Project M4, M9 and F6 Final Report Enabling Technologies

This report is a synopsis of research compiled and carried out within the Predictive Mineral Discovery CRC F3 project "Micrometallogeny of hydrothermal fluids". The F3 project's original objectives were: (1) Geology-driven terrain and ore fluids investigations to evaluate the chemistry and fluid processes within mineral systems in order to extend the focus of fluid studies beyond direct ore deposit analysis. (2) LAICPMS and PIXE technique and methodology development were techniques utilized throughout the project and methodologies were developed for their combined application. (3) Diamond-cell autoclave experiments component of the project was a scoping-collaboration in year one of F3 with the Museum of South Australia. (4) Database development and fusion with numerical modelling resulted in development of a web-based database for fluid inclusion research has been successful and is currently accessed at http://www.ga.gov.au/minerals/research/methodology/geofluids/flincs_about.jsp

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.

The principal objective of the H4 Project was to evaluate existing techniques and develop new enabling technologies in geochronology and isotope geoscience to significantly improve our ability to constrain the timing of ore formation and, therefore, expand predictive capabilities. A fundamental goal was the evaluation of existing dating methods and interpretations, particularly with respect to gold deposits in low grade terrains, and to investigate potential new dating methods such as 40Ar/39Ar laser probe analyses of mica-bearing pyrite linked to gold mineralisation. A second major goal of the H4 project was to initiate development of halogen/noble gas geochemistry technology and expertise within the pmd *CRC to enable this unique geochemical method to be applied to ore deposits in the flagship terrains in the second stage programme of pmd *CRC.

Western Victoria is host to several world class sediment-hosted gold deposits (e.g. Stawell, Ballarat, Bendigo) that have been studied on an individual basis, generally without reference to a well-constrained regional structural and stratigraphic framework. The configuration and availability of fluid conduits (shear zones or other structural settings and appropriate host lithologies) over time is clearly an important factor in the formation of these mineral deposits but the distribution and profiles of fluid pathways with increasing crustal depth are often imprecisely known. It is also probable that the mineralising fluids were not locally sourced, but travelled long distances from their point of origin, making it imperative that all potential fluid conduits be mapped in 3D so that any sub-surface linkages or networks of fluid pathways be identified. These pathways then need to be incorporated into the 3D regional framework so that the key conduits and structures can be further investigated to establish their precise role in either controlling or sustaining fluid flow over geological time scales appropriate for the formation of a major ore-body. The Stawell Zone in western Victoria is ideally placed for such a case study because it contains sequences that relate to the mineralisation types found in Tasmania and those identified in central Victoria and NSW.

The project initially focused on the St. Ives gold camp with additional studies on the Golden Mile and selected areas in the Kalgoorlie-Kambalda corridor. Additional resources were provided by St. Ives Gold Company Pty Ltd and Placer Dome to support researchers on-site at St. Ives, Kanowna Belle and Wallaby. These resources are managed through MERIWA project M358 and selected results of this project, as well as information from the pmd *CRC Y2 project, are integrated into the Final Report.

Y3 Additional reports, St. Ives Gold camp

Scale integrated studies in the Eastern Goldfields Province: From Brownfields to Greenfields (Y3 team)

Scale integrated alteration studies at Kanowna Belle

Whole-rock and fluid chemistry for alteration mapping and fluid identification (Neumayr et al)