Knowra Marine isotope stages Marine isotope stages Marine isotope stages are numbered intervals of the past identified from changes in oxygen-isotope ratios in marine sediment records. They provide a framework for reconstructing climate cycles, especially during the Quaternary.
Oxygen isotope ratio : The relative abundance of oxygen isotopes, commonly expressed as the ratio of oxygen-18 to oxygen-16. Stage boundaries and patterns are identified through changes in this measured ratio.
Quaternary : The geological period spanning approximately the last 2.58 million years, marked by repeated ice ages. Most named marine isotope stages describe climate cycles within this period.
Pleistocene : The geological epoch from about 2.58 million to 11,700 years ago, characterized by repeated glacial cycles. Marine isotope stages provide a detailed climate chronology across much of this epoch.
Marine Isotope Stage 5e : The warm substage of marine isotope stage 5 associated with the Eemian interglacial. Its warm conditions contrast with the colder stages that flank it.
Foraminifera : Single-celled organisms, many of which build shells that preserve chemical records of the water in which they lived. Their shells supply much of the marine oxygen-isotope evidence used to define stages.
Stable isotope : An isotope that does not undergo radioactive decay over observable timescales. Oxygen-isotope records compare stable isotopes preserved in sediment materials.
Last Glacial Maximum : The interval when global ice sheets reached their greatest extent during the last glacial period, around 26,000 to 19,000 years ago. Its timing is commonly associated with marine isotope stage 2.
Dansgaard–Oeschger event : A rapid warming and cooling fluctuation recorded especially clearly in Greenland ice cores during the last glacial period. These abrupt events are shorter than the broad intervals represented by most stage numbers.
Ice volume : The total amount of water stored as land ice at a given time. Growing ice sheets preferentially store lighter oxygen, shifting seawater isotope ratios.
Oxygen-18 : A stable, relatively heavy isotope of oxygen with eight protons and ten neutrons. Its proportion relative to oxygen-16 shifts with ice volume and temperature.
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