Transkei Basin, southwestern Indian Ocean: Bright spots as an indication for a restricted circulation

• Main Author: Uenzelmann-Neben, Gabriele
• Format: Conference Object
• Language: unknown
• Published: 2013
• Subjects: Indian; Weddell; Weddell Sea
• Online Access: https://epic.awi.de/id/eprint/32666/; https://hdl.handle.net/10013/epic.41229

During the break-up of Gondwana and the development of smaller crustal blocks several isolated basins were formed repeatedly. This led to a restricted exchange of water masses between the Tethys and these basins as well as the evolving South Atlantic and Weddell Sea. Anoxic conditions resulted in the deposition of black shales as observed in the Transkei Basin and the northern Mozambique Basin. Later tectonic movements allowed the formation of traps and pathways for fluids, which have been formed in conjunction with the black shales and high sedimentation rates proximal to the continent. The release of these fluids has been related to earthquakes as the initiator and slumps (e.g. the Agulhas Slump) and slides as an effect. The Transkei Basin, located between two Large Igneous Provinces (LIP, Agulhas Plateau and Mozambique Ridge) was formed during the Cretaceous magnetic quiet zone so the exact formation age is unclear. I propose to drill the Transkei Basin to recover complete sedimentary and basement volcanic rock sequences. The sediments preserved in this basin record an at least 100 m.y. history of the most extreme climates of the past 200 Ma, global anoxia, perturbation of geochemical cycles and major changes in marine biota. The overall goal is a quantitative characterisation and understanding of biogeochemical cycles and marine ecosystem reactions to environmental and climate changes at the onset, during and after major greenhouse episodes. I suggest to determine the age of the basin formation, it’s relation to the neighboured LIPs, the nature and age of the bright spots interpreted as black shales, and determine the spatial and temporal variability of the lysocline-CCD and OMZ.