PRELIMINARY WORK ON THE STRATIGRAPHY OF THE LOWER PORTION OF THE NORTHEAST SHALE, CHAUTAUQUA COUNTY, NEW YORK

Western New York has a number of Upper Devonian marine shales. While those that contain biocrises related to the end Devonian extinctions have been intensively studied, the others have received little attention. This study measured and described an interval of the lower Northeast Shale in Canadaway Creek, south of Fredonia NY. Samples were collected at regular intervals to look at the elemental variation in the interval with XRF analysis. The measured section covered about 20 meters of the estimated Northeast Shale thickness of 100-200 meters. The stratigraphy was dominated by crumbly, grey shale with thin (> 4 cm), more resistant siltstone beds. The siltstone beds become thicker and more abundant in the upper part of the measured section. The siltstone beds tended to persist for tens of meters laterally along the outcrop. No macroscopic body fossils were observed. Only one ambiguous trace fossil / sole mark was observed—but it was distinctive for internal pyritization it exhibited in section. The paleoenvironmental interpretation is of a subtidal basin with aerobic seafloor conditions, occasionally draped with siltier storm deposits.

Preliminary XRF results show anomalously high concentrations of sulfur that were not apparent at the outcrop. The cause of this high sulfur content is a subject for continued study. The high concentrations gradually decrease up section. A minor high angle reverse fault with an offset of less than a meter was observed near the base of the section. Future work will use the XRF data to better understand the changing local paleoenvironmental conditions.