Post-Eocene seismic stratigraphy of the deep ocean basin adjacent to the southeast African continental margin: a record of geostrophic bottom current systems

Sedimentary deposits on the southern South African continental margin: Slumping versus non-deposition or erosion by oceanic currents?

“…2). Intra-Tertiary reflectors are not discussed by Broad et al (2006) and, based on their reflection characteristics, have hence been interpreted (reflectors O, M, and P) using the seismostratigraphic model of Niemi et al (2000), which is applied to the part of the seismic data crossing the Agulhas Passage. Six sedimentary units can be defined for the Agulhas Passagegeomorphological unit (b).…”

“…Six sedimentary units can be defined for the Agulhas Passagegeomorphological unit (b). The dating of those units and the top reflectors is based on Niemi et al (2000). We distinguish between sedimentary units of Cretaceous, Late Eocene-Oligocene, OligoceneMiddle Miocene, Middle Miocene-Early Pliocene, and Early PlioceneHolocene age (Table 1; Fig.…”

“…3). The details of the correlation of our seismic data with the seismostratigraphic model defined by Niemi et al (2000) can be found in Schlüter and Uenzelmann-Neben (2007).…”

“…Hence, the Neogene units represent an archive of the modified circulation and climate. Study of the deep sea units has led to models for the development of climate and oceanic currents in the South African gateway (Dingle et al, 1987;Dingle and Camden-Smith, 1979;Niemi et al, 2000;Schlüter and Uenzelmann-Neben, 2008), but little is known about the Neogene units on the South African continental margin. Major open questions in this context are: what effect did the modifications in circulation and climate have on the deposits on the continental shelf and slope?…”

Giant mounded drifts in the Argentine Continental Margin: Origins, and global implications for the history of thermohaline circulation

“…The interaction of one or more water masses with a smooth-morphology margin may cause large drifts, but a complex physiography can create multiple vortices associated with each water mass, and both the erosive and depositional features can become difficult to decipher (Faugères et al, 1999;Stow et al, 2002a;Hernández-Molina et al, 2008a;Rebesco and Camerlenghi, 2008). Some contourite deposits represent giant, mounded elongated contourite drifts (hereafter, giant drifts) extending along large distances (Faugères et al, 1999;Hernández-Molina et al, 2008b;Stow et al, 2008), such as those described in the Weddell and Scotia Basins (Maldonado et al, 2003(Maldonado et al, , 2006, south-westernmost Indian Ocean (Niemi et al, 2000;UenzelmannNeben, 2001UenzelmannNeben, , 2002 and Greenland margin (Hunter et al, 2007). These giant drifts are generated during a long period of relatively stable hydrological conditions that lead to long-term bottom water flows.…”