Publication Date:
2017-04-04
Description:
Current velocities and vertical sediment fluxes in the Var submarine canyon were assessed at three stations
respectively at 800 m, 1200 m and 1800 m depth, using moorings deployed for 4 months during
winter 2008–2009. During this period, we observed three major sediment gravity flows, all characterized
by sudden increases in current velocity that lasted 2–5 h and by downward particle fluxes. Each gravity
flow, described using a high frequency current meter and two Acoustic Doppler Current Profiler (75 and
300 kHz ADCP) showed distinctive features. The first event, triggered during a flood of the Var River, was
determined to be a hyperpycnal current with a large vertical extent (〉100 m high) and relatively low
velocity (40 cm s 1). The second event, observed after a Var River flood, was more energetic with a maximum
horizontal current peak of 60 cm s 1 but with a low vertical extent (30 m high). This event was
considered to be a turbidity landslide. The third was the result of a local canyon wall failure. It was characterized
by a speed of 〉85 cm s 1. These peaks of current speed were associated with large clouds of
material that transported sediment along the canyon and reached up to 200 g m 2 d 1 of sediment
(〉1 g m 2 d 1 of organic carbon). Our measurements in the Var canyon show the important role of gravity
flows transporting particulate matter to the deep-sea floor. These large inputs of sediment and organic
carbon may have a significant impact on deep-sea carbon storage in the Mediterranean Sea.
Description:
Published
Description:
138-153
Description:
1.8. Osservazioni di geofisica ambientale
Description:
JCR Journal
Description:
restricted
Keywords:
submarine canyon
;
gravity flows
;
03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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