Earth magmatic-seawater hydrothermal alteration revealed through satellite-borne Hyperion imagery at Panorama, Western Australia

Hyperion hyperspectral VNIR-SWIR satellite imagery were evaluated for mapping hydrothermal alteration mineralogy associated with Archaean magmatic-seawater convective cells at Panorama, Pilbara Block, Western Australia. The Panorama geology is well exposed in cross section over a 30 km strike length revealing the complete geometry of the hydrothermal system. The hydrothermal discharge sites developed economic sulphide mineralisation as well as early life. Previous studies of airborne hyperspectral HyMap imagery from the same area, showed that both the alteration mineralogy and geometry of the hydrothermal system could be mapped. Critical SWIR-active OH-bearing alteration minerals include: white mica (with variations in Tschermak substitution); topaz; pyrophyllite; chlorite-epidote; and amphibole. The Hyperion SWIR data, following processing to correct for column-striping and atmospheric radiative transfer, revealed a similar suite of OH-bearing mineralogy, except for topaz. The resultant Hyperion-derived mineral maps of white mica abundance and Al-chemistry (Tschermak substitution) correlate well with the corresponding HyMap white mica maps, which clearly define the location of the discharge sites. The greater spatial coverage of the Hyperion image track also revealed new information about the hydrothermal plumbing, especially within the granite.