SIMS Measurement of Magnesium Isotopic Ratios in Primitive Meteorites

Much information about the origin of the primordial solar nebula has been acquired by the investigation of primitive meteorites including the discovery of 16O excess by CLAYTON et al. [1], 26Mg excess originated from the in situ decay of now-extinct 26A1 (half life = 7.2 × 106 y) by GRAY and COMPSTON [2] and 24Mg excess by NISHIMURA and OKANO [3]. These were obtained by the investigations of the Allende and other primitive meteorites. Based on the data, the primordial solar nebula is thought to contain two or more components from different sources.