Abstract

An inclusion of graphite in zircon from the diamond- and tourmaline-bearing rocks of the Kokchetav massif (Northern Kazakhstan) has been studied. The inclusion, associated with diamond crystals, was identified within the marginal part of the zircon grain. The Raman spectrum of the graphite inclusion is characterized by the presence of an intense band at 1350 cm^–1, which is indicative of a high degree of disorder in its structure. An investigation of this inclusion by means of transmission electron microscopy (TEM) allowed us to identify nine randomly oriented high-ordered submicron grains of graphite without relics of diamond. Thus, the presence of the intense band at 1350 cm^–1 in the Raman spectra of graphite is not a necessary evidence of its low degree of crystallinity and particularly its formation as a result of diamond graphitization. The formation of the polycrystalline aggregates, consisting of submicron grains of well-ordered graphite, might have been related to rapid crystallization from a high-density C–O–H fluid.

中文翻译：

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哈萨克斯坦北部Kokchetav地块高压变质岩中多晶石墨聚集体的形成

摘要

已经研究了哈萨克斯坦北部科克切塔夫地块的金刚石和电气石岩中锆石中的石墨夹杂物。在锆石晶粒的边缘部分发现了与金刚石晶体相关的夹杂物。石墨夹杂物的拉曼光谱的特征是在1350 cm ^–1处存在一个强带，这表明其结构高度无序。通过透射电子显微镜（TEM）对这种夹杂物的研究使我们能够鉴定出9个无金刚石的随机取向的高阶亚微米石墨颗粒。因此，在1350 cm ^–1处存在强频带石墨的拉曼光谱中的H 2 O 3并不是其低结晶度的必要证据，尤其不是由于金刚石石墨化而形成的。由有序石墨的亚微米晶粒组成的多晶聚集体的形成，可能与从高密度C–H–H流体中快速结晶有关。