Abstract: Trace Fossils of Chagrin Formation (Upper Devonian, Northeast Ohio)

R. G. Osgood, Jr.

Nine localities in the upper 100 m of the Chagrin Formation (Upper Devonian, northeast Ohio) were sampled normal to the strike, over a distance of 150 mi (240 km). The trace fossils Zoophycos, Rhizocorallium jenense, Bifungites, Rusophycus sp., ?Tigillites, and others were collected. Of especial interest is cf. Rusophycus; the 12-cm width exceeds the dimensions of nearly all marine Late Devonian arthropods. Other significant finds are burrows of linguloid brachiopods and the enigmatic resting and dwelling traces of what may be a phyllocarid or eocarid crustacean.

These trace fossils place the upper Chagrin within the Cruziana ichnofacies. However, it was impossible to subdivide the Cruziana facies as others have done with different rock units; the geographic distribution of Chagrin trace fossils is anomalous. Nevertheless, an important association is Rhizocorallium jenense and Zoophycos, believed to be unique to shallow-water Paleocene rocks in Spain. Although the Chagrin also appears to have been deposited in shallow-marine water, many workers favor a deep-water origin for Zoophycos. The relative paucity of Chagrin trace fossils downdip is attributed to the vagaries of preservation rather than to a change in bathymetry or energy level. Siltstones and fine-sandstone beds are relatively common in the eastern outcrops and rare in the west. Analy is of tool marks and regional tectonics indicate an eastern source for the Chagrin clastic rocks.

AAPG Search and Discovery Article #90972©1976 AAPG-SEPM Annual Convention and Exhibition, New Orleans, LA