ABSTRACT
Previous work by many authors has implied that the Antarctic ice
sheet
underwent a major expansion in the latest Miocene. It was intended
in the
present study to use the oxygen isotope event, which could be
expected
to accompany this glacial expansion, as a stratigraphic marker to
aid in
the correlation of several DSDP Sites. Samples were taken at
approximately
100,000 year intervals throughout the latest Miocene and early
Pliocene
sections at Sites 237 and 249 in the western Indian Ocean, Site
360 in
the South Atlantic and Site 231 in the Gulf of Aden. Oxygen
isotope analyses
were done on bulk samples of juvenile planktonic foraminifera and
calcium
carbonate analyses, size separations, and
dissolution/fragmentation studies
were done by conventional techniques.
A cool period is recognized between about 5.7 m.y. and 4.9 m.y. at
all four sites, but it is not consistently observed in the oxygen
isotope
records from these sites. This implies that the latest Miocene
expansion
of the Antarctic ice sheet did not produce an oxygen isotopic
anomaly of
sufficient magnitude to be a reliable world-wide stratigraphic
marker.
Attempts to correlate sedimentologic events between sites have
revealed
that the biostratigraphy currently available in the Initial
Reports of
the Deep Sea Drilling Project for the late Miocene and early
Pliocene is
not precise to more than about 300,000 years.
Scanlon, K.M., 1979. Paleoclimatic Implications of Oxygen Isotope
and
Sedimentological Study of Late Miocene and Early Pliocene
Sediments from
the South Atlantic, Western Indian Ocean, and the Gulf of Aden.
Unpublished
MSc. thesis, State University of New York at Albany. 73pp., +vii.
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