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: $ 0.22万
• 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: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=536410
• 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CO2）的钾质超镁质火成岩，其伴生矿物可能含有钻石。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，可以在经济上可行。金伯利岩的特点是具有明显的非等晶结构，这是由于大晶和/或巨晶（主要是橄榄石）的存在而形成的，这些大晶和/或巨晶（主要是橄榄石）镶嵌在细粒基质中。钻石的浓度，即单个金伯利岩矿体内的钻石等级，在很短的距离内变化很大，这使得有效的提取过程具有挑战性。金伯利岩的质地及其矿物成分的丰度对钻石等级有很大影响。因此，为了对钻石品位进行可靠的预测，准确和高空间分辨率地确定金伯利岩中矿物成分的丰度是有价值的。在这一过程中，必须特别强调区分在遗传上与钻石有关的矿物阶段，例如地幔衍生的橄榄石大晶体，和导致金伯利岩矿石稀释的矿物/岩石成分，例如乡村岩石包体。为此，我们建议使用反射光谱成像技术。利用可见光、近红外和中红外波长，我们的目标是利用反射成像光谱技术为金伯利岩岩心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，并协助岩心的等级评估。