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Continuous Mineral Mapping of Core Using Hyperspectral Imaging; Example from the Upper Cretaceous Austin Chalk Marathon 1 Robert Todd Core, Central Louisiana

Abstract

Hyperspectral imaging (HI) is a method of observing and enhancing geological rock properties that are not readily apparent visually. Originally developed for the mining industry, HI uses a combination of short-wave infrared light (SWIR) and long-wave infrared light (LWIR) to create a visual ‘map’ of the minerals on the surface of a core that respond to reflectance principles. HI, which requires no special preparation other than that the core be slabbed, clean, and dry, can be rapidly obtained and provides mineralogical and chemical results related to various energy emitted in wavelength spectrum by either halogen bulb reflectance (short-wave quantification) or heat reflectance spectra (long-wavelength quantification). We collected hyperspectral core imaging data of the Austin Chalk Robert Todd core in central Louisiana to obtain detailed, high-resolution mineralogical and textural information and investigate the application of hyperspectral imaging as an integrative tool. Digital HI-derived single mineral curves calibrated to X-ray diffraction (XRD) data were imported as curves to display mineralogical variations with depth alongside overlays showing the textural relationships of the mineralogical assemblages, rock typing models, X-ray fluorescence (XRF) data, and rock-mechanics data. We integrated the hyperspectral data with core description, thin-section, XRF and XRD to identify Milankovitch cycles and aid in quantification and property ‘up-scaling’ from SEM and thin-section scales to understand the mechanical stratigraphy.