Cartigny P, Harris JW, Javoy M
P. Cartigny and M. Javoy, Laboratoire de Geochimie des Isotopes Stables, Universite de Paris VII, Institut de Physique du Globe de Paris (IPGP), 4 Place Jussieu, 75251 Paris Cedex 05, France. J. W. Harris, Department of Geology and Applied Geol.
Science. 1998 May 29;280(5368):1421-4. doi: 10.1126/science.280.5368.1421.
Eclogitic diamonds have a large range of delta13C values, whereas peridotitic diamonds do not. Paired delta15N-delta13C-N variations in 40 eclogitic diamonds from the Jwaneng kimberlite in Botswana show that neither the influence of recycled biogenic carbon nor the global and primordial heterogeneity of mantle carbon are likely for the origin of the large delta13C range; the data instead support a fractionation process. It is proposed that carbonatitic mantle melts from which diamonds crystallize undergo different evolutions before diamond precipitation, when percolating through either a peridotite or an eclogite. These different evolutions, reflecting the presence or absence of olivine, can account for their respective delta13C distributions.
榴辉岩型金刚石具有大范围的δ13C值，而橄榄岩型金刚石则不然。对博茨瓦纳Jwaneng金伯利岩中40颗榴辉岩型金刚石的δ15N-δ13C-N配对变化研究表明，大范围δ13C值的起源不太可能是再生生物成因碳的影响，也不是地幔碳的全球和原始不均一性；相反，数据支持分馏过程。有人提出，金刚石从中结晶的碳酸盐地幔熔体在金刚石沉淀之前，当渗透过橄榄岩或榴辉岩时会经历不同的演化。这些反映橄榄石存在与否的不同演化，可以解释它们各自的δ13C分布。
