CRC LEME
Open File Report 146
ABSTRACT
Resonance Acoustic Profiling Trials in Australia
Report prepared by Valery Lazebnick, Boris Matveev and Bronislav
Koulmametiev of InterGeoRAP Consulting (St Petersburg, Russia)
Edited and compiled by Matthias Cornelius
InterGeoRAP Consulting is an independent geophysical firm established
in St. Petersburg, Russia. They have developed a new ground acoustic
technique - Resonance Acoustic Profiling (RAP) - that could potentially
be suitable for mapping regolith and shallow bedrock units as well
as certain subsurface features such as cavities. RAP has the potential
to offer an alternative or form an addition to traditional geophysical
techniques and drilling.
The technique was introduced to CRC LEME, which helped to arrange
the RAP trials in Australia at properties of some sponsoring mining
companies. The objectives of the trials include:
- Carrying out independent tests of the new technique.
- Evaluating the potential of the RAP technique for 3 dimensional
mapping of regolith and shallow bedrock features.
The trials took place at well-explored areas chosen by the sponsoring
companies and unknown to the RAP team. Representatives from CRC
LEME accompanied the team on five of these field visits. The 23-day
field trials were conducted in the Northern Territory, the Kimberley,
five project areas in the Eastern and Northern Goldfields, and at
AGSO's Gilmore Project in New South Wales.
This report includes both the RAP geophysical models and geological
information provided to CRC LEME in confidence by sponsor companies.
The geological information was not disclosed to the RAP team until
the completion of the final data processing.
Best results were achieved for settings such as volcanic pipes
and sub-vertical or steeply inclined bedrock structures. An established
set of survey and processing algorithms, developed by InterGeoRAP
in other parts of the world, allows optimal interpretation of these
structures with minimum calibration requirements. The trials also
demonstrated the ability of the RAP technique
to clearly delineate major interfaces such as the boundaries between
regolith and bedrock and alluvium and regolith. Encouraging results
were also obtained for deep regolith profiles and may allow to delineate
internal regolith features such as silicification, Fe oxide enrichment
and collapsed zones within clayey units. More reliable interpretation
of the acoustic properties of various regolith materials requires
further calibration and better geological information to establish
optimal survey and processing algorithms.
The RAP trials in Australia have confirmed the validity of the
new technique under independent supervision of CRC LEME and the
sponsoring companies, and have demonstrated the potential of RAP
to play an important role in mineral exploration in Australia, both
for supergene and bedrock-hosted mineral deposits. In addition,
there may be applications in environmental, geotechnical and other
geoscientific areas.
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