Nature - Variations of Oxygen-18/Oxygen-16 and Carbon-13/Carbon-12 in the Calcium Carbonate Pleistocene Varved Clays from Toronto, Canada Skip to main content Thank you for visiting nature.com.

Some grains in Ryugu had an oxygen-17/18 ratio that matched that of AGB stars. Only one grain high in oxygen-18 showed a ratio consistent with a supernova. Traveling through deep time and space.

THE relative differences in the ratios oxygen-18 to oxygen-16 and carbon-13 to carbon-12 of some hundred and fifty carbonate rocks, including fourteen sedimentary limestones, ninety metamorphic ...

In the 3.4-billion-year-old zircons, the team measured ratios of oxygen-18 to oxygen-16 that were as low as 0.1 per mil — a measurement of the ratio of those isotopes when compared to a standard ...

A study of the upper atmosphere's composition has successfully measured an increased presence of the oxygen-18 isotope (18 O) compared to the lighter and most common isotope 16 O. Studies have shown ...