CRC LEME
Open File Report 100
ABSTRACT
Further geochemical studies of the soil at the Steinway Gold
Prospect, Kalgoorlie, Western Australia
Lintern, M.J. and Craig, M.A.
This study is located in the central and northern part of the prospect
where the thickness of transported overburden is variable but greater
than 20 m, and the depth to mineralization is about 30 to 40 m.
The great thickness of sediments is similar to other sites within
the Kalgoorlie area studied in this project, but the presence of
the Au at the surface makes it highly unusual. It was considered
that a more detailed study of the nature of Au in the 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 as a result of its proximity to the buried
mineralization.
The principal results are summarized as follows:
- Microscopically visible Au was present in some ferruginous granules;
- Gold concentrations of individual ferruginous granules are extremely
variable, ranging from <40 to 1500 ppb;
- Total Au content of coarse material are weakly related to the
total Au content of the soil.
Specific targeting of the calcareous horizon has been demonstrated
to maximize the probability of sampling the most consistently auriferous
sample in all landscape regimes in the Kalgoorlie region. In relict
and erosional regimes, such sampling may accurately define drilling
targets. However, in depositional regimes, the results for Steinway
indicate that there is no direct link with mineralization. Here,
although the Au anomaly in the calcareous soil directly overlies
buried mineralization, the data suggest that it is derived from
detrital Fe granules in the soil, rather than the mineralization
itself.
It is concluded that, in depositional areas, sampling of calcareous
material at best may indicate the potential of the (sub-)catchment.
It is suggested, therefore, that for such landscape regimes, wider
sampling intervals should be used, with a follow-up requirement
that deep samples be collected including basal sands or ferruginous
material in saprolite.
Last updated: Sunday, August 05, 2001 12:21:00
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