金伯利岩与金刚石

Kimberlite and Diamond

本文简要介绍了自然界分布极少,来源最深的一种火成岩——金伯利岩、其中的地幔捕虏体以及金刚石的特征,他们三者有着密切成因联系。金伯利岩岩浆来自深达200km的地幔,地幔内部在高温、高压及低氧逸度的环境下可以结晶出金刚石,当岩浆快速上升时携带了地幔捕虏体及其解体矿物,金刚石也是被携带的矿物之一。除了碳的微粒通过固体扩散形成金刚石外,流体及熔体对金刚石生长过程所起的作用也不可忽视。

The characteristics of kimberlites, their mantle xenoliths and diamonds are briefly introduced in this paper. Very close petrogenesis relationship between them has been recognized. Kimberlites are rare igneous rock types discovering in the earth and the kimberlitic magmas derived from mantle at ca. 200 km depth. Diamonds are crystallized and stabilized at high pressure, high temperature and low oxygen fugacity condition in the mantle. When the kimberlitic magmas rapid ascend they can carry mantle rocks and their segregated minerals such as olivines, garnets, pyroxenes, spinals etc. to uplift from mantle to upper crust or surface. A very important event is the diamonds also as xenocrystals born by magma and preserved in kimberlites. Except the solid diffuse of carbon particles, melts and fluids are the non-neglected factors at the formed processes of diamonds.