SEQUENCES IN UPPER DEVONIAN BLACK SHALES OF THE APPALACHIAN BASIN: MIDDLESEX, RHINESTREET, AND THE FRASNIAN-FAMENNIAN BOUNDARY INTERVAL

Five prominent black shales delineate post-Hamilton depositional cycles in the relatively conformable and continuous strata of western New York: Geneseo-Genesee Group, Middlesex-Sonyea Group, Rinestreet-lower West Falls Group, Pipe Creek-upper West Falls Group, and Dunkirk-Canadaway Group. Recognition of these black shale-deepening cycles within and outside the Appalachian Basin ranges from probable, for example the Pipe Creek Shale and black shale bed in the upper Hanover to the Kellwasser intervals of western Europe; to possible, for example the Middlesex in the Europe, Norh Africa, and the Canning Basin of Australia, to problematic, for example correlation of the basal Rhinestreet Shale in New York to the base of the Dowelltown Member of the Chattanooga Shale in Tennessee.

Recognition of smaller scale cycles and high order sequences is possible in some cases. The Pipe Creek Shale and Upper Kellwasser bed are tentatively recognized in the Chattanooga Shale of westernmost Virginia. Tectonic and regional depositional differences make recognition of the Frasnian-Famennian boundary on and across the Cincinnati Arch difficult based solely on lithostratigraphy. Here, conodont biostratigraphy indicates an early and persistent development of black shale inboard of the Appalachian Basin, but small bed to bed changes may correlate between basins, such as thin green-gray shale partings in the Antrim and Grassy Creek shales.