Download Guidebook as .pdf (1.8 Mb) - Carolina Geological Society

Richard A. Laws, W. Burleigh Harris and Victor A. Zullo
from the base of the Blue Bluff Marl up to the sample at
156.6 feet contain a nannofossil assemblage typical of NP
16. Sphenolithus spiniger and Discoaster martinii which
occur in sample 156.6 have LO in NP 16. The interval from
150 feet to 83 feet in VSC-4 contains rare, poorly preserved,
long-ranging species. This interval includes the upper Blue
Bluff Marl, the Utley member and the lower half of the Griffins
Landing Member (see Figure 2). The sample at 82 feet
contain Chiasmolithus oamaruensis, the indicator for NP 18
to NP 20 in Martini’s zonation (Upper Eocene). Samples of
the Griffins Landing Member from other cores in the area
contain Isthmolithus recurvus the indicator for NP 19/20.
The Utley Member was barren of nannofossils and correlation
of it is based on other evidence.
Harris, W.B., V.A. Zullo, and R. A. Laws in press. Coastal onlap
stratigraphy of the onshore Paleogene, southeastern Atlantic
Coastal Plain, U.S.A.; in Posamentier et al., (eds.), Sequence
stratigraphy and facies associations. International Assoc. of
Sedimentol., Spec. Pub. 18.
Martini, E. 1971. Standard Tertiary and Quaternary calcareous nannoplankton
zonation; in A. Farinacci (ed.), Proceedings II
Planktonic conference, Roma, 1970, 2:739-785.
Okada, H. and D. Bukry 1980. Supplementary modification and
introduction of code numbers to the low-latitude coccolith biostratigraphic
zonation (Bukry, 1973, 1975). Mar. Micropaleontol,
5:321-325.
Perch-Nielsen, K. 1985. Cenozoic calcareous nannoplankton; in
H.M. Bolli, J.B. Saunders, and K. Perch-Nielsen (eds.), Plankton
Stratigraphy, Cambridge University Press, 1032 p.
Sequence Stratigraphy
Four middle Eocene depositional sequences are recognized
in the Savannah River area. The Congaree Formation
is represented by two of the sequences, the Warley Hill Formation
by one sequence, and the Blue Bluff Marl (McBean)
by one sequence. The Congaree Formation is these cores
does not contain an abundant calcareous nannofossil suite;
however, the occurrence of Lophodolithus mochlophorus,
which has a last occurrence (LO) in NP 15, at 237 feet suggests
assignment of the Congaree Formation to the TA3.3
cycle of Haq et al. (1987). Harris et al. (in press) indicate that
the Congaree Formation is represented by two depositional
sequences (TA3.3 and TA3.2) in Savannah River area.
Although a depositional sequence is recognized between the
Congaree Formation and the Blue Bluff Marl which may
correlate to the Warley Hill Formation, calcareous nannofossils
do provide definitive age control. This sequence is
assigned to the TA3.4 cycle on the basis of superposition and
correlation. The Blue Bluff Marl contains an abundant calcareous
nannofossil suite including Sphenolithus spiniger
and Discoaster martinii which have LO in NP 16. Based on
their occurrence this sequence is assigned to the TA3.6/3.5
cycle of Haq et at. (1987). The depositional sequence represented
by the Utley Formation, although barren, is assigned
to the TA4.1 cycle of Haq et al. (1987) on the basis of superposition
and correlation to the “scutella bed” of the lower
Moodys Branch Formation of the eastern Gulf Coastal Plain
and exposures along the Savannah River. The Griffins Landing
Member of the Dry Branch Formation is placed in the
TA4.2 cycle of Haq et al. (1987) on the basis of occurrence
of Chiasmolithus oamaruensis which is the indicator for NP
18 to NP 20 in Martini’s zonation and the occurrence of Isthmolithus
recurvus, an indicator for NP 19/20 in samples
from other cores in the area that are correlative.
REFERENCES
Haq, B.U., J. Hardenbol, and P.R. Vail 1987. Chronology of fluctuating
sea levels since the Triassic. Science, 235:1156-1167.
62