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Economic Geology of Big Chimney Quadrangle, Kanawha County, West Virginia

John F. Windolph, Jr.

Recent geologic mapping of Pennsylvanian strata in the Big Chimney quadrangle, 2.5 mi northeast of Charleston, West Virginia, suggests a possible association between syntectonic depositional influences and the occurrences of economically important mineral deposits. Coal and flint clay were deposited in the Charleston Sandstone (Middle Pennsylvanian) during periods of stillstand. The Mahoning Sandstone Member is disconformable with underlying strata and locally contains Precambrian and early Paleozoic pebbles. The member is thick in synclinal troughs and thin or absent on the crests of anticlines where there also is a thinner underlying stratigraphic sequence.

Flint clay deposits reach their maximum quality on the crests of anticlines and in areas adjacent to suspected paleotopographic highs. These deposits are laterally gradational with underclay, ganister, and paleosol. The Elk fireclay (No. 6 Block underclay) may in part have originated as a volcanic ash fall. The No. 5 Block coal bed reaches 60 in. in thickness on the Milliken anticline and has minor fault displacement at Big Chimney. The Pittsburgh coal bed is as much as 90 in. thick, cropping out in high ridges. It is absent on the northern edge and eastern part of the quadrangle.

More than 260 oil and gas wells have been drilled in the overlapping Elk-Poca, Big Chimney, and Blue Creek gas or oil fields. Natural gas, paraffin-base oil, and/or minor amounts of condensate are produced from structural and stratigraphic traps in four units: the Weir Formation (sand) and the Oriskany, Keefer, and Tuscarora Sandstones. The Oriskany Sandstone, however, is used almost exclusively as a gas-storage reservoir. Oil is produced largely from repressurized stripper wells.

AAPG Search and Discovery Article #91031©1988 AAPG Eastern Section, Charleston, West Virginia, 13-16 September 1988.