Construction and destruction of cratons

Archean (> 2.5 Ga) and Proterozoic cratons on the globe preserve important records of the formation and long-term evolution of continents. Cratons are devoid of recent seismic and volcanic activity and as such are characterized by thick crust (ca. 50 km) and refractory lithospheric mantle (ca. 150 km), a cold geotherm, low density and high viscosity. However, recent works demonstrate that cratons may not be always so stable. The cratonic lithosphere in some regions has been severely disturbed or reactivated in post-Archean times, resulting in significant loss or modification to the refractory lithospheric “root”. Examples come from the North China Craton (NCC) in East Asia (e.g., [Menzies et al., 1993], [Menzies et al., 2007], [Griffin et al., 1998], [Zhang et al., 2002], [Zhang et al., 2012] and [Santosh, 2010]), the southwestern part of the Kaapvaal Craton in South Africa (Kobussen et al., 2008), the Wyoming Craton in North America (Carlson et al., 1999), and the Brazil Craton in South America (Beck and Zandt, 2002), etc. Among these, the eastern part of the NCC is considered as one of the best examples for wholesale destruction of a cratonic root (e.g., [Carlson et al., 2004] and [Zhu et al., 2011]). This region is presently underlain by a thin (< 80 km), hot (~ 65 mW/m2) and fertile lithosphere which is in striking contrast to the thick (> 200 km), cold (~ 40 mW/m2) and refractory lithosphere sampled by Paleozoic xenolith-bearing diamondiferous kimberlites. A lithosphere transformation model through the interaction between the remaining lithospheric mantle peridotite and diverse origin melts was proposed to interpret the mantle compositional change from the thinned Paleozoic refractory to the Cenozoic fertile mantle (Zhang et al., 2002).