CHAPTER 8: THE FRASNIAN STRATA - LOWER UPPER DEVONIAN - OF NEW YORK STATE

Marine Frasnian strata in New York comprise the middle and upper parts of the Genesee Group, the entire Sonyea and West Falls groups, and all but the upper part of the Java Group, consisting of facies that grade from offshore dark-colored shale and pelagic limestone in the west to sandy nearshore deposits, which interface with coeval terrestrial facies in central and eastern New York. These strata contain tephra beds, brachiopods, conodonts, goniatites, spores, and other flora and fauna, that allow global correlation and recognition of zonal and stage boundaries. The current best age determination of the duration of the Frasnian is from 382.31 + 1.08/–1.36 to 372.15 + 0.46/–0.46 Ma. Five third–order cyclic packages are recognized by distinct black shale-gray shale groups. In the offshore marine strata in western New York the base of the Frasnian is placed at or near the top of the Lodi Limestone Bed in the Penn Yan Formation based on the first occurrence of the conodont Ancyrodella rotundiloba pristina Khalymbadzha and Chernysheva 1970. The top of the Frasnian and corresponding base of the Famennian is at or near the top of the Pt. Gratiot Bed in the upper Hanover Formation based on the first occurrence of Palmatolpeis subperlobata Branson and Mehl 1934 and Palmatolepis triangularis Sannemann 1955. Eastward, in shallower marine and terrestrial strata, location of the stage boundaries are based on recognition of key beds and sequence stratigraphic interpretations. Frasnian strata in New York State are correlative with corresponding strata of the Burket and Harrell shales in Pennsylvania, the Flynn Creek and Dowelltown members of the Chattanooga Shale in the southern Appalachian Basin, the Blocher and Selmier members of the New Albany Shale in the Illinois Basin, and the Squaw Bay Limestone and Norwood and Paxton members of the Antrim Shale in the Michigan Basin.