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 53

The distribution of gold and other elements in soils at the Granny Smith Gold Deposit, Western Australia

Lintern, M.J. and Butt, C.R.M.

The distribution of Au and other elements was examined at the Granny Smith Au deposit, south of Laverton. The area is extensively covered by hardpan, which is particularly common in the northern part of the Yilgarn Craton and inland Australia. Five profiles were studied, some to 10 m depth, for textural, geochemical and mineralogical characteristics pertaining to the distribution of Au and other elements. Laboratory studies were performed to examine the nature and behaviour of Au in the soil. Selected bedrock samples were analysed for trace elements in order to determine their potential as pathfinders for Au mineralization. This study was to complement work previously performed south of the Menzies Line where a strong association was found between pedogenic carbonate and Au.

The distribution of Au at Granny Smith appears to be primarily related to the contact between transported and residual components of the hardpan and is coincident with a trend towards increasingly alkaline conditions. South of the Menzies Line, such a change of pH has no significant effect on the distribution of Au. Segregations of hardpan material from contact between the transported and residual components indicates that the matrix does not necessarily contain all the Au because some is associated with lithorelic fragments cemented within the matrix. Furthermore, there does not appear to be any general mineralogical, geochemical or textural associations of Au with other components within the profiles, although these do exist within individual profiles. Laboratory experiments indicate that some Au is associated with specific extractable phases within the soil e.g., manganese oxides, organic material and soluble silica but, compared with Au that can be leached using water or iodide alone, they do not represent a highly significant fraction. Gold is generally found to be at least as soluble in water and iodide as in some soils south of the Menzies Line, but mobility in the surficial environment appears to be severely restricted due to encapsulation within the hardpan cement. Re-adsorption of dissolved Au by hardpan is possible, but is weaker than that occurring with ferruginous soils in the south.

Arsenic, W. Mo and, perhaps, Sb are associated with primary mineralization, but only As is retained at detectable concentrations in the upper regolith. Barium, Cu and Zn are weakly enriched in bedrock and are retained in the upper saprolite; however, Ba may also indicate the presence of felsic rocks, such as granodiorite, rather than mineralization. The generally low abundances of Bi, Cd, In, Pb, Se and Ag in primary mineralization eliminate them as potential pathfinder elements.

The work highlights the problems associated with exploration for Au in areas dominated by hardpan. Further studies and examples are required before any recommendations on specific sampling procedures can be made.

Last updated: Thursday, January 06, 2000 08:59 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