Airborne hyperspectral characterisation of hydrothermal alteration in a regolith-dominated terrain, southern Gawler Ranges, South Australia

Key alteration minerals associated with epithermal and porphyry Cu-Au mineralisation have been successfully identified using HyMap airborne hyperspectral imagery in a regolith-dominated terrain in the southern Gawler Ranges, South Australia. Alteration assemblages were mapped using Spectral Feature...

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Bibliographic Details
Published in:Australian journal of earth sciences 2021-05, Vol.68 (4), p.590-608
Main Authors: Caruso, A. S., Clarke, K. D., Tiddy, C. J., Lewis, M. M.
Format: Article
Language:English
Subjects:
Airborne remote sensing
Algorithms
Alunite
Analytical methods
Copper
Gawler Ranges
Gold
Hydrothermal alteration
HyMap
hyperspectral imagery
Hyperspectral imaging
Identification
Image analysis
Image processing
Imagery
mineral exploration
Mineralization
Mineralogy
Minerals
Porphyry copper
Pyrophyllite
Regolith
regolith-dominated terrain
Sediment samples
Soil surfaces
Spatial distribution
Spectra
Spectral Feature Fitting
Terrain
X rays
X-ray diffraction
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Summary:Key alteration minerals associated with epithermal and porphyry Cu-Au mineralisation have been successfully identified using HyMap airborne hyperspectral imagery in a regolith-dominated terrain in the southern Gawler Ranges, South Australia. Alteration assemblages were mapped using Spectral Feature Fitting, a spectral matching algorithm, identifying the spatial distribution of localised advanced argillic and broader argillic alteration. X-ray diffraction (XRD) analysis was undertaken to independently identify the mineralogy of 57 surface soil and rock samples collected from the study area. This analysis confirmed the presence of key alteration minerals including alunite, pyrophyllite and dickite. The integration of spectral and XRD analytical techniques allowed interpretation of mineralogical patterns across the landscape. This study demonstrates that it is possible to identify surface alteration related to potential mineralisation using airborne hyperspectral imagery and semi-quantitative XRD even in a weathered regolith-dominated terrain. KEY POINTS Advanced argillic and argillic alteration identified through hyperspectral image analysis in a regolith-dominated terrain X-ray diffraction used to validate the presence of advanced argillic alteration minerals alunite, pyrophyllite and dickite in the landscape Relationship of advanced argillic and argillic alteration interpreted in two key landscape features in the context of a porphyry mineral system Demonstrates potential for detection of alteration signatures with airborne hyperspectral imagery in regolith-dominated terrains elsewhere
ISSN:0812-0099
1440-0952
DOI:10.1080/08120099.2020.1826122