Syndepositional lateral migration of hyperpycnal lobes in submarine ramp systems. Early Miocene, Austral Basin, Argentina

PONCE, J.J.; OLIVERO, E.B.; MARTINIONI, D.R.

Ushuaia, Tierra del Fuego

Conferencia; Sediment Transfer from Shelf to Deepwater-Revisiting the Delivery Mechanisms; 2008

During the Cenozoic the foredeep of the Austral Basin in Tierra del Fuego evolved as a ramp system until the Middle Miocene. This ramp system controlled in several ways the hyperpycnal lobe accumulation features in the Upper Cabo Ladrillero Beds. If compared to more restricted slope breaks, e.g. in some deltaic systems, the larger length of the slope in ramp systems promotes thesustained acceleration of hyperpycnal flows, allowing for the transfer of a large volume of sediments to the deep sea and favoring the deposition of thick sedimentary successions in internal areas of the basin. The main objective of this study is to document the internal arrangement of these hyperpycnal lobe systems -which are the dominant depositional elements within this unit- and to discuss the variability in geometry and sedimentary facies produced by the lateral migration of lobes during one hyperpycnal discharge.