Benthic foraminifera and paleoecology of the Pliocene Yorktown and Chowan River Formations, Lee Creek Mine, North Carolina, USA

Pliocene deposits assignable to the Yorktown Formation (Sunken Meadow, Rush mere, and Morgarts Beach Members) and Chowan River Formation (Edenhouse Mem ber) yielded 129 species and subspecies of benthic foraminifera. Twenty-six taxa, selected on the basis of consistent occurrence (present in 50% or mo re of the samples) and relative abundance (3% or more of the benthic assemb lage in at least one sample), account for 88% of the identifiable specimens . From among these 26, principal components analysis identified 14 species that account for nearly 90% of the faunal variation, and cluster analyses r evealed distinct stratigraphic assemblages that in general conform to the l ithologic subdivisions. The most dramatic faunal change corresponds to the boundary between the Sunken Meadow and Rushmere Members. Based upon the ben thic foraminiferal faunas, the Sunken Meadow, Rushmere, and Morgarts Beach Members of the Yorktown Formation were deposited in middle to outer neritic , outer neritic, and middle neritic environments, respectively. The Edenhou se Member of the Chowan River Formation was deposited in an inner to middle neritic environment. Paleobathymetric interpretations based on benthic for aminifera are consistent with those based on other fossil groups. Paleotemperature implications of the benthic foraminiferal assemblages are not entirely consistent with previous studies. Whereas numerous studies hav e concluded that Pliocene temperatures at middle and high latitudes were si gnificantly warmer than modern temperatures, the benthic foraminiferal faun as encountered in our study suggest paleotemperatures comparable to those o f today. Evidence from benthic foraminifera at the Lee Creek Mine is not su fficient basis to question studies indicating warmer mid-latitude Pliocene seas. Rather, it is likely that localized conditions have overprinted the l arger-scale climatic signal.