Crustal evolution in north-east and east Africa from model Nd ages

摘要: The relationships between the various crustal provinces that comprise north-east and east Africa are far from clear reflect diverse tectonic magmatic processes which took place during Proterozoic. Here we present results of an Nd isotope study on major rock units Pan-African (1,100–500 Myr BP) terrane. Charnockites Jabel Uweinat, a basement inlier at junction Egypt, Libya Sudan, yield middle Archaean model ages, whilst ages <1,200 have been obtained in belt Eastern Desert Egypt to north-west Kenya. This, therefore, represents westward extension juvenile crust Arabian Shield (Fig. 1). shield itself is characterized by comparatively rapid growth1, probably accreting island arc environment2. Between two areas, there marginal zone rocks with relatively low ɛNd(T) values (see Table 1) due increased contributions pre-Pan African crust. Overall, those Damara Namibia3 exhibit wide range +7.5 −18.0 reflects regional changes style not readily reconciled simple models for evolution average continental