Craton

Extended crust}}

A craton (kratos; Greek for strength) is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. Cratons are generally found in the interiors of continents and are formed of a crust of lightweight felsic igneous rock such as granite attached to a section of the upper mantle. A craton may extend to depth of 200 km.

Cratons are subdivided geographically into geologic provinces, each province being classified as an Archon, a Proton or a Tecton according to its age:

Archons: consist of rocks from the Archaean era, older than 2.5 billion years (2.5 Ga).
Protons: consist of rocks from the early to middle Proterozoic era, older than 1.6 Ga.
Tectons: consist of rocks from the late Proterozoic era, with ages between 1.6 Ga and 800 million years (800 Ma).

As minerals (such as precious metals and diamonds) in the Earth's crust tend to become separated with time, the oldest cratons are of the greatest interest to mining companies. Cratons are still being discovered as prospectors search the globe.

Named cratons, listed by continent, include:

Australia
*Altjawarra craton
*Central craton
*Curnamona craton, South Australia
*Gawler craton, central South Australia
*Pilbara craton, Western Australia
*Yilgarn craton, Western Australia

Americas

North American cratons and basement rocks.