|dc.description.abstract||Two siliciclastic-filled paleocaverns within the Mississippian (Osagean) Burlington-
Keokuk Limestone, which were formed in pre-Desmoinesian (Middle Pennsylvanian) time,
are described from exposures in Dade County, Missouri. Petrographic and sedimentological
analyses suggest that these cave-fills were derived from terrestrial sources. The age of the
cave-fills were determined to be Late Atokan (Lower Pennsylvanian) based on their spore
and pollen assemblage.
One of the caves examined is filled primarily with coarse to fine-grained sand.
Sedimentary structures include plane-beds, cross-stratification, scours, flaser bedding, softsediment
deformed layers, flame structures, and normal-graded bedding. Cave-roof collapse
and associated boudinage, as well as slack water shales, separate thick sandstone layers. This
paleocavern has been interpreted to have been filled by fluviokarst processes with sediment
entering primarily through sinking streams.
The cave-fill in the other paleocave examined is primarily mudrock, shale, and sandy
siltstone with some roof-collapse breccia. These rocks contain abundant organic matter,
including wood fragments and charcoal, as well as abundant pyrite and secondary sulfate
minerals. This paleocave has been interpreted to have been filled by soil and residuum
entering through sinkhole collapses beneath marshes or swamps and by some in-flowing,
low-energy water currents.
The recharge points of a cave can be inferred by the type of sediments that it is filled
with and recharge points dictate cave geometry. These recharge points can be seen on
subsurface maps and an area of possible paleocaves can be drawn between these points.
Sandstone cave-fill and fractured limestone host-rock around shale-filled caves are potential
hydrocarbon reservoirs in the subsurface of Kansas and northern Oklahoma.||en_US