Intraplate stable continental interior (Archean to Proterozoic, 4.0–1.0 Ga)
typical scale
Hundreds to thousands of kilometers across; lithospheric keel 200–350+ km thick
characteristic lithology
Granite-greenstone terrains, tonalite-trondhjemite-granodiorite (TTG) gneiss, and depleted harzburgite roots
examples
Laurentia (North American), Kaapvaal, Pilbara, Yilgarn, Baltic, and Amazonian Cratons
Core Principles & Analysis
Named from the Greek kratos ('strength'), cratons are the ancient Precambrian cores of continents, consisting of exposed crystalline basement rock (continental shields) and surrounding areas covered by flat-lying sedimentary strata (platforms).
As proposed by Thomas H. Jordan in 1978, cratons survive for billions of years without subducting because extreme Archean melt extraction left a dry, magnesium-rich, iron-depleted peridotite mantle root (200–350 km deep) whose low chemical density offsets thermal contraction.
The cold, thick lithospheric keels beneath Archean cratons cross the diamond stability field below ~150 km depth, serving as the source region from which kimberlite pipes transport natural diamonds to the surface.