Petrography and palynology of the Blue Gem coal bed (Middle Pennsylvanian), southeastern Kentucky, USA

Susan M. Rimmer, James C. Hower, Timothy A. Moore, Joan S. Esterle, Richard L. Walton, Charles T. Helfrich

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Petrographic and palynological trends in the Blue Gem coal bed (Middle Pennsylvanian Westphalian B, Breathitt Formation), a thin, low-sulfur, low-ash coal in southeastern Kentucky, were studied in order to establish a depositional model for the seam. Within the study area, the coal bed averages 67 cm and has two distinct zones. The lower and middle parts of the seam (the lower 45-55 cm) are enriched in well-preserved vitrinite and are dominated by arborescent lycopods, sphenopsids, and tree ferns. Fusinite-rich layers, dominated by arborescent lycopods, but also containing herbaceous lycopods and sphenopsids, occur within the lower and middle parts of the seam. The upper part of the seam (the upper 15-25 cm) is recognizable in the field and is distinct in that it contains a greater amount of degraded macerals, and is characterized by high palynomorph diversity, primarily by miospores that are associated with sphenopsids, herbaceous lycopods and arborescent lycopods. These data, in conjunction with geochemical data available for the seam, suggest that initially the peat swamp was fairly diverse and well-nourished (the base of the seam being characterized by a relatively diverse miospore assemblage and a slightly higher ash content). Following this initial planar stage, the Blue Gem peat swamp was probably planar to slightly domed during accumulation of most of the lower and middle parts of the seam, as suggested by the very low ash and sulfur contents, the high telovitrinite content, and the preponderance of arborescent lycopod spores. In its final stages, the peat swamp was domed and is characterized by a more diverse flora and greater levels of degradation of the peat constituents. Sulfur content of this seam is generally low (<1%) but can increase locally to 3-4%. Factors influencing sulfur content include the thickness and nature of the overburden (shale versus sandstone) and petrographic composition. (C) 2000 Elsevier Science B.V. All rights reserved.

Original languageEnglish
Pages (from-to)159-184
Number of pages26
JournalInternational Journal of Coal Geology
Issue number2-3
StatePublished - Jan 2000

Bibliographical note

Funding Information:
The authors are thankful for support of this research by the University of Kentucky Institute for Mining and Minerals Research, the US Bureau of Mines, and the Kentucky Energy Cabinet, Commonwealth of Kentucky. The authors are grateful for the cooperation of Richland Coal, who provided unlimited access to their mines, and for the help of Gerald Yahne, the company's geologist. The manuscript was improved considerably by the reviews of Andrew Scott and Alan Cook. We also thank Cortland Eble for his help with questions on the palynology.


  • Kentucky
  • Low-ash coal
  • Low-sulfur coal
  • Palynology
  • Petrography
  • Vitrinite macerals

ASJC Scopus subject areas

  • Fuel Technology
  • Geology
  • Economic Geology
  • Stratigraphy


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