Corescan Logging in Copper Porphyry

13 Jan 2016

Hyperspectral classification image overlaid on photographyApplications in Green Fields Exploration

High precision, accurate hyperspectral core imaging data is used
to identify and map suites of porphyry mineralogy, both primary
and secondary alteration.

Mineral maps:

    • reveal paragentic relationships and other textures (eg. pervasive vs. veined)
    • act as proxy for hydrothermal fluid temperature and chemistry
    • reveal specific indicator minerals and/or assemblages associated with Cu-Mo (Au,Ag) mineralisation

Copper Basin, AZ Porphyry Exploration

Corescan data from the Copper Basin Cu-Mo porphyry prospect in central Arizona is used to identify eleven (11) separate mineral species throughout seven (7) separate boreholes. An additional eight (8) sub-species (changing mica chemistry and crystallinity) are also identified. Located in the Laramide-aged porphyry district of Arizona (near both Jerome and Bagdad), this system has ~1km of vertical extent and ~1.5km² of exposed alteration and mineralisation. Proterozoic granites cut by younger Laramide quartz-diorite stocks and dikes which are in-turn cut by younger stockworks and breccias are altered to typical porphyry assemblages: propylitic, phyllic, argillic and potassic.

Of particular importance in porphyry exploration is the logging and identification of mica species including white micas (paragonite, muscovite, phengite), biotite/phlogopite and chlorite (chamosite, clinochlore). Mica chemistry and degree of crystallinity is measured and logged by hyperspectral Corescan imaging and aids in ore-vectoring. Spectral signatures shown Above-Right

Below: Spectral scanning of approximately 70 m of cut core maps the spatial distribution of typical porphyry alteration and reveals potential assemblages related to copper mineralisation. In combination with lithological control, the assemblage defined by Chlorite+Phlogopite+Fe-rich, High-Crystallinity White Mica (Phengite) appears to correlate with increased copper grade. Such relationships help to define ore zones and direct future drilling.

Copper Basin Corescan Results