Geochemical blocks for predicting large ore deposits—concept and methodology

Abstract Regional geochemical data for 39 elements from several millions of stream sediment samples were obtained in China's national geochemical mapping program. This program was carried out over a 24-year period and covered more than 6 million km 2 of China. By examining this large data set, broad geochemical patterns other than dispersion halos and dispersion trains can be discerned. These broad geochemical patterns, such as geochemical regions, geochemical provinces, geochemical megaprovinces and geochemical domains, are the surface expressions of large blocks of rock with higher metal contents. These large “geochemical blocks” are the net results of the earth's original heterogeneity and the distribution and redistribution of metals during the evolution of earth. Large geochemical blocks will provide large metal endowments necessary for the formation of large to giant ore deposits. The geochemical block concept has the capacity to change mineral exploration strategy and methodology in China, providing a powerful tool for global mineral potential assessment and inspiring new ideas for exploration geochemistry, ore-genesis and metallogeny.