Detection of K-alteration in the Cloncurry District, NW Queensland, using hyperspectral mineral maps

Laukamp, C., Cudahy, T., Oliver, N.H.S., and Cleverley, J.S. (2008) Detection of K-alteration in the Cloncurry District, NW Queensland, using hyperspectral mineral maps. In: Australian Earth Sciences Convention, pp. 159-160. From: Australian Earth Sciences Convention 2008, 20-24 July 2008, Perth, WA, Australia.

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Abstract

Potassic alteration in the Cloncurry District is spatially and genetically related to IOCG deposits in the eastern Moutn Isa Inlier, NW Queensland. Hyperspectral images, released by the collaborative Queensland NGMM project between GSQ and CSIRO, were validated as new tool for the detection of mineralisation related hydrothermal footprints.

At the IOCG deposit of Ernest Hentry geochemically discrete alteration shells correspond to distinct mineral distributions. Regional sodic-calcic alteration was overprinted by potassic alteration with coeval biotite- and magnetite-veining, which was in turn altered by Cu-Au mineralisation and K-feldspar-alteration. The various envelopes of potassic alteration are interpreted as a general indicator for IOCGs in the Mount Isa Inlier (Mark et al., 2006, Min. Dep., v. 40, 769-801).

A combination of specific mineral maps, derived from hyperspectral imaging in the VNIR to SWIR-range, is sued to detect potassic alteration in the Cloncurry District. "MgOH composition-" and "Fe²⁺ associated with MgOH-maps" enable us to separate amphibolite facies metasediments form hydrothermal breccias and various mafic units in the field area, based on their distinct amphobole and chlorite chemistry. Within some of the mafic intrusives these maps exhibit a change in the chemistry of the MgOH-bearing silicates, characterised by an increaes of the Mg-content from core to rim. A change of the whole-rock chemistry is also characterised by an increasing K-feldspar-content towards the rim. Although K-feldspar can not be detected in the VNIR- to SWIR-range, weathering products of K-feldspare like muscovite and Illite are picked up by the "White mica abundance-" and "White mica composition-maps". The remotes sensing results are confirmed by PIMA analyses and will be compared with XRD-results.

Our study shows that hyperspectral mineral maps successfully identify hydrothermal alteration patterns and can be used as a powerful tool for exploration of IOCGs in the Mount Isa Inlier.

Item ID: 29294
Item Type: Conference Item (Abstract / Summary)
ISSN: 0729-011X
Date Deposited: 17 Sep 2013 06:20
FoR Codes: 04 EARTH SCIENCES > 0402 Geochemistry > 040201 Exploration Geochemistry @ 100%
SEO Codes: 84 MINERAL RESOURCES (excl. Energy Resources) > 8401 Mineral Exploration > 840199 Mineral Exploration not elsewhere classified @ 100%
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