|KGS Home > Coal > Coal Research > Coal Availability|
Steve Greb Abstracts, 2
Greb, S.F., Eble, C.F., and Nelson, W.J., 1999, Controls on Pennsylvanian paleoenvironments in the Illinois Basin (abs): North-central Geological Society of America Meeting, Champaign-Urbana, Geological Society of America, Abstracts with Programs, v. 31, no.5, A-18.
Stratigraphic analyses of the Illinois basin shows that the relative influences of tectonic accommodation space, eustacy, and climate changed during the Pennsylvanian and profoundly influenced the lateral extent and thickness of coal-bearing strata. Cross sections and isopach maps indicate maximum tectonic accommodation space developed in the Morrowan and decreased upward. In western Kentucky, the thickness of the Morrowan strata (Caseyville equivalent) is 50 times more in basin center than margin; lower Atokan (top Caseyville to Lead Creek Ls.) 42 times more; upper Atokan (Lead Creek Ls. to Curlew Ls.) 3 times more; Desmoinesian 1.3 times more. The decrease in tectonic accommodation is associated with a relative increase in the lateral continuity of strata with the maximum continuity of coals and carbonates increasing from less than 10% on a line of section in the Morrowan and lower Atokan, to nearly 50% in the upper Atokan, to more than 95% in the Desmoinesian.
These changes profoundly influenced sediment deposition and preservation. During the early Morrowan, deposition was confined to structurally influenced paleovalleys, and was dominated by fluvial sedimentation of extrabasinal, quartz-rich sands in trunk streams and then tidal and marine sedimentation in backfilled estuaries. When the valleys were filled, sedimentation became unconfined but was still influenced by sediment subsidence within paleovalleys and structure, even into the Atokan. Low continuity of lithofacies in the lower Atokan, and abundant evidence of tidal sedimentation may reflect highly embayed coastal settings and continued structural influences. Decreasing accommodation led to increasing continuity of paleoenvironments in the upper Atokan and possibly less embayed coasts into the Desmoinesian. Classic cyclothems of the Desmoinesian reflect deposition in relatively stable coastal paleoenvironments in which eustatic controls dominated over tectonic controls. During the Desmoinesian, coals reached their widest extents. Analysis of coals indicate a shift from everwet to more seasonal paleoclimates from the Atokan into Desmoinesian.
Greb, S.F., Chesnut, D.R., Jr., Eble, C.F., Nelson, W.J., and Blake, B.M., 1998, Changing influences of tectonics, eustacy, and climate on Pennsylvanian coals in the Illinois and Appalachian basins (abs): Geological Society of America Annual Meeting, Toronto, Geological Society of America, Abstracts with Programs, v. 30, p. A-47
Stratigraphic interval thickness, coal distribution, palynology, and sedimentology were compared between two basins for each Pennsylvanian stage to determine controls on coals. The Illinois Basin is a cratonic basin and the central Appalachian Basin is a foreland basin. If tectonic effects are limited to each basin, then stratigraphic differences between basins suggest tectonic influences, whereas similarities suggest more widespread climatic and eustatic influences.
For the Illinois and central Appalachian Basins, cross sections and isopach maps indicate maximum tectonic accommodation space in the early Morrowan. Accommodation decreases upward, resulting in less difference between basin-margin and basin-center thicknesses in the Desmoinesian. In the Appalachian Basin, the basin depocenter shifts northward through time. Increased accommodation toward basin axes led to thickening of individual coal-clastic cycles, and splitting and development of coal zones, except where replaced by thick sandstones.
Climatic influences varied throughout the Pennsylvanian, probably because of changing paleolatitudinal position, and possibly eustatic effects. Paleokarst and paleosols increase northward in both basins, as a result of exposure, onlap, and possibly changing climate through time. Compositional differences between Morrowan and later sandstones may suggest changing source areas and climate. Compositional analysis of coals suggests ever-wet tropical conditions, analogous to modern Indonesian domed mires, in the upper Morrowan and Atokan. The lack of domed mires and the development of extensive paleosols in the upper Middle and Upper Pennsylvanian indicate increasing seasonality. These differences are partly responsible for the quality differences between heavily mined central Appalachian coals (low in sulfur), which are mostly Morrowan, and Illinois Basin coals (higher in sulfur), which are mainly Desmoinesian.
Greb, S. F., 1998, Paleoslope movements in Pennsylvanian coal-bearing strata of the central Appalachian basin-Are any signatures of ancient earthquakes? (abs): Geological Society of America Annual Meeting, Toronto, Geological Society of America, Abstracts with Programs, v. 30, p. A-400.
Paleoslope movements, such as slumps and flows, are well known from many coal basins. In the central Appalachian Basin, paleoslumps have been triggered by excessive loading, overpressurization of channel banks and bar slopes, and synsedimentary faulting. Syn-sedimentary faulting has been inferred where paleoslumps occur along faults, exhibit movement in the direction of throw, and often growth on the down side of the slump glide plane. Fault-margin paleoslumps have similar deformation features as other types of paleoslumps. In some cases, coals beneath slumps along faults exhibit tears with clastic injection features, which are inferred to have formed through high hydrostatic pressure. Also, some of the largest paleoslumps occur along fault margins. But clastic injection structures and large slump blocks are not enough to indicate if slumps were triggered by an earthquake, if fault-created scarps failed after the quake, or if slumps were caused by creep rather than sudden seismic shock.
If paleoslope movements were triggered by seismic shock, they should occur near a fault or structural hinge line, fail in the direction of movement, and should occur in multiple areas at the same stratigraphic horizon. Deformation should decrease away from the inferred source. The likelihood of other triggering events should also be assessed. If deformation occurs in different lithofacies, lithofacies-controlled triggering mechanisms can be eliminated as possible causes.
One seismically triggered paleodebris flow may be the Poison Honey beds, in the Early Pennsylvanian (Morrowan) Alvy Creek Formation. Mass flows occurred on the downthrown side of a small fault, moved in the direction of throw, and contain siderite clasts from the upthrown fault block. A kilometer away, unusual overturned flow rolls and soft-sediment deformation occur at the same stratigraphic horizon, suggesting a widespread trigger that was not confined to a single lithofacies, and deformation decreasing away from the fault. Because debris flows in the Pennsylvanian of the central Appalachian Basin are rare, the Poison Honey beds were probably not triggered by more common sedimentary processes.
Greb, S.F., and Chesnut, D. R., Jr., 1998, Impact of an astrobleme on coal mining in part of the Eastern Kentucky Coal Field, (abs): American Association of Petroleum Geologists Bulletin, v. 81, n. 9, p. 1767.
Mining of the Path Fork and Hance coals near Middlesboro in southeastern Kentucky is locally disrupted by the Middlesboro astrobleme, an inferred celestial impact structure. The impact structure has been previously mapped and consists of an inner region of deformed strata 3 miles (4.8 km) wide, bordered by a ring of arcuate faults, most exhibiting down-to-the-axis displacement. The center of the feature contains a rebound structure, in which strata from the Lower Pennsylvanian Lee sandstones are reported to have been brought to the surface. The impact is post-Late Pennsylvanian, pre-Quaternary in age. All that remains is the eroded, circular core of the impact structure, which provided the flat land upon which Middlesboro was settled.
Small, unmapped faults between or splintering off of the mapped rim faults are the most common mining problem. Analysis of mine maps shows that several deep mines stopped along unanticipated rim faults associated with the impact structure. A recent excavation on the north rim intersected several normal faults, brecciated and highly deformed gray shales, and a coal tilted almost on end. On the southern rim, surface mines have also recently crossed unmapped faults. Between two faults, a doubling of coal beds was reported. Local brecciation of the Hance coal along one of the faults, and dips of more than 40 percent, have been documented. Sudden loss of coal, changes in coal dip, and brecciation related to the astrobleme affect mining in a way that is, as far as we know, unique to this area.
Greb, S.F., and Weisenfluh, G.A., 1998, Mining geology of the Hazard No. 8 coal, Four Corners Formation, Middle Pennsylvanian, Eastern Kentucky Coal Field, (abs): American Association of Petroleum Geologists Bulletin, v. 81, n. 9, p. 1767.
The Hazard No. 8 bed is a bituminous coal of Middle Pennsylvanian (Atokan) age that is of mineable thickness over a large part of the Eastern Kentucky Coal Field. Geologic factors that affect mining of this bed are mostly related to variable roof conditions and coal quality. Specific roof lithotypes that affect mining include (1) carbonaceous shales with abundant plant debris, (2) thin coal beds and claystones in the immediate roof of the seam, (3) narrow cutouts and roof rolls, and (4) interlaminated lithologies with weak bedding-plane contacts. In a recent case study, quartz arenitic sandstones above the coal contained numerous deformational structures, including flow rolls and paleoslumps, that may also affect mining. In addition, a previously unrecognized monoclinal structure has been identified in the southeastern part of the coal field that is associated with changes in roof lithofacies and exhibits locally steep coal dip.
The roof rocks above the coal appear to have been deposited in channel, splay, and flood-plain settings. Paleosols and peats draping irregular flood deposits led to the variable riders and claystones seen in the roof. Flow rolls and paleoslumps are abundant along channel trends and appear to be more common in the case study area than elsewhere, suggesting local influences, either excessive pore pressure in the orthoquartzites compared to the regionally more common lithic arenites, or syndepositional movement on the monocline. Recognizing common deformation along sandstone margins in the roof allows for possible adverse roof conditions to be recognized in advance of mining, even if specific paleoslumps cannot be identified.
More than 5,000 miles of road, 2,700 miles of rail, and 1,000 miles of navigable river are approved for hauling coal in Kentucky. Of 250 preparation plants identified in Kentucky, 206 are served by rail. To efficiently calculate distances between various aspects of Kentucky's coal infrastructure, as well as other applications, the Kentucky Geological Survey has developed a GIS database on active and inactive coal-preparation plants, coal-loading facilities, and associated infrastructure in the Commonwealth of Kentucky with funding from the Tennessee Valley Authority. Geographic information systems are well suited for databases of infrastructure information because they link geographically referenced data sets, for roads, railroads, locations of buildings or facilities such as preparation plants, and allow comparisons and calculations within and between each data set. The database was constructed in ARC/INFO® and designed to be used in ArcView®. Data tables were constructed in Microsoft Access® and imported into ARC/INFO.
The locations of coal-haul roads, railroads, and navigable riverways were compiled from files downloaded in digital form from the U.S. Geological Survey Web site. These DLG's were originally 1:100,000-scale topographic maps, which were divided into eight pieces for storage convenience at the Web site. Thus, a total of 122 pieces, which comprised the 34 maps covering the state of Kentucky, were downloaded for this project. Editing and attribute assignment were based on information from numerous sources including the Kentucky Transportation Cabinet, Kentucky Office of Coal Marketing and Export, Governor's Office for Coal and Energy Policy, and the Kentucky Energy Cabinet.
Greb, S.F., Eble, C.F., and Hower, J.C., 1997, Architectural Analysis of Coal-A Method for Recognizing Paleomire Successions in Coal Beds: (abs) Geological Society of America Abstracts with Programs, v. 29, no. 7, p. A-203.
Interpretations of coals in terms of paleomire morphology often concentrate on the coal bed as a single unit. However, many mined coal beds are composed of multiple coal benches that merge to form thick coals. In order to better understand bench-scale variation of coal beds, a conceptual model for architectural analysis of coals is proposed. First, the extent of partings and splits are categorized. These are analogous to the bounding surfaces of clastic architectural analysis as they represent hiatal and erosive surfaces. Extensive partings, which can be thought of as higher order bounding surfaces, are used to define coal benches. Within benches, at least four compositional groupings are noted, analogous to lithofacies divisions of clastic architectural analysis. Compositional groupings are defined on the basis of quality, palynology, and petrography similar to the manner in which grain size and bedding are used to define clastic lithofacies. The juxtaposition of compositional groupings within benches are then used to interpret paleomire morphology, similar to the manner in which combinations of lithofacies are used to interpret larger architectural elements (e.g., channels) in clastic successions.
Bench-scale architectural analysis of Appalachian basin coals suggests that many coal beds developed as mire successions, or multiple mire successions, rather than as single mires. Variation in the paleotopography upon which the peat accumulated, clastic influx, base-level changes, and syndepositional faulting often influenced individual benches of the coal bed differently, resulting in variable quality and thickness for the whole coal. Architectural analysis provides an exploration tool that includes elements of coal quality, rather than just thickness. In many cases, the thickest part of an individual coal bed does not have the best quality because it represents the amalgamation of multiple coal benches, some having poorer quality than others.
Greb, S. F., and Eble, C.F., 1996, The role of accommodation space in Pennsylvanian peat accumulation along the flanks of the Central Appalachian basin: (abs) Geological Society of America Abstracts with Programs, p. A-209.
Greb, S. F., Eble, C. F., and Hower, J. C., 1996, Coal-bench architecture as a means of understanding regional changes in coal thickness and quality: (abs) Bulletin American Association of Petroleum Geologists, v. 80, p. 1524.
Greb, S.F., Weisenfluh, G.A., Andrews, R.E., and Hiett, J.K., 1996, Availability of the Fire Clay (Hazard No. 4) Coal in Part of the Eastern Kentucky Coal Field: (abs) University of Pittsburgh, 13th Annual Pittsburgh Coal Conference, Pittsburgh PA., p.198-203.
The Fire Clay (Hazard No. 4) coal is one of the most heavily mined beds in the Eastern Kentucky Coal Field, which is part of the Appalachian Basin. Available resources for the coal were calculated for an area of 15 7.5-minute quadrangles that accounts for 43 percent of current annual Fire Clay coal production. This study differs from previous coal-availability studies in that a single coal bed was analyzed across several 7.5-minute quadrangles rather than multiple coals in a single quadrangle being analyzed. Original Fire Clay coal resources for the study area are estimated at 1.7 billion tons (Bt). Coal mined or lost in mining is estimated at 449 million tons (Mt), resulting in 1.3 Bt of remaining Fire Clay resources. Of the remaining resources, 400 Mt are restricted from mining, mostly because of coal considered too thin (less than 28 in., 71 cm) to economically mine with present market conditions and mining technology. The total coal available for mining in the study area is 911 Mt or 51.7 percent of the original resource. Of the 911 Mt, 75 percent is less than 42 inches (1.06 m) in thickness, and most of this resource is below drainage.
Greb, S.F., Williams, D.A., and Williamson, A.D., 1992, Geology and stratigraphy of the Western Kentucky Coal Field: Kentucky Geological Survey, Series, XI, 77p.
The Pennsylvanian rocks of the Western Kentucky Coal Field produce between 40 and 55 million tons of coal a year from as many as 45 coal seams; however, three seams produce more than 75 percent of the total. In addition, Pennsylvanian strata contain numerous oil and natural gas reservoirs, tar-sand reservoirs, and industrial minerals. Pennsylvanian sandstones are also some of the most important bedrock aquifers in the coal field. Because of the economic importance of the Pennsylvanian strata to the region and the Commonwealth as a whole, a better understanding of the rocks is needed. This description of the nomenclature of Pennsylvanian strata in the Western Kentucky Coal Field also provides information on their mineral resources and geology. New stratigraphic names, based on regional agreements among the state geological surveys of Kentucky, Illinois, and Indiana, are also presented.
The book contains 58 figures and is divided into the following sections:
Greb, S.F., and Chesnut, D.R., Jr., 1995, Tectonic, climatic, and eustatic controls on Morrowan sedimentation in the Central Appalachian Basin: (abs) Geological Society of America, Abstracts with Programs, v. 27, A-32.
Greb, S.F., Weisenfluh, G.A., Andrews, R.E., and Hiett, J.K., 1995, Geology and coal availability of the Fire Clay coal (Middle Pennsylvanian, Breathitt Formation, across a 15-quadrangle area of the Eastern Kentucky Coal Field: (abs) Geological Society of America, Abstracts with Programs, v. 27, A-138.