The origin and formation of metamorphic microdiamonds from the Kokchetav massif, Kazakhstan: a nitrogen and carbon isotopic study

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• 作者：Cartigny ; Pierre ; De Corte ; Katrien ; Shatsky ; Vladislav S. ; Ader ; Magali ; De Paepe ; Paul ; Sobolev ; Nikolay V. ; et. al.
• 关键词：Metamorphic microdiamond ; Nitrogen ; Carbon
• 刊名：Chemical Geology
• 出版年：2001
• 出版时间：July 1, 2001
• 年：2001
• 卷：176
• 期：1-4
• 页码：265-281
• 全文大小：857 K

文摘

This study reports δ¹³C, δ¹⁵N and N-content values for microdiamonds from ultrahigh-pressure metamorphic rocks of the Kokchetav massif in Kazakhstan. Both alluvial diamonds and in-situ diamonds from a garnet–clinopyroxene rock and a marble (i.e. a garnet–pyroxene dolomitic rock) were investigated. In-situ diamonds were analysed in batches, because of their small size (average 40 μm), whereas the larger alluvial diamonds were analysed individually. The latter group has δ¹³C-values ranging from −15.92‰ to −10.57‰, δ¹⁵N from −1.8‰ to +1.1‰ and N-contents from 2300 to 3650 ppm. Diamonds from the garnet–clinopyroxene rock yield mean values of −10.50‰ for δ¹³C, +5.9‰ for δ¹⁵N and a high average nitrogen content of 11,150 ppm. Values for diamonds in marble are −10.19‰, +8.5‰ and 2650 ppm, respectively.