Ichnology of the Miocene hyperpycnites of the Austral Basin, Tierra del Fuego, Argentina

CARMONA, N.B.; PONCE, J.J.; OLIVERO, E.B.; LÓPEZ CABRERA, M.I.; MARTINIONI, D.R.

Sediment Transfer from Shelf to Deepwater - Revisiting the Delivery Mechanisms. AAPG Hedberg Research Conference Guidebook.

Año: 2008; p. 49 - 59

In the foreland Austral Basin, the absence of an extended shelf, the synsedimentary tectonic activity, and the existence of steep slopes related to uplifted areas within the orogen favor the acceleration of hyperpycnal flows. These flows develop during extraordinary fluvial discharges, constitute an important mechanism of basinward sediment transfer (Mulder and Syvitski, 1995), and generate very complex sedimentary deposits (e.g. Ponce et al., 2004, 2007a, b). In the last years there has been a better recognition and understanding of the hyperpycnal depositional systems, with many studies mainly focused on the sedimentary processes and on the characterization of the internal facies arrangements and geometry of these deposits. However, specific details of the trace fossils found in hyperpycnites (e.g. distribution of the biogenic structures, ichnodiversity, bioturbation intensities, etc.) have not yet been evaluated. Therefore, the detailed study of the Miocene hyperpycnite successions outcropping along the Atlantic coast of Tierra del Fuego, Argentina, provide a great opportunity to analyze the spatial distribution of the trace fossils and to discuss the stress factors associated to the hyperpycnal flow processes.