16 AFRICA/North African Phanerozoic Figure Hercynian compression as result of a Late Carboniferous plate collision between Laurasia and Gondwana (After Doblas et al (1998).) Figure Block diagrams illustrating the geological evolution of the High Atlas, including Triassic Jurassic rifting, Cretaceous and Cenozoic inversion (After Stets and Wurster (1981).) Pangaean Supercontinent by insulation and blanketing processes which triggered large-scale mantle-wide upward convection and general instability of the supercontinent Mesozoic Extension The opening of the Central Atlantic in the Triassic– Early Jurassic and contemporaneous separation of the Turkish–Apulian Terrane from north-east Africa initiated a significant extensional phase in North Africa which included graben formation in the Atlas region (Figure 5), rifting from Syria to Cyrenaica (NE Libya) and extension in offshore Libya and in the Oued Mya and Ghadames (¼Berkine) basins in central and eastern Algeria Rift-related Triassic volcanism occured in the northern Ghadames and Oued Maya basins A second important Mesozoic extensional phase in North Africa occurred during the Early Cretaceous, related to the opening of the South and Equatorial Atlantic Ocean As a result, a complex of failed rift systems originated across North and Central Africa with the formation of half-grabens in, for example, the Egyptian Abu Gharadig Basin and in the Libyan Sirte Basin The Mesozoic extensional phase also triggered increased subsidence in several Saharan Palaeozoic basins, leading to deposition of thick, continental