Spectral imaging of kimberlite drill core for mineral mapping

点击翻译按钮获取中文摘要

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.