oregenesis

Ore genesis is the study of how and where economically valuable mineral deposits form. It encompasses the physical and chemical processes that concentrate metals into ore bodies, and the geological settings in which these processes operate. Ore genesis links the source of metals, the transport medium, and the depositional environment to the final ore.

Most ore-forming systems are driven by tectonic and magmatic activity. They are commonly grouped into magmatic, magmatic-hydrothermal, hydrothermal, sedimentary, and supergene or metasomatic categories. Magmatic processes concentrate metals during the differentiation of crustal or mantle magmas, or through the segregation of sulfide-rich liquid. Magmatic-hydrothermal and hydrothermal systems involve hot fluids that transfer metals from a magmatic source and then deposit them as sulfide, oxide, or gangue minerals when chemistry changes, pressure drops, or temperatures fall. Sedimentary deposits form when metals are concentrated by chemical or mechanical processes in sediments or sedimentary basins, examples include SEDEX and stratiform deposits, while placer deposits accumulate dense minerals by gravity in rivers and shorelines. Metasomatic and metamorphic processes can rework existing rocks to concentrate metals during crustal deformation.

Signatures of ore genesis include mineral assemblages, isotopic ratios, and fluid inclusions that reveal sources, temperatures, and depths. Understanding ore genesis informs exploration strategies and ore-body distribution models, helping predict the location and nature of undiscovered deposits. Typical target commodities include copper, gold, lead, zinc, iron, tin, nickel, and platinum-group elements, often in association with distinctive ore- and fluid-geochemical signatures.