Geophysical study of the conjugate East African and East Antarctic margins

• Main Author: Leinweber, Volker Thor
• Format: Thesis
• Language: unknown
• Published: 2011
• Subjects: Antarc*; Antarctic; Antarctica; Cosmonauts sea; Prince Harald Coast
• Online Access: https://epic.awi.de/id/eprint/25564/; https://hdl.handle.net/10013/epic.38600

In earth’s history, large assemblies of continental masses, so-called supercontinents, occurred episodically. The last ones, Pangaea and Gondwana, broke up in Triassic to Jurassic times. The distribution of the landmasses has major influences on the climate and biosphere on earth. To have detailed knowledge about the timing and devolution of the assembling and decomposition processes of these large continents is thus important as framework for many earth-related scientific disciplines. This study deals with the movements between Africa and Antarctica in Middle Jurassic to Lower Cretaceous times. Only a thin stripe of seafloor, the Africa-Antarctica corridor, provides direct evidence of these movements. Although the kinematic history between the two continents is quite well constrained for Cenozoic times, little is known about the Jurassic processes, mainly due to the lack of data on the conjugate continental margins. New wide-angle seismic and potential field data were thus acquired on both conjugate margins during four scientific campaigns between 2006 and 2010 by AWI and co-operation partners to gather information about the age and origin of the crust in the Africa-Antarctica corridor. On both conjugate sides, aseismic plateaus exist, whose origin is unclear. The assumption of continental crust underneath the Mozambique Ridge, the Northern Natal Valley and the Mozambique Coastal Plains produces significant overlaps with Antarctica in many Gondwana reconstructions. On the conjugate margin, the Astrid Ridge is a poorly studied feature whose history is apparently related to the formation of the oldest crust in the Africa-Antarctica corridor. Aeromagnetic measurements in the southwestern Enderby Basin/Cosmonauts Sea east of the Gunnerus Ridge were conducted in 2006. The data clearly image the continent-ocean-transition offshore Prince-Harald Coast. No magnetic spreading anomalies can be seen in the data, however. The oceanic crust is thus interpreted of having formed during times of the Cretaceous Normal ...