AN OUTRAGEOUS CONCEPTUAL MODEL FOR A REALLY STRANGE CAVE

Relatively recently a rather interesting cave has been found and explored. The cave is located SW of Nashville TN, where Silurian rocks are overlain by Lower Mississippian rocks (Devonian rocks are missing). What is very interesting about the cave passages is that they have formed as much in clastic rocks as thin carbonates, although of course this may not be unique. One entrance is a shaft, in, and often the roof also is, a carbonate (Fort Payne Formation). It appears to have formed near an unconformity and there are other unique features nearby, such as the Howell Impact Structure, (and others spanning the same age range) which seem to have occurred generally before or near the same time (~400 - 340 Ma), but again some of the stratigraphic section is missing. The cave has a relatively large stream, but its geochemistry is strange in that it is very (ridiculously) low in any dissolved solutes, as also are nearby springs. The cave presently has ~ 95 km (~60 miles) of mapped passages in an intense maze where there are two or three levels, but the plan pattern footprint is only about 2.5 x 1 km (1.5 x 0.7 miles). The stratigraphy follows a notable Upper Silurian (Lau) extinction event. Initial thoughts were of possible hydrothermal origin, it is (geologically) not far from some magmatic features, that are mid-Tertiary age. This is a wonderful problem for someone to work on.