CONODONTS IN THE MARCELLUS SHALE SUBGROUP (MIDDLE DEVONIAN) IN WESTERN NEW YORK STATE AND MAGNETIC SUSCEPTIBILITY CORRELATION OF CONODONT-POOR STRATA IN THE OATKA CREEK FORMATION

The Marcellus Shale subgroup in western New York State consists of the Union Springs Formation and the overlying Oatka Creek Formation which mark a significant deepening and facies change over the platform carbonates of the Onondaga Limestone. West of the Genesee River Valley the Union Springs Formation pinches out. The very top of the Seneca Member of the Onondaga is characterized by Polygnathus linguiformis γ1b morphotype and Icriodus expansus. The lowest Union Springs conodonts are also dominated by Po. linguiformis γ1b and I. expansus which were recovered, although rare, throughout the formation. The Cherry Valley Limestone Member in the lower Oatka Creek Formation is dominated by Po. linguiformis Cherry Valley morphotype, Po. linguiformis γ1a morphotype, and I. expansus. The thin East Berne Member did not yield any conodonts. The Hallihan Hill Bed and equivalent LeRoy Bed, which mark the base of the Chittenango Member, yielded I. expansus, I. angustus, and several specimens of Polygnathus and Tortodus. The Chittenango black shales yielded Po. linguiformis γ1a and Po. pseudofoliatus. Polygnathus costatus costatus reported from the Seneca indicates the costatus Zone; Tortodus kockelianus reported from the base of the Cherry Valley indicates the kockelianus Zone, which has led to the Union Springs to be assigned to the australis Zone. Conodonts from the East Berne and Chittenango were not zone determinative, but a positive abrupt shift in bulk magnetic susceptibility (MS) of δ 0.5 in the lower East Berne and a long term increase of δ 1.25 through the Chittenango are consistent with the MS shift associated with the Eifelian-Givetian boundary and suggest that the East Berne is ensensis Zone and the Chittenango is hemiansatus Zone. Six distinct MS intervals were recognized in the East Berne and Chittenango members from two drill cores in the Genesee River Valley that may allow correlation of strata in the absence of high resolution conodont control.