FN Archimer Export Format
PT J
TI Vertical grain-size variability within a turbidite levee: Autocyclicity or allocyclicity? A case study from the Rhone neofan, Gulf of Lions, Western Mediterranean
BT 
AF DENNIELOU, Bernard
   HUCHON, Agnès
   BEAUDOUIN, Célia
   BERNE, Serge
AS 1:1;2:1,2;3:3;4:1;
FF 1:PDG-DOP-DCB-GM-LES;2:;3:;4:PDG-DOP-DCB-GM-LES;
C1 IFREMER, DROGM, F-29280 Plouzane, France.
   Inst Univ Europeen Mer, UMR 6538, F-29280 Plouzane, France.
   Univ Lyon 1, CNRS, UMR 5565, Ctr Paleontol Strat & Paleoecol, F-69622 Villeurbanne, France.
C2 IFREMER, FRANCE
   IUEM, FRANCE
   UNIV LYON, FRANCE
SI BREST
SE PDG-DOP-DCB-GM-LES
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-univ-france
IF 2.029
TC 32
TU Centre national de la recherche scientifique
   Institut français de recherche pour l'exploitation de la mer
   Service Hydrographique et Océanographique de la Marine
   Université de Bretagne Occidentale
   Université de Bretagne-Sud
UR https://archimer.ifremer.fr/doc/2006/publication-2311.pdf
LA English
DT Article
CR GMO2 - CARNAC
   IMAGES V LEG 1-MD114
   IMAGES V LEG 4-MD114
   MARION
   STRATAFORM 1
   ZAIANGO1
   ZAIANGO2
BO Le Suroît
   Marion Dufresne
   L'Atalante
DE ;Allocyclicity;Amocyclicity;Grain size;Channel levee;Turbidite
AB The fining upward trend commonly described on levees of turbidite systems can be either attributed to changes in the sediment supply (external forcing = allocyclic) or changes in the spillover processes related to the growth of the levee (internal forcing = autocyclic). However the real causes remain speculative and difficult to demonstrate. Knowledge of vertical change in flow velocity (or grain size) in turbidity currents, of the turbidity current's height, as well as the growth rate of a levee are theoretically sufficient to describe the evolution of the grain size of a leveed turbidite sequence deposited by spillover processes. A piston core (MD99-2344) retrieved on the right levee of the Petit-Rhone neofan, sampled an 8.50 m long turbidite sequence containing more than one hundred turbidite beds and showing a marked fining upward trend. With the help of two profiles describing respectively the vertical velocity [Stacey, M. and Bowen, A.J., 1988b. The vertical structure of turbidity currents and a necessary condition for self-maintenance, Journal of Geophysical Research, pp. 3543-3553.] and the vertical grain size [Migeon, S., 2000. Dunes geantes et levees sedimentaires en domaine marin profond: approche morphologique, sismique et sedimentologique. PhD Thesis, Universite Bordeaux 1, Talence, France, 288 pp.] of a turbidity current, and a simple graphical method, we test several hypotheses on the height of the turbidity current and on the grain size at the bottom of the turbidity current and we attempt to reproduce the vertical fining upward trend. Our results show that the fining upward trend of the turbidite facies can be explained by the aggradation of the turbidite levee and the gradual confinement of the turbidity currents in the channel. This is, therefore, an autocyclical phenomenon. However a high frequency variability of the grain size overprinted on the trend cannot be explained by internal forcing and is believed to be allocyclical, depending on changes to the sediment input. The vertical grain-size profile allows more realistic flow conditions to be determined and shows that the vertical velocity profile does not describe the ability of turbidity current to transport sediment. This simple graphical method allows a better understanding and quantification of the forcing on turbidite deposits and improves description of the characteristics of the turbidity currents from the grain size of the deposits.
PY 2006
PD DEC
SO Marine Geology
SN 0025-3227
PU Elsevier
VL 234
IS 1-4
UT 000243253100012
BP 191
EP 213
DI 10.1016/j.margeo.2006.09.019
ID 2311
ER

EF