PALEOECOLOGY OF THE BASAL-MOST GIVETIAN (MIDDLE DEVONIAN) DARK SHALES IN EASTERN NEW YORK STATE

The great mass of sediments that comprise the Devonian Catskill Delta have at their base a widespread, variable thickness of dark-gray to black shale. Known largely as the Marcellus Shale, this sedimentary package not only preserves truly economic resources in the form of hydrocarbons, but also important paleontologic resources in the form of highly variable faunal remains recording an important interval in life history. Several key, worldwide bioevents take place during the interval of time recorded by the Marcellus Shale, including the Stony Hollow and Kacak bioevents.

The Stony Hollow bioevent represents the influx of a tropical, warm-water fauna into the temperate regions of the Appalachian Basin in the latest Eifelian. A strange mixture of Old World and Eastern North Americas realm taxa were present during this time across much of eastern North America. This fauna only lasted for a short time in the Appalachian Basin (~1/2 of a 3rd order depositional cycle)and was replaced by a cool-water fauna during the Kacak bioevent associated with a worldwide sea level rise during the latest Eifeilan-earliest Givetian.

The first occurrence of this cool-water fauna in the Appalachian Basin is recorded in the Dave Elliot Bed (DEB) of the East Berne Member of the Mount Marion Fm. The fauna of the DEB is entirely a Hamilton-type fauna and statistical testing of the biofaces preserved along a deep to shallow water gradient from south to north along the present-day Hudson Valley shows that these are typical Hamilton-type biofacies,