80 Paleontology II, Mesozoic and Cenozoic (Posters)

Tuesday, 16 March 2010
1:30 PM - 5:35 PM
International ABCDF

FORAMINIFERA AND PALEOENVIRONMENTS OF PLIO-PLEISTOCENE STRATA IN NORTH AND SOUTH CAROLINA

Paper number: 80-8
Program: Technical Sessions
Time: 1:30 PM – 5:35 PM

Authors

Abstract

Foraminiferal assemblages were studied from three stratigraphic units in North and South Carolina, the upper James City Formation on the Neuse River near James City, NC, the Chowan River Formation at Colerain Bluff on the Chowan River, NC, and the Waccamaw Formation on the Waccamaw River near Tilly Lake, SC. Foraminiferal faunas form the basis for paleoenvironmental interpretations of the three formations at the study sites. Approximately 50 grams of bulk sample from each locality were disaggregated with Calgon solution, wet sieved through 1 mm and 63 mm sieves, and oven dried at about 50 oC. Three hundred foraminifers were picked and identified from each sample. Relative abundance of species, particularly dominant taxa, form the basis for interpretations of paleoenvironments, including salinity, temperature and water depths.

The fauna from the Waccamaw Formation included 22 species and was dominated by Cibicides sp. A, Amphistegina gibbosa and Epistominella sp. F (38%, 17%, and 8% of total specimens counted, respectively). The Chowan River Formation contained 10 species including Nonion aff. advenum pustulosum (56%), Epistominella danvillensis (21%) and Discorbinella sp. A (14.4%). The assemblage from the upper James City Formation contains at least 17 species, and is dominated by Nonion aff. advenum pustulosum (60%), Cibicides sp. A (10%) and Quinqueloculina lamarckiana (7%). All three assemblages indicate a warm, subtropical, near-shore, shallow water, normal marine paleoenvironment. These interpretations are consistent with results from studies of the mollusk faunas from the same localities. Faunas from the upper James City and Chowan River formations are most similar and least diverse, whereas the fauna from the Waccamaw Formation has higher species richness and equitability. The differences may be due to different ages of these units or to the close geographic proximity of the Chowan River and James City localities as opposed to the Waccamaw locality geographically separated ~400 km to the south.