Komatiites Kaapvaal Craton

FIGURE 3.25 The secular cooling curve for the potential temperature of the Earth s mantle (from Richter, 1988) and calculated upper mantle potential temperatures based on basalt chemistry (Abbott et al., 1994 - shaded field). Also shown are the potential temperatures for komatiites from Barberton Greenstone Belt (Barb) and the Belingwe Greenstone Belt (Bel), estimated komatiite temperatures from Grove and Parman (2004) and the calculated temperature of the subcontinental lithosphere from beneath the Kaapvaal Craton (Richardson et al., 1984). 

Wilson, A.H., 2003. A new class of silica enriched, highly depleted komatiites in the southern Kaapvaal Craton, South Africa. Precambrian Res., 127, 125-41. 

Condie ICC. and Crow C., 1990, Early Precambrian within-plate basalts from the Kaapvaal craton in southern Africa a case for contaminated komatiites. J. Geol, 98, 100-107. Condie K.C., Wilks M., Rosen D.M. and Zlobin VX., 1991, Geochemistry of metasediments om the Precambrian Hapschan series, eastern Anabar Slueld, Siberia. Free. Res., SO, 37-47. 

Some of the oldest preserved oceanic plateau sequences are those found in —3.5 Ga Barberton and Pietersberg belts of the Kaapvaal Shield of southern Africa (De Wit et aL, 1987 Smith and Erlank, 1982). These belts contain pillow basalts and komatiites, with chemical signatures (Lahaye et aL, 1995) suggesting a likely origin as part of an oceanic plateau. The Pilbara craton of Australia appears to possess some of the oldest oceanic plateau material so far identified (Green et aL, 2000) in the —3.5 Ga Coonterunah and Warrawoona Groups. 

---