Métivier, François1, Eric Lajeunesse1, Pierre Lancien1, Marie-Christine
(1) Institut de Physique du Globe de Paris, Paris, France
(2) Institut Francais du Petrole, Rueil-Malmaison Cedex, France
ABSTRACT: Simulating Sinuous Channel Incision in Flume Experiments: a Key to Understand the Processes in Meandering Canyons and Channels
Analog modeling is an essential source of information to better understand the processes controlling the development of canyons and channelized systems in the deep offshore.
Our experimental setup consists in 2 m X 0.5 m flume filled with fresh water. The flume bottom simulates a sub-marine ramp draped by a sediment blanket. A sustained density flow is simulated by a continuous brine stream injected at the top of the ramp. For a specific range of parameters, the brine stream induces erosion of the sediment layer and the gradual incision of a canyon, either straight or sinuous. The eroded sediment is deposited in a frontal depositional lobe which progrades downstream as the canyon develops.
It appears that for a given slope, only small injection flow-rates below a given threshold, can create incision. This promotes the idea that density flows would be the fundamental process for canyon incision, rather than turbiditic surges.
An optical acquisition technique has been recently developped. It enables us to measure instantaneously the topography of the sediment surface at successive times, during the canyon formation and frontal lobe deposition. By computing the difference between successive topography maps, we can elaborate time-varying maps of sedimentation and erosion rates in the system. Stacking of these maps produce a 3D cube of sedimentation rates showing autocyclic phases of incision, by-pass and sedimentation.
Cross-sections through this 3D cube show morphologies very similar to those observed on seismic acquisitions performed in the Recent Orenoque channel system.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.