Date of Award
Master of Science (MS)
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, Kathryn M., "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" (1979). Geology Theses and Dissertations. 79.