A Brief Review Of Marine Isotope Stages

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Kendra McKoy 11/11/14 Paleoceanography Draft 1 A brief review of Marine Isotope stages Introduction The creation of marine isotope stages we know today was a carminative effort between several scientists and research institutions across decades. It first started with Cesare Emiliani who transferred to the University of Miami’s Institute of Marine Science in 1957. Emiliani had been investigating the cause and nature of Quaternary glaciations by examining foraminifera fossils from the marine sedimentary record for the Pleistocene Age. Moving to the University of Miami offered new opportunities for Emiliani to work with ongoing drilling projects and trained individuals. Emiliani’s work was heavily influenced by Harold Urey’s 1947 work on…show more content…
Oxygen isotope ratios change in the ocean primarily due to precipitation and evaporation. When water evaporates from the surface, lighter 16O is preferentially removed and turned into vapor while the heavier 18O is preferentially left behind. With time, this causes the ocean to be 16O depleted or 18O enriched. If the cloud precipitates out, the first isotopes to be released are the heavier 18O while the 16O remain as vapor. It is important to note that complete precipitation or evaporation results in no fractionation since all molecules of water are precipitated or evaporated out. Rayleigh fractionation occurs as the water vapor moves poleward and begins precipitating out the heavier isotopes until the vapor is progressively more enriched in light isotopes (Figure 1). The lighter isotopes can then be stored as terrestrial ice. This mechanism explains how on long timescales the oxygen isotope ratio can change when forming or collapsing large ice sheets. Because the changes in the isotopic ratio are so small, delta notion was adopted with the use of an international standard. The original standard, adopted in 1968 by the International Atomic Energy Agency, was called Standard Mean Ocean Water (SMOW) but has been retired for the current standard Vienna Standard Mean Ocean Water (VSMOW). The calculation for δ18O is defined as follows: δ^18 O=[(〖(_^18)O/(_^16)O
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