may be part of the late Oligocene carbonate rock underlying the oyster- 

 bearing deposits. 



f . Miocene Deposits . Sediments of probable Miocene age occur in 

 cores 95 and 96 from northeastern Onslow Bay. In addition, cores 91 and 

 93 contain an anamalous mixture of shallow marginal marine and planktonic 

 foraminifera (possibly detrital or reworked), which appear to be of 

 Miocene age. Cores 91 and 93 have not been studied in any detail because 

 the older fauna appears to be displaced. 



The Miocene sediments in core 95 consist of silty sand and shells 

 with a phosphorite content of around 25 percent, the highest found in 

 any of the ICONS cores. Nearly all of the phosphorite consists of pelle- 

 toid grains that are well rounded and typically have a dull waxy amber 

 to dark-brown color. Glauconite is also present and in greater frequency 

 than in any other material in the Onslow Bay cores. Foraminifera in core 

 95 are sparse but well preserved. The assemblage is dominated by two 

 species --Hansawaia oonaentrioa (Cushman) and Bolivina pau Z-a CCushman). Plank- 

 tonic species are rare relative to the nearby core 96. 



Miocene sediment in core 96 is a silty, sandy barnacle plate hash 

 containing abundant foraminifera. The abundance of barnacle plates is 

 a distinctive feature of this sediment, though abundant barnacle plates 

 also occur in type G sediment. The two deposits, however, can be readily 

 separated by differences in color, degree of recrystalization, and faunal 

 content. The foraminiferal assemblage of core 96 is diverse but dominated 

 by abundant specimens of large Cibiai-des floridanus (Cushman). This species 

 has been widely reported as showing considerable diversity in form. The 

 specimens in core 96 are similar to those illustrated by Figure 1 in Todd 

 and Low (1976) . Other common benthonic types in core 96 are Ci-bicrides 

 lobatulus (Walker and Jacob), Cibicides pseudoungerianus (Cushman), and 

 Bolivina pau Z^a (Cushman and Cahill). Planktonic species are well repre- 

 sented in this deposit. The most common species are Globovotatia obesa 

 Bolli and Globigevinoides triZobus. Core 97, which lies seaward of core 

 96, contains many reworked foraminifera of this assemblage and may either 

 closely overlie the same deposit or the fauna may be detrital elements. 



Cores 95 and 96 probably correlate with either the middle or late 

 Miocene rocks described by Brown, Miller, and Swain (1972) from well 

 and outcrop data on the adjacent coastal plain. They describe the middle 

 Miocene beds as predominantly composed of clay (partly diatomaceous) , 

 limestone, dolomite, shells, sand, and phosphatic sand. Late Miocene 

 deposits are characterized as highly shelly gray clay, fine to medium 

 clayey and shelly sand, shell hash, and limestone. 



Kimrey (1965) described interbedded phosphatic sands, silts, clays, 

 diatomaceous clays, and phosphatic limestone in the North Carolina Coastal 

 Plain for which he proposed the name Pungo River Formation. This unit 

 has been correlated with the middle Miocene Calvert Formation of Maryland 

 and Virginia (Brown, 1958; Gibson, 1967). The stratigraphy of the Pungo 

 River Formation was mapped and further described by Miller (1971) . Late 



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