Download Full Text (9.2 MB)
Dr. Benjamin Datillo
Department of Geosciences
Indiana University – Purdue University Fort Wayne
The Waynesville formation is part of the stratigraphic succession of Indiana bedrock which allows us to look back on environmental conditions during the late Ordovician period, 450 million years ago. Due in part to a fossil record which is overwhelminlgly dominated by a single species, the Waynesville formation functions as an outdoor labratory illustrating various preservation processes operating on directly comparable shells. Shell blackening during preservation has been a particular point of interest. Based on the correlation of shell blackening with occurrences of shell fragmentation and abrasion in large brachiopods, the shell blackening seen in Upper Ordovician (Cincinnatian) brachiopods has previously been identified as a sign of long residence on the sea floor, and has been attributed to the accumulation of iron sulfides and organics in microborings. This in turn suggests extremely low oxygen microenvironments within shells. The results of our studies are broadly consistent with prior hypotheses.
Earth Sciences | Physical Sciences and Mathematics
O'Malley, Paul; Argast, Anne S.; and Brett, Carlton, "The Microstructure of Pyrite Blackening in Fossil Shells" (2015). 2015 IPFW Student Research and Creative Endeavor Symposium. 52.