Tidal Origin of a Mississippian Oolite on the West Virginia Dome
Petrographic descriptions, sedimentary structures, and facies analysis document the predominantly tidal control on deposition of the Pickaway Limestone. Cross-bedded ooid-peloid grainstones accumulated over the West Virginia dome as decimeter-sized intertidal sand waves and metersized subtidal sand waves. Evidence of tidal sedimentation includes bidirectional foresets, tidal bedding, mud drapes, reverse grading, wavy bedding, reactivation surfaces, and tidal bundles. Sand holes, desiccation cracks, mud chips, and interbeds of red shale and finely crystalline dolomite formed during periods of subaerial exposure, whereas ripple bedding hints of occasional wave activity. Storms passing over the sand waves produced thin sets of trough cross-beds and plane beds. Major storms also led to the migration of the subtidal sand waves over other facies. In the quiet offshore environment, pelletal-skeletal packstones and wackestones were deposited, although advancing spillover lobes or tempestites produced interbedded sets of ooid grainstone.
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A coincidence of tectonic, eustatic, and geochemical conditions resulted in substantial deposits of oolitic limestone during later Mississippian time in the continental United States. These oolitic limestones have formed petroleum reservoirs with favorable primary and secondary recovery characteristics. Significant potential reserves in stratigraphic traps remain to be discovered and developed in these reservoirs.