South Arm Ore Deposits zero to hero course: The SWIR spectroscopy of white micas at Olympic Dam

Phengite is the main potassic dioctahedral mica identified at the Olympic Dam iron oxide–copper–gold (IOCG) deposit, South Australia, where its mineral chemistry is quite variable. These differences can be explained by contrasting degrees of hydrothermal alteration. In the heavily-sericitized, ore-bearing rocks, the phengites display a lower-Si content, a higher-Al content, and a lower Mg-number than the phengites from the weakly-sericitized alteration halo that surrounds the deposit. High-Al phengite produces a spectral absorption feature at 2.206 μm, and this feature is displaced to 2.213 μm for low-Al phengite. A drill core profile produced using reflectance spectra collected from drill core shows changes in phengite mineral chemistry and phengite abundance as a function of depth. In general, reflectance spectroscopy can be used to characterize the aluminum content of potassic dioctahedral micas like phengite, and this information can be used to infer the degree of sericitic alteration that has occurred as a result of hydrothermal fluid flow.

Chair: Mirella Terrones

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Ore deposit zero to hero course
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