CRC LEME
Open File Report 158
ABSTRACT
Teilta regolith project: Groundwater geochemistry
P. de Caritat & D. Kirste
The groundwaters from the Teilta 1:100,000 mapsheet area were
sampled and analysed with the aim of studying the processes that
affect their composition, in a bid to further develop hydrogeochemistry
as a tool for mineral exploration in areas of regolith cover. Those
groundwaters are quite distinct in hydrogeochemical character from
most of the other groundwaters studied in the Curnamona Province.
They are Na-HCO3 rich, warm and may be quite reducing. They are
particularly depleted in SO4, which tends to have an average to
high ?34S composition. We interpret this to be a reflection of the
incursion of Great Artesian Basin groundwaters at the northern end
of the regional study area. These waters have undergone bacterial
sulfate reduction (BSR). The combined effect of BSR is to make the
waters look ‘less interesting’ from a mineral exploration
perspective (lower excess S, and higher S isotopic ratio). The lesson
for mineral exploration is that less stringent selection criteria
(lower Relative S excess, higher S isotopic composition of dissolved
SO4 cutoffs) should be applied to groundwaters that have been affected
by BSR, when trying to identify those that indicate interaction
by sulfide mineralisation under cover. Even despite this, a few
groundwater compositions suggest proximity to mineralisation, using
the indicators developed in Caritat et al. (in press).
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