Abstract

A discontinuous portion of the upper bench of the Beckley bed (Westphalian A) in southern West Virginia was examined in regard to its areal distribution, horizontal and vertical trends in chemistry, horizontal trends in petrographic composition, and its facies relationships with encasing sediments. The results of this examination were compared to those of a process model for the development of ombrogenous mire systems in tidally influenced coastal areas of Sarawak, East Malaysia. The results of these comparisons suggest a strong parallel between the two areas. The ombrogenous mire system that formed the upper bench of the Beckley bed initially developed as small individual topogenous peat swamps in a tidal flat setting. With time, the small individual peat swamps coalesced into an ombrogenous mire system that resulted in a coal bench that covers about 65 sq km. The mire system was eventually covered by channel deposits from a deltaic distributary system. The mire system that developed for the coal bench shows distinct zonation of dull and bright macrolithotypes (dull on the margins and bright in the interior) and contains high concentrations of ash and sulfur in its margins and base. Coal thickness, chemistry and petrographic data allow differentiation of the raised interior from the more topogenous areas of the mire. The interior portions are interpreted as those areas of the bench that are > 65 cm thick and average > 85% vitrinite group macerals, 5.5% ash and 0.60% sulfur. The more topogenous areas of the mire system, which were subjected to flooding, oxidation and sediment influx are < 65 cm thick and average < 65% vitrinite group macerals, 15.1% ash and 1.81% sulfur. In addition, the amount of preserved cell structure, irrespective of maceral group, appears to increase toward the margins of the bench. These trends are consistent with observations in the peat deposits of Sarawak, East Malaysia.

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