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SUMMARY:How new deep-sea observations change turbidity current models - Ma
 tthieu Cartigny\, Uni of Durham
DTSTART:20200507T103000Z
DTEND:20200507T113000Z
UID:TALK140911@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:The ocean floor comprises two thirds of our planet\, and it ho
 sts spectacular networks of channels and canyons formed by often powerful 
 episodic sediment-laden flows\, called turbidity currents. These submarine
  channels can extend for thousands of kilometres into the deep ocean\, and
  are fed by submarine canyons that are as big as the Grand Canyon. The tur
 bidity currents that created these channels remain poorly understood\, as 
 measurements of their velocities and sediment concentrations are only avai
 lable in seven locations worldwide. This lack of observations reflects the
  relatively inaccessible and powerful nature of the flows\, some of which 
 powerful enough to drag 2\,000 kg anchors for kilometres along the ocean f
 loor. Fortunately\, new technology now allow us to monitor turbidity curre
 nts in unprecedented detail. \n\nThese new field observations are importan
 t as turbidity currents are of societal and economic relevance. These flow
 s are the main supplier sediment\, organic carbon and nutrients to much of
  the deep-sea\, as turbidity currents rival rivers in their global capacit
 y to transport sediment across our planet. These fluxes make turbidity cur
 rents an important part of the carbon cycle that affects long term climate
  change\, and they sustain rare ecological communities on the deep sea bed
 . Turbidity currents pose a hazard to submarine infrastructure\, and have 
 forced pipeline operators to invest millions of dollars in re-routing pipe
 lines. Furthermore\, these flows create the largest sedimentary bodies on 
 our planet (e.g. the Bengal submarine fan holding tens of million km3 of s
 ediment)\, and these sedimentary body host a significant part of our oil a
 nd gas reservoirs. \n\nHere I will present observations of three turbidity
  current monitoring sides: submarine channels in Canadian fjords\, Montere
 y Canyon and the Congo Canyon. The observations show that turbidity curren
 ts can substantially deviate \nfrom the textbook models. The dynamics of t
 he turbidity currents are controlled by a fast-moving and dense frontal ce
 ll that set-up the more dilute cloud that is seen in most models. Addition
 ally\, the observations show a bifurcation in the behaviour of the flows\,
  where a flow either develops as fast and dense or as slow and dilute. Fur
 thermore\, the observations provide new insights into the mixing processes
  that occur between these flows and the ambient seawater. Overall\, the ne
 w seafloor data will hopefully play a key role in validating and modifying
  existing turbidity current models.
LOCATION:Zoom - please contact admin@bpi.cam.ac.uk if you wish to particip
 ate but on NOT on the BPI seminar list
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