Porphyry Copper Prospectivity Map of Northern Vancouver Island, Canada
Catchment basins have been defined for regional stream sediment (moss mat) samples from northern Vancouver Island in the example shown here. A thematic map based on percentiles from a weighted sums model (WSM) developed for porphyry Cu mineralisation has been developed following levelling of the Cu data for the effects of elevated Cu in regionally extensive basalts. The weighted sums model has also been adjusted for the effects of differential dilution as a function of catchment area. The final processed product provides a good fit to known porphyry Cu deposits and occurrences, and highlights several catchment basins worthy of further investigation.
Catchment basins highlighted in red on the image to the left either contain known porphyry Cu deposits or are highly prospective for their discovery (from Arne & Brown, 2014).
Down-hole Plots from the VG Discovery in the Yukon Territory, Canada
These plots demonstrate how mineralogical (hyperspectral) and geochemical data can be integrated to enlarge an exploration target
Geochemical data are even more informative when integrated with other data sets, particularly mineralogical information. However, integration with geophysical, geological and structural information also allows a much more sophisticated and meaningful interpretation of geochemical data. In the example shown here, drill core geochemical data from a gold deposit are shown with the results from hyperspectral analysis in the short wave infrared (SWIR) range. The antimony (Sb) data define a larger halo around the mineral deposit than the gold (Au) data alone.
The Na/Al molar ratio tracks the destruction of albite during hydrothermal alteration, whereas the wavelength position of the dominant Al-OH absorption peak in alteration white mica (wavWtMica) tracks potassic alteration associated with the gold mineralization. The position of this peak records a shift from background phengitic white mica to dominantly muscovitic white mica (sericite) in an aureole surrounding gold mineralization. Note that the elevated Sb and shift in white mica composition could be detected using field portable instrumentation (portable XRF and SWIR spectrometer, respectively).