Carbon isotope fractionation between graphite and diamond during shock experiments
Carbon isotope fractionation between graphite and diamond during shock experiments
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DOI：
10.1111/j.1945-5100.2003.tb00311.x
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发表时间：
2003-08
影响因子：
2.2
通讯作者：
T. Maruoka;C. Koeberl;J. Matsuda;Y. Syono
中科院分区：
文献类型：
--
作者：
T. Maruoka;C. Koeberl;J. Matsuda;Y. Syono
摘要-测量了冲击产生的金刚石和冲击石墨的碳同位素组成，其峰值压力范围为37至52 GPa。在密封容器中生成的金刚石的δ 13 C值普遍低于初始石墨。初始石墨和冲击石墨/金刚石之间的碳同位素组成的差异可能反映了石墨/金刚石氧化过程中的动力学同位素分馏和/或可能由样品中的杂质引起的分析工件。压力对石墨和金刚石之间的同位素分馏的影响可以从使用通气容器生产的无杂质金刚石的δ 13 C值来估计，在金刚石形成期间或之后，孔隙空间中的气体（包括氧气）从通气容器逸出（例如，0.039 ± 0.085‰。任何由石墨到金刚石的冲击转化引起的同位素分馏都太小，以至于在与地球撞击成坑过程有关的天然冲击诱导金刚石-石墨系统中无法检测到。
Abstract— Carbon isotopic compositions were measured for shock‐produced diamond and shocked graphite formed at peak pressures ranging from 37 to 52 GPa. The δ13C values of diamonds produced in a sealed container were generally lower than that of the initial graphite. The differences in the carbon isotopic composition between initial graphite and shocked graphite/diamond may reflect kinetic isotopic fractionation during the oxidation of the graphite/diamond and/or analytical artifacts possibly induced by impurities in the samples. The pressure effect on the isotopic fractionations between graphite and diamond can be estimated from the δ13C values of impurity‐free diamonds produced using a vented container from which gases, including oxygen, in pore spaces escaped during or after the diamond formation (e.g., 0.039 ± 0.085‰ at a peak pressure of 52 GPa). Any isotopic fractionation induced by shock conversion of graphite to diamond is too small to be detected in natural shock‐induced diamond‐graphite systems related to terrestrial impact cratering processes.