Sebastien Migeon1, B. Savoye1, D.J.W. Piper2, J.-C. Faugeres3
(1) Laboratoire Environnements Sedimentaires, IFREMER, Plouzane, France
(2) Atlantic Geoscience Centre, BIO, Dartmouth, NS
(3) Universite Bordeaux, Talence, France
ABSTRACT: Processes of Construction of Turbidite Sediment Waves (Present Var Deep-Sea Fan - NW Mediterranean Sea)
Sediment waves are very common sedimentary structures on most turbidite system levees. Today, no accepted explanation for their construction has been developed. With the availability of new exploration tools and the movement of the oil industry towards deep-water, a significant advance in our understanding of sediment waves on turbidite levees can be made.
The Var fan is located in the Ligurian Sea (France). It has a right-hand asymetrical levee : the Var sedimentary Ridge where migrating sediment waves developed during the Quaternary. The waves are still active under present flow conditions in the distal part of the Ridge whom height is about 15-30 metres.
An active sediment wave
has been studied using high-resolution seismic profiles and 3 cores collected on the upstream, crest and downstream flank. Core-to-core correlations revealed a depositional contrast between the sandier upstream flank and the muddier downstream flank. The comparison of seismic-reflection data and cores suggests that sediment-
wave
construction occurs under supercritical conditions and results from preferential deposition of sediment on the upstream flank, while erosional processes predominate on the downstream flank. This suggests that each flow deccelerate on the upstream flank then re-accelerate before the crest and on the downstream flank. Turbidity currents and hyperpycnal currents are the main identified actors participating in the
wave
construction.
The strong differences of deposition processes across each sediment wave
result through time in the individualisation of numerous, large and more or less interconnected sandy bodies in the distal part of the Ridge, that could constitute a
potential
reservoir.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado