Unfolding primary composition of kimberlite melt and processes of mantle enrichment in critical metals; their effect on economic value of kimberlites

揭示金伯利岩熔体的主要成分和关键金属的地幔富集过程；

• 批准号: 572209-2022
• 负责人: Fedortchouk, YanaY
• 金额: $ 1.82万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Alliance Grants
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=750928
• 关键词: Unfolding; primary; composition; kimberlite; melt

Kimberlites, the deepest mantle magmas that reach the surface of the Earth, are the hosts to the major economic diamond deposits. Kimberlites originate deep (> 150 km) in subcontinental mantle due to poorly understood processes of chemical enrichment of the mantle with rare and volatile elements including some of the critical metals. This makes understanding of processes of kimberlite melt production in the mantle very important. The proposed project aims to establish the composition, origin and evolution of primary kimberlite melt and its effect on the eruption mechanism and kimberlite geology. The existing views on the composition of primary kimberlite melt vary between carbonatitic and silicate melt based on (i) study of bulk rock geochemistry and mineralogy of kimberlites and on (ii) experimental melting of possible mantle sources of kimberlites. The proposed project will integrate these studies with a novel method which examines the reaction between kimberlite magma and mantle minerals carried by kimberlites (diamond, chromite, ilmenite, garnet). In response to the crystallization conditions and composition of kimberlite magma, these minerals develop: (i) dissolution features, (ii) compositional zoning, and (iii) rims of secondary mineral phases. The proposed study will use high-pressure-experiments to examine these reactions and apply the results to natural diamonds and Fe-Ti oxides from worldwide kimberlite localities. Collaboration with diamond mining industry provides an exceptional access to the samples with geological control from specific depths and units within composite kimberlite pipes. Knowledge of the composition and evolution of kimberlite melt is essential for understanding: mantle processes leading to kimberlite magmatism, causes of the large variation in kimberlite geology, and their effect on diamond economic potential. The study aims to develop new analytical methods to help improving exploration techniques and assessment of kimberlite bodies, for sustaining and adding value to the existing mines. The proposed research will help to unravel deep mantle processes and improve exploration techniques to benefit diamond mining industry in Canada, the third world largest diamond producer.

金伯利岩是到达地球表面的最深地幔岩浆，是主要经济钻石矿藏的宿主。金伯利岩起源于大陆次大陆地幔深处(&gt；150公里)，这是由于人们对地幔中稀有和挥发性元素(包括一些关键金属)的化学富集化过程知之甚少。这使得对地幔中金伯利岩熔体产生过程的了解变得非常重要。该项目旨在确定原生金伯利岩熔体的组成、成因和演化，及其对喷发机制和金伯利岩地质的影响。对原生金伯利岩熔体成分的认识在碳酸盐熔体和硅酸盐熔体之间存在差异，其依据是：(1)金伯利岩块体岩石地球化学和矿物学研究；(2)金伯利岩可能地幔来源的实验熔融。拟议的项目将把这些研究与一种新的方法结合起来，该方法研究金伯利岩岩浆与金伯利岩所携带的地幔矿物(钻石、铬铁矿、钛铁矿、石榴石)之间的反应。根据金伯利岩浆的结晶条件和成分，这些矿物形成：(I)溶解特征，(Ii)成分分带，(Iii)次生矿物相的边缘。这项拟议的研究将使用高压实验来检查这些反应，并将结果应用于来自世界各地的金伯利岩地区的天然钻石和铁钛氧化物。与钻石采矿业的合作提供了从特定深度和复合金伯利岩管内的地质控制单元获得样品的特殊途径。了解金伯利岩熔体的组成和演化对于理解：导致金伯利岩岩浆作用的地幔过程、金伯利岩地质差异大的原因及其对钻石经济潜力的影响是必不可少的。这项研究旨在开发新的分析方法，以帮助改进金伯利岩体的勘探技术和评估，以维持和增加现有矿山的价值。拟议中的研究将有助于揭示深部地幔过程，改进勘探技术，使加拿大的钻石采矿业受益。加拿大是世界第三大钻石生产国。