Abstract
This study presents recently collected data examining the organic petrology, palynology, mineralogy and geochemistry of the Gray Hawk coal bed. From the Early Pennsylvanian, Langsettian substage, Gray Hawk coal has been mined near the western edge of the eastern Kentucky portion of the Central Appalachian coalfield. While the coal is thin, rarely more than 0.5-m thick, it has a low-ash yield and a low-S content, making it an important local resource. The Gray Hawk coal palynology is dominated by Lycospora spp., and contains a diverse spectrum of small lycopods, tree ferns, small ferns, calamites, and gymnosperms. The maceral assemblages show an abundance of collotelinite, telinite, vitrodetrinite, fusinite, and semifusinite. Fecal pellet-derived macrinite, albeit with more compaction than is typically seen in younger coals, was observed in the Gray Hawk coal. The minerals in the coal are dominated by clay minerals (e.g., kaolinite, mixed-layer illite/smectite, illite), and to a lesser extent, pyrite, quartz, and iron III hydroxyl-sulfate, along with traces of chlorite, and in some cases, jarosite, szomolnokite, anatase, and calcite. The clay minerals are of authigenic and detrital origins. The occurrence of anatase as cell-fillings also indicates an authigenic origin. With the exception of Ge and As, which are slightly enriched in the coals, the concentrations of other trace elements are either close to or much lower than the averages for world hard coals. Arsenic and Hg are also enriched in the top bench of the coal and probably occur in pyrite. The elemental associations (e.g., Al2O3/TiO2, Cr/Th-Sc/Th) indicate a sediment-source region with intermediate and felsic compositions. Rare metals, including Ga, rare earth elements and Ge, are highly enriched in the coal ashes, and the Gray Hawk coals have a great potential for industrial use of these metals. The rare earth elements in the samples are weakly fractionated or are characterized by heavy-REE enrichment, indicating an input of natural waters or probably epithermal solutions.
Highlights
The Lower Pennsylvanian Langsettian-substage Gray Hawk coal bed (Figure 1) has been mined in a small area in the western part of the Kentucky portion of the Central Appalachian coalfield; the samples considered here are from five 71⁄2-minute quadrangles in three counties (Figure 2)
We briefly summarize historical data from Kentucky Geological Survey, U.S Geological
Examples of the inertinite-maceral macrinite in the Gray Hawk were discussed by Hower et al [2], and are further discussed here in light of their implications for our understanding of the role of insects and other arthropods in the development of coal macerals [2,3]
Summary
The Lower Pennsylvanian Langsettian-substage Gray Hawk coal bed (Figure 1) has been mined in a small area in the western part of the Kentucky portion of the Central Appalachian coalfield; the samples considered here are from five 71⁄2-minute quadrangles in three counties (Figure 2). (This observation is based on observations by Hower and Eble in their several decades of experience with the Kentucky coal mining industry; for example, one mine, bidding for a university contract requiring “washed”. Examples of the inertinite-maceral macrinite in the Gray Hawk were discussed by Hower et al [2], and are further discussed here in light of their implications for our understanding of the role of insects and other arthropods in the development of coal macerals [2,3]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
