Quantifying downhole silicate mineralogy ? HyLogger with thermal infrared

Abstract

Thermal infrared spectroscopy (TIR) (6000 ? 14500 nm) has recently become available through HyLogger technology. Framework silicates such as quartz, feldspar, garnet, pyroxene and olivine have primary molecular responses at these wavelengths. With this new suite of minerals visible to the automated scanner, studies using semi-quantitative methods will be able to map key alteration vectors with which geologists are familiar. The Haylands Prospect, south of Morgan, South Australia offered the opportunity to demonstrate the capabilities of the new system mapping albite, quartz, microcline and carbonate in addition to chlorite and sericite offered by the shortwave infrared detectors. TIR spectroscopy can assist in delineating regional alteration systems, such as albitisation and K-feldspar alteration. Such alteration styles are a feature of many mineral systems, including regional alteration associated with iron oxide-copper-gold systems.