Search CRC LEME :

powered by FreeFind

Publication Policy

Open File Report Series

OFRS Index


Regolith Maps

Annual Reports

Articles & Papers


Minerals Briefs

"Focus on Salt"

Other LEME Reports

Order Form

Open File Report 109

Eastern Goldfields Field Excursion Field Guide

Butt, C.R.M., Smith, R.E., Dell, M., Anand, R.R.,Lintern, M.J., Gray, D.J., Vinar, J., Bristow, A.P.J., Churchward, H.M., Varga, Z.S. and Wildman J.E.

AMIRA Project 409, Geochemical exploration in areas of transported overburden, Yilgarn Craton and environs, has, as its principal objective, the development of geochemical exploration methods for areas having a substantial cover of surficial sediments, through investigations of the processes of geochemical dispersion from concealed mineralization. An important aspect of the project is to translate research findings into practical outcomes. Field excursions have a significant role in this process, for they permit geologists and geochemists from the research group and the supporting companies to examine key sites together. This interaction promotes a much freer exchange of ideas than is possible during, for example, the formal atmosphere of seminars. The project has several important research sites and districts across the Yilgarn Craton. It is impractical to visit all of these in one excursion. The excursion in August 1995 examined sites in the Murchison and adjacent areas, including Mt Gibson, Mt Magnet, Baxter and Fender, having a variety of different types of transported overburden. Each is characterized by the development of red-brown hardpan in the surface horizons but, except at Mt Gibson, Pedogenic carbonates are rare or absent. This second excursion is to the Eastern Goldfields region and again provides an opportunity to examine a range of different overburden types and offers a comparison between areas having a strong development of pedogenic carbonates, south of the Menzies line, and those having red-brown hardpans, to the north.

The first visit is to the Kanowna Belle gold mine. This has not, in fact, been studied during this project, but it was an important site for AMIRA Project 240A, Yilgarn Lateritic Environments. It serves as an excellent introduction to many of the important features of the regolith of the Kalgoorlie region and to the usefulness of surface soil sampling in areas of shallow transported cover, including the use of pedogenic carbonates as sample media. The excursion then visits two areas within which the effectiveness of surface sampling has been investigated where mineralization concealed by deeper sediments, in both cases associated with palaeochannels. Steinway and Greenback have supergene mineralization within and beneath 15-25 m of oxidizing sediments. There is a surface anomaly at Steinway, whereas there is none at Greenback, although mineralization is shallower and has been mined. The anomaly at Steinway is now considered possibly coincidental, a result of natural contamination - a common and potentially misleading feature of the region. Argo and Apollo are concealed beneath reducing lake sediments and channel sediments. Although Au is again concentrated in the calcareous horizons of the soils, there is no surface anomaly. Partial extraction analyses appear to be ineffective in defining anomalies in either the Steinway or Argo-Apollo areas.

On the second day, the excursion visits the Safari prospect at Mt Celia, and Golden Delicious, on or north of the Menzies line. Carbonates are present at both sites, though commonly deeper in the regolith (below 2-5 m) than the pedogenic carbonates further south. Selective sampling of carbonates appears to give a good response at Mt Celia, where the cover is shallow (mostly <10 m) and, for the most part, overlies truncated profiles. At Golden Delicious, about 17 m of sediments overlie residual profiles truncated to approximately the mottled zone. There is no geochemical expression of the mineralization in the sediments, but dispersion along the unconformity gives a widespread anomaly, particularly associated with ferruginous nodules and mottles.

Near Laverton, the South Lancefield, Telegraph and Beasley Creek pits have Permian boulder clays exposed in the walls. These have not been examined for their geochemical response, although some results from the dispersion study at Beasley Creek, carried out during AMIRA Projects 240 (Laterite Geochemistry) and 241 (Weathering Processes) are given in this guide. The excursion then travels to Bronzewing, to examine sites where essentially complete profiles are preserved, with lateritic residuum close to the surface (Laterite pit) or buried beneath alluvium and colluvium that includes lateritic debris (Central pit). A similar situation is present at North Pit, Lawlers, the last stop, where lateritic duricrust is buried by 20 m of sediments.

The authors of the articles in the guide wish to thank Colin Steel and Angelo Vartesi for drafting the diagrams, and Gill Ashton for preparing and compiling the final manuscript. Gill Ashton also assisted with much of the organization of the excursion. We are also grateful to Kanowna Belle Gold Mines, Newcrest, St Ives Gold Mines, RGC Exploration, Acacia Resources Ltd., Metex Resources Ltd., Great Central Mines and Plutonic Resources for permitting access to their mines and exploration properties.

Last updated: Sunday, August 05, 2001 14:06:32


Cooperative Research Centres Australia

About Us | News & Events | Research
Publications | Education | Staff Only | Links

Contact Us | Disclaimer | Sitemap
© CRC LEME 2004

CRC LEME is established and supported under the Australian Government's Cooperative Research Centres Program. The CRC Program is an Australian Government initiative which brings together research groups with common interests.

CRC LEME Core Parties