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.