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Paper No. 1
Presentation Time: 1:30 PM
CONODONTS FROM THE MAUCH CHUNK GROUP (CHESTERIAN), SOUTHERN WEST VIRGINIA, USA
Seventy-five samples were collected from twelve marine-influenced named members in the Chesterian Bluefield, Hinton, and Bluestone Formations (Mauch Chunk Group) in extreme southern West Virginia to improve the correlation of these units and to further evaluate their paleoecology. Forty-six of the samples contained conodonts. The Mauch Chunk conodont fauna is typical of Chesterian rocks except that abundances are low and intraspecific variation is high. Cavusgnathus dominates the collection both in number of specimens and number of samples from which it was recovered. Kladognathus is next in abundance of specimens followed by Gnathodus, Hindeodus, Lochriea, Hindeodontoides, and Vogelgnathus.
The dominance of Cavusgnathus suggests a mostly nearshore environment with variable salinity, energy, and sediment load. Kladognathus, Gnathodus, and Hindeodus show a preference for relatively normal salinity, however, and their varying association with Cavusgnathus suggests local and temporary intervals of greater environmental stability. Gnathodus, Hindeodus, Kladognathus, Lochriea, and Vogelgnathus are most abundant in one of the samples in the Pride Shale Member (Bluestone Formation), the most nearly open marine of our samples.
The discrepancies in Illinois Basin conodont ranges as compared with other areas in combination with the relative paucity of conodonts in this study make correlation with the type Chesterian difficult, and so our overall correlation is based on limited conodont evidence. In the Illinois Basin, Cavusgnathus naviculus occurs first in the Menard Limestone and in West Virginia in the Avis Limestone Member (Hinton Formation). C. monoceras, commonly referred to Adetognathus unicornis, is present in the Clore Formation, Kinkaid Limestone, and Grove Church Shale in the Illinois Basin and in the Pride and the Bramwell Member (Bluestone Formation) in West Virginia, thus supporting the correlation of those units. Species of Gnathodus in the Pride and Bramwell are absent in the Illinois Basin but co-occur in other parts of the world very high in the Serpukhovian (Chesterian) just into the Bashkirian.