Spectral imaging of kimberlite drill core for mineral mapping

用于矿物测绘的金伯利岩钻芯光谱成像

• 批准号: 446595-2012
• 负责人: Rivard, Benoit
• 金额: $ 3.53万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=554464
• 关键词: Spectral; imaging; kimberlite; drill; core

Kimberlites are a group of volatile-rich (primarily CO2) potassic ultramafic igneous rocks, which can contain diamonds as an accessory mineral. Worldwide, less than 1% of the kimberlites contain diamonds in sufficient quantities to be economically viable. Kimberlites are characterized by a distinctly inequigranular texture, which results from the presence of macrocrysts and/or megacrysts (primarily olivine) that are set in a finer-grained matrix. The concentration of diamonds, i.e. the diamond grades within a single kimberlite ore body can vary substantially over short distance, which makes an efficient extraction process challenging. Diamond grades are greatly influenced by the texture of a kimberlite and by the modal abundance of its mineral constituents. For a reliable prediction of the diamond grade, it is, therefore, valuable to determine the modal abundance of the mineral components within a kimberlite accurately and with high spatial resolution. In this process, particular emphasis has to be put on the distinction between mineral phases that are genetically linked to diamonds, such as mantle-derived olivine macrocrysts, and mineral/rock components that cause a dilution of the kimberlite ore, such as country rock xenoliths. To assist with this, we propose using reflectance spectroscopy imaging technology. Using visible, near-infrared, and mid-infrared wavelengths, we aim to create accurate mineral map images using reflectance imaging spectroscopy for kimberlite drill cores. These images will be used to identify and label different kimberlite facies, and assist with the grade assessment of the drill core.

金伯利岩是一组富含挥发物（主要是二氧化碳）的钾质超镁铁质火成岩，其中可能含有钻石作为副矿物。在世界范围内，只有不到 1% 的金伯利岩含有足够数量的钻石以实现经济上的可行性。金伯利岩的特征是明显不等粒度的结构，这是由于存在于更细粒度的基质中的大晶体和/或巨晶体（主要是橄榄石）造成的。钻石的浓度（即单个金伯利岩矿体内的钻石品位）可能在短距离内发生很大变化，这使得高效的提取过程充满挑战。钻石等级很大程度上受金伯利岩结构及其矿物成分丰度的影响。因此，为了可靠地预测钻石品位，以高空间分辨率准确确定金伯利岩内矿物成分的模态丰度非常有价值。在此过程中，必须特别强调与钻石遗传相关的矿物相（例如地幔橄榄石宏观晶体）和导致金伯利岩矿石稀释的矿物/岩石成分（例如围岩捕虏体）之间的区别。为此，我们建议使用反射光谱成像技术。我们的目标是利用可见光、近红外和中红外波长，利用反射成像光谱为金伯利岩钻芯创建准确的矿物图图像。这些图像将用于识别和标记不同的金伯利岩相，并协助评估钻芯的品位。