Sentences with phrase «oxygen isotope ratios for»
To date, we have a full complement of analyses for about three years of growth for one tusk from the Taimir Peninsula of Siberia (the Jarkov mammoth; ca. 20,300 rybp) and growth increment and tusk apatite carbon and oxygen isotope ratios for two to three years of growth from two tusks from Wrangel Island (4,400 and 4,120 year bp).
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To date, we have a full complement of analyses for about three years of growth for one tusk from the Taimir Peninsula of Siberia (the Jarkov mammoth; ca. 20,300 rybp) and growth increment and tusk apatite carbon and oxygen isotope ratios for two to three years of growth from two tusks from Wrangel Island (4,400 and 4,120 year bp).
The team then compared the oxygen isotope ratio for each year's wet season from 1990 to 2010 with a cyclone activity index of the average accumulated energy expended, based on factors such as number of cyclones, cyclone strength, size and time on storm track.
Not exact matches
He realized that the skewed oxygen isotope ratios could be explained if the rock had been exposed to martian air or water for a long period.
By applying uranium - thorium dating to the corals and measuring ratios of oxygen isotopes in their skeletons, her lab reconstructed ocean temperatures for much of the last 7000 years.
Back at their Georgia Tech lab, they analyzed the stalagmites for the ratio of oxygen isotopes contained in samples of calcium carbonate, the material from which the stalagmites were formed.
The most convincing evidence for this, says Jouzel, comes from isotope ratios; ice that has frozen in site has a higher proportion of water molecules containing the heavy form of oxygen, oxygen - 18, than that of ice that has been transported over long distances by weather systems.
«Scientists use the ratio of the various sulfur isotopes as their strongest evidence for atmospheric oxygen.»
For decades, scientists studying climate change have measured the oxygen isotope ratio in tree - ring cellulose to determine the ambient temperature and relative humidity of past climates.
The group highlighted the added value of measuring paired coral strontium / calcium ratios (Sr / Ca) and oxygen isotope ratios (δ18O), two key proxies for sea surface temperature that are often referred to as paleothermometers (δ18O also reflects sea surface salinity).