Diamond resorption in kimberlite and the mantle

大多数宝石钻石是从金伯利岩中开采出来的，金伯利岩是一种深层形成的火山岩，它将钻石从地幔的生长区域带到地表。即使在邻近的金伯利岩管道中，钻石的质量和等级也会有很大差异。金刚石在地幔中停留和在金伯利岩岩浆中上升过程中，经历了部分溶蚀和再吸收，对周围介质条件敏感。现有的金刚石勘探方法是利用地幔源矿物的化学成分来确定其在地幔含金刚石不同部位的来源。然而，钻石和其他地幔矿物的表面形态包含了大量关于钻石居住条件以及在地幔和金伯利岩岩浆中保存潜力的未开发信息。该项目将研究来自加拿大和博茨瓦纳几个金伯利岩地点的钻石样本，这些地点已知位于金伯利岩管道内。将天然金刚石的表面特征与受控条件下金刚石溶解实验的产物进行比较。该研究采用了一种创新的方法，用原子力显微镜定量表征金刚石的溶解特征。获得的数据将使我们能够探索一些矿物，如铬铁矿、钛铁矿、磷灰石，作为金伯利岩流体的指示物，以及它们在钻石勘探中的潜在用途，以预测金伯利岩岩浆中的流体状态和钻石保存。将最先进的科学成像和实验方法与戴比尔斯地质学家的专业知识相结合，将为了解金伯利岩岩浆作用的基本原理和改进勘探方法提供独特的成果。该项目将研究钻石晶体所记录的地幔交代作用的性质，确定金伯利岩上升期间岩浆流体的存在和组成，这种流体对钻石种群特征的影响，以及它在金伯利岩侵位中的作用。加拿大已经成为第三大钻石生产国。该研究将为金伯利岩就位期间的钻石保存评估提供低成本的分析方法。

The majority of gem diamonds are mined from kimberlites - the deeply formed volcanic rocks, which carry diamonds from their growth region in the Earth's mantle to the surface. The diamond quality and grade can vary considerably even in neighboring kimberlite pipes. During residence in the mantle and ascent in kimberlite magma, diamond undergo partial dissolution and develop resorption features, which are sensitive to the conditions of the surrounding media. The existing diamond exploration methods use chemical composition of mantle-derived minerals to confirm their origin in the diamondiferous parts of the mantle. However, the surface morphology of diamond and other mantle minerals contain a wealth of unexplored information about the conditions of diamond residence as well as preservation potential in the mantle and in the kimberlite magma. This project will study diamond samples from several Canadian and Botswana kimberlite localities with known position within a kimberlite pipe. Surface features on natural diamonds will be compared to the products of diamond dissolution experiments at controlled conditions. The study uses an innovative method of quantitative characterization of diamond dissolution features with an Atomic Force Microscopy. The obtained data will allow us to explore a number of minerals such as chromite, ilmenite, apatite as an indicators of kimberlitic fluid and their potential use in diamond exploration for predicting fluid regime and diamond preservation in kimberlite magma. Combining state-of-the-art scientific imaging and experimental methods with the expertise of DeBeers geologists will provide unique outcomes for the understanding of fundamentals of kimberlite magmatism and refining the exploration methods. The project will examine the nature of mantle metasomatism recorded by the diamond crystals, determine the presence and composition of magmatic fluid during the kimberlite ascent, the effect of this fluid on the features of diamond population, and its role in kimberlite emplacement. Canada has emerged as the third largest diamond producer. The study will provide low cost analytical methods for assessment of diamond preservation during kimberlite emplacement.