Molluscan stable isotope temperature estimates of the southwestern Ross Sea during the Early Oligocene and Early Miocene, CRP-2/2A and CRP-3, Victoria Land basin, Antarctica

• Main Authors: Lavelle, M., Fielding, C.R., Hall, M.A., Thomson, M.R.A.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Terra Antartica Publication 2001
• Subjects: Ross Sea; Victoria Land; McMurdo Sound; Antarc*; Antarctica
• Online Access: http://nora.nerc.ac.uk/id/eprint/19811/; http://www.mna.it/english/Publications/TAP/TA_pdfs/Volume_08/CRP3_Science_Results/TA_08_439_Lavelle.pdf

Stable isotope analyses of marine bivalve growth increment samples have been used to estimate early Oligocene (29.4 - 31.2) Ma and early Miocene (24.0 Ma) seafloor palaeotemperatures from the southwestern continental margin of the Ross Sea. Measured d18O values average +2.5‰ in the early Miocene and range between +1.26 to +3.24‰ in the early Oligocene. The results show that palaeoceanographic conditions in McMurdo Sound during the mid-Cenozoic were significantly different from those of today. The minimum estimated spring through late summer seasonal temperature range was 3°C during the early Miocene and between 1 and 5°C during the early Oligocene. This compares to the equivalent modern day range of <0.5°C within the sound. Absolute seawater temperatures at <100 m depth were of the order of 5 to 7°C during both time slices, compared to modern day values of -1.4 to -1.9°C in the same area. The results are in broad agreement with early Oligocene Mg/Ca temperature estimates from deep Atlantic foraminifera as well as estimates from local terrestrial palynology and palaeobotany.