Petrology, palynology, and geochemistry of the Pond Creek coal (Pennsylvanian, Duckmantian), Pike County, Kentucky: Overprints of penecontemporaneous tectonism and peat doming
Introduction
The Pennsylvanian (Bashkerian, Duckmantian) Pond Creek coal (Fig. 1) has long been one of the most important coals in eastern Kentucky. In the later 1980's, the peak of coal production in Kentucky, Pike County trailed only Campbell County, Wyoming, the home of the largest Powder River Basin mines, in U.S. coal production (from 1971 to 1988, Kentucky was the leading coal producing state). At that time, the high volatile A bituminous, low-S Pond Creek coal accounted for 35–40% of the production in Pike County (Hower et al., 1991).
As part of the effort by the University of Kentucky's Center for Applied Energy Research to characterize the important coals in the state, a comprehensive sampling of several of the major Pond Creek coal mines was undertaken (Fig. 2). Studies of the petrology and lithology (Hower and Pollock, 1988; Hower et al., 1990), geochemistry (Hower and Bland, 1989), palynology (Helfrich and Hower, 1991), and the relationship of the coal lithology to the regional structure (Hower et al., 1991) were the products of the sampling.
As a broad summary, Hower et al. (1991) found that the thickness and quality of the Pond Creek coal was closely related to its position relative to the northwestward-plunging, N20°E-trending Belfry anticline (Chesnut Jr., 1988, Coskren and Rice, 1979, Hunt et al., 1937, Rice et al., 1977). The coal to the northwest of the anticline has a high-TiO2, high-Zr durain and dull clarain lower bench; a middle bench with relatively high-CaO with enrichment in Ba and Sr and, to a lesser extent, Mn, Cu, and Ni; and a high-S, high K2O/Al2O3 dull lithotype zone at the top of the coal. The main bed Pond Creek coal zone thins across the Belfry anticline accompanied by the thinning of the interval between the main bed and the rider coal. Consequently, the relatively high-S rider was often mined along with the main coal bed, resulting in the reporting of greater thicknesses of mined Pond Creek coal compared to the northwest and southeast of the anticline (Rice, 1963, Wolcott and Jenkins, 1966). The region to the southeast of the anticline, arguably representing the highest quality (lowest S, lowest ash yield in the beneficiated coal), has several lithotypes that pinch out towards the anticline (four at the base of the coal and a thin durain at the top of the coal bed) and three lithotypes that are present in all of the sampled sites to the southeast of the anticline (Fig. 3; Table 1). Collectively, the nature of the coal throughout the region indicates that the Belfry anticline and the Pond Creek mire were contemporaneous features, with the rising anticline influencing the lithology and chemistry of the peat/coal. Similar relationships between penecontemporaneous tectonism and coal lithology have been noted for other coals (the Taylor through the Hazard No. 8) in eastern Kentucky (Hower et al., 1992); the Stockton coal in Martin County, Kentucky (Greb et al., 2005); and the Upper Elkhorn No. 2 coal in southern Pike and Floyd counties, Kentucky (Raione et al., 1991).
In this study, the petrographic nature of the coal in the sections to the southeast of the anticline, specifically in the Lick Creek (McKay and Alvord, 1969) and Jamboree 7.5′ (Outerbridge and Van Vloten, 1968) quadrangles, is re-examined using revised petrographic nomenclature (ICCP, 1998; 2001; Pickel et al., 2017) and revised interpretations of depositional environments (Dai et al., 2020). Following the philosophy of the discussions by Dai et al. (2020), we do not rely on the maceral-ratio approach to the interpretation of the coal facies; rather, this work is based on direct interpretations of the megascopic and microscopic petrology, the palynology, and the geochemistry (ash, major oxides, minor elements) of the coals.
Section snippets
Methods
The maceral analysis was completed at the University of Kentucky Center for Applied Energy Research (CAER) on previously made 2.54-cm-diameter epoxy-bound particulate pellets. In case where repolishing was necessary, the final polishing step utilized a 0.5-μm-alumina on a wetted silk pad. The microscopic examination was made on a Leitz Orthoplan microscope using 50× reflected-light oil-immersion objectives. Both white-light and blue-light-excitation illumination was used as necessary. Maceral
Basic petrology
The simplified coal maceral composition is shown in Table 2, with expanded versions on tables in the Supplementary files. The rank of the coals, based on vitrinite maximum reflectances generally in the 1.00–1.10%Rmax range, is high volatile A bituminous.
As noted by Hower et al., 1990, Hower et al., 1991, the Pond Creek coal in eastern Pike County consists of a bright lithotype (zone 0) present at only the easternmost site; a basal durain (zone 1) overlain by a bright lithotype (zone 2) and a
Conclusions
The Pond Creek coal in the Lick Creek and Jamboree 7 ½’ quadrangles in Pike County, Kentucky, are composed of a sequence of lithologic zones reflecting the combined impacts of penecontemporaneous uplift of the northeast-southwest-trending Belfry anticline and the alternating development of planar (lithologic zones 0 through 3 and 5 through 7) and ombrogenous (lithologic zone 4) peatlands. Vertical changes through the deposition of the zone 4 bright lithotypes are seen in the decrease in total
Declaration of Competing Interest
The authors declare no conflicts of interest.
Acknowledgments
This short review is, as noted, a summary of many works built from the mid-1980's collection of the Pond Creek coal by Jim Hower and the late Don Pollock, the palynology studies of Charles Helfrich, and the geochemical insight of Al Bland. We thank the management of the Kentucky Energy Cabinet Laboratory, the predecessor of the Center for Applied Energy Research, for their indulgence as we conducted this sampling. The sampling would not have been possible without the access provided by Kentucky
References (41)
- et al.
Recognition of peat depositional environments in coal: a review
Int. J. Coal Geol.
(2020) - et al.
Palynologic and petrographic variation in the Pond Creek coal bed, Pike County, Kentucky
Org. Geochem.
(1991) - et al.
Geochemistry of the Pond Creek Coal Bed, Eastern Kentucky Coalfield
Int. J. Coal Geol.
(1989) - et al.
Petrology of the Pond Creek coal bed in eastern Kentucky
Org. Geochem.
(1988) - et al.
Notes on the mechanisms of coal metamorphism in the Pennsylvania Anthracite Fields
Int. J. Coal Geol.
(2019) - et al.
Petrology of the Fire Clay coal, Bear Branch, Perry County
Kentucky. Int. J. Coal Geol.
(2022) - et al.
Evaluating the extent to which wildfire history can be interpreted from inertinite distribution in coal pillars: an example from the late Permian, Kuznetsk Basin, Russia
Int. J. Coal Geol.
(2012) - et al.
On the fundamental difference between coal rank and coal type
Int. J. Coal Geol.
(2013) - et al.
Classification of liptinite – ICCP System 1994
Int. J. Coal Geol.
(2017) - et al.
Influence of regional structure on the development and quality of the Upper Elkhorn no. 2 coal bed, eastern Kentucky
Int. J. Coal Geol.
(1991)
Observations on the nature and origin of fusain
Int. J. Coal Geol.
The pre-Quaternary history of fire
Palaeogeogr. Palaeoclimatol. Palaeoecol.
Coal petrology and the origin of coal macerals: a way ahead?
Int. J. Coal Geol.
Observations and experiments on the origin and formation of inertinite group macerals
Int. J. Coal Geol.
The nature and influence of fire in Carboniferous ecosystems
Palaeogeogr. Palaeoclimatol. Palaeoecol.
The taphonomy of charcoal following a recent heathland fire and some implications for the interpretation of fossil charcoal deposits
Palaeogeogr. Palaeoclimatol. Palaeoecol.
Mycorrhizal networks: Mechanisms, ecology and modelling
Fungal Biology Reviews
Stratigraphic Analysis of the Carboniferous Rocks of the Central Appalachian Basin
The ecology of peatlands
Sci. Prog.
Contour map of the base of the Pennsylvanian System, Eastern Kentucky
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