Paleoceanography of the Ames Seaway (Late Carboniferous), Northern West Virginia

Glen K. Merrill, Steven J. Kivett

Three roughly north-south transects across Conemaugh rocks in eastern Ohio into northwestern West Virginia, the Burning Springs Anticline in north-central West Virginia, and southwestern Pennsylvania into northern West Virginia have produced samples from the Ames Member at more than 200 localities. Nearly all of these samples have produced conodonts.

Two kinds of conodont analyses are useful in assessing paleoceanographic conditions that prevailed during the Ames marine event. Biofacies analysis permits contouring relative ratios among common genera for determining paleosalinities and thus facilitate estimations of nearness to shore and basin dimensions. Measuring conodont abundance against internal (simple frequencies) and external (averaged frequencies of faunas of similar age) standards makes it possible to not only see the areas of rapid sediment accumulation that filled the basin and destroyed marine conditions, but to assess the relative time during which the sea occupied a given area. The external standards allow rough quantification of these "dwell times." Furthermore, because the transgressive portion of the Ames marine i cursion aparently was both tectonically produced and quite rapidly developed, the length of time the seaway was developed at a particular place consisted mostly of the regressive portion of the sedimentary couplet that was gradual and sedimentologic in nature. This in turn, places constraints upon the average rate for the northward progradation of the shoreline.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995