Open File Report 95
Geochemical studies of the soil at the Runway Gold Prospect,
Kalgoorlie, Western Australia
The CSIRO-AMIRA Project "Exploration in Areas of Transported
Overburden, Yilgarn Craton and Environs" (Project 409) has,
as its principal objective, development of geochemical methods for
mineral exploration in areas with substantial transported overburden,
through investigations of the processes of geochemical dispersion
from concealed mineralization. The Project has two main themes.
One of these, 'Surface and subsurface expression of concealed mineral
deposits' is addressed by this report, which focuses on the soil
geochemistry of the Runway Au prospect (Kalgoorlie Area).
This study is located in the northern part of the Runway Au prospect
where the thickness of transported material is less than 2 m, and
the depth to mineralization (beneath barren saprolite) is of the
order of 50 m. While the thickness of transported material is not
substantial, the great thickness of barren saprolite provides an
important contrast with depositional terrain environments from the
Kalgoorlie area which have similar thicknesses of barren overburden.
It is considered that a detailed study of the nature of Au in surficial
material from such an environment will enhance our understanding
of the processes whereby Au may (or may not) be enriched in the
surficial environment in areas of substantially transported material.
The results for this study are summarized below:
- Surficial samples (0 - 2 m) are anomalous in Au, As, Sb and
W. Multi-element geochemistry may be a useful adjunct exploration
tool in this area since data from KCGM indicate that As, Sb and
W are associated with mineralization;
- Gold appears to be associated with carbonate in surficial material,
but it is also present in saprolite, which occurs close to the
- Partial extraction techniques indicate that the proportions
of water-soluble Au are lower and iodide-soluble Au higher than
for areas of deeply transported cover;
- Biogeochemical data indicate that some Au is present in bluebush
samples overlying mineralization but that the data are close to
- Selection and analysis of components within samples may be used
to enhance concentrations in excess of the bulk sample concentration
for selected elements; Au concentrations may be higher in the
calcareous and/or ferruginous granule component of the sample.
Last updated: Friday, July 21, 2000 04:24 PM