Author name: Martin Reich

Supergene metal deposits host a comprehensive record of climate-driven geochemical reactions that may span the entire Cenozoic. Products of these reactions can be dated by a variety of radiogenic isotopic methods, such as 40Ar/39Ar, (U–Th)/He, U–Pb, and U-series. The frequency of mineral precipitation, determined by dating a representative number of samples of a particular mineral collected from distinct parts of the supergene ore body, refl ects times in the geological past when weathering conditions were conducive to water–rock interaction. The frequency of mineral precipitation through time permits identifying periods in the geological past when climatic conditions were most conducive to chemical weathering and supergene ore genesis.

Supergene metal deposits form when common rock types or deeply buried primary ore bodies are exposed at or near the Earth’s surface and undergo oxidation, dissolution and reconcentration of the metals. Supergene metal deposits are economically interesting because of their accessibility for extraction and increased grades. Scientifically they are attractive because of their mineralogical diversity and what they reveal about surficial history. Apart from supplying mankind’s need for metals, supergene metal deposits provide clues about our past climate and offer an unparalleled opportunity to explore the long-term corrosion behavior of natural and man-made materials and their environmental impact.