Gold distribution in the Earth’s crust
Gold is a chemical element of huge economic value but our understanding of its distribution in the Earth’s crust and mantle is poor. One of the reasons for this is that the gold concentration is very low in crustal rocks, and the element is therefore difficult to analyse for. Recent work using analytical methods with ultra-low detection limits show that gold is very heterogeneously distributed in the crust and concentrations in sedimentary, metamorphic and volcanic rocks vary from 0.01 to 30 ppb (Pitcairn et al., 2006a, 2006b). Complete characterisation of the distribution and heterogeneity of gold in the Earths crust and mantle has been limited by use of methodologies with very high detection limits too close to the concentration of gold in the samples being analysed. This project uses an ultra-low level method for gold analysis set up at IGV, Stockholm University to analyse large suites of different rock types in order to better constrain the concentration of gold in the crust and mantle. This project would provide a more accurate composition of the Earth’s crust, insight into the cycling of gold between crust and mantle reservoirs, and would provide a new database of background gold concentrations.
Pitcairn, I.K., Teagle, D.A.H., Craw, D., Olivo, G.R., Kerrich, R., Brewer, T.S. (2006a) Sources of metals in orogenic gold deposits: insights from the Otago and Alpine Schists, New Zealand. Economic Geology, v. 101, p. 1525–1546
Pitcairn, I.K., Warwick, P.E., Milton, J.A., Teagle, D.A.H. (2006b) A method for ultra-low level analysis of gold in rocks: Analytical Chemistry, v. 78 (4), p. 1280–1285