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 35

Exploration geochemistry about the Mt Gibson Gold Deposits, Western Australia. Progress to 31st March 1989

Anand, R.R., Smith, R.E., Innes, J. and Churchward, H.M.

A regolith, landform, and geochemical orientation study about the S, C, and N lateritic Au deposits at Mt Gibson clarifies landscape evolution and geochemical dispersion in terms of the dynamics of formation, preservation, and dismantling of the undulating lateritic weathering mantle.

The relatively complex regolith and vegetation patterns are explained in terms of the distribution of (i) sub-areas of erosion of the lateritic mantle to the level of saprolite, (ii) sub-areas of essentially-complete lateritic mantle, and (iii) sub-areas characterized by depositional accumulation of detritus provided by the dismantling of the lateritic mantle up-slope, commonly burying the essentially complete laterite weathering profile in the local foot slopes and lowlands.

The regolith units were mapped over the central 3 km by 5 km area, the regolith stratigraphy established, and units of the upper regolith were characterized in field profiles petrographically, mineralogically, and chemically. An idealized regolith-landform facies model has been erected for use in predictions in appropriate terrain, and for planning and integrating follow-up research. Geochemical analyses of samples of the loose pisolitic, nodular laterite unit collected systematically both from surface and from pit walls, where the unit occurred sub-surface, document the characteristics of the lateritic Au deposits. These and earlier results of the orientation study show that the lateritic Au ore, and the area peripheral to it, is a multi-element, chalcophile, geochemical anomaly, measuring 1-1.5 km across and greater than 4 km in length, with a Au, Ag, Pb, As, Bi, Sb, W association.

Within the loose lateritic unit, and in the underlying duricrust, coincident highs of several of these elements in centres within the overall anomaly suggested a close genetic link with bedrock sources, now verified by occurrences of gold-bearing quartz-hematite veining in saprolitic bedrock revealed by exploration and mining.

Geochemical results of 37 samples of the underlying lateritic duricrust show similar strengths and associations of elements as seen for the unit consisting of loose lateritic pisoliths and nodules. Close comparisons of the geometry of the dispersion patterns of these two closely related regolith units await the result of current research on more extensive sampling of the duricrust.

Last updated: Thursday, January 06, 2000 08:10 AM


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