ReviewContrasting ore styles and their role in understanding the evolution of the Altaids

- Porphyry Cu(Au/Mo) deposits are diagnostic to compressional thickened continental crust.
- VMS deposits are diagnostic to extensional thin arc-related basins.
- Orogenic gold deposits are diagnostic to transpressional boundary.
- Coeval porphyry-type and VMS-type ore deposits occurred widely throughout the Altaids.
- Porphyry deposits outline the distribution of diverse-origin continental fragments, which is much smaller than the whole area of the Altaids.
- The ages of the orogenic gold deposits indicate that the orogenic duration is outside the time bracket of the Altaids.

The Altaids is a Paleozoic orogenic collage in central Asia. It occupies ~ 10% of the Eurasian continent, and it is one of the richest concentrations of mineral deposits in the world, comparable to those of the Circum-Pacific and Tethyan orogenic belts. In particular, it contains many types of hydrothermal ore deposits that are sensitive to the nature and origin of their host terranes, including porphyry copper (gold-molybdenum), volcanogenic massive sulfide copper-lead-zinc and orogenic gold deposits, which are all diagnostic of convergent continental margins, extensional arc-related submarine basins, and transpressional terrane boundaries. Within the Altaids, porphyry copper deposits are mostly concentrated within the Kazakhstan and Tuva-Mongolia micro-continents, where they formed almost continuously from the Early Ordovician to Permian; only a few are Cambrian and Triassic, and most are Late Carboniferous. Most volcanogenic massive sulfide ore deposits are distributed along the South Urals and Rudny Altai in the western Altaids, where they formed in a short time-window from the Early to Middle Devonian. Important orogenic gold deposits formed along regional strike-slip faults between craton, island arc or micro-continent boundaries from the Neoproterozoic to Permian, mostly in the Early Permian. In limited key areas volcanogenic massive sulfide deposits formed upon much older (> 100 Ma) basement rocks than those of coeval porphyry deposits indicating that the Altaids could not have developed from a single arc. Furthermore, the porphyry deposits outline the distribution of several continental fragments, the combined area of which is far less than that of the Altaids, which suggests that extensive new juvenile material has been added into island arc systems, which may have been accreted to surrounding continental margins. These metallogenic distributions in localized areas were a result of the mechanisms of crustal growth within the overall tectonic evolution of the Altaids, and they are consistent with the interpretation that the Altaids is a multiple subduction-accretion collage.