The seaway south of South Africa represents a critical gateway within the global circulation. Here, warm surface and cold deep and bottom water masses meet and lead to a transfer of heat and salt between the Indian and Atlantic Oceans. This transfer maintains the global thermohaline circulation. The paths of the oceanic currents are strongly influenced by the seafloor topography observed in this region. Thus, the tectonic evolution of the South African continental margin and the gateway starting in Cretaceous times are of major importance in order to understand the evolution of the current system and the transition from the Greenhouse to the Icehouse world.The gateway itself is characterized by the Agulhas Plateau, which has been postulated to originate in the interaction of the Bouvet Hotspot and a triple junction and thus to fall within the world-wide suite of Large Igneous Provinces [Gohl and Uenzelmann-Neben, 2001; Parsiegla, et al., 2008; Uenzelmann-Neben, et al., 1999]. A similar structure has been identified for the crust of the southern Mozambique Ridge [Gohl, et al., 2008]. This rises the question whether those two LIP events were related, their emplacement happened at the same time and how they tie in with other LIP events observed in Late Cretaceous times such as the formation or the Kerguelen LIP. Furthermore, we may speculate on the effect those magmatic events had on the evolution of both oceanic currents and the climate.Similarities as well as differences in crustal structure and evolution and later sedimentary development will be presented for those two structures based on seismic refraction and reflection data. References:Gohl, and G. Uenzelmann-Neben (2001), The crustal role of the Agulhas Plateau, southwest Indian Ocean: Evidence from seismic profiling, Geophysical Journal International, 144, 632-646.Gohl, K., et al. (2008), Is the Mozambique Ridge related to the Agulhas Plateau Large Igneous Province?, Geophysical Research Letters.Parsiegla, N., et al. (2008), The Agulhas Plateau: Structure and evolution of a Large Igneous Province, Geochemistry Journal International, 174, 336-350.Uenzelmann-Neben, G., et al. (1999), Agulhas Plateau, SW Indian Ocean: New evidence for extensive volcanism, Geophysical Research Letters, 26, 1941-1944.
Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 3: Lessons from the Past > WP 3.2: Tectonic, Climate and Biosphere Development from Greenhouse to Icehouse