کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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4553217 | 1627948 | 2012 | 16 صفحه PDF | دانلود رایگان |
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.
► The floods of the Var River explain the trigger of the hyperpycnal currents in the Var submarine canyon.
► Three gravity flows were observed in the Var canyon characterized by increase in current and particles.
► Gravity flows transported lot of material along the entire canyon.
► The large input of sediment has a significant impact on the bottom of the deep Mediterranean Sea.
Journal: Progress in Oceanography - Volume 106, November 2012, Pages 138–153