Morphology and sedimentary architecture of a modern volcaniclastic turbidite system: The Cilaos fan, offshore La Reunion Island

作者：Sisavath Emmanuelle^*; Babonneau Nathalie; Saint Ange Francky; Bachelery Patrick; Jorry Stephan J; Deplus Christine; De Voogd Beatrice; Savoye Bruno

来源：Marine Geology, 2011, 288(1-4): 1-17.

DOI：10.1016/j.margeo.2011.06.011

• turbidite
• deep-sea fan
• volcaniclastic
• La Reunion Island

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.

• 出版日期2011-10-1