Turbidity Currents in Submarine Canyons

Turbidity Currents in Submarine Canyons Latest News

A recent study published in ACS Environmental Science & Technology has provided the first direct evidence of turbidity currents transporting microplastics into the deep sea through submarine canyons, even in areas not fed by rivers (e.g., Whittard Canyon off Ireland).

What are Turbidity Currents?

• Turbidity currents are rapid, downslope flows of water heavily laden with sediments, increasing the water’s density.
• They function similarly to underwater avalanches, triggered by:
  • Earthquakes
  • Submarine landslides
  • Slope failures and other geological disturbances
• Key Features of Turbidity Currents
  • As turbidity increases, water becomes denser and less transparent.
  • These flows erode the seafloor, forming and enlarging submarine canyons.
  • They deposit sediment in graded layers, with coarser particles settling first and finer ones later.
  • Aid in deep-sea sedimentation and shaping oceanic topography.

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Submarine Canyons

• Submarine canyons are narrow, steep-sided underwater valleys found on continental slopes and rises, often extending from the continental shelf into the deep ocean.
• They are carved out mainly by erosional forces like turbidity currents, similar to how river canyons are formed on land.
• Globally, there are about 9,477 known submarine canyons, covering nearly 11% of continental slope areas.
• Canyons on active margins (tectonically active zones) tend to be steeper and shorter, while those on passive margins are more gradual.
• Their walls can be nearly vertical and are prone to collapse, adding sediment to turbidity flows.

Types of Submarine Canyons

• Bank: A flat-topped elevation on continental margins, formed by erosional and depositional processes, e.g., Dogger Bank in the North Sea.
• Shoal: A shallow area of sediment accumulation, often hazardous to navigation, and generally found at depths <10 meters at low tide.
• Reef: Built from calcareous skeletons of corals and algae; coral reefs are biodiversity hotspots and prominent in the Pacific Ocean, associated with guyots and seamounts.

Source: PHY