CRC LEME
Open File Report 168
ABSTRACT
Preliminary Biogeochemical Studies at Barns Gold Prospect, Gawler
Craton, South Australia
M.J Lintern
CRC LEME Open File Report 168 / CSIRO Exploration and Mining Report
1238F (August 2004)
This report presents outcomes of a collaborative research project
between CRC LEME, Department of Primary Industries and Resources,
South Australia (PIRSA) and Adelaide Resources NL that commenced
in 2003. It was agreed, between the parties, that this report could
be released into the public domain immediately.
Executive Summary
This report describes (i) preliminary biogeochemical investigations
on the role of vegetation in the mobilization and recycling of Au
and other metals in the regolith and (ii) the potential of vegetation
as a sample medium to see through sand cover. It forms part of the
CRC LEME Project “Gold and trace metal geochemistry in calcrete-bearing
and non-calcrete- bearing regolith”. The site chosen for this
study is the Barns Gold Prospect located in the northern Eyre Peninsula
(South Australia). Here, a seif dune (with natural vegetation) overlays
Au mineralization and provides an opportunity to study Au transport
in a recent regolith setting. Melaleuca and Eucalyptus leaves, adjoining
branches and fruiting bodies were sampled (i) at about 200 m intervals
along a 5 km traverse bordering a dune and (ii) at about 25 m intervals
across a dune profile. Both traverses crossed mineralization occurring
nearby in weathered bedrock at about 35 m depth beneath leached
saprolite. Gold concentrations reached a maximum of 1.3 ppb but
not near the known extent of mineralization. However, pathfinders
(Ag, Bi and Pb), and other elements not known to be associated with
the deposit (Co, Sb, W and Ta), were anomalous in plant samples
from over mineralization.
The Barns Gold Prospect was originally discovered from a Au in
calcrete surface anomaly and this appears to be the best method
of surficial sampling in this terrain. Calcrete sampling provides
broad, coherent anomalies and whilst more difficult to implement
in dunes, where calcrete is located deep in the profile, vegetation
may not provide a practical alternative.
M.J. Lintern
Study Leader
August 2004
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