Metallogeny is the study of the genesis of mineral deposits, with emphasis on their relationship in space and time to regional petrographic and tectonic features of the Earth’s crust. The term has been used for both metallic and nonmetallic mineral deposits.
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Research has indicated that there is variation in the distribution of mineral deposits within the crust of Earth. Rather, some deposit types are more likely to be abundant in particular locations. Metallogenic provinces are large regions or belts with considerable dimensions marked by a notable concentration of deposits of specific mineral resources, such as gold, iron, or copper.
It’s important to note that not all deposits in a province are formed at the same time. There are certain periods in the geological past (Metallogenic epochs) in which specific mineral resources are deposited. Rock formations of these periods are important for the exploration of such minerals.
Metallogenic Epocs
Metallogenic epochs are units of geologic time during which favourable conditions existed, resulting in a significant concentration of resources of one metal formed in one or more provinces.
Geologists have identified various metallogenic epochs throughout geological time. These are few Metallogenic Epocs with notable mineralisation.
Archean Metallogenic Epoc:
- Chromite
- PGM
- Cu- Fe – Ni
- Au
- Some VMS
Proterozoic Metallogenic Epoc:
- Placer Au & U deposits
- PGM
- Chromite
- BIF
- Fe – Ti oxides with anorthosite massifs.
- Diamonds in kimberlites?
- Sediment hosted Cu
Phanerozoic Metallogenic Epoc:
- Phosphorites: Proterozoic – Cambrian boundary
- Podiform (Alpine type) chromite
- Coal: Carboniferous
- PCD’s (Mesozoic)
- Residual (Cretaceous – Recent).
Metallogenic Province
Metallogenic province is an area characterized by a particular assemblage of mineral deposits, or by one or more characteristic types of mineralization. A metallogenic province may have had more than one episode of mineralization, or metallogenic epoch.
These mineral deposit groupings emerge because deposit-forming processes, such as magma body emplacement and sedimentary basin development, are controlled by regional processes that affect the Earth’s surface.
Plate tectonics controls, directly or indirectly, the shape and location of features like continents and oceans, volcanoes, sedimentary basins, and mountain ranges. For example, Plate tectonics controls the distribution of hydrothermal mineral deposits formed because of volcanism, as the majority of volcanism occurs along plate margins.
Porphyry copper deposits are generated because of volcanism along a subduction zone; this gives rise to metallogenic provinces parallel to subduction plate margins.
Similar to metallogenic provinces, geologists have identified various metallogenic provinces which were favorable geological sites for deposition of particular mineral or mineral assemblages. For example, few of such metallogenic provinces are –
Cordilleran Metallogenic Province:
- Deposit Types: Copper, gold, silver, and porphyry deposits.
- Geological Features: Subduction zones, volcanic arcs, and associated tectonic activity.
Siberian Metallogenic Province, Siberia, Russia:
- Deposit Types: Nickel, platinum-group elements (PGE), and copper deposits.
- Geological Features: Associated with large igneous provinces and layered intrusions.
Bushveld Complex, South Africa:
- Deposit Types: Platinum, palladium, and chrome deposits.
- Geological Features: Layered mafic to ultramafic intrusions.
Peru-Chile Metallogenic Province, Western South America:
- Deposit Types: Copper, gold, and silver deposits.
- Geological Features: Result of subduction-related tectonic processes along the Andean convergent boundary.
Greenland-Iceland-Faeroe Province (GIFP):
- Deposit Types: Rare Earth Elements (REEs), Tantalum (Ta), Niobium (Nb).
- Geological Features: Associated with alkaline magmatism and carbonatite complexes.
Kambalda Nickel Belt, Western Australia:
- Deposit Types: Nickel sulfide deposits.
- Geological Features: Archean greenstone belts and komatiitic lava flows.
Carlin Trend, Nevada, USA:
- Deposit Types: Carlin-type gold deposits.
- Geological Features: Sedimentary rocks, often associated with fault zones and intrusive rocks.
