Conspicuous seismic reflections in Upper Cretaceous sediments as evidence for black shales off South Africa

• Main Authors: Uenzelmann-Neben, Gabriele, Schlüter, Philip
• Format: Conference Object
• Language: unknown
• Published: 2009
• Subjects: South Atlantic Ocean
• Online Access: https://epic.awi.de/id/eprint/20921/; https://hdl.handle.net/10013/epic.33224

The late Cretaceous is commonly associated with greenhouse climate, which comes along with worldwide occurring, so called Oceanic Anoxic Events (OAE), and the ongoing break up of the Gondwana super-continent. Especially the opening of the South Atlantic Ocean and the beginning closure of the Tethys initiated strong variations of the ocean's currents flow paths and lead to a rapid climate change. Only little is known about these changing conditions and OAE appearances, in particular south of South Africa, at that time. A set of high resolution seismic reflection data from the submarine Transkei Basin south of South Africa shows various depositional stages for this area since the late Cretaceous. In these seismic sections, a recurrently appearing very high amplitude horizon within rather weak to homogeneous Upper Cretaceous reflections was observed. This reflector could roughly be dated to a time between ~ 80 Ma - ~ 85 Ma, which falls within the last documented big OAE 3 in the Upper Cretaceous. According to the appearance and reflection characteristics of this conspicuous reflector as well as its time/depth information, it could be the first report of black shales in a deep- sea basin within this region. Moreover, associated with the black shales, it could be the first evidence of an OAE south of South Africa.