Morphology and sedimentary architecture of a modern volcaniclastic turbidite system: The Cilaos fan, offshore La Reunion Island
|Author(s)||Sisavath Emmanuelle1, 2, Babonneau Nathalie3, Saint-Ange Francky4, Bachelery Patrick2, Jorry Stephan1, Deplus Christine5, de Voogd Beatrice6, Savoye Bruno1|
|Affiliation(s)||1 : IFREMER, Lab Environm Sedimentaires, F-29280 Plouzane, France.
2 : Univ Reunion, Inst Phys Globe Paris CNRS, UMR7154, Lab GeoSci Reunion, St Denis 97715 9, Reunion.
3 : Univ Brest, IUEM, UMR CNRS 6538, Brest, France.
4 : Geol Survey Canada Atlantic, Bedford Inst Oceanog, Dartmouth, NS B2Y 4A2, Canada.
5 : Inst Phys Globe, F-75238 Paris 05, France.
6 : Univ Pau & Pays Adour, CNRS, UMR 5212, F-64000 Pau, France.
|Source||Marine Geology (0025-3227) (Elsevier Science Bv), 2011-10 , Vol. 288 , N. 1-4 , P. 1-17|
|WOS© Times Cited||24|
|Keyword(s)||turbidite, deep-sea fan, volcaniclastic, La Reunion Island|
|Abstract||Recent oceanographic surveys revealed the existence of five volcaniclastic deep-sea fans off La Reunion Island. The Cilaos fan is a large volcaniclastic submarine fan, connected to rivers that episodically experience torrential floods through a narrow and steep shelf-slope system. New piston cores presented in this study together with echosounder profiles give new insight into the evolution, of this extensive and sand-rich turbidite system. The Cilaos fan extends over 15,000 km(2) on an abyssal plain and is compartmentalized by topographic highs. Located southwest of the island, the sedimentary system consists of a canyon area and a deep sea fan divided into a proximal and a distal fan. The proximal fan is characterized by its wide extent and coarse-grained turbidites. The distal fan is characterized by elongated structures and fine-grained turbidites. A detailed morphological study of the fan which includes the analysis of swath bathymetry, backscatter, echosounder, and piston core data shows that the Cilaos fan is a complex volcaniclastic deep-sea fan, highly influenced by preexisting seafloor irregularities. The canyons and the slope area show a complex and evolving sediment feeding system with a direct sediment input by the river and irregular sediment supply by submarine landslide. Three main construction stages are identified for this system: (1) an old incision phase of the channels forming wide turbidites extending over the entire distal fan; (2) a period of no or low activity characterized by a thick layer of hemipelagic mud; and (3) a local reactivation of the channel in the proximal fan. Each stage seems to be linked to a different sediment source with a progressively increasing contribution of hemipelagic sediment and mud in younger stages. (C) 2011 Elsevier B.V. All rights reserved.|