The Late-Quaternary deposits of the Piedra Buena Terrace (Patagonian continental slope, SW Atlantic): An example of interaction between bottom currents and seafloor morphology

• Published in: Marine Geology
• Main Authors: Isola, José Ignacio, Bravo, María Emilia, Bozzano, Graziella, Palma, Fermin Ignacio, Ormazabal, Juan Pablo, Principi, Sebastián, Spoltore, D., Martín, Rodrigo Sebastian, Esteban, Federico Damián, Tassone, Alejandro Alberto
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Science
• Subjects: ARGENTINIAN CONTINENTAL MARGIN; MIXED SYSTEMS; MULTI-BEAM BATHYMETRY; SEISMIC INTERPRETATION; WESTERN SOUTH ATLANTIC; https://purl.org/becyt/ford/1.5; https://purl.org/becyt/ford/1; Antarctic; Pampa; Piedra Buena; Antarc*
• Online Access: http://hdl.handle.net/11336/140591

The Piedra Buena Terrace (PBT), situated in the Patagonian continental slope, is swept by the vigorous flow of Antarctic-sourced bottom water masses, and intersected by a considerable submarine canyon system. It thus represents a world-class natural laboratory to investigate the sedimentary dynamics of deep-ocean settings influenced by both, along-slope, and down-slope sedimentary processes. In the framework of the Pampa Azul project, the PBT was surveyed with swath bathymetry and a high-resolution parametric sub-bottom seismic profiler and sampled at several locations with a 7 m long gravity corer. Through the integration of the acoustic data, grain size results from a sediment core and two AMS 14C ages this work attempts to: (1) describe for the first time the detailed geomorphology of a poorly known region of the Patagonian continental slope; (2) depict the principal sub-surface seismic units, illustrating their internal structure, geometry, and distribution; (3) establish a correlation between sub-surface seismic facies and sediment deposits using the first age constraints for this region; (4) propose a model with the depositional history of the PBT, focusing on the interaction between along-slope and down-slope processes and seafloor morphology. The acquired bathymetric data imaged with unprecedent detail the geomorphology of the southern part of the PBT revealing the presence of a field of kilometric-sized, sub-circular, crater-like depressions, and a submarine canyon. The analyzed seismic sub-bottom profiles showed that the shallow sedimentary structure of the study area is represented by patchy-mounded deposits characterized by three distinctive features: cyclic stacks of two seismic facies (FA and FB), mounded shape, and preferential location northwards the morphological depressions and the submarine canyon. Integration of a seismic sub-bottom profile with one sediment core indicates that the alternation of seismic facies reflects variations in the hydrodynamic conditions. FA is related to a high to ...