Distribution of Trace Elements Within Coal Lithotypes and Depositional Settings of Some South-Central West Virginia Coals

Jeffrey W. Martin, Victor V. Cavaroc, Ronald V. Fodor

Recent studies associate trace element distribution in coal seams with coal lithotype. Our x-ray fluorescence and instrumental neutron activation analyses of 43 bituminous coal samples from the Pocahontas, New River, Kanawha, and Allegheny Formations in south-central West Virginia show that, on average, bright coals (vitrains and vitrain-rich clarains) contain high concentrations of Cl (1,600 ppm), Co (11 ppm), Fe (14,000 ppm), S (11,200 ppm), and Sr (117 ppm), and dull coals (durains and durain-rich clarains) are relative enriched in Al (35,200 ppm), Ce (78 ppm), Cr (47 ppm), Cs (1.5 ppm), Eu (1.5 ppm), Sc (13 ppm), Se (13 ppm), Si (69,200 ppm), Th (14 ppm), Ti (3,800 ppm), U (2.4 ppm), V (106 ppm), and Zr (110 ppm). Cluster and discriminant function analyses based on co centrations of these elements correctly classify over 90% of the samples by coal lithotype.

Attempts to correlate trace elements in coal with specific depositional settings, however, have generally been less successful. Our data indicate that field-interpreted depositional settings of sampled coal seams can be characterized by the distribution of certain trace elements if bright and dull lithotypes are treated as separate groups during statistical analyses. The coal seam facies tested represent back-barrier, lower delta, transitional delta, and upper delta environments. Discriminant function analysis of bright coals based on Al, As, Br, Co, Eu, Fe, Se, and Si concentrations assigns 97% of the samples to their appropriate depositional facies. All dull coals are also correctly classified according to depositional setting using S, V, and Zr as the discriminating variables.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.