金刚石伴生矿物中的烃类包裹体问题(英文)

THE PROBLEM OF HYDROCARBON INCLUSIONS IN THE DIAMOND ASSOCIATED MINERALS

首次在Mir金伯利岩筒中的锆石中发现了烃类包裹体。利用低温荧光光谱仪测定出烃类包裹体的成分为萘和菲的同系物 ,芘 ,1,12苯并芘等 ;其成分与Udachnaya岩筒中的橄榄石内的烃类和Mir岩筒中的石榴石中的烃类的成分相近。测定出锆石的δ13C值为 - 2 1 83‰～ - 3 3 5 4‰ ,与用榴辉岩共生组合中最轻的金刚石测出的同位素δ13C值范围相符。文中引述了有关有机物来源的讨论及多环芳烃 (PAH)由缩聚作用形成的论述。伴生矿物中相当数量的PAH的存在证明在形成金刚石及其伴生矿物的情况下 ,若有相当浓度的自由氢存在则可能发生缩聚作用。这些缩聚作用中碳的来源显然与形成金刚石时碳的来源是相同的 (即液态的CH4,CO及CO2 )。

The hydrocarbon inclusions were found in zircons from the Mir kimberlite pipe for the first time. By using low-temperature spectrofluorimetry, the content of the hydrocarbon inclusions was identified to be the albocarbon and phenanthrene homologues, pyrene and 1,12-benzopyrene, which is similar to that of hydrocarbons in the olivine from the Udachnaya pipe and in the garnet from the Mir pipe. The value δ 13 C of zircons was determined to be -21.83‰～-33.54 ‰ which corresponds to the δ 13 C range of isotope that was found in the lightest diamonds of the eclogitic paragensis. The paper reviews the discussions on the origin of the organic matter and the formation of polycyclic aromatic hydrocarbons (PAH) by the polycondensation processes. The presence of PAH in noticeable quantities in associated minerals proved that under the conditions of formation of diamond and its associated minerals, the polycondensation processes can take place if there is a significant concentration of free hydrogen. The source of carbon for these processes and for the diamond formation was obviously the same (CH 4 , CO and CO 2 in the fluid state).