PAUCITY OF STRATA ASSIGNED TO THE PTEROSPATHODUS CELLONI SUPERZONE (TELYCHIAN, LLANDOVERY, SILURIAN) IN THE EASTERN PORTION OF THE MIDWESTERN BASINS AND ARCHES REGION

Telychian strata are present throughout the eastern portion of the Midwestern Basins and Arches region (MBA) in New York, Ohio, Kentucky, and Indiana, with nearly all of those strata assigned to either the Pterospathodus eopennatus Superzone or Pt. amorphognathoides amorphognathoides Zonal group. Strata assigned to the Pt. am. amorphognathoides Zonal group typically overlie strata assigned to the Pt. eopennatus Superzone, or even older, Aeronian strata. The Pt. celloni Superzone is mostly absent throughout the eastern part of MBA. Strata assigned to the Pt. am. amorphognathoides Zonal group overlying strata assigned to the Pt. eopennatus Superzone include Willowvale Shale or Westmoreland Hematite overlying Sauquoit Shale in central New York, Rockway Dolomite or Williamson Shale overlying Merritton Limestone in western New York, Estill Shale overlying Waco Formation in western Ohio and Kentucky, Williamson Shale overlying the Merritton Limestone in the subsurface of northeastern Ohio (two of the units comprising what drillers recognized as the “Packer Shell”), and Osgood Formation overlying Lee Creek Formation in Indiana. The only location currently identified in the eastern MBA where there are strata assigned to the Pt. celloni Superzone (Pt. am. angulatus Zone) underlying strata assigned to the Pt. am. amorphognathoides Zonal group is near Rochester, New York, where most of the Williamson Shale assigned to the latter zone overlies the basal Second Creek Phosphate Bed and black shales in the lower part of that same formation in which the former zone is recognized. Sea-level curves show high sea levels recorded in strata assigned to the Pt. celloni Superzone, and some/most of the strata assigned to the Pt. am. amorphognathoides Zonal group and show lower sea levels recorded in strata assigned to the Pt. eopennatus Superzone, including a significant drop in sea level near the top of that superzone. The sea-level record would seem to favor deposition of, and less erosion of, strata assignable to the Pt. celloni Superzone, than strata assignable to the Pt. eopennatus Superzone. Tectonic activity along the Appalachian Orogenic Belt must have played an important role in the eastern portion of the MBA in New York, Ohio, Kentucky, and Indiana during the 1.5 to 3.0 million years of time represented by the Pt. celloni Superzone.