The Mozambique Ridge (MOZR) and the Agulhas Plateau (AP) are prominent bathymetrically elevated rises off south-eastern Africa connected by a rise of less bathymetric expression. Intuitively, this observation would imply that the plateaus and rises underwent a related crustal formation. Deep crustal ocean-bottom seismometer data and a multichannel seismic reflection profile from the southern MOZR show evidence for its predominantly oceanic crustal origin with excessive volcanic eruption and magmatic accretion phases. The lower two-thirds of the crustal column exhibit P-wave velocities of more than 7.0 km/s, increasing to 7.5-7.6 km/s at the crustal base. These velocities suggest that the lower crust was accreted by large volumes of mantle-derived material to form an over-thickened equivalent of an oceanic layer 3. When comparing the velocity-depth model and the observations of the seismic reflection data with those of the AP, a resemblance can be established which concludes that a greater Southeast African Large Igneous Province (LIP) must have formed between 140 and 95 Ma in phases of highly varying magmatic and volcanic activities. The timing, size, and formation history of the Southeast African LIP is almost analog to that of the Kerguelen-Heard Plateau, which provokes speculation about related processes of periodic magma generation at that time.
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