30 Pander Society Symposium—Mixed-Up Conodonts: Extracting Useful Information and Solving Geologic Puzzles Using Stratigraphic Leaks and Redeposited Faunas
Friday, 13 April 2007
8:10 AM - 12:00 PM
REWORKED CONODONTS: TILLS, SINKHOLES, AND TERRA ROSSA
Paper number: 30-3
Program: SYMPOSIA SESSIONS
Time: 8:40 AM – 9:00 AM
Authors
Abstract
In central Missouri, samples were collected from five more or less vertical Pennsylvanian solution fills and one sink hole in the Burlington Limestone (Mississippian). In the five fills Gnathodus texanus dominated and all specimens were compatible with a Middle Mississippian age, strongly suggesting the former presence of the Keokuk Limestone as a phantom formation above the Burlington. The ages of the conodonts from the sinkhole, however, indicate considerable transport, which has not yet been interpreted. Conodonts include specimens of Ordovician (4), Devonian (2), Middle Mississippian (3), and Pennsylvanian (1) age. In north-central Indiana a large sinkhole formed during mid-Tertiary time on Silurian rocks with clays sealing the sink. Conodonts from the red clay show that it was essentially in situ because all the conodonts, including Pterospathodus, found in it are present in the underlying bedrock.
One sample was taken from a fresh cut in terra rossa in southern Indiana. It yielded seven Pa elements of Cavusgnathus and one M element of Kladognathus, both present in the underlying Upper Mississippian limestone. I interpret this sample as having been formed in situ although there is some thought of downhill transport for terra rossa development.