El 10 de Septiembre 2008
Some melting of enriched lithospheric mantle (SCLM) may also produce alkaline magmas (Menzies, 1987), particulariy in cratonal areas and along the margins of the area affected by the asthenospheric diapir. This may explain the trend toward more alkalinity away from the rift axis, but the role of the lithospheric source is far from clear. Kampunzu and Mohr (1991) suggested that the ultra-alkaline activity is typically located on transverse structural zones, especially south of the equator. Macdonaid et al. (1994) proposed that the ultra-alkaline carbonatite-nephelinite-kimberlite series is restricted in the Cenozoic to areas of cratonal crust (the Tanzanian Craton), whereas mainly alkaline basalt-trachyte dominates in areas of thinned crust north of the craton.
