CRC LEME
Open File Report 79
PIRSA Report Book 2000/00003
ABSTRACT
Regolith Studies related to the Birthday Gold Prospect, Gawler
Craton, South Australia
M J Lintern, M J Sheard and G Gouthas
Our knowledge of geochemical dispersion of Au and Au pathfinders
in the Gawler Craton (South Australia) is poor since there have
been very few published research or orientation studies. In this
study at the Birthday Gold Prospect, the applicability of geochemical
dispersion models identified in Western Australia to sites in the
Gawler Craton were investigated. The specific objectives of the
study were to (I) undertake a detailed orientation survey in an
area of known Au mineralisation, (ii) establish a regolith framework,
(iii) identify potential sample media, and (iv) recommend the most
appropriate ways to explore in this area. A 1.5 km line (the "regolith
traverse") was chosen for the study of lateral and vertical
geochemical dispersion and regolith stratigraphy.
The Birthday Gold Prospect (Minotaur Gold NL; EL 1900) occupies
an area of low topographic relief in a semi-arid environment approximately
750 km north west of Adelaide, South Australia. Drill hole intercepts
indicate a complex, deeply weathered regolith. The upper regolith
(0-6 m) is characterised by the development of silcrete and calcrete
on a thick (<2 m) horizon of locally transported materials, overlying
Archaean rocks deeply weathered to clay-rich saprolite to about
30-40 m depth. Geochemical results confirmed anomalous Au concentrations
in calcrete above mineralisation (maximum of 13 ppb) above 2 zones
of bedrock mineralisation at about 30 m depth. However, concentrations
were also high in a separate area (14 ppb) where no mineralisation
has been identified. Anomalous concentration of Au above mineralisation
also appear to persist in the upper regolith (beneath the calcrete)
and it is this feature that distinguishes the false anomaly from
the true.
Last updated: Tuesday, September 26, 2000 09:30 AM
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