Characterization of the hydrothermal systems associated with Archean VMS-mineralization at Panorama, Western Australia, using hyperspectral, geochemical and geothermometric data

Airborne hyperspectral imagery was used to study the distribution of white mica minerals in Archean (3.2 Ga) submarine hydrothermal systems associated with volcanogenic massive sulfide mineralization in a well-exposed volcanic sequence of the Soansville greenstone belt in the Pilbara, Western Australia. White mica mineral abundance and distribution maps were compared with published hydrothermal alteration maps and differences were interpreted using whole-rock geochemistry and temperature estimates from oxygen isotope geothermometric studies of hydrothermally altered rocks. Three different zones were identified from the hyperspectral imagery: 1) Al-rich white mica zones in the upper parts of the volcanic sequence which are related to recharge of unevolved seawater, 2) Al-poor white mica zones at middle and upper levels of the volcanic sequence predominantly related to K alteration by more-evolved hydrothermal fluids, and 3) high to intermediate Al-content white mica zones in lower levels of the sequence and in cross-cutting zones related to intense alteration by laterally flowing and upwelling evolved fluids. The integrated study of the spatial distribution of hyperspectrally detected white mica minerals together with published maps and rock analyses allowed characterization of the hydrothermal systems and reconstruction of paleo fluid pathways. (C) 2011 Elsevier B.V. All rights reserved.