Seismic images of contourites forming continental slope terraces at the Argentine Margin: implications for past changes in thermohaline circulation

• Main Authors: Gruetzner, Jens, Uenzelmann-Neben, Gabriele, Franke, D.
• Format: Conference Object
• Language: unknown
• Published: 2010
• Subjects: Antarc*; Antarctic; NADW; North Atlantic Deep Water; North Atlantic
• Online Access: https://epic.awi.de/id/eprint/22479/; https://hdl.handle.net/10013/epic.34879

An extensive (> 11000 km) set of high quality seismic reflection profiles from the Argentine continental margin shows a significant contourite system formed by the interaction of northward flowing Antarctic water masses and southward flowing North Atlantic Deep Water (NADW). Here, we focus on a set of ~50 km wide terraces on the lower slope separated by contouritic channels. An initial age frame was developed by mapping regional reflectors and seismic units known from previous studies. The sedimentary layer between regional reflectors AR 4 and AR 5 spanning roughly the time interval from the Eocene/Oligocene boundary to the early middle Miocene thickens towards the East forming a giant buried drift and also towards the West building plastered drifts below the Piedra Buena Terrace. In contrast to this the sediments of late Miocene to recent age are very thin or completely eroded over the Piedra Buena terrace but form drifts at the Valentin Feilberg terrace that can be divided into subunits whose reflections show good lateral continuity. With an age of ~15 Ma for reflector AR5 the average sedimentation rate since the middle Miocene is estimated to be > 10 cm/ka.