Final Reports (Stage One Projects)
Project F1-2: Fluid processes and geochemical modelling
Introduction
This project was set up to demonstrate how geochemistry is able add-value to exploration. The project has produced improved total system ore genesis models, a comprehensive up-to-date database and associated software tools for hydrothermal geochemistry modelling.
High Impact Outcomes
The project has produced tools that:
- Predict the processes that led to formation of certain mineral deposits.
- Predict possible alteration assemblages and mineral paragenesis.
- Understand which are the most important or effective processes in mineral deposit formation.
- Is positioned to build computer models of mineral deposit formation
Companies should now be able to routinely using these techniques to lower exploration risk, reduce expenditure, and shorten times towards discovery. However implementation of the techniques require improved on-site and other training, semi-automated conversion of model results into 3D datasets and models, and persistent interchange between researchers and explorers.
Research Summary
Geochemical modeling is directed towards solution of the patterns and vectors indicated in the schematic figure. The purpose is to be able to take existing or new geochemical, petrographical and/or fluid inclusion datasets and identify fluid pathways of interest.
The geochemical modeling approach is a new way to systematically test alternative models, without prejudice. For example, the long-standing model for genesis of Archean lode gold deposits involves, in essence, regional metamorphism releasing basalt-equilibrated fluids into focused shear zones. This and other models are used to identify the location of gold precipitation.
A relatively time-consuming and somewhat expensive method to determine whether granitoids are important for gold or not is to embark on a comprehensive geochronological program. A much simpler test is to construct geochemical models within which granites are important, or not, and see if the outcomes match the known distribution of mineral assemblages.
Some examples of the modelling by pmd*CRC
Figure 11 (see Final Report). We have calculated the mineral assemblages and extracted out those minerals which may have a definable geophysical signal. The horizontal lines might represent the zoning one would observe at progressively higher crustal levels (T on left axis). Predicted geophysical signals could be calculated (see below).
An exciting development has been in the area of predicted aeromagnetics, gravity, radiometrics, electrical response and PIMA response arising from geochemical simulations. Other work by pmd *CRC is developing the processes needed to be able to incorporate geochemical model results into predictive geophysical models and inversions.
Figure 12: Following on from the model above, we have developed at least a conceptual modeling protocol whereby we can determine semi-quantitative or qualitative (as in this case) geophysical responses to the modeled outflow scenarios. The challenge now is to routinely incorporate such outputs into the model results and test them against real datasets.
Summary of Research outcomes
A unified thermodynamic database is being used in several modeling packages (HCh, GWB, Fastflo), that will ensure stability and a high degree of communication and collaboration in the future.
The modeling techniques are now much more utilitarian and portable.
We have demonstrated the power of the modeling in several ore deposit types, the best results being generated in modeling of greenschist-facies lode gold systems.
The number of people using the software has improved throughout the life of the CRC.
There is now an immense opportunity for industry to use these techniques in routine and novel exploration programs. There are great opportunities remaining in attempting to fuse geochemical model outputs with predictive geophysical signals. There are opportunities, currently being explored, in the area of fusion of geochemical with geomechanical modeling.
List of Partners & Sponsors
The Partners
- James Cook University
- Geoscience Australia
- CSIRO EM
- Monash University
- University of Western Australia
Along with collaboration with
- University of Tasmania
- University of Adelaide/Museum of Sth Australia
- Ed Mikuki & Associates
- Doug Mason & Associates
- Moscow State University
The project gratefully acknowledges the input from sponsor companies including:
- AngloGold Ashanti
- Placer Dome Asia Pacific (now Barrick)
* Please not that references and appendices are not published in this Final Report Summary. These can be found in the Final Report and available via the links below.
Full Report 
30.8Mb
Appendices
- Annual Review, Canberra 2002
- Annual Review, Perth 2003
- General Presentations
- Yilgarn PDT Delivery Workshop December 2004
- Mt Isa PDT Delivery Workshop March 2005
- Courses
For Further Information Contact
Project Leader
James Cleverley
CSIRO EM
Tel: 08 64368714
Email: james.cleverley@csiro.au
