1.A synthetic element produced in trace quantities by heliumisotope bombardment of curium. All isotopes are radioactive, chiefly by emission of alpha particles. Atomic number98; mass numbers244 to254; half-lives varying from25 minutes to800 years.
2.Heliumisotope ratio is 5-6 Ra (atmospheric 3He/ 4He ratio) in some OIB, which are mainly located in Southern Hemisphere (such as St Helena, Gough and Tristan, French Polynesia and others), and 10-35 Ra in others (i.e., Iceland, Loihi, Hawaii, etc.) .
3 He 4 He值为 5～ 6Ra 的OIB主要分布在南半球 ,而分布于冰岛和夏威夷 (包括Loihi)等地的OIB3 He 4 He值为 10～ 35Ra。收藏指正
