Nanometre-sized mineral and fluid inclusions in cloudy Siberian diamonds: new insights on diamond formation
Nanometre-sized mineral and fluid inclusions in cloudy Siberian diamonds: new insights on diamond formation
复制标题
DOI：
10.1127/0935-1221/2008/0020-1815
复制
发表时间：
2008-05
影响因子：
2.1
通讯作者：
A. Logvinova;R. Wirth;E. Fedorova;N. Sobolev
中科院分区：
文献类型：
--
作者：
A. Logvinova;R. Wirth;E. Fedorova;N. Sobolev
研究了来自Internatsionalnaya矿的四颗云状八面体金刚石和来自Yubileynaya矿（雅库特）的一颗云状八面体金刚石中的纳米级孤立包裹体。透射电子显微镜（TEM）技术，如电子衍射，分析电子显微镜（AEM），电子能量损失谱（EELS）和高分辨率电子显微镜（HREM），以及线扫描和元素映射的样品。所有的晶体都表现出八面体的外部习性与不透明的中央立方体的核心，包含许多纳米夹杂物。所有尺寸范围在30和800 nm之间的纳米夹杂物反映了金刚石的习性，并被认为是原生的，与宿主金刚石同生的。它们由多相组合组成，其中包括固相（硅酸盐、氧化物、碳酸盐）、盐水（卤化物）和流体气泡。这些包裹体成分相对均匀，含有可区分的结晶相和流体相。含铝高镁硅酸盐、白云石、Ba-Sr碳酸盐、金云母、钛铁矿、铁方镁石、磷灰石、磁铁矿、K-Fe硫化物（二水镁矾？）和蓝晶石的电子衍射图谱已被确定为结晶矿物相，除了Ba-Sr碳酸盐。金刚石中的CaF 2相和类斜辉石相等几种包裹体从未被报道过。卤化物相为KCl。气泡中K、Cl、O、P含量高，S、Ba、Si、Ti含量低。在TEM箔中从所有研究的金刚石中鉴定出碳酸盐。它们与硅酸盐、氧化物和硫化物一起出现在所有组合中，并显示出普遍富集不相容的元素，如Sr和Ba。某些元素的变化可以通过流体/熔体的分离结晶或具有不同成分的流体（碳酸盐岩、水溶性矿物、盐水）的混合来解释。
Nanometre-sized isolated inclusions have been studied in four cloudy octahedral diamonds from the Internatsionalnaya and one from the Yubileynaya mines (Yakutia). Transmission electron microscopy (TEM) techniques such as electron diffraction, analytical electron microscopy (AEM), electron energy-loss spectroscopy (EELS) and high-resolution electron microscopy (HREM) were applied as well as line scan and elemental mapping of the samples. All crystals exhibit octahedral external habit with opaque central cuboid cores that contain numerous nano-inclusions. All nano-inclusions in the size range between 30 and 800 nm reflect the diamond habit and are considered primary, syngenetic to host diamond. They are composed of multi-phase assemblages, which include solid phases (silicates, oxides, carbonates), brines (halides), and fluid bubbles. These inclusions are relatively homogeneous in composition and contain distinguishable crystalline and fluid phases. Al-bearing high-Mg silicate, dolomite, Ba-Sr carbonate, phlogopite, ilmenite, ferropericlase, apatite, magnetite, K-Fe sulfides (djerfisherite?) and kyanite have been identified as crystalline mineral phases by electron diffraction patterns, except the Ba-Sr carbonate. Several phases, including CaF 2 and clinohumite-like phases, have never been reported as inclusions in diamond. The halide phase was KCl. Bubbles contained high K, Cl, O, P and less S, Ba, Si, Ti components. Carbonates were identified in TEM foils from all studied diamonds. They occur in all assemblages with silicates, oxides, and sulfides and show a general enrichment in incompatible elements such as Sr and Ba. Some elemental variations may be explained by fractional crystallization of fluid/melt or mixing of fluids with different compositions (carbonatitic, hydrous-silicic, brines).