金刚石中岩浆熔融包裹体

MAGMA MELT INCLUSIONS IN DIAMONDS

在我国数颗金刚石中发现了罕见的岩浆熔融包裹体.包裹体物质由球粒和基体组成,球粒主要为Fe质球、Si-Fe质球和Si-Fe-Mg质球,基体成分为Si-Al-K质、Si-Mg-Fe质和Si-Fe-Ca质等.不同金刚石中包裹体成分变化较大,推测包裹体(球体和基体)是经熔离作用的岩浆熔体在温度下降、氧逸度很低和淬火作用条件下形成的.金刚石的结晶可能与火山喷发作用有关.

The occurence of magma melt materials as inclusions in diamonds has been found from the Fuxian, Monying mines and Dingjiagang diamond placer mine, China.The inclusions in diamonds are of 30 -85μm in size, with black or deep brown colour and with weak metallic luster. The inclusion materials in diamonds consist of some spheres and groundmass, which are uncommon in diamonds.The spheres are of ferroball, silicon-ferroball and mafelsic ball, and the groundmass are high in SiO2, Al2O3, K2O, SiO2, FeO, CaO and SiO2, FeO, MgO in different diamonds .The authors conclude that a certain material of a quenched or temperature unequilibrated melt was present as inclusion in the diamonds. These inclusions can be deduced to be magma formed after a liquid immiscibility phase of the melt from which diamonds were formed, giving rise to the assumption that the formation of diamonds might be related with volcanic eruption.