Oxygen isotope ratio cycle likely driven by the Lomagundi carbon isotope excursion. Oxygen isotope ratio cycle Oxygen isotope ratio cycles are cyclical variations in the ratio of the abundance of oxygen with an atomic mass of 18 to the abundance of oxygen with an atomic mass of 16 present in some substances, such as polar ice or calcite in ocean core samples, measured with the isotope fractionation. The ratio is linked to water temperature of ancient oceans, which in turn reflects ancient climates. Cycles in the ratio mirror climate changes in geologic history. Oxygen (chemical symbol O) has three naturally occurring isotopes: O, O,
Isotopes of seaborgium Isotopes of seaborgium Seaborgium <nowiki>(</nowiki>Sg) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was Sg in 1974. There are 12 known radioisotopes from Sg to Sg and 2 known isomers (Sg and Sg). The longest-lived isotope is Sg with a half-life of 3.1 minutes. "This section deals with the synthesis of nuclei of seaborgium by so-called "cold" fusion reactions. These are processes that create compound nuclei at low excitation energy (~10–20 MeV, hence "cold"), leading to a higher probability of