata. Late Middle Pennsylvanian and earliest Late Pennsylvanian strata in the Appalachian Basin correlate with the Radiizonates difformis (RD), Mooreisporites inusitatus (MI), Schopfites colchesterensis-S. dimorphus (CP), and Lycospora granulata-Granasporites medius (GM) spore assemblage zones of the Eastern Interior, or Illinois Basin. In the Western Interior Basin, these strata correlate with the middle-upper portion of the Torispora securis-Laevigatosporites globosus (SG) and lower half of the Thymospora pseudothiessenii-Schopfites dimorphus (PD) assemblage zones. In western Europe, late Middle Pennsylvanian and earliest Late Pennsylvanian strata correlate with the middle-upper portion of the Torispora securis-T. laevigata (SL) and the middle part of the Thymospora obscura-T. thiessenii (OT) spore assemblage zones. Allegheny Formation coal beds also correlate with the Torispora securis (X) and Thymospora obscura (XI) spore assemblages, which were developed for coal beds in Great Britain. ?? 2002 Elsevier Science B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2002

Comparison of the Eastern and Western Kentucky coal fields (Pennsylvanian), USA-why are coal distribution patterns and sulfur contents so different in these coal fields?

More than 130 Mt of Pennsylvanian coal is produced annually from two coal fields in Kentucky. The Western Kentucky Coal Field occurs in part of the Illinois Basin, an intercratonic basin, and the Eastern Kentucky Coal Field occurs in the Central Appalachian Basin, a foreland basin. The basins are only separated by 140 km, but mined western Kentucky coal beds exhibit significantly higher sulfur values than eastern Kentucky coals. Higher-sulfur coal beds in western Kentucky have generally been inferred to be caused by more marine influences than for eastern Kentucky coals. Comparison of strata in the two coal fields shows that more strata and more coal beds accumulated in the Eastern than Western Kentucky Coal Field in the Early and Middle Pennsylvanian, inferred to represent greater generation of tectonic accommodation in the foreland basin. Eastern Kentucky coal beds exhibit a greater tendency toward splitting and occurring in zones than time-equivalent western Kentucky coal beds, which is also inferred to represent foreland accommodation influences, overprinted by autogenic sedimentation effects. Western Kentucky coal beds exhibit higher sulfur values than their eastern counterparts, but western Kentucky coals occurring in Langsettian through Bolsovian strata can be low in sulfur content. Eastern Kentucky coal beds may increase in sulfur content beneath marine zones, but generally are still lower in sulfur than mined Western Kentucky coal beds, indicating that controls other than purely marine influences must have influenced coal quality. The bulk of production in the Eastern Kentucky Coal Field is from Duckmantian and Bolsovian coal beds, whereas production in the Western Kentucky Coal Field is from Westphalian D coals. Langsettian through Bolsovian paleoclimates in eastern Kentucky were favorable for peat doming, so numerous low-sulfur coals accumulated. These coals tend to occur in zones and are prone to lateral splitting because of foreland tectonic and sedimentation influences. In contrast, Westphalian D coal beds of western Kentucky accumulated during low differential tectonic accommodation, and therefore tend to be widespread and uniform in characteristics, but exhibit higher sulfur values because they accumulated in seasonally drier paleoclimates that were unfavorable for peat doming. Hence, basin analyses indicate that many differences between the mined coals of Kentucky's two coal fields are related to temporal changes in paleoclimate and tectonic accommodation, rather than solely being a function of marine influences. ?? 2002 Elsevier Science B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2001

Dips, ramps, and rolls- Evidence for paleotopographic and syn-depositional fault control on the Western Kentucky No. 4 coal bed, tradewater formation (Bolsovian) Illinois Basin

The Western Kentucky No. 4 coal is a high-volatile B to high-volatile C bituminous coal that has been heavily mined along the southern margin of the Western Kentucky Coal Field. The seam has a reputation for rolling floor elevation. Elongate trends of floor depressions are referred to as "dips" and "rolls" by miners. Some are relatively narrow and straight to slightly curvilinear in plan view, with generally symmetric to slightly asymmetric cross-sections. Others are broader and asymmetric in section, with sharp dips on one limb and gradual, ramp-like dips on the other. Some limbs change laterally from gradual dip, to sharp dip, to offset of the coal. Lateral changes in the rate of floor elevation dip are often associated with changes in coal thickness, and in underground mines, changes in floor elevation are sometimes associated with roof falls and haulage problems. In order to test if coal thickness changes within floor depressions were associated with changes in palynology, petrography and coal quality, the coal was sampled at a surface mine across a broad. ramp-like depression that showed down-dip coal thickening. Increment samples of coal from a thick (150 cm), down-ramp and thinner (127 cm), up-ramp position at one surface mine correlate well between sample sites (a distance of 60 m) except for a single increment. The anomalous increment (31 cm) in the lower-middle part of the thick coal bed contained 20% more Lycospora orbicula spores. The rolling floor elevations noted in the study mines are inferred to have been formed as a result of pre-peat paleotopographic depressions, syn-depositional faulting, fault-controlled pre-peat paleotopography, and from compaction beneath post-depositional channels and slumps. Although the association of thick coal with linear trends and inferred faults has been used in other basins to infer syn-depositional faulting, changes in palynology within increment samples of the seam along a structural ramp in this study provide subtle evidence of faulting within a specific increment of the coal itself. The sudden increase in L. orbicula (produced by Paralycopodites) in a single increment of a down-ramp sample of the Western Kentucky No. 4 coal records the reestablishment of a rheotrophic mire following a sudden change in edaphic conditions. Paralycopodites was a colonizing lycopod, which in this case became locally abundant after the peat was well established along a fault with obvious growth during peat accumulation. Because many coal-mire plants were susceptible to sudden edaphic changes as might accompany faulting or flooding, changes in palynology would be expected in coals affected by syn-depositional faulting. ?? 2001 Elsevier Science B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2001

The geology and palynology of lower and Middle Pennsylvanian strata in the Western Kentucky Coal Field

The Western Kentucky Coal Field is the southern tip of the Eastern Interior, or Illinois Basin. Pennsylvanian rocks in this area, which include conglomerate, sandstone, shale, limestone and coal, were deposited primarily in coastal-deltaic settings at a time when western Kentucky was located close to the equator. This paper discusses temporal changes in regional sedimentation patterns and coal-forming floras of Lower and Middle Pennsylvanian strata in the Western Kentucky Coal Field. Lower Pennsylvanian strata of the Caseyville Formation are characterized by paleovalley-filling sedimentation patterns and extabasinal quartz pebbles. Caseyville Formation coals are characterized thin and discontinuous and were strongly influenced by subsidence within underlying paleovalleys, and the dissected lower Pennsylvanian paleotopography. Caseyville coals are commonly dominated by Lycospora, but can also have variable palynofloras, which probably reflects variable edaphic conditions and edge effects within small, patchy paleomires. Tradewater Formation strata show increased marine influences and tidal-estuarine sedimentation, especially in the middle and upper parts. Coal beds in the lower part of the Tradewater typically are thin and discontinuous, although some economically important beds are present. Coals become thicker, more abundant and more laterally persistent towards the top of the formation. Palynologically, lower and middle Tradewater Formation coals are dominated by Lycospora, but begin to show increased amounts of tree fern spores. Middle and upper Tradewater coals are thicker and more continuous, and contain high percentages of tree fern spores. In addition, cordaite pollen is locally abundant in this interval. Carbondale and Shelburn (Desmoinesian) strata are much more laterally continuous, and occur within classic cyclothems that can be traced across the coal field. Cyclothems have long been interpreted as being eustatically driven, and glacio-eustacy controlled not only sedimentation but also the formation of Desmoinesian paleomires. Palynologically, Carbondale and Shelburn coals are either dominated by Lycospora or have heterogeneous palynofloras. Palynologic and coal-quality data suggest that hydrologic base level may have been the primary control on Desmoinesian paleomires, rather than paleoclimate, as the coals display rheotrophic, rather than ombrotrophic characteristics. ?? 2001 Elsevier Science B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2001

Brecciated and mineralized coals in Union County Western Kentucky coal field

Coals from the D-2 and D-3 boreholes in the Grove Center 7 1/2 min quadrangle, Union County, KY, have been found to be highly brecciated and mineralized. The mineralization is dominated by a carbonate assemblage with minor sulfides and sulfates. Included among the secondary minerals is the lead selenide, clausthalite. Overall, the emplacement of secondary vein minerals was responsible for raising the rank of the coals from the 0.6-0.7% Rmax range found in the area to as high as 0.95-0.99% Rmax. A 1.3-m-thick coal found in one of the boreholes is unique among known Western Kentucky coals in having less than 50% vitrinite. Semifusinite and fusinite dominate the maceral assemblages. The coal is also low in sulfur coal, which is unusual for the Illinois Basin. It has an ash yield of less than 10%; much of it dominated by pervasive carbonate veining. The age of the thick coal in core D-2 is similar to that of the Elm Lick coal bed, found elsewhere in the Western Kentucky coalfield. The coals in D-3 are younger, having Stephanian palynomorph assemblages. ?? 2001 Elsevier Science B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2001

Temporal and spatial variations in fly ash quality

Fly ash quality, both as the amount of petrographically distinguishable carbons and in chemistry, varies in both time and space. Temporal variations are a function of a number of variables. Variables can include variations in the coal blend organic petrography, mineralogy, and chemistry; variations in the pulverization of the coal, both as a function of the coal's Hardgrove grindability index and as a function of the maintenance and settings of the pulverizers; and variations in the operating conditions of the boiler, including changes in the pollution control system. Spatial variation, as an instantaneous measure of fly ash characteristics, should not involve changes in the first two sets of variables listed above. Spatial variations are a function of the gas flow within the boiler and ducts, certain flow conditions leading to a tendency for segregation of the less-dense carbons in one portion of the gas stream. Caution must be applied in sampling fly ash. Samples from a single bin, or series of bins, m ay not be representative of the whole fly ash, providing a biased view of the nature of the material. Further, it is generally not possible to be certain about variation until the analysis of the ash is complete. ?? 2001 Elsevier Science B.V. All rights reserved.

Fuel Processing Technology↗
USGS2000

Metalliferous coals of the Westphalian A Joggins Formation, Cumberland basin, Nova Scotia, Canada: Petrology, geochemistry, and palynology

Five coals of Westphalian A (early Middle Pennsylvanian) age were sampled from the Joggins Formation section exposed along Chignecto Bay at Joggins, Nova Scotia. Coal beds along the bay were mined beginning in the early 17th century, yet there have been few detailed published investigation of the coal beds of this classic section. The lowermost coal, the Upper Coal 28 (Upper Fundy), is a high-vitrinite coal with a spore assemblage dominated by arboreous lycopsid spores with tree ferns subdominant. The upper portions of the coal bed have the highest ratio of well-preserved to poorly-preserved telinite of any of the coals investigated. Coal 19 ('clam coal') has 88% total vitrinite but, unlike the Fundy coal bed, the telinite has a poor preservation ratio and half the total vitrinite population comprises gelocollinite and vitrodetrinite. The latter coal bed is directly overlain by a basin-wide limestone bed. The Lower Kimberly coal shows good preservation of vitrinite with relatively abundant telinite among the total vitrinite. The Middle Kimberly coal, which underlies the tetrapod-bearing lycopsid trees found by Lyell and Dawson in 1852, exhibits an upward decrease in arboreous lycopod spores and an upward increase in the tree fern spore Punctatisporites minutus. Telinite preservation increases upwards in the Middle Kimberly but overall is well below the preservation ratio of the Upper Fundy coal bed. The coals all have high sulfur contents, yielding up to 13.7% total sulfur for the lower lithotype of the Upper Fundy coal bed. The Kimberly coals are not only high in total and pyritic sulfur, but also have high concentrations of chalcophile elements. Zinc, ranging up to 15,000 ppm (ash basis), is present as sphalerite in fusain lumens. Arsenic and lead each exceed 6000 ppm (ash basis) in separate lithotypes of the Kimberly coals. Together these data are consistent with elevated pH in planar mires. The source of the elemental enrichment in this presumed continental section is enigmatic. (C) 2000 Elsevier Science B.V. All rights reserved.Five coals of Westphalian A (early Middle Pennsylvanian) age were sampled from the Joggins Formation section exposed along Chigneto Bay at Joggins, Nova Scotia. All the coals were found to have high sulfur contents. Overall, the data obtained are consistent with elevated pH in planar mires.

International Journal of Coal Geology↗
USGS2000

Block coals from Indiana: Inferences on changing depositional environment

Significant differences in coal petrography, palynology and coal quality were found between the Lower Block and Upper Block Coal Members (Brazil Formation, Pennsylvanian) in Daviess County, Indiana. The Lower Block Coal Member ranges in thickness from 51 to 74 cm and the Upper Block Coal Member ranges from 20 to 65 cm. Average sulfur content and ash yield of the Lower Block coal (0.98%, 7.65%) are lower than in the Upper Block coal. Megascopically, the coals show distinct differences. The Lower Block is a banded coal with numerous thin fusain horizons and a thin clay parting in the lower third of the seam. The Upper Block coal has a dulling-upward trend, with a bright clarain found at the base that grades into a clarain and then into a durain in the upper portion of the seam. Vitrinite content of the Lower Block coal ranges from 63% to 78%, with the highest vitrinite content found in the middle portion of the seam. In the Upper Block coal, vitrinite content ranges from 40% to 83%, with the highest values found in the lower part of the seam. Ash yield is higher in the upper part of the Upper Block coal, reaching up to 40%. The Lower Block coal is dominated by lycopod trees and tree ferns. The Upper Block coal shows marked differences in spore assemblages between lower and upper parts of the seam. The lower half is dominated by large lycopod trees and tree ferns, similar to the Lower Block coal. The upper half is dominated by small lycopods, mainly Densosporites and Radiizonates. These differences between the Lower Block and Upper Block Coal Members are significant correlation tools applicable to mining exploration and chronostratigraphy. (C) 2000 Elsevier Science B.V. All rights reserved.Significant differences in coal petrography, palynology and coal quality were found between the Lower Block and Upper Block Coal Members (Brazil Formation, Pennsylvanian) in Daviess County, Indiana. The Lower Block Coal Member ranges in thickness from 51 to 74 cm and the Upper Block Coal Member ranges from 20 to 65 cm. Average sulfur content and ash yield of the Lower Block coal (0.98%, 7.65%) are lower than in the Upper Block coal. Megascopically, the coals show distinct differences. The Lower Block is a banded coal with numerous thin fusain horizons and a thin clay parting in the lower third of the seam. The Upper Block coal has a dulling-upward trend, with a bright clarain found at the base that grades into a clarain and then into a durain in the upper portion of the seam. Vitrinite content of the Lower Block coal ranges from 63% to 78%, with the highest vitrinite content found in the middle portion of the seam. In the Upper Block coal, vitrinite content ranges from 40% to 83%, with the highest values found in the lower part of the seam. Ash yield is higher in the upper part of the Upper Block coal, reaching up to 40%. The Lower Block coal is dominated by lycopod trees and tree ferns. The Upper Block coal shows marked differences in spore assemblages between lower and upper parts of the seam. The lower half is dominated by large lycopod trees and tree ferns, similar to the Lower Block coal. The upper half is dominated by small lycopods, mainly Densosporites and Radiizonates. These differences between the Lower Block and Upper Block Coal members are significant correlation tools applicable to mining exploration and chronostratigraphy.

Conference Paper↗
USGS1999

Sulfur variability and petrology of the Lower Block Coal Member (Pennsylvanian) in Southwest Indiana

The Lower Block Coal Member (Pennsylvanian-Atokan, Westphalian C) is an economic low-to medium-sulfur, low-ash coal resource in the Illinois Basin. Sulfur content is generally low (averaging 1.0%) in the study area, but varies over short distances. Higher sulfur areas occur as isolated pods and epigenetic pyrite increases significantly in the upper third of the selected columns in higher sulfur areas. Sulfur variations cannot be predicted by typical geologic characteristics such as roof lithology, seam thickness, or seam elevation. Petrographic analysis shows that pyrite is generally associated with brighter microlithotypes, except in higher sulfur areas where infilling pyrite forms are associated with inertite. Higher sulfur areas reflect the water chemistry of the paleomire during and shortly after peat accumulation. Locally, abundant pyrofusinite provided additional pore space for pyrite precipitation.The Lower Block Coal Member (Pennsylvanian-Atokan, Westphalian C) is an economic low- to medium-sulfur, low-ash coal resource in the Illinois Basin. Sulfur content is generally low (averaging 1.0%) in the study area, but varies over short distances. Higher sulfur areas occur as isolated pods and epigenetic pyrite increases significantly in the upper third of the selected columns in higher sulfur areas. Sulfur variations cannot be predicted by typical geologic characteristics such as roof lithology, seam thickness, or seam elevation. Petrographic analysis shows that pyrite is generally associated with brighter microlithotypes, except in higher sulfur areas where infilling pyrite forms are associated with inertite. Higher sulfur areas reflect the water chemistry of the paleomire during and shortly after peat accumulation. Locally, abundant pyrofusinite provided additional pore space for pyrite precipitation.

International Journal of Coal Geology↗
USGS1999

Observations on the palynology, petrography and geochemistry of the Western Kentucky number 4 coal bed

Eight bench-column samples of the Western Kentucky Number 4 coal bed, collected from an area along the southern margin of the Western Kentucky Coal Field, were analyzed palynologically, petrographically, and geochemically to document both temporal and spatial variability among these parameters. The Western Kentucky Number 4 coal occurs near the top of the Tradewater Formation, is of Early Desmoinesian age, and is correlative with the lower part of the Allegheny Formation of the Appalachian Basin, and Late Bolsovian strata of western Europe. Palynologically, the coal is co-dominated by spores that were produced by lycopod trees (Lycospora and Granasporites medius) and tree ferns. Thin-walled tree fern spores (Punctatisporites minutus, P. minutus, P. rotundus) are more abundant than thick-walled forms (Laevigatosporites globosus, P. granifer). Calamitean spores (Calamospora and Laevigatosporites spp.) are locally abundant as is cordaitean pollen (Florinites). Small fern (Granulatisporites) and small lycopod spores (Densosporites, Cirratriradites, Endosporites and Anacanthotriletes spinosus) are present, but occur in minor amounts. Temporal changes in palynomorph composition occur, but are not uniform between columns. Spatial variability among columns is also evident. Petrographically, the coal is dominated by vitrinite macerals, with telinite and telocollinite generally occurring more commonly than desmocollinite and gelocollinite. Basal benches typically contain high percentages of vitrinite; middle benches usually contain higher percentages of liptinite and inertinite. In about half the studied columns, the terminal coal benches show a slight increase in vitrinite. In the study area, the petrography of the Western Kentucky Number 4 coal is more uniform than the palynology. Ash yields and total sulfur contents are temporally uniform in some columns, but variable in others. In the latter case, higher percentages of ash and sulfur occur at the base of the bed and decrease up to the middle of the bed. The terminal benches of these columns often, but not always, show slight increases in ash or sulfur. Both syngenetic and epigenetic forms of sulfur are present in the Western Kentucky Number 4 coal. The high vitrinite contents and moderate to high sulfur contents suggest that the Western Kentucky Number 4 paleomire was mainly planar and rheotrophic throughout its developmental history. Groundwaters carrying dissolved solutes may have helped neutralize the normally acidic interstitial peat waters allowing for the production of sulfide minerals. Several of the columns with high sulfur contents at the base of the bed occur in faulted areas. The faults could have promoted the flow of groundwaters through the peat, providing an increased dissolved load for acid mitigation and sulfide formation. The concentration of sulfur at the base of the bed may be a function of the peat/underclay contact enhancing sulfide formation. The clay layer may also have acted as an impermeable boundary for downward moving groundwaters, causing mainly lateral, rather than vertical movement along the base of the coal bed.Eight bench-column samples of the Western Kentucky Number 4 coal bed were analyzed palynologically, petrographically, and geochemically to study both temporal and spatial variability among these parameters. Palynologically, the coal is co-dominated by spores that were produced by lycopod trees and tree ferns. Petrographically, the coal is dominated by vitrinite macerals, with telinite and telocollinite generally occurring more commonly than desmocollinite and gelocollinite. The petrography of the coal was found to be more uniform than the palynology.

International Journal of Coal Geology↗
USGS1999

Lanthanide, yttrium, and zirconium anomalies in the Fire Clay coal bed, Eastern Kentucky

The Fire Clay coal bed in the Central Appalachian basin region contains a laterally-persistent tonstein that is found in the coal throughout most of its areal extent. The tonstein contains an array of minerals, including sanidine, ??-quartz, anatase and euhedral zircon, thhat constitutes strong evidence for a volcanic origin of the parting. For this study, five samples of the tonstein and four sets of coal samples underlying the tonstein were collected from five sites in eastern Kentucky. Inductively coupled plasma-mass spectroscopy (ICP-MS) analysis of the tonstein and underlying coal collected from four sites in eastern Kentucky show that although Zr concentrations are high in the tonstein (570-1820 ppm on a coal-ash basis (cab)), they are highest in the coal directly underlying the tonstein (2870-4540 ppm (cab)). A similar enrichment pattern is observed in the concentration of Y plus the sum of the rare earth elements (Y + ??REE): total Y + ??REE concentrations in the five tonstein samples range from 511 to 565 ppm (cab). However, Y + ??REE contents are highest in the coals directly underlying the tonsteins: values range from 1965 to 4198 ppm (cab). Scanning electron microscopy of samples from coal which directly underlies two of the tonstein samples show that REE-rich phosphate, tentatively identified as monazite, commonly infills cracks in clays and cells in clarain and vitrain. Zircon is rare and commonly subhedral. On the basis of coal chemistry and grain morphology, we suggest that volcanic components in the tonstein were leached by ground water. The leachate, rich in Y and REE precipitated as authigenic mineral phases in the underlying coal.The Fire Clay coal bed in the Central Appalachian basin region contains a laterally-persistent tonstein that is found in the coal throughout most of its areal extent. The tonstein contains an array of minerals, including sanidine, ??-quartz, anatase and euhedral zircon, that constitutes strong evidence for a volcanic origin of the parting. For this study, five samples of the tonstein and four sets of coal samples underlying the tonstein were collected from five sites in eastern Kentucky. Inductively coupled plasma-mass spectroscopy (ICP-MS) analysis of the tonstein and underlying coal collected from four sites in eastern Kentucky show that although Zr concentrations are high in the tonstein (570-1820 ppm on a coal-ash basis (cab)), they are highest in the coal directly underlying the tonstein (2870-4540 ppm (cab)). A similar enrichment pattern is observed in the concentration of Y plus the sum of the rare earth elements (Y+???REE): total Y+???REE concentrations in the five tonstein samples range from 511 to 565 ppm (cab). However, Y+???REE contents are highest in the coals directly underlying the tonsteins: values range from 1965 to 4198 ppm (cab). Scanning electron microscopy of samples from coal which directly underlies two of the tonstein samples show that REE-rich phosphate, tentatively identified as monazite, commonly infills cracks in clays and cells in clarain and vitrain. Zircon is rare and commonly subhedral. On the basis of coal chemistry and grain morphology, we suggest that volcanic components in the tonstein were leached by ground water. The leachate, rich in Y and REE precipitated as authigenic mineral phases in the underlying coal.

International Journal of Coal Geology↗
USGS1999

Depositional history of the Fire Clay coal bed (Late Duckmantian), Eastern Kentucky, USA

More than 3800 coal thickness measurements, proximate analyses from 97 localities, and stratigraphic and sedimentological analyses from more than 300 outcrops and cores were used in conjunction with previously reported palynological and petrographic studies to map individual benches of the coal and document bench-scale variability in the Fire Clay (Hazard No. 4) coal bed across a 1860 km2 area of the Eastern Kentucky Coal Field. The bench architecture of the Fire Clay coal bed consists of uncommon leader benches, a persistent but variable lower bench, a widespread, and generally thick upper bench, and local, variable rider benches. Rheotrophic conditions are inferred for the leader benches and lower bench based on sedimentological associations, mixed palynomorph assemblages, locally common cannel coal layers, and generally high ash yields. The lower bench consistently exhibits vertical variability in petrography and palynology that reflects changing trophic conditions as topographic depressions infilled. Infilling also led to unconfined flooding and ultimately the drowning of the lower bench mire. The drowned mire was covered by an air-fall volcanic-ash deposit, which produced the characteristic flint clay parting. The extent and uniform thickness of the parting suggests that the ash layer was deposited in water on a relatively flat surface without a thick canopy or extensive standing vegetation across most of the study area. Ash deposits led to regional ponding and establishment of a second planar mire. Because the topography had become a broadly uniform, nutrient-rich surface, upper-bench peats became widespread with large areas of the mire distant to clastic sources. Vertical sections of thick (> 70 cm), low-ash yield, upper coal bench show a common palynomorph change from arborescent lycopod dominance upward to fern and densospore-producing, small lycopod dominance, inferred as a shift from planar to ombrotrophic mire phases. Domed mires appear to have been surrounded by wide areas of planar mires, where the coal was thinner (< 70 cm), higher in ash yield, and dominated by arborescent lycopods. Rectangular thickness trends suggest that syndepositional faulting influenced peat accumulation, and possibly the position of the domed mire phase. Faulting also influenced post-depositional clastic environments of deposition, resulting in sandstone channels with angular changes in orientation. Channels and lateral facies were locally draped by high-ash-yield rider coal benches, which sometimes merged with the upper coal bench. These arborescent-lycopod dominant rider coal benches were profoundly controlled by palcotopography, much like the leader coal benches. Each of the benches of coal documented here represent distinctly different mires that came together to form the Fire Clay coal bed, rather than a single mire periodically split by clastic influx. This is significant as each bench of the coal has its own characteristics, which contribute to the total coal characteristics. The large data set allows interpretation of both vertical and lateral limits to postulated domed phases in the upper coal bench, and to the delineation of subtle tectonic structures that allow for meaningful thickness projections beyond the limits of present mining.A study was conducted to analyze the depositional history of the Fire Clay coal bed in the eastern Kentucky coal field. The study involved over 3800 coal thickness measurements, proximate analyses from 97 localities, and stratigraphic and sedimentological analyses from more than 300 outcrops and cores in conjunction with previously reported palynological and petrographic studies to map individual benches of the coal and document bench-scale variability.

International Journal of Coal Geology↗
USGS1997

Coal quality trends and distribution of potentially hazardous trace elements in eastern Kentucky coals

Coal in the Eastern Kentucky coalfield has been, and continues to be, a valuable energy resource, especially for the electric utility industry. However, Federal mandates in Titles III and IV of the Clean Air Act Amendments of 1990 have placed increasingly stringent demands on the type and grade of coal that can be burnt in an environmentally acceptable manner. Therefore, a greater understanding of the spatial and temporal distribution of thickness and quality parameters, and the geologic factors that control their distribution, is critical if the Eastern Kentucky coalfield is to continue to be a major producer of high-quality coal. Information from the Kentucky Geological Survey's Coal Resource Information System database is used in this paper to document the geographic and stratigraphic distribution of important factors such as bed thickness, calorific value, ash yield and total sulfur content. The distribution of 15 elements that naturally occur in trace amounts in Kentucky coal is also discussed, as these elements may require monitoring with passage of Title III of the Clean Air Act Amendments of 1990.

Kentucky↗
USGS1997

Channel-fill coal beds along the western margin of the Eastern Kentucky Coal Field

Four channel-filling coal beds from the lower part of the Breathitt Formation (lower Middle Pennsylvanian, late Westphalian A) were examined palynologically, petrographically and geochemically to determine the paleoenvironmental conditions under which these peats accumulated. These results were then compared with detailed sedimentological analyses of the strata overlying the coal in the channels to see if any genetic relationship between coal composition and the origin of the overburden could be drawn. All four of the coal beds used in this study are located in the western-most part of the Eastern Kentucky Coal Field and occur at, or near, the Early Pennsylvanian unconformity (0–30 m). Lycospora and Densosporites (and related crassicingulate taxa, e.g. Cristatisporites , Cingulizonates and Radiizonates ) dominate the studied assemblages, with Granulatisporites (and related trilete, sphaerotriangular genera, e.g. Leiotriletes and Lophotriletes ), Laevigatosporites and Schulzospora being common accessory genera. Petrographically, all four coals contain high percentages of vitrinite macerals (avg. 78.6% mineral matter free), moderate amounts of liptinite (or exinite) macerals (avg. 14.9%, mmf) and low percentages of inertinite macerals (avg. 6.5%, mmf). Strata above the coals consist of dark, carbonaceous shales, and heterolithic strata that exhibit varying degrees of bioturbation. Commonly occurring trace fossils include Arenicolites , Monocraterion , Planolites and Skolithos . Although marine-influenced strata, as determined from detailed sedimentology and ichnology (the study of trace fossils), covers all four coal beds, they are not uniformly high in total total sulfur content as might be expected. Rather they are extremely variable, ranging from 1–9% (dry basis) total sulfur. Ash yields are also variable ranging from 6.2–54.3% (dry basis). It is probable that the origin of the very first sediments covering the peat, as well as the amount of brackish water influence during peat accumulation, were important factors in determining the total sulfur content of the resultant coal. Initial sedimentation of fresh water clays and silts may have acted as a barrier to downward percolation/diffusion of sulfate bearing waters, or may have served as a site for sulfide formation, thereby keeping the total sulfur content of the underlying coal low. If initial sedimentation was of brackish or marine origin, as indicated by bioturbated laminae directly above the coal, or if the peat was subject to frequent brackish or marine water influence during accumulation, then sulfide generation might proceed unchecked, resulting in high sulfur coal.

International Journal of Coal Geology↗